Digital signal recording apparatus

<b>BACKGROUND OF THE INVENTION</b>

1. Field of the Invention:

The present invention relates to a digital signal recording apparatus for recording a digital signal such as an audio signal. More specifically, the present invention relates to a digital signal recording apparatus for performing a recording operation in a standard recording mode and a long-time recording mode in which information can be recorded on one and the same recording medium for a time longer than that of the standard recording mode.

2. Description of the Related Art:

In recent years, various recording and reproducing apparatuses have been remarkably developed in order to improve the quality of a video by using digital coding technologies. Under these circumstances, a digital video cassette recorder (VCR) is expected to be a next-generation VCR which is sure to replace a currently used analog VCR in the near future. In order to realize a home-use digital VCR, the information is required to be recorded in a smaller-sized cassette for a long time. Accordingly, it is indispensable to introduce high-efficiency coding technologies into such a digital VCR for reducing the amount of information of the digital video signal while preventing considerable degradation in the quality of the video. A standard format of the home-use digital VCR (DVCR) utilizing the high-efficiency coding technologies is published in the "Basic Specifications for Consumer-Use Digital VCR" by HD Digital VCR Conference in August 1993. This DVCR can record a currently used TV signal in compliance with a REC601 standard on a magnetic tape at a data rate of 25 Mbps.

Hereinafter, the operation of such a DVCR will be briefly described. When the currently used TV signal to be input is an analog signal, the analog signal is A/D converted and then filtered so that the sampling ratio among a luminance (Y) signal, a first color difference (R-Y) signal and a second color difference (B-Y) signal becomes 4:1:1 in the horizontal direction. Needless to say, when the input TV signal is a digital signal, there is no need for the A/D conversion. Thereafter, the order of the signals is changed and a predetermined video signal processing such as a compression processing is performed depending upon the necessity, thereby outputting a video data. In this case, an important data, such as a data indicating whether the input video is to be reproduced in an NTSC mode or in a PAL mode, which is indispensable for reproducing the video data will be called an "auxiliary data". The auxiliary data is inserted into the video data. Thereafter, an error correction coding is performed and the video data is modulated by a modulator so as to be converted into a recording signal suitable for a magnetic recording. Then, the signal is recorded on a magnetic tape. According to the basic specifications for consumer-use digital VCR, a NTSC TV signal is recorded by dividing one frame into ten tracks.

In a generally used DVCR, a track is composed of a predetermined number of sectors and gaps between adjacent sectors, and a sector is composed of a predetermined number of synch blocks, run-ups, guards and the like. Tracking information, an audio data, a video data, a sub-code data and the like are assigned in the respective sectors. An auxiliary data is assigned and inserted into the identical sector where the audio data and the video data are assigned.

It is generally considered to be indispensable for a recording apparatus for recording a video signal to edit various data on a field basis or on a frame basis. Therefore, not only a video data and an audio data but also a sub-code data and an auxiliary data can be edited as a whole on a field basis or on a frame basis. In order to realize such an edition, a field address for identifying a field, a track address determined by regarding one field as a period, and a block address determined by regarding one track as a period are generally provided. Alternatively, a frame address for identifying a frame, a track address determined by regarding one frame as a period, and a block address determined by regarding one track as a period can also be provided.

As described in Japanese Patent Application No. 6-38248 entitled "Digital Signal Recording and Reproducing Method", the auxiliary data is periodically recorded at respectively different positions in the respective tracks in order to eliminate the influence of a burst error, a scratch and the like on a magnetic tape and to obtain the data easily during a trick play reproduction.

In a currently used VTR of a VHS system, a video data can be recorded in following two recording modes, i.e., a standard recording mode and a three-time-longer recording mode in which a video data can be recorded on one and the same tape for a time three times as long as the time in the standard recording mode. Therefore, in practically using a home-use DVCR, the video data is frequently required to be recorded in a long-time (e.g., three-time-longer) recording mode rather in the standard recording mode.

A DVCR allowing for recording a data in a long-time recording mode by a high-efficiency coding technique is disclosed, for example, in Japanese Laid-Open Patent Publication No. 5-183869 entitled "Digital Video Signal Recording Apparatus". In the technique disclosed in the patent publication, the ratio of the sampling numbers for the luminance signal in the standard recording mode with respect to the long-time recording mode is set to be 3:2. However, if the sampling frequency for the luminance signal in the standard recording mode is 13.5 MHz, for example, then the luminance signal in the long-time recording mode has a frequency band of 9 MHz. As a result, the resolution obtained in the long-time recording mode becomes inferior to that obtained by a conventional analog S-VHS. In addition, according to the standard REC601, the sampling ratio among the luminance signal, the first color difference signal and the second color difference signal is set to be 4:1:1 in recording the currently used TV signal in the standard recording mode by using a home-use DVCR. In this case, if the sampling frequency for the luminance signal in the long-time recording mode is set to be two-thirds of the sampling frequency for the luminance signal in the standard recording mode, then the sampling ratio becomes (8/3) 1:1, so that it becomes very difficult to use a common circuit by way of a blocking or the like in both modes.

In addition, in the case where a block having the same addresses as those of a block for the standard recording mode is used in the long-time recording mode, then a correct frame cannot be designated by a frame address. Furthermore, if a signal for the standard recording mode and a signal for the long-time recording mode are tried to be continuously recorded on one and the same tape by inserting an auxiliary data into a frame by beginning with the position of the head track of the frame for both the signals, then the auxiliary data can not be inserted periodically. As a result, an error is likely to be caused in detecting the auxiliary data immediately after scanning the boundary between the recording region for a standard recording mode and the recording region for a long-time recording mode during the reproducing operation, and an algorism for detecting the position of the auxiliary data becomes more complicated, so that the size of the circuit becomes disadvantageously increased and the delay in the detection time is increased.

It cannot be identified whether the reproduced data is recorded in the standard recording mode or in the long-time recording mode until the contents of the auxiliary data are examined. Therefore, in the case where detection errors are successively caused in a trick play reproduction, in particular, the reproduction processing is likely to be performed by mistaking a signal recorded in the long-time recording mode for a signal recorded in the standard recording mode, and a large defect is possibly generated in the video reproduced on a screen.

Recently, as well as the currently used standard TV signal, a HDTV signal and a signal for a 16:9 wide screen TV have been more and more practically used. Therefore, a home-use DVTR allowing for recording the plural kinds of TV signals in common will be required in the near future. It is possible to commonly perform the signal processing and use the same recording head between the format for recording the standard TV signal and the format for recording the HDTV signal after the variable-length coding has been performed. However, it is difficult to commonly use the other portions of the circuit, because the number of the blocks per segment of the currently used TV signal, i.e., 6 blocks × 5 = 30, is different from the number of the blocks per segment of the HDTV signal, i.e., 8 blocks × 5 = 40. If independent circuits are provided for the respective TV signals, then the cost of the apparatus is adversely increased, so that it becomes very difficult to use such an apparatus as a home-use apparatus.

<b>SUMMARY OF THE INVENTION</b>

According to the present invention, a digital signal recording apparatus for recording a video signal on a recording medium is provided. The digital signal recording apparatus includes: a mode setting section for setting a recording mode, the recording mode being one of a standard recording mode and a long-time recording mode having a longer recording time than that of the standard recording mode; a sampling section for sampling the video signal at a sampling number corresponding to the recording mode set by the mode setting section, the sampling number when the selected recording mode is the long-time recording mode being smaller than the sampling number when the selected recording mode is the standard recording mode; a coding section for coding the video signal sampled by the sampling section at a compression rate corresponding to the recording mode set by the mode setting section, the compression rate when the selected recording mode is the long-time recording mode being higher than the compression rate when the selected recording mode is the standard recording mode; and a recording section for recording the video signal coded by the coding section on a recording medium.

In one embodiment, the sampling number when the selected recording mode is the long-time recording mode is substantially equal to two-thirds of the sampling number when the selected recording mode is the standard recording mode.

In another embodiment, the compression rate when the selected recording mode is the long-time recording mode is substantially equal to four-thirds of the compression rate when the selected recording mode is the standard recording mode.

In still another embodiment, the video signal includes a luminance signal and a color difference signal. The sampling section includes: a luminance signal sampling section for sampling the luminance signal at a sampling frequency corresponding to the recording mode set by the mode setting section; a line decimating section for decimating lines with respect to the color difference signal; and a section for selectively outputting one of the color difference signal and a color difference signal with the lines decimated by the line decimating section in accordance with the recording mode set by the mode setting section.

In still another embodiment, the sampling frequency when the selected recording mode is the long-time recording mode is substantially equal to three-quarters of the sampling frequency when the selected recording mode is the standard recording mode.

In still another embodiment, the sampling frequency when the selected recording mode is the long-time recording mode is 10.125 MHz, and the sampling frequency when the selected recording mode is the standard recording mode is 13.5 MHz.

In still another embodiment, the video signal includes a luminance signal and a color difference signal. And the sampling section includes: a rate change section for changing a rate at which the luminance signal is sampled; a section for selectively outputting one of the luminance signal and a luminance signal with the rate changed by the rate change section in accordance with the recording mode set by the mode setting section; a line decimating section for decimating lines with respect to the color difference signal; and a section for selectively outputting one of the color difference signal and a color difference signal with the lines decimated by the line decimating section in accordance with the recording mode set by the mode setting section.

According to another aspect of the present invention, a digital signal recording apparatus for recording a video signal on a recording medium is provided. The digital signal recording apparatus includes: a mode setting section for setting a recording mode, the recording mode being one of a standard recording mode and a long-time recording mode having a longer recording time than that of the standard recording mode; a sampling section for sampling the video signal at a sampling number corresponding to the recording mode set by the mode setting section, the sampling number when the selected recording mode is the long-time recording mode being smaller than the sampling number when the selected recording mode is the standard recording mode; a restraining section for restraining a gain of the video signal sampled by the sampling section in a frequency band exceeding a predetermined frequency, the gain when the selected recording mode is the long-time recording mode being smaller than the gain when the selected recording mode is the standard recording mode; a coding section for coding the video signal with the gain restrained by the restraining section at a compression rate corresponding to the recording mode set by the mode setting section, the compression rate when the selected recording mode is the long-time recording mode being higher than the compression rate when the selected recording mode is the standard recording mode; and a recording section for recording the video signal coded by the coding section on a recording medium.

According to still another aspect of the present invention, a digital signal recording apparatus for recording a video signal on a recording medium, in a case where a number of horizontal effective pixels of the video signal is not N (an integer) times as large as a number of horizontal pixels of a macro block, or in a case where a number of vertical effective pixels of the video signal is not N times as large as a number of vertical pixels of a macro block, is provided. The digital signal recording apparatus includes: a dividing section for dividing the video signal into a plurality of macro blocks; a judging section for judging whether each of the plurality of macro blocks corresponds to an extra portion of the horizontal effective pixels or an extra portion of the vertical effective pixels; a generating section for generating a pseudo macro block having a predetermined pixel value; a selection section for selecting one of the macro block divided by the dividing section and the pseudo macro block generated by the generating section based on a result obtained by the judging section; a coding section for coding the macro block selected by the selection section; and a recording section for recording the video signal coded by the coding section on a recording medium.

In one embodiment, all pixel values in the pseudo macro block generated by the generating section are equal.

In another embodiment, the pseudo macro block generated by the generating section consists of a plurality of small blocks, and the small blocks respectively have different pixel values in the pseudo macro block.

According to still another aspect of the present invention, a digital signal recording apparatus for recording a digital signal on a recording medium is provided. The digital signal recording apparatus includes: a mode setting section for setting a recording mode, the recording mode being one of a standard recording mode and a long-time recording mode having a longer recording time than that of the standard recording mode; a coding section for coding the digital signal so as to have a data amount corresponding to the recording mode set by the mode setting section, the data amount when the selected recording mode is the long-time recording mode being smaller than the data amount when the selected recording mode is the standard recording mode; an auxiliary data adding section for adding an auxiliary data to the data coded by the coding section in accordance with the recording mode set by the mode setting section; and a recording section for recording the data to which the auxiliary data is added on the recording medium.

In one embodiment, the auxiliary data adding section includes: an auxiliary data generating section for generating an auxiliary data in accordance with the recording mode set by the mode setting section; a control section for generating a control signal indicating a position to which the auxiliary data is inserted in accordance with the recording mode set by the mode setting section; and an auxiliary data inserting section for inserting the auxiliary data into the coded data at the insertion position indicated by the control signal. The insertion position of the auxiliary data is controlled by the control section so that the auxiliary data is inserted at a predetermined period, irrespective of whether the selected recording mode is the long-time recording mode or the standard recording mode.

In another embodiment, the recording section divides and records the data to which the auxiliary data is added on m × (2n + 1) tracks (where m is 2, 4, 6, ... and n is 1, 2, 3, ...) on the recording medium when the selected recording mode is the standard recording mode, while the recording section divides and records the data to which the auxiliary data is added on 2n + 1 tracks on the recording medium when the selected recording mode is the long-time recording mode.

According to still another aspect of the present invention, a digital signal recording apparatus for recording a digital signal on a recording medium is provided. The digital signal recording apparatus includes: a mode setting section for setting a recording mode, the recording mode being one of a standard recording mode and a long-time recording mode having a longer recording time than that of the standard recording mode; a coding section for coding the digital signal so as to have a data amount corresponding to the recording mode set by the mode setting section, the data amount when the selected recording mode is the long-time recording mode being 1/n as small as the data amount when the selected recording mode is the standard recording mode; and a recording section for recording the coded data on a recording medium having a plurality of tracks. The recording section includes: an address generating section for generating a track address designating one of the plurality of tracks in accordance with the recording mode set by the mode setting section, the address generating section generating a track address cyclicly repeated at a period of n frames when the selected recording mode is the long-time recording mode and a track address cyclicly repeated at a period of one frame when the selected recording mode is the standard recording mode; and an address adding section for adding the track address to the coded data.

In one embodiment, the address generating section further generates a frame address for identifying each frame of the video signal.

In another embodiment, the address generating section generates a track address having an identical value with respect to two adjacent tracks having respectively different azimuths among the plurality of tracks.

In still another embodiment, in the case of recording a currently used TV signal having 525 lines and 60 fields, the recording section records the n frames of the TV signal on ten tracks, while in the case of recording a currently used TV signal having 625 lines and 50 fields, the recording section records the n frames of the TV signal on twelve tracks.

In still another embodiment, n = 1 in the standard recording mode, and n = 2 in the long-time recording mode.

According to still another aspect of the present invention, a digital signal recording apparatus for recording a digital signal on a recording medium is provided. The digital signal recording apparatus includes: a signal mode setting section for setting a signal mode, the signal mode being one of a HDTV signal mode, a wide TV signal mode, and a standard TV signal mode; an A/D converting section for analog/digital converting a video signal by sampling the video signal including a luminance signal, a first color difference signal and a second color difference signal at a sampling frequency corresponding to the signal mode set by the signal mode setting section, a ratio among a sampling frequency when the signal mode is the HDTV signal mode, a sampling frequency when the signal mode is the wide TV signal mode, and a sampling frequency when the signal mode is the standard TV signal mode being 4:2:1; an effective pixel extracting section for extracting effective pixels from the digitized video signal at a sampling number corresponding to the signal mode set by the signal mode setting section, a ratio among a sampling number when the signal mode is the HDTV signal mode, a sampling number when the signal mode is the wide TV signal mode, and a sampling number when the signal mode is the standard TV signal mode being 4:2:1; a blocking section for dividing a pixel data output from the effective pixel extracting section into rectangular blocks on a screen with respect to the luminance signal and the first and the second color difference signals; a macro blocking section for composing one macro block by assembling blocks of the luminance signal, the first color difference signal and the second color difference signal which are located at the same position on the screen; a segmentalizing section for composing one segment by assembling a predetermined number of macro blocks; a coding section for coding the segment, an amount of a coded data being controlled to be substantially equal to a predetermined amount on a segment basis; and a recording section for recording the data coded by the coding section on a recording medium having a plurality of tracks in accordance with the signal mode set by the signal mode setting section, the recording section recording the coded data on a number 4n (n is a positive integer) of tracks per frame when the signal mode is the HDTV signal mode; on a number 2n of tracks per frame when the signal mode is the wide TV signal mode; and on a number n of tracks per frame when the signal mode is the standard TV signal mode.

In one embodiment, the A/D converting section samples the luminance signal at 40.5 MHz and the first and the second color difference signals at 13.5 MHz when the signal mode is the HDTV signal mode; samples the luminance signal at 20.25 MHz and the first and the second color difference signals at 6.75 MHz when the signal mode is the wide TV signal mode; and samples the luminance signal at 10.125 MHz and the first and the second color difference signals at 3.375 MHz when the signal mode is the standard TV signal mode.

In another embodiment, a ratio among a number of the horizontal effective pixels extracted by the effective pixel extracting section from the video signal when the signal mode is the HDTV signal mode, a number of the horizontal effective pixels extracted by the effective pixel extracting section from the video signal when the signal mode is the wide TV signal mode and a number of the horizontal effective pixels extracted by the effective pixel extracting section from the video signal when the signal mode is the standard TV signal mode is 2:2:1, and a ratio among a number of vertical effective lines extracted by the effective pixel extracting section from the video signal when the signal mode is the HDTV signal mode, a number of vertical effective lines extracted by the effective pixel extracting section from the video signal when the signal mode is the wide TV signal mode and a number of vertical effective lines extracted by the effective pixel extracting section from the video signal when the signal mode is the standard TV signal mode is 2:1:1.

In a digital signal recording apparatus according to the present invention, when the input video signal is recorded in a long-time recording mode, by reducing the sampling number as compared with the sampling number in a standard recording mode and increasing the compression rate, the amount of the information to be recorded in the long-time recording mode is made smaller than the amount to be recorded in the standard recording mode. As a result, it is possible to record the information on one and the same recording medium for a longer time.

In addition, by restraining a high-frequency band of the video signal, a larger amount of information can be assigned in a low-frequency band which is important for the visual impression of the video. As a result, even when a video recorded in the long-time recording mode is reproduced, a video of sufficiently high quality can be obtained by a home-use apparatus.

Furthermore, in a digital signal recording apparatus according to the present invention, it is possible to simplify the high efficiency coding processing in the long-time recording mode. Even when the signals in different recording modes are recorded on an identical recording medium, the auxiliary data can be inserted periodically. As a result, it is possible to prevent an error in detecting the auxiliary data and generate a correct track address in the long-time recording mode. Moreover, in order to implement an apparatus having such a configuration, it is not necessary to considerably increase the size of the circuit. Therefore, the recording apparatus of this invention can attain much practical effect.

In addition, in a digital signal recording apparatus according to the present invention, in the case of recording a video signal by digitizing the signal and utilizing a high efficiency coding technique, the processing of the signals can be commonly performed in a HDTV signal recording mode, a wide TV signal recording mode and a standard TV signal recording mode. As a result, most portions of the circuit can be commonly used for processing the signals, and a sufficiently wide band and an allowable video quality can be obtained in the standard TV signal recording mode. Accordingly, the recording apparatus of this invention can be utilized very effectively in practical use.

Thus, the invention described herein makes possible the advantage of providing a digital signal recording apparatus allowing for recording a digital data in a long-time recording mode in which the data can be recorded on a recording medium for a time longer than that of the standard recording mode.

This and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.

<b>BRIEF DESCRIPTION OF THE DRAWINGS</b>

Figure <b>1</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a first preferred embodiment of the present invention.

Figure <b>2A</b> is a schematic diagram showing a sampling number per frame in the standard recording mode.

Figure <b>2B</b> is a schematic diagram showing a sampling number per frame in the long-time recording mode.

Figure <b>3</b> is a schematic diagram showing macro blocks composing a video segment in the standard recording mode.

Figure <b>4</b> is a schematic diagram showing macro blocks composing a video segment in the long-time recording mode.

Figure <b>5</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a second preferred embodiment of the present invention.

Figure <b>6</b> is a schematic diagram illustrating a rate change processing to be performed in the second and fourth preferred embodiments of the present invention.

Figure <b>7</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a third preferred embodiment of the present invention.

Figure <b>8</b> is a graph showing the characteristics of the luminance signal when the luminance signal is input to a blocker.

Figure <b>9</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a fourth preferred embodiment of the present invention.

Figure <b>10</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a fifth preferred embodiment of the present invention.

Figure <b>11</b> is a schematic diagram showing an arrangement of the macro blocks in the long-time recording mode.

Figure <b>12</b> is a block diagram showing a configuration for a simplified blocker.

Figure <b>13</b> is a block diagram showing a configuration for a selector.

Figure <b>14</b> is a schematic diagram showing a configuration for a screen on which the video signal recorded in the long-time recording mode is reproduced.

Figure <b>15</b> is a block diagram showing a configuration for an auxiliary data adder.

Figure <b>16A</b> is a schematic diagram showing a track pattern in the case where the data is recorded in the standard recording mode.

Figure <b>16B</b> is a schematic diagram showing a track pattern in the case where the data is recorded in the long-time recording mode immediately after the data has been recorded in the standard recording mode.

Figure <b>16C</b> is a schematic diagram showing a track pattern in the case where the data is recorded in the standard recording mode immediately after the data has been recorded in the long-time recording mode.

Figure <b>17</b> is a schematic diagram showing a configuration for a recording coder.

Figure <b>18A</b> is a schematic diagram showing a preferred arrangement of the addresses in the standard recording mode.

Figure <b>18B</b> is a schematic diagram showing a preferred arrangement of the addresses in the long-time recording mode.

Figure <b>19</b> is a schematic diagram showing a recording pattern for a conventional recording apparatus.

Figure <b>20</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a sixth preferred embodiment of the present invention.

Figure <b>21</b> is a schematic diagram showing a positional relationship between the video segment and the macro blocks in recording the HDTV signal by using the recording apparatus of the present invention.

Figure <b>22</b> is a schematic diagram showing a positional relationship between the video segment and the macro blocks in recording the wide TV signal by using the recording apparatus of the present invention.

<b>DESCRIPTION OF THE PREFERRED EMBODIMENTS</b>

Hereinafter, the present invention will be described by way of illustrative examples with reference to the accompanying drawings.

<b>Example 1</b>

Figure <b>1</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a first example of the present invention. It is noted that the components having the same configuration or function will be denoted by the same reference numerals in the following description.

The digital signal recording apparatus includes a mode setter <b>100</b> for setting the recording mode to be either one of a standard recording mode and a long-time recording mode. The mode setter <b>100</b> outputs mode information <b>101</b> indicating the set mode. In accordance with the mode information <b>101</b>, the digital signal recording apparatus processes a luminance signal <b>Y</b>, a color difference signal (<b>R-Y</b>) and a color difference signal (<b>B-Y</b>) to be input through input terminals <b>102</b>, <b>103</b> and <b>104</b> respectively. After these signals are variable-length coded, a video signal is output through an output terminal <b>122</b> by the digital signal recording apparatus.

The digital signal recording apparatus further includes A/D converters <b>105</b>, <b>106</b> and <b>107</b> and a sampling frequency setter <b>108</b>. The inputs of the A/D converters <b>105</b>, <b>106</b> and <b>107</b> are connected with the input terminals <b>102</b>, <b>103</b> and <b>104</b>, respectively. The A/D converters <b>105</b>, <b>106</b> and <b>107</b> convert an analog signal into a digital signal. A clock <b>109</b> is supplied from the sampling frequency setter <b>108</b> to the A/D converter <b>105</b>. The sampling frequency of the A/D converter <b>105</b> is set by the clock <b>109</b> and is variable. On the other hand, the sampling frequencies of the A/D converters <b>106</b> and <b>107</b> are fixed.

The digital signal recording apparatus further includes: a delay circuit <b>112</b>; line decimators <b>110</b> and <b>111</b>; and switches <b>113</b>, <b>114</b> and <b>115</b>. The delay circuit <b>112</b> is connected with the output of the A/D converter <b>105</b>, thereby delaying the luminance signal by a time corresponding to the processing time of the line decimators <b>110</b> and <b>111</b>. The line decimator <b>110</b> is connected with the output of the A/D converter <b>106</b>, and decimates the color difference signal (<b>R-Y</b>) on a line basis after limiting the vertical band of the color difference signal (<b>R-Y</b>) to one half. The line decimator <b>111</b> is connected with the output of the A/D converter <b>107</b>, and decimates the color difference signal (<b>B-Y</b>) on a line basis after limiting the vertical band of the color difference signal (<b>B-Y</b>) to one half. The input of the switch <b>113</b> is connected with the output of the A/D converter <b>105</b> and the output of the delay circuit <b>112</b>, thereby outputting either the output of the A/D converter <b>105</b> or the output of the delay circuit <b>112</b> in accordance with the mode information <b>101</b>. The input of the switch <b>114</b> is connected with the output of the A/D converter <b>106</b> and the output of the line decimator <b>110</b>, thereby outputting either the output of the A/D converter <b>106</b> or the output of the line decimator <b>110</b> in accordance with the mode information <b>101</b>. The input of the switch <b>115</b> is connected with the output of the A/D converter <b>107</b> and the output of the line decimator <b>111</b>, thereby outputting either the output of the A/D converter <b>107</b> or the output of the line decimator <b>111</b> in accordance with the mode information <b>101</b>.

The digital signal recording apparatus further includes: a blocker <b>116</b>; an orthogonal transformer <b>117</b>; a quantizer <b>118</b>; a quantization controller <b>119</b>; and a variable-length coder <b>121</b>. The blocker <b>116</b> is connected with the outputs of the switches <b>113</b>, <b>114</b> and <b>115</b>, and forms a block consisting of 64 pixels, i.e., eight horizontal pixels × eight vertical lines, from the signals input in the order of the raster scanning in accordance with the mode information <b>101</b>, thereby outputting a signal on a block basis. The orthogonal transformer <b>117</b> performs a two-dimensional orthogonal transform on a block basis consisting of (8 × 8) pixels. The quantizer <b>118</b> quantizes the output of the orthogonal transformer <b>117</b>. The quantization step in the quantizer <b>118</b> is determined by the quantization information <b>120</b> output from the quantization controller <b>119</b>. The quantization controller <b>119</b> determines the quantization step in the quantizer <b>118</b> in accordance with the mode information <b>101</b> so that the amount of the data after the high-efficiency coding becomes a predetermined amount or less. The variable-length coder <b>121</b> variable-length codes the output of the quantizer <b>118</b>. The variable-length coded video signal is output through an output terminal <b>122</b>.

Hereinafter, the operation of the digital signal recording apparatus of this example having the above configuration will be described.

The mode setter <b>100</b> sets the mode information <b>101</b> to be "0" in the standard recording mode and "1" in the long-time recording mode. The selected mode information <b>101</b> is supplied to the sampling frequency setter <b>108</b>, the switches <b>113</b>, <b>114</b> and <b>115</b>, the blocker <b>116</b> and the quantization controller <b>119</b>.

The luminance signal <b>Y</b> and the color difference signals (<b>R-Y</b>) and (<b>B-Y</b>) input through the terminals <b>102</b>, <b>103</b> and <b>104</b> are converted into digital signals by the A/D converters <b>105</b>, <b>106</b> and <b>107</b>, respectively. The sampling frequency setter <b>108</b> outputs a clock <b>109</b> having a different frequency to the A/D converter <b>105</b> in accordance with the mode information <b>101</b>. The sampling frequency for the luminance signal in the A/D converter <b>105</b> is determined by the clock <b>109</b>. The clock <b>109</b> is set so as to have a frequency of 13.5 MHz in the standard recording mode and a frequency of 10.125 MHz in the long-time recording mode. That is to say, the sampling frequency for the luminance signal in the long-time recording mode is set to be three-quarters of the sampling frequency for the luminance signal in the standard recording mode. The sampling frequency for the color difference signals is always fixed at 3.375 MHz in both the modes.

When the mode information <b>101</b> is set to be "0", the switches <b>113</b>, <b>114</b> and <b>115</b> are controlled to select the outputs of the A/D converters <b>105</b>, <b>106</b> and <b>107</b>. On the other hand, when the mode information <b>101</b> is set to be "1", the switches <b>113</b>, <b>114</b> and <b>115</b> are controlled to select the output of the delay circuit <b>112</b> and those of the line decimators <b>110</b> and <b>111</b>. Therefore, the outputs of the A/D converters <b>105</b>, <b>106</b> and <b>107</b> are input to the blocker <b>116</b> in the standard recording mode, while the outputs of the delay circuit <b>112</b> and the line decimators <b>110</b> and <b>111</b> are input to the blocker <b>116</b> in the long-time recording mode.

Figure <b>2A</b> shows the sampling number of a unit frame to be input to the blocker <b>116</b> in the standard recording mode. As shown in Figure <b>2A</b>, the sampling number per frame in the standard recording mode is: 720 pixels × 480 lines + 180 pixels × 480 lines × 2 = 518400 samples/frame.

Figure <b>2B</b> shows the sampling number of a unit frame to be input to the blocker <b>116</b> in the long-time recording mode. As shown in Figure <b>2B</b>, the sampling number per frame in the long-time recording mode is: 540 pixels × 480 lines + 180 pixels × 240 lines × 2 = 345600 samples/frame. Accordingly, the total number of the samples in the long-time recording mode is two-thirds of the sampling number in the standard recording mode.

The blocker <b>116</b> blocks the luminance signal and the color difference signals which have been input in the order of the raster scanning. Each of the blocks consists of 64 pixels, i.e., eight horizontal pixels × eight vertical lines, and then outputs a signal on a five macro block basis. The macro block is herein composed of the blocks for the luminance signal and the blocks for the color difference signals which are located at the same position on the screen.

Figure <b>3</b> shows the macro blocks to be output from the blocker <b>116</b> as a unit (hereinafter, referred to as a "video segment") for the high-efficiency coding in the standard recording mode. In this example, one video segment consists of five macro blocks <b>300</b>, <b>301</b>, <b>302</b>, <b>303</b> and <b>304</b>. Each of the macro blocks <b>300</b>, <b>301</b>, <b>302</b>, <b>303</b> and <b>304</b> consists of six blocks, i.e., four luminance signal blocks, one R-Y color difference signal block and one B-Y color difference signal block. Therefore, one video segment consists of thirty blocks.

Figure <b>4</b> shows the macro blocks to be output from the blocker <b>116</b> as a video segment in the long-time recording mode. In this example, one video segment consists of five macro blocks <b>400</b>, <b>401</b>, <b>402</b>, <b>403</b> and <b>404</b>. Each of the macro blocks <b>400</b>, <b>401</b>, <b>402</b>, <b>403</b> and <b>404</b> consists of eight blocks, i.e., six luminance signal blocks, one R-Y color difference signal block and one B-Y color difference signal block. Therefore, one video segment consists of forty blocks. The number of the video segments per frame and the number of the macro blocks per frame in the long-time recording mode are one half as small as the number of the video segments per frame and the number of the macro blocks per frame in the standard recording mode, respectively.

The data output from the blocker <b>116</b> on the video segment basis is input to the orthogonal transformer <b>117</b> and an (8 × 8) two-dimensional orthogonal transform is performed therein. The coefficient obtained by the two-dimensional orthogonal transform is quantized by the quantizer <b>118</b>. The quantization step in the quantizer <b>118</b> is determined by the quantization controller <b>119</b>. The quantization controller <b>119</b> determines the quantization step so that the data amount after the data in one video segment has been coded becomes equal to or less than a predetermined data amount. That is to say, the coefficients of the respective blocks are quantized at a predetermined number of quantization steps, the amount of the data to be generated during the variable-length coding is presumed, and the quantization steps are determined so that the data amount after the coding becomes a predetermined amount or less. The coefficients quantized at the determined quantization steps are variable-length coded based on a Huffman table by the variable-length coder <b>121</b>.

As described referring to Figures <b>3</b> and <b>4</b>, the number of the blocks per video segment is 30 in the standard recording mode and 40 in the long-time recording mode. On the other hand, the amount of the coded data in one video segment is controlled to be equal in both the modes by the quantization controller <b>119</b>. As a result, the compression rate in the long-time recording mode becomes four-thirds of the compression rate in the standard recording mode.

The data high-efficiency coded by the above-described method is output from the code-word output terminal <b>122</b>. A parity for an error correction coding is added to the coded signal if necessary, and then recorded on a recording medium.

As is apparent from the foregoing description, according to the method of this example, the sampling frequency of the A/D conversion for the luminance signal in the long-time recording mode is set to be three-quarters of the sampling frequency of the A/D conversion for the luminance signal in the standard recording mode; the lines are decimated with respect to the color difference signals, thereby reducing the data amount to two-thirds before the high-efficiency coding is performed; and the number of the blocks per video segment in the long-time recording mode is set to be four-thirds of the number of the blocks per video segment in the standard recording mode, thereby setting the compression rate in the long-time recording mode to be four-thirds of the compression rate in the standard recording mode, so that it is possible to reduce the amount of the data to be recorded in the long-time recording mode to be one half of the amount of the data to be recorded in the standard recording mode.

Example 2

Figure <b>5</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a second example of the present invention. The digital signal recording apparatus of this example includes a rate changer <b>500</b> instead of the delay circuit <b>112</b>.

In the first example, the sampling frequency for the luminance signal in the A/D converter <b>105</b> is selected in accordance with the mode information <b>101</b>. On the other hand, in this example, the sampling frequency for the luminance signal in the A/D converter <b>105</b> is fixed at 13.5 Mhz irrespective of the mode information <b>101</b>. In the long-time recording mode, by A/D converting the luminance signal and then changing the rate of the luminance signal by using the rate changer <b>500</b>, the sampling number of the luminance signal in the long-time recording mode can be reduced to three-quarters of the sampling number of the luminance signal in the standard recording mode.

Figure <b>6</b> illustrates the rate change operation performed by the rate changer <b>500</b>. In Figure <b>6</b>, the open circles indicate the sampled values when the sampling frequency is 13.5 MHz. The rate changer <b>500</b> calculates the sampled values, indicated by the closed circles, corresponding to the sampling frequency of 10.125 MHz by using the sampled values indicated by the open circles. After the rate is changed, the digital signal recording apparatus of this example operates in the same way as the digital signal recording apparatus of the first example. Therefore, the description thereof will be omitted herein.

As described above, according to the method of this example, the clock supplied to the A/D converter <b>105</b> in the standard recording mode can be commonly used in the long-time recording mode, too. As a result, by using a digital processing portion only, the video data can be satisfactorily processed in the long-time recording mode.

Example 3

Figure <b>7</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a third example of the present invention. The digital signal recording apparatus of this example includes a digital filter <b>700</b> instead of the delay circuit <b>112</b>.

The method of the third example is different from the method of the first example in that the luminance signal is A/D converted and then the frequency components of the luminance signal in the high-pass band are restrained by using the digital filter <b>700</b>.

Figure <b>8</b> is a graph showing the frequency characteristics of the luminance signal after the A/D conversion and those of the luminance signal after the digital filtering. In Figure <b>8</b>, the curve <b>800</b> indicates the characteristics of the luminance signal sampled at a frequency of 13.5 MHz in the standard recording mode; the curve <b>801</b> indicates the characteristics of the luminance signal sampled at a frequency of 10.125 MHz in the long-time recording mode; and the curve <b>802</b> indicates preferable characteristics of the luminance signal in the long-time recording mode to be obtained by restraining the characteristics indicated by the curve <b>801</b> in the high-pass band by using the digital filter <b>700</b>.

The gain of the luminance signal in the standard recording mode is defined to be 0 dB at a frequency of 5.75 MHz or less, and -12 dB or less at a frequency of 6.75 MHz according to the standard REC601 (as indicated by the curve <b>800</b>). Since the sampling frequency for the luminance signal in the long-time recording mode becomes three-quarters of the frequency in the standard recording mode, the gain of the luminance signal in the long-time recording mode becomes 0 dB at a frequency of 4.31 MHz or less and -12 dB or less at a frequency of 5.06 MHz according to the standard REC601 (as indicated by the curve <b>801</b>).

However, as described in the first example, the compression of the data in the long-time recording mode is performed at a compression rate which is four-thirds of the compression rate in the standard recording mode. Therefore, unless the data is processed in an appropriate manner, a sufficient amount of codes cannot be assigned in the low to middle frequency regions considerably affecting the visual quality of the video unlike the standard recording mode, so that the quality of the video is degraded. In order to prevent such a degradation, the frequency components in the high-pass band of 5 MHz or more is sufficiently attenuated by using the digital filter <b>700</b>, and the frequency components in the band of 4 to 5 MHz is also attenuated to a certain degree in order to facilitate the design of the filter <b>700</b>. As a result, the codes in such an amount as not to considerably degrade the resolution can be assigned to the low to middle frequency regions. The specific characteristics of the digital filter <b>700</b> can be arbitrarily selected while examining the quality of the processed video.

As described above, according to the method of this example, by sufficiently attenuating the frequency components of the luminance signal in the high-pass band in the long-time recording mode, it is possible to prevent a considerable degradation of the quality of the video during a coding processing.

Example 4

Figure <b>9</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a fourth example of the present invention. The digital signal recording apparatus of this example additionally includes a digital filter <b>700</b> of the third example immediately adjacent to the rate changer <b>500</b> of the second example. In this example, the clock of the luminance signal can be commonly used for the A/D conversion in both modes; the data can be satisfactorily processed in the long-time recording mode by using a digital processing portion only; and the same effects as those described in the third example can be attained by using the digital filter <b>700</b>. In this example, the digital filter <b>700</b> is operated after the rate is changed. However, in general, the rate change is frequently realized by using a digital filter. Accordingly, the rate changer <b>500</b> can be integrally formed with the digital filter <b>700</b>.

Example 5

Figure <b>10</b> is a block diagram showing a configuration for a digital signal recording apparatus according to a fifth example of the present invention. In Figure <b>10</b>, the reference numerals denote as follows: <b>1000</b> is a simplified blocker; <b>1001</b> is an auxiliary data adder; <b>1002</b> is an error correction coder; <b>1003</b> is a recording coder; <b>1004</b> is a recording amplifier; <b>1005</b> is a recording head; <b>1006</b> is a magnetic tape; <b>1007</b> is an audio signal input terminal; <b>1008</b> is an audio signal coder; <b>1009</b> is a tape speed controller; and <b>1010</b> is a tape transporting motor.

Hereinafter, the operation of the digital signal recording apparatus of the fifth example will be described. It is noted that the operations of the respective components denoted by <b>110</b> to <b>115</b> and <b>117</b> to <b>121</b> are the same as those of the components denoted by the same reference numerals in the third example. In this example, the digital filter <b>700</b> described in the third example is used for processing the luminance signal. Alternatively, the delay circuit <b>112</b> described in the first example can be used instead.

Figure <b>11</b> shows an exemplary arrangement of a plurality of macro blocks in the long-time recording mode. In this example, the luminance signal per frame consists of 540 horizontal pixels × 480 vertical lines while one macro block consists of 24 horizontal pixels × 16 vertical lines. Accordingly, one frame is divided into 675 macro blocks, i.e., 22.5 horizontal macro blocks × 30 vertical macro blocks. In this case the number of the horizontal pixels per frame is not N times as large as the number of the horizontal pixels per macro block, so that the macro block (MB44) at the right end has an elongate configuration in the vertical direction.

In the case where such elongate macro blocks as those shown in Figure <b>11</b> exist, a conventional method requires a larger number of line memories as compared with the case of processing ordinary macro blocks.

However, according to the method of this example, it is possible to simplify the blocking process by using a simplified blocker <b>1000</b>, and prevent the number of the circuits to be used.

Figure <b>12</b> is a block diagram showing a detailed configuration for the simplified blocker <b>1000</b> of this example. As shown in Figure <b>12</b>, the simplified blocker <b>1000</b> includes: a memory <b>1202</b>; a selector <b>1203</b>; an address controller <b>1206</b>; and a pseudo macro block detector <b>1207</b>.

As shown in Figure <b>12</b>, three kinds of digital video signals <b>Y, R-Y</b> and <b>B</b>-<b>Y</b> input from a video signal input terminal <b>1201</b> are input to the memory <b>1202</b> and the address controller <b>1206</b>. The address controller <b>1206</b> detects an effective pixel range based on the horizontal and vertical synchronization signals of the input video signals, thereby controlling the address so that the video signals input to the memory on the respective horizontal lines are read out in the order of the macro blocks. As a result, the video signals are output from the memory <b>1202</b> on a macro block basis. The macro blocks included in the input video signals output from the memory <b>1202</b> are herein referred to as "input macro blocks".

When the address of the macro block at the right end in the horizontal direction within one frame, i.e., the region of the twelve pixels at the right end of Figure <b>11</b>, is output from the address controller <b>1206</b>, the pseudo macro block detector <b>1207</b> outputs a pseudo macro block detection signal to the selector <b>1203</b>. When the pseudo macro block detection signal is not input to the selector <b>1203</b>, the selector <b>1203</b> outputs the input macro block via an output terminal <b>1205</b>. On the other hand, when the pseudo macro block detection signal is input to the selector <b>1203</b>, the selector <b>1203</b> outputs a predetermined value via the output terminal <b>1205</b>. The macro block having the predetermined value output from the selector <b>1203</b> when the pseudo macro block is detected will be called a pseudo macro block herein.

In this example, the macro block with a particular shape at the right end in Figure <b>11</b> is replaced by the pseudo macro block, so that it is not necessary to read the input video signal from the memory <b>1202</b> during the period. Therefore, no address generator and no memory region for storing the video signal are required for the macro block with this particular shape. As a result, even when the number of the horizontal or vertical effective pixels in one frame is not N times as large as the number of the horizontal or vertical effective pixels in one macro block, there is no need for providing an address generator or increasing the capacity of the memory.

Next, referring to Figure <b>13</b>, an exemplary pseudo macro blocker (or the selector <b>1203</b> shown in Figure <b>12</b>) will be described. In Figure <b>13</b>, the reference numerals denote as follows: <b>1301</b> is an input macro block input section; <b>1302</b> is a 128 generating section; <b>1303</b> is a pseudo macro block detecting section; <b>1304</b> is a switch; and <b>1305</b> is a macro block output section.

When the pseudo macro block detection signal is not input from the pseudo macro block detecting section <b>1303</b>, the switch <b>1304</b> shown in Figure <b>13</b> outputs the input macro block input from the input macro block input section <b>1301</b> to the macro block output section <b>1305</b>. On the other hand, when the pseudo macro block detection signal is input from the pseudo macro block detecting section <b>1303</b>, the switch <b>1304</b> outputs a value of 128 generated by the 128 generating section <b>1302</b> to the macro block output section <b>1305</b>. As a result, when the pseudo macro block is detected, the value of 128 is always output as the pixel value of the pseudo macro block.

By using such a configuration, all the pixel values within the pseudo macro block are fixed at 128, so that the video coding considerably reduces the amount of the data. Therefore, it is possible to assign a code-word data in other input macro blocks to a part of the code-word region to which the pseudo macro block is assigned, thereby reducing the compression rate of the input macro block and improving the quality of the reproduced video.

Consequently, in this example, by setting the pixel value of the pseudo macro block to be constant, it is possible to improve the quality of the reproduced video in the input macro block.

Figure <b>14</b> shows an exemplary configuration for the screen when such a pseudo macro block is used. The region for the pseudo macro block is indicated by the hatching at the right end in Figure <b>14</b>. In Figure <b>14</b>, all the data in the pseudo macro block region is reproduced at a pixel value of 128, so that the region is recognized as a horizontal blanking region and causes no visual disturbance.

The technique using a pseudo macro block of this example is applicable to any arbitrary macro block structure or frame structure. The pixel value in the pseudo macro block is not limited to 128 employed in this example, but an arbitrary value can be selected. The pixel values within the pseudo macro block can be varied in the respective small blocks.

In a reproducing apparatus to which the simplified blocker <b>1000</b> is applied, the pixel value in the pseudo macro block region can be replaced by an arbitrary value and then output during the reproducing operation, in the same manner as a coder.

Figure <b>15</b> is a block diagram showing a detailed configuration for the auxiliary data adder <b>1001</b> of this example. As shown in Figure <b>15</b>, the auxiliary data adder <b>1001</b> includes: an auxiliary data generator <b>1501</b>; an auxiliary data inserter <b>1502</b>; and a controller <b>1503</b>. The digital data is input to the auxiliary data inserter <b>1502</b> via an input terminal <b>1500</b>, and a signal to which the auxiliary data is inserted is output from the auxiliary data inserter <b>1502</b> via an output terminal <b>1504</b>. The mode information <b>101</b> is input to the auxiliary data generator <b>1501</b> and the controller <b>1503</b> via a mode information input terminal <b>1505</b>.

In this example, the video data is assumed to be input via the input terminal <b>1500</b> and the amount of the information in the long-time recording mode is assumed to be one half of the amount of the information in the standard recording mode. In this case, the information is recorded by using ten tracks per frame in the standard recording mode and five tracks per frame in the long-time recording mode, for example.

First, a case where the recording operation is performed in the standard recording mode will be described. An auxiliary data is generated by the auxiliary data generator <b>1501</b>. The auxiliary data is inserted into the coded video data by the auxiliary data inserter <b>1502</b>. The position of the video data into which the auxiliary data is inserted is controlled by the controller <b>1503</b>.

Figure <b>16A</b> schematically shows the position on the recording track into which the auxiliary data is inserted. As shown in Figure <b>16A</b>, the auxiliary data is repeatedly and periodically inserted into the positions <b>A</b> and <b>B</b> from the head track of the frame. More specifically, the auxiliary data is inserted in the order of A→B→A→B→ ...

Next, a case where the recording operation is continuously performed on a track in the long-time recording mode immediately after the recording operation on the same track in the standard recording mode is finished. In this case, when the video data for the long-time recording mode is input, the mode information <b>101</b> input from the mode information input terminal <b>1505</b> is switched from "0" (for the standard recording mode) into "1" (for the long-time recording mode). Thereafter, the auxiliary data for the long-time recording mode generated by the auxiliary data generator <b>1501</b> is inserted by the auxiliary data inserter <b>1502</b> with the insertion position controlled by the controller <b>1503</b>.

In the same way as in the standard recording mode, the auxiliary data is periodically inserted into the different positions from the head track of the frame. In the long-time recording mode, since the number of the recording tracks per frame is 2n + 1 (n = 1, 2, ...; in this example, n = 2), the controller <b>1503</b> controls the insertion at a period of two frames. More specifically, as shown in Figure <b>16B</b>, the auxiliary data is inserted in the order of C→D→C→D→C in the recording start frame and in the order of D→C→D→C→D in the next frame. As a result, the period of the positions into which the auxiliary data is inserted is the same as that in the standard recording mode.

On the other hand, in the case where the recording operation is continuously performed on a track in the standard recording mode immediately after the recording operation on the same track in the long-time recording mode is finished, the start position of the standard recording is controlled by the controller <b>1503</b> so that the standard recording is started immediately after a frame in which the last insertion position of the auxiliary data is the position <b>C</b> by using a number <b>m</b> of frames (m = 2, 4, 6, ...; in this example m = 2) for the long-time recording mode as an edition unit. The recording pattern obtained in this way is shown in Figure <b>16C</b>. As shown in Figure <b>16C</b>, the period of the insertion positions of the auxiliary data is maintained in both of the portions where the video data is recorded in the standard recording mode and in the portions where the video data is recorded in the long-time recording mode.

As described above, according to the method of this example, by controlling the insertion positions of the auxiliary data and the timing for switching the recording modes, it is possible to maintain the period of the insertion positions of the auxiliary data even when the video data is recorded on one and the same tape-shaped recording medium in both modes. As a result, the auxiliary data can be detected during the reproduction operation by commonly using a detector and detection timings for the standard recording mode, irrespective of whether the video data is recorded in the standard recording mode or in the long-time recording mode.

In this example, the video data is recorded by using ten tracks per frame in the standard recording mode and five tracks in the long-time recording mode. However, the number of the tracks to be used is not limited thereto. Since the amount of information to be recorded in the long-time recording mode is 1/m (m = 2, 4, 6,...) as small as the amount of the information to be recorded in the standard recording mode, the number of the recording tracks in the long-time recording mode can be generally expressed by 2n + 1, while the number of the recording tracks in the standard recording mode can be generally expressed by m × (2n + 1). It is obvious that the same effects can be generally attained irrespective of the number of the recording tracks to be used.

In this example, the data to be recorded is assumed to be a video data. However, it is obvious that the same effects can be attained if other kinds of data such as an audio data is recorded. A video signal, an audio signal or the like can be compressed by any arbitrary method such as a DCT, a DPCM or the like.

The detailed contents of a track have not specifically been mentioned in the above description. A track may have any arbitrary contents. The auxiliary data principally consists of the information required for reproducing an audio data, a video data or the like. However, the auxiliary may have any arbitrary content.

An appropriate error correction code is added by the error correction coder <b>1002</b> to the data to which the auxiliary data has been added in accordance with the mode information <b>101</b>.

Figure <b>17</b> is a block diagram showing a detailed configuration for the recording coder <b>1003</b>. In Figure <b>17</b>, the reference numerals denote as follows: <b>1700</b> is a data input terminal; <b>1701</b> is a mode information input terminal; <b>1702</b> is an address adder; <b>1703</b> is a frame control signal generator; and <b>1704</b> is a recording data output terminal. Hereinafter, the operation of the recording coder <b>1003</b> of this example will be described. In this example, it is assumed that a video data is input, and that a one-frame control is performed in the standard recording mode while a two-frame control is performed in the long-time recording mode. However, the control can be performed on an n-frame basis in the same way.

The frame control signal generator <b>1703</b> generates a one-frame control signal when the mode information <b>101</b> is "0" in order to synchronize the frames with each other on a one-frame basis. On the other hand, when the mode information <b>101</b> is "1", the frame control signal generator <b>1703</b> generates a two-frame control signal in order to synchronize the frames with each other on a two-frame basis. In the case where the input video signal is a composite signal, the two-frame control signal can be synchronized with the color frame period thereof.

Referring back to Figure <b>10</b>, the processing of an audio data will be described. When the audio signal input from an audio signal input terminal <b>1007</b> is an analog signal, the audio signal is A/D converted and then processed by an audio signal coder <b>1008</b>. Needless to say, when the audio signal input from the audio signal input terminal <b>1007</b> is a digital signal, there is no need for performing the A/D conversion. The audio signal is blocked by performing predetermined audio signal processings such as a filtering, a rearrangement, a compression and the like if necessary in accordance with the mode information <b>101</b>, so as to be output as an audio data. Thereafter, the blocked data is error correction coded by the error correction coder <b>1002</b>; an address for recording is added to the data by the recording coder <b>1003</b>; and the data is amplified by the recording amplifier <b>1004</b> and then recorded on the magnetic tape <b>1006</b> by the recording head <b>1005</b>.

The tape speed controller <b>1009</b> determines a tape transporting speed suitable for the respective modes in accordance with the mode information <b>101</b> and controls the tape transporting motor <b>1010</b>.

In this case, the audio data is recorded on the respective tracks in the same recording pattern as that described in the conventional example. However, since the tape transporting speed is different, the pattern to be actually formed on the tape possibly has a slightly different track angle.

The sub-code data and the auxiliary data which are assembled on a one-field basis or on a one-frame basis can be assembled on a two-frame basis in accordance with the two-frame control signal. In order to use the arrangement of these data in the same way as the data recorded by a conventional recording apparatus, an address is composed of a frame address for identifying a frame, a track address provided at a period of two frames and a block address provided at a period of one track. For example, in a recording apparatus in which one frame is composed of ten tracks, the frame addresses and the track addresses can be arranged as shown in Figures <b>18A</b> and <b>18B</b>. In Figures <b>18A</b> and <b>18B</b>, the track address is begun with 0, and the same value is assigned to two adjacent tracks having different azimuths. The same result is obtained irrespective of how the values are assigned. That is to say, the assignment can be begun with any other value; the value can be changed in every track; and the value can increase or decrease. In this example, the recording pattern for a track shown in Figure <b>19</b> is employed. However, the same result can be obtained in any form such as the number of the sectors. According to the present invention, an address is added after the error correction coding is performed. However, if the recording is performed in the order of the addition of an address, the error correction coding with respect to the address and the data, and generation of a parity, the same effects can be attained.

In the case of recording a currently used TV signal having a system of 525 lines and 60 fields, the n frames of the TV signal can be recorded on ten tracks, while in the case of recording a currently used TV signal having a system of 625 lines and 50 fields, the n frames of the TV signal can be recorded on twelve tracks. In such a case, n can be 1 in the standard recording mode and n can be 2 in the long-time recording mode.

As described above, according to the method of this example, by compressing a video signal at a rate n times as high as a conventional rate and using a track address for designating a track at a period of n frames, the recording can be performed for a time longer than a conventional time. In addition, by commonly using a recording apparatus with the same configuration in both the standard recording mode and the long-time recording mode, almost no circuits are required to be additionally provided except for the circuits necessary for a high compression. Furthermore, any method can be used for compressing a video signal and an audio signal.

Example 6

Figure <b>20</b> is a block diagram showing a configuration for a digital video signal recording apparatus according to a sixth example of the present invention. In Figure <b>20</b>, the reference numerals denote as follows: <b>2000</b> is a TV signal mode setter for setting the recording mode of this apparatus to be any of a HDTV signal recording mode, a wide TV signal recording mode and a standard TV signal recording mode; <b>2001</b> is TV signal mode information set by the TV signal mode setter <b>2000</b>; <b>2002</b> is an effective pixel extractor for extracting effective pixels from the pixel data of the input video signal; <b>2003</b> is a blocker for composing a block consisting of eight horizontal pixels × eight vertical lines from the input signal so as to output a signal on a block basis; <b>2004</b> is a macro blocker for composing a macro block from the blocks of the luminance signal, one block of one of the color difference signals included in substantially the same region on the screen, and one block of the other color difference signal; <b>2005</b> is a segmentalizer for composing a segment by assembling five macro blocks from five different positions on the screen which are distant from each other; <b>2006</b> is a coder for coding the video signal so that the amount of the codes becomes an amount predetermined on a segment basis or less. The coder <b>2006</b> includes: an orthogonal transformer <b>117</b>; a quantizer <b>118</b>; a quantization controller <b>119</b> for determining the quantization steps in the quantizer <b>118</b> so that the data amount after a high-efficiency coding becomes a predetermined amount or less; and a variable-length coder <b>121</b>. Hereinafter, the operation of the digital signal recording apparatus of this example will be described with reference to Figure <b>20</b>.

The TV signal mode setter <b>2000</b> sets the recording mode of this apparatus to be any of the HDTV signal recording mode, the wide TV signal recording mode and the standard TV signal recording mode, thereby outputting the control signals corresponding to the respective modes.

The luminance signal <b>Y</b>, and two kinds of color difference signals <b>C</b>_<b>R</b> and <b>C</b>_<b>B</b> input from the input terminals <b>102</b>, <b>103</b> and <b>104</b>, respectively, are converted into digital signals by the A/D converters <b>105</b>, <b>106</b> and <b>107</b>. The sampling frequency setter <b>108</b> sets the sampling frequencies of the A/D converters <b>105</b>, <b>106</b> and <b>107</b> based on the TV signal mode information <b>2001</b> output from the TV signal mode setter <b>2000</b>.

In the HDTV signal recording mode, the sampling frequency of the A/D converter <b>105</b> is set to be 40.5 MHz, and the sampling frequencies of the A/D converters <b>106</b> and <b>107</b> are set to be 13.5 MHz. In the wide TV signal recording mode, the sampling frequency of the A/D converter <b>105</b> is set to be 20.25 MHz, and the sampling frequencies of the A/D converters <b>106</b> and <b>107</b> are set to be 6.75 MHz. In the standard TV signal recording mode, the sampling frequency of the A/D converter <b>105</b> is set to be 10.125 MHz, and the sampling frequencies of the A/D converters <b>106</b> and <b>107</b> are set to be 3.375 MHz.

The digitally converted luminance signal output from the A/D converter <b>105</b> is input to the effective pixel extractor <b>2002</b>. The vertical pass-bands of the two digitally converted color difference signals output from the A/D converters <b>106</b> and <b>107</b> are limited to one half by the line decimators <b>110</b> and <b>111</b>, and then the lines of the two color difference signals are decimated on a line basis, so as to be input to the effective pixel extractor <b>2002</b>.

The effective pixel extractor <b>2002</b> extracts the effective pixel data to be actually coded and recorded from the input pixel data. In this example, the effective pixel data is extracted based on the mode information output from the mode setter <b>100</b> as follows. In the HDTV signal recording mode, the pixel data corresponding to 1080 horizontal pixels × 960 vertical lines is extracted from the luminance signal and the pixel data corresponding to 360 horizontal pixels × 480 vertical lines is extracted from the color difference signals. In the wide TV signal recording mode, the pixel data corresponding to 1080 horizontal pixels × 480 vertical lines is extracted from the luminance signal and the pixel data corresponding to 360 horizontal pixels × 240 vertical lines is extracted from the color difference signals. In the standard TV signal recording mode, the pixel data corresponding to 540 horizontal pixels × 480 vertical lines is extracted from the luminance signal and the pixel data corresponding to 180 horizontal pixels × 240 vertical lines is extracted from the color difference signals.

The blocker <b>2003</b> composes blocks, each of which consists of 64 pixels, i.e., eight horizontal pixels × eight vertical lines, from the pixel data extracted by the effective pixel extractor <b>2002</b> from each of the luminance signal and the color difference signals, thereby outputting a signal on a block basis.

The macro blocker <b>2004</b> composes and outputs one macro block from the blocks of the luminance signal, one block of one of the color difference signals included in substantially the same area on the screen, and one block of the other color difference signal. In this example, a macro block is composed of eight DCT blocks, i.e., the six blocks of the luminance signal and two color difference signal blocks as shown in Figure <b>4</b>.

The segmentalizer <b>2005</b> composes one segment by assembling a plurality of macro blocks from the positions on the screen which are distant from each other in order to average as much as possible the amount of the codes to be generated in one segment functioning as a coding unit. In this example, one segment is composed of five macro blocks. The positional relationships among the macro blocks composing the segment in the HDTV signal recording mode, the wide TV signal recording mode and the standard TV signal recording mode are shown in Figures <b>21</b>, <b>22</b> and <b>3</b>, respectively.

The segmentalized video data is coded so that the amount of the codes thereof does not exceed the code amount predetermined by the coder <b>2006</b> on the segment basis. The numbers of the segments in one frame for the respective recording modes are as follows: in the HDTV signal recording mode, 45 horizontal macro blocks × 60 vertical macro blocks / 5 = 540 segments as shown in Figure <b>21</b>; in the wide TV signal recording mode, 45 horizontal macro blocks × 30 vertical macro blocks / 5 = 270 segments as shown in Figure <b>22</b>; and in the standard TV signal recording mode, 22.5 horizontal macro blocks × 30 vertical macro blocks / 5 = 135 segments as shown in Figure <b>3</b>. When the numbers of the recording tracks per frame to be formed on the magnetic tape <b>1006</b> in the respective recording modes are assumed to be 20, 10 and 5, the number of the segments per track becomes 27 in all the recording modes. When the amount of the codes to be recorded on one track is assumed to be A bits, the amount of the codes usable in one segment is equal in all the recording modes, i.e., A/27 bits.

The data high-efficiency coded in the above-described manner is recorded on the magnetic tape <b>1006</b> by forming recording tracks thereon by a helical scanning after the data is supplied through the same path as in the fifth example. The data is recorded on 20 tracks per frame in the HDTV signal recording mode; on 10 tracks per frame in the wide TV signal recording mode; and on 5 tracks per frame in the standard TV signal recording mode.

The tape speed controller <b>1009</b> controls the rotation speed of the tape transporting motor <b>1010</b> in accordance with the TV signal mode information <b>2001</b> output from the TV signal mode setter <b>2000</b>, thereby varying the tape transporting speed of the magnetic tape <b>1006</b> so as to equalize the width of the recording tracks in the respective recording modes.

As is apparent from the foregoing description, in the case where the digital video signal recording apparatus of this example is applied to a digital VTR for recording a HDTV signal, a wide TV signal and a standard TV signal, by setting the ratio of the sampling frequencies, the effective sampling numbers and the numbers of the recording tracks per frame for the respective TV signals to be 4:2:1, the macro blocks for the respective TV signals can be composed in the same way; and by using the same compression rate for the respective TV signals, it is possible to commonly use a macro blocking section and a coding section which have conventionally been difficult to commonly use, so that it becomes possible to commonly use a considerable portion of the circuit for constituting a digital VTR for recording a HDTV signal, a wide TV signal and a standard TV signal.

It is noted that the sampling frequencies, the effective sampling numbers and the numbers of the recording tracks per frame for the respective TV signals described in the foregoing examples are not limited to those shown specifically therein so long as the proportional relationship thereof in the respective recording modes satisfies the predetermined ratio.

In the foregoing examples, the sampling frequencies are varied in accordance with the respective recording modes. However, the sampling frequencies of the A/D converters <b>105</b>, <b>106</b> and <b>107</b> are fixed at a minimum common multiple of the sampling frequencies corresponding to the respective recording modes, i.e., the sampling frequency for the luminance signal is fixed at 40.5 MHz in this example. However, the sampling frequency can be changed into 20.5 MHz and 10.125 MHz by performing a digital filtering processing and a pixel decimating processing in accordance with the respective recording modes.

In this example, the color difference signals are subjected to a line-sequential processing. However, even when the line-sequential processing is not performed, the same effects can be attained according to the present invention.

One segment is composed by the segmentalizer <b>2005</b> by assembling five macro blocks in this example. However, one segment can compose of any other number of macro blocks so long as the segment can be composed in the same way in the respective recording modes.

In the above description, the coding performed by the coder <b>2006</b> is an orthogonal transform. However, the same effects can be attained by performing any other coding processing according to the present invention.

In this example, the configuration of a scanner such as a disposition of the recording head <b>1005</b> on a rotational cylinder is not particularly mentioned. Any configuration can be employed so long as a ratio of the numbers of the recording tracks formed on the magnetic tape <b>1006</b> corresponds to the respective recording modes.

In this example, three kinds of video signals are recorded in the three kinds of recording modes, i.e., the HDTV signal recording mode, the 16:9 wide TV signal recording mode and the standard TV signal recording mode. However, the same effects can be attained by regarding the wide TV signal recording mode as a standard TV signal recording mode and the standard TV signal recording mode as a standard TV signal long-time recording mode.

In addition, the same effects can be attained by using two kinds of video recording signals, i.e., the HDTV signal and the standard TV signal.

It is noted that the data of the video signal recorded by the digital video signal recording apparatus of this invention can be decoded and reproduced by performing a procedure opposite to the procedure of the signal processing performed by the digital video signal recording apparatus.

Various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the scope and spirit of this invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description as set forth herein, but rather that the claims be broadly construed.