Embedded audio routing switcher

CROSS-REFERENCE TO RELATED APPLICATIONS

0001This application is a continuation of U.S. patent application Ser. No. 12/448,498 titled “EMBEDDED AUDIO ROUTING SWITCHER” and filed Jun. 22, 2009, which is based upon and claims the benefit of priority, under 35 U.S.C. §365 of International Application No. PCT/US2006/48697 filed on Dec. 20, 2006, which was published in accordance with PCT Article 21(2) on Jul. 3, 2008, in English, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

0002The present invention generally relates to switching systems and more particularly to systems and methods including a serial digital video router switching matrix with full embedded audio switching capability, which is independent from the video switching.

BACKGROUND

0003Routing switchers may also be called signal selectors, audio/video (AV) selectors or simply routers. A standard routing switcher may have multiple video and audio signals from a number of sources, such as Videotape Recorders, Media Servers, Satellite Receivers, etc. connected to the routers inputs. The router's output or outputs can go to one or more destinations, such as Videotape Recorders, Video/Audio Mixers, Video/Audio Monitors, etc. Which input connects to which output(s) may be selected by a user with the push of a button, without disconnecting/reconnecting audio and video cables.

0004In a television facility, a single program may require switching to a plurality of different channels or stations. In some situations, the audio that is embedded may not be appropriate for each channel. For example, a different language may be needed or a dubbed version of the audio track may be required. In these situations, the audio output must be switched independently from the video. A routing switcher may be employed to perform this task.

0005When constructing a signal switching infrastructure for a television facility, a choice needs to be made to use video with embedded audio as a single switching level or to use independent audio routing matrices to switch audio separately from video. The advantages of switching video with embedded audio include a substantial reduction of switching hardware and system cabling when compared with separate audio switching matrices. Many modern devices such as video tape recorders, media servers and master control switchers support video inputs and outputs with embedded audio.

0006A principal disadvantage is that conventional serial digital video switching matrices do not permit independent switching of the embedded audio streams within the video signal. This makes it difficult to combine, e.g., the video from input #1 with the audio from input #2 at an output of the switching matrix. In many facilities, especially production/post production, or where multi-channel and/or multilingual audio must be considered, this limitation has dictated the use of a separate audio switching infrastructure.

0007In the past, separate audio switching infrastructures have been employed (with the attendant increase in cost, space needed, cabling and power consumption). Hybrid systems using outboard audio embedding and de-embedding devices in conjunction with serial digital video switching matrices have also been employed. This alternative is also costly and complex to implement.

SUMMARY

0008In an aspect of the invention, an apparatus includes a separator for selectively separating audio from input signals including video with audio, a switcher for selectively transferring the input signals to at least one output, a multiplexed path for sending the separated audio signal to the at least one output, the at least one output being configured for selectively directing the input signals and separated audio signals.

0009In another aspect of the invention, an apparatus includes at least one input board configured to receive digital input signals, the digital input signals including video with embedded audio, the at least one input board including: a de-embed module configured to d-embed audio from each of the digital input signals, a time division multiplexer configured to multiplex all of the de-embedded audio to at least one output board, a crosspoint matrix configured to receive the digital input signals and transfer the digital input signals to the at least one output board, a time division multiplexed path configured to transport the de-embedded audio signals to the at least one output board separately from the digital input signals, and the at least one output board configured to route one of the digital input signals and selected de-embedded audio signals in accordance with a routing control setting.

0010In a further aspect of the invention, a method includes separating audio from input signals including video with audio, transferring selectively the input signals to at least one output, sending the separated audio signal to the at least one output, and selectively directing the input signals and separated audio signals with the at least one output.

0011In a yet further aspect of the invention, a method for routing video signals with embedded audio through a routing switcher includes receiving digital input video signals with embedded audio, de-embedding an audio portion from the digital input signals while separately maintaining the digital input signals, and time division multiplexing the audio portion of all of the digital input signals for transfer to an output stage on a time division multiplexed path. The digital input signals are transferred to the output stage separately from time division multiplexed audio signals. At least one of the digital input signals and the time division multiplexed audio signals are routed to a destination.

BRIEF DESCRIPTION OF THE DRAWINGS

0012The advantages, nature, and various additional features of the invention will appear more fully upon consideration of the illustrative embodiments now to be described in detail in connection with accompanying drawings wherein:

0013<figref idref="DRAWINGS">FIG. 1</figref> is a diagram showing an exemplary routing switcher for routing audio embedded signals in accordance with one embodiment;

0014<figref idref="DRAWINGS">FIG. 2</figref> is a block diagram showing an output stage in greater detail;

0015<figref idref="DRAWINGS">FIGS. 3A and 3B</figref> are diagrams showing an exemplary routing switcher for routing audio embedded signals where a crosspoint matrix has been adapted to provide a time division multiplexed path for separately transferred audio signals in accordance with another embodiment;

0016<figref idref="DRAWINGS">FIGS. 4A and 4B</figref> are diagrams showing another exemplary routing switcher for routing audio embedded signals where a crosspoint matrix has been adapted to provide a time division multiplexed path for separately transferred audio signals in accordance with another embodiment; and

0017<figref idref="DRAWINGS">FIG. 5</figref> is a flow diagram showing an exemplary method for routing audio embedded signals in accordance with one embodiment.

0018It should be understood that the drawings are for purposes of illustrating the concepts of the invention and are not necessarily the only possible configuration for illustrating the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

0019The present invention provides systems and methods for fully embedded audio switching capability for a serial digital video router. The serial digital video router switching matrix can provide the fully embedded audio switching independently from the video switching. The router can be employed in high definition and/or standard definition applications. By providing full independent switching of the audio signals included in the serial digital video bit-streams, reduction in cost and complexity is provided and greater flexibility is achieved in selecting input and outputs for the system.

0020It is to be understood that the present invention is described in terms of a television facility; however, the present invention is much broader and may include any audio/video system, which receives a plurality of audio and visual signals from one or more sources to be routed to one or more destinations. Content may be received by any method for example, delivered over a network, e.g., telephone, cable, computer, satellite, etc. The present invention is described in terms of a television network application; however, the concepts of the present invention may be extended to other applications, e.g., cable, satellite network, wireless and wired network types.

0021It should be understood that the elements shown in the FIGS, may be implemented in various forms of hardware, software or combinations thereof. Preferably, these elements are implemented in a combination of hardware and software on one or more appropriately programmed general-purpose devices, which may include a processor, memory and input/output interfaces.

0022The present description illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope.

0023Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.

0024Thus, for example, it will be appreciated by those skilled in the art that the block diagrams presented herein represent conceptual views of illustrative circuitry embodying the principles of the invention. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudocode, and the like represent various processes which may be substantially represented in computer readable media and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

0025The functions of the various elements shown in the figures may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (“DSP”) hardware, read-only memory (“ROM”) for storing software, random access memory (“RAM”), and non-volatile storage.

0026In the claims hereof, any element expressed as a means for performing a specified function is intended to encompass any way of performing that function including, for example, a) a combination of circuit elements that performs that function or b) software in any form, including, therefore, firmware, microcode or the like, combined with appropriate circuitry for executing that software to perform the function. The invention as defined by such claims resides in the fact that the functionalities provided by the various recited means are combined and brought together in the manner which the claims call for. It is thus regarded that any means that can provide those functionalities are equivalent to those shown herein.

0027Referring now in specific detail to the drawings in which like reference numerals identify similar or identical elements throughout the several views, and initially to <figref idref="DRAWINGS">FIG. 1</figref>, an illustrative system <b>10</b> shows a portion of the internal circuitry for a serial digital routing switcher for a television facility. System <b>10</b> includes a plurality of input boards <b>12</b> and a plurality of output boards <b>14</b>. Each input board <b>12</b> includes one or more video inputs <b>16</b>. In this example, all inputs include embedded audio. Inputs <b>16</b> preferably include serial digital video (SDV) with an embedded digital audio stream <b>15</b>, e.g., a stream conforming to the Audio Engineering Society/European Broadcasting Union (AES/EBU) Standard or AES for short. In this example, each input board provides several functions. These functions include SDV signal processing by a processor <b>19</b>. Signal processing may include many different processes. For example, signal detection, equalization of the stream, data re-clocking, etc.

0028Integrated audio de-embedding is employed for each serial digital video (SDV) input <b>16</b>. Each input board <b>12</b> de-embeds the audio (AES/EBU or simply AES) from the SDV input signal by employing a de-embed module <b>20</b>. All the de-embedded audio signals are then combined together on one or more time division multiplexed (TDM) bit-stream(s) <b>24</b> by a time division multiplexer (TDM) <b>22</b>. The TDM bitstream(s) <b>24</b> are connected directly to video switching matrix output circuits <b>26</b> on output boards <b>14</b>. The serial digital video signals with their embedded audio <b>15</b> are also connected to inputs of a video switching matrix <b>30</b>.

0029In cases where a given output needs the video with its original embedded audio signal <b>15</b>, the output of the video switching matrix <b>30</b> (e.g., a serial digital video crosspoint matrix) is connected directly to a given output (output board <b>14</b>) and the original embedded audio is simply passed through with the video <b>15</b>′. In cases where a given output (output board <b>14</b>) needs different audio signals which are embedded in the video signal, the audio is selected from the TDM stream(s) <b>24</b> by a router control system and a time division demultiplexer <b>32</b> demuxes the signals and combines the video using audio embedding circuitry <b>34</b> associated with the given output. The desired signal may be selected using the time division demultiplexer <b>32</b> on the output board <b>14</b>.

0030Audio is preferably embedded in the digital video bitstream <b>15</b> in the Horizontal Ancillary Data space in accordance with the signal format standards defined by the Society of Motion Picture and Television Engineers (SMPTE). Audio is de-embedded by module <b>20</b> by selecting the desired audio channel ancillary data from the serial digital video bit stream <b>15</b>, buffering the data, and reformatting as an AES/EBU digital audio bit stream. Video and audio signal selection is controlled by a routing switcher control system <b>52</b>. Video and audio are usually presented to the operators as separate signal levels on the routing control panels and graphical user interfaces (e.g., control <b>52</b>). This enables the operator to either select both video and audio from the same input (in which case the audio already embedded with the video is used), or the operator may select video from one input and audio from one or more alternate inputs (in which case the desired audio signals are selected from the audio TDM stream <b>24</b> and applied to an audio embedding circuit <b>34</b> of the appropriate output. A routing selection may be made by an operator, by a program or by hardware based on operating conditions or presettings.

0031In one embodiment, a first SDV signal is received with embedded audio and a second SDV signal is received from a different source. In accordance with this embodiment, the first and second signals have their audio deembedded and provided to output boards. The output boards can embed the audio from the first signal into the second signal and vice versa. Alternately, the outputted first and second signals may both be able to use the audio of the original first signal, or the outputted first and second signals may both be able to use the audio of the original second signal. Since all audio streams are available any audio or combination of audio channels can be selected and output including the SDV with fully embedded audio streams. This has many advantages and provides great flexibility in selecting output hardware for optimizing the outputs of the system for entertainment value or other reasons.

0032Referring to <figref idref="DRAWINGS">FIG. 2</figref>, output board or stage <b>14</b> includes a TDM audio demultiplexer <b>32</b>, an audio embedding circuit <b>34</b>, and a serial digital video (SDV) re-clocking circuit <b>36</b>. The SDV signal is fed from an output of the crosspoint matrix (<b>30</b>, <figref idref="DRAWINGS">FIG. 1</figref>) to the video input of the audio embedding circuit <b>34</b>. The TDM audio demultiplexer <b>32</b> receives the TDM audio stream and, under the control of the routing control system <b>52</b> (<figref idref="DRAWINGS">FIG. 1</figref>), can decode selected audio signals from the TDM audio stream and apply the audio to the audio inputs of the audio embedding circuit <b>34</b>. The audio embedding circuit <b>34</b> is directed by the router control system <b>52</b> to pass one or more channels of the audio already embedded in the SDV signal (in cases where the audio originally associated with the video is needed), or to embed one or more audio signals from the TDM audio demultiplexer <b>32</b> (in cases where different audio signals are needed). The output of the audio embedding circuit <b>34</b> includes both video and one or more channels of embedded audio; this output is applied to the SDV re-clocker module <b>36</b> which extracts a clock signal from the SDV signal and uses the clock signal to re-clock the SDV signal thereby removing jitter.

0033In another embodiment, in addition to or instead of constructing a new system with purpose-built TDM paths from inputs to outputs, it is also possible to implement the present principles in existing serial digital video switching matrices. One way of doing this may include replacing conventional input and output circuits with those including audio de-embedding, embedding and time division multiplex (TDM) bussing. The TDM busses would be distributed from the input circuits to the output circuits by dedicating existing paths in a video switching matrix for the use of TDM. This results in an equivalent system to the one schematically represented in <figref idref="DRAWINGS">FIG. 1</figref>.

0034For the approach using existing hardware, the TDM bit rate is preferably compatible with the video switching matrix, in practice either the standard definition component serial digital bit rate 270 Mb/s (64 audio channels) or the high definition component serial digital bit rate of 1.48 Gb/s (up to 352 audio channels) should be employed. Since this scheme uses some of the video routing paths for the TDM busses, the effective matrix size may be reduced. <figref idref="DRAWINGS">FIGS. 3 and 4</figref> show illustrative examples of modified router switch designs in accordance with the present principles.

0035Referring to <figref idref="DRAWINGS">FIGS. 3A, 3B, 4A, and 4B</figref>, a Grass Valley Trinix™ 128×128 matrix (<figref idref="DRAWINGS">FIGS. 3A AND 3B</figref>) and a Grass Valley Trinix™ 256×256 matrix (<figref idref="DRAWINGS">FIGS. 4A and 4B</figref>) are illustratively shown. These example devices show the possibility of including audio only inputs and outputs in the system, which can provide additional audio tracks to be combined with audio. Separate audio inputs/outputs may be employed with the embodiment shown in <figref idref="DRAWINGS">FIG. 1</figref> as well. Devices <b>200</b> and <b>220</b> can include single AES/EBU (Audio Engineering Society/European Broadcasting Union) digital audio streams or they could include TDM streams including multiple audio channels such as the 270 Mb/s and 1.485 Gb/s streams described previously or the industry standard Multichannel Audio Digital Interface (MADI) format.

0036Referring to <figref idref="DRAWINGS">FIGS. 3A AND 3B</figref>, a router <b>200</b> includes a 128×128 wideband digital crosspoint matrix <b>130</b> that is reduced to a 124×112 matrix. The reduced matrix size is employed to provide TDM paths <b>111</b> through the matrix <b>130</b>. In this embodiment, SDV with embedded audio inputs <b>15</b> include thirty-one inputs per input board <b>14</b>. Since this design includes four input boards, there are one hundred and twenty four inputs in total. In addition, audio only inputs or a TDM input stream <b>110</b> may be provided, e.g., one per board (4 total). The input <b>110</b> may include multiple audio channels such as the 270 Mb/s and 1.485 Gb/s streams for television.

0037As described above, signal processing by a processor <b>19</b> is performed and the audio is de-embedded (<b>20</b>). Time division multiplexing (<b>22</b>) is performed and may include the TDM input <b>110</b> as well as all of the de-embedded audio from signals <b>15</b>, which is placed on paths <b>111</b> and transported through the matrix <b>130</b>. The video with embedded audio signals <b>15</b>′ are also transported to the output boards <b>16</b>. In this example, four output boards <b>16</b> are available. Each output board <b>16</b> includes twenty eight outputs (total 112 outputs). The audio outputs <b>110</b>′ (AES or TDM) for this system may include four per board (16 total). The routing (<b>32</b>), embedding (<b>34</b>) and reclocking (<b>36</b>) are also performed as previously described.

0038Referring to <figref idref="DRAWINGS">FIG. 4</figref>, a router <b>220</b> includes a 256×256 wideband digital crosspoint matrix <b>132</b> that is reduced to a 248×192 matrix. The reduced matrix size is employed to provide TDM paths <b>111</b> through the matrix <b>132</b>. In this embodiment, SDV with embedded audio inputs <b>15</b> includes thirty-one inputs per input board <b>14</b>. Since this design includes eight input boards, there are two hundred and forty eight inputs in total. In addition, audio only inputs or a TDM input <b>110</b> may be provided, e.g., one per board (8 total). The input <b>110</b> may include multiple audio channels such as the 270 Mb/s and 1.485 Gb/s streams for television.

0039As described above, signal processing by a processor <b>19</b> is performed and the audio is de-embedded (<b>20</b>). Time division multiplexing (<b>22</b>) is performed and may include the TDM input <b>110</b> as well as all of the de-embedded audio from signals <b>15</b>, which is placed on paths <b>111</b> and transported through the matrix <b>132</b>. The video with embedded audio signals <b>15</b> are also transported to the output boards <b>16</b>. In this example, eight output boards <b>16</b> are available. Each output board <b>16</b> includes twenty four outputs (total 192 outputs). The audio outputs <b>110</b>′ (AES or TDM) for this system may include eight per board (64 total). The routing (<b>32</b>), embedding (<b>34</b>) and reclocking (<b>36</b>) are also performed as previously described. In <figref idref="DRAWINGS">FIGS. 3A, 3B, 4A, and 4B</figref>, the audio inputs <b>110</b> may include audio streams from any source and may be employed to provide a desired audio stream for selection by a routing control system (not shown). Matrixes <b>130</b> and <b>132</b> may be reduced by other amounts, as needed.

0040Referring to <figref idref="DRAWINGS">FIG. 5</figref>, an illustrative method for routing video signals with embedded audio through a routing switcher is depicted in accordance with one embodiment. In block <b>302</b>, digital input video signals with embedded audio (or audio only signals) are received. These signals are preferably received using an input board having a de-embed module. In block <b>304</b>, an audio portion is de-embedded from the digital input signals while separately maintaining the digital input signals (the audio only signals are maintained as well). The audio portion is time division multiplexed for alt of the digital input signals for transfer to an output stage on a time division multiplexed path in block <b>306</b>. The time division multiplexed path may include a separate bus or a path through a crosspoint matrix, where at least a portion of a crosspoint matrix is used to implement the path. A reduction in the matrix size may be employed to permit the time division multiplexed path through the matrix.

0041In block <b>310</b>, the digital input signals are transferred to the output stage separately from time division multiplexed audio signals. The digital input signals are preferably transferred using the crosspoint matrix, and are transferred with the original embedded audio. In block <b>312</b>, the time division multiplexed audio signals are demultiplexed to provide the signal to particular destinations or to simply reproduce the audio to be re-embedded with a same or different video signal In accordance with particular requirements, if needed. In block <b>314</b>, embedding a time division multiplexed audio signal into to a digital input signal or video signal may be performed to reconstitute a video signal with new embedded audio. In block <b>316</b>, reclocking may be performed, if needed, by extracting a clock signal from the SDV signal to re-clock the SDV signal thereby removing jitter.

0042In block <b>320</b>, an audio only input may be provided and configured to receive an audio signal or a time division multiplexed audio signal for transfer to the output stage. The audio only signals are available for mixing with video signals as with de-embedded audio signals. The audio only input may be received and employed at any point in the operation. In block <b>322</b>, at least one of the digital input signals and the time division multiplexed audio signals are routed to a destination from the output stage. The destination is usually selected by a routing control system, by a user, by a program, in accordance with preselected conditions, etc. For example, if an original audio stream is sent with English audio and the film is sent to a Spanish station, the Spanish audio may be preselected for a given destination from a particular output board or stage. The signals are routed to destinations based on a router control system or programmed selections (e.g., routing settings).

0043Having described preferred embodiments for an embedded audio routing switcher (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments of the invention disclosed which are within the scope and spirit of the invention as outlined by the appended claims.