Method and device for multimedia transcoding client

Multimedia transcoding client device and method

<p>The present invention relates to a device for transcoding a coded data stream, and more particularly to a portable transcoder client device and method having a universal host interface such as USB, IEEE1394, and the like. By using a portable transcoder device, transcoding of, for example, a data stream from an MPEG-2 video stream to an H.264 video stream can be converted at high speed without using the resources of the host system.</p>

<p>The use of high-capacity multimedia data such as video/audio is gradually spreading due to the development of efficient compression technology, the improvement of PC performance used by individuals, and the spread of the Internet. </p><p>As for the video/audio compression technology, the standard technology is widely distributed through standardization work. However, the compression codec continues to develop, and streams generated by various codecs coexist. This is because, even for the same content, an appropriate codec must be used according to the playback environment. Sometimes, a stream encoded by the first standard is converted to a second standard for playback. In this case, a technique for efficiently transcoding a multimedia stream between different standards is required.</p><p>In recent years, as the quality of video/audio streams has been improved day by day, even general consumers are universally demanding high-definition data streams. However, transcoding a two-hour data stream of high quality, such as a movie, is a time-consuming task unless it is a high-performance computer.</p><p>Looking at a multimedia compression standard widely used recently, a bit stream encoded according to the MPEG-2 standard is used in terrestrial digital broadcasting and high-definition video content storage media such as DVD or Bluray. Most digital broadcast receivers or personal video recorders (PVR) for digital broadcast recording currently on the market include an audio/video separator capable of decoding MPEG-2 standard bitstreams, an MPEG-2 video decoder, It has a built-in Dolby AC3 audio decoder.</p><p>In addition, a service using video content of a relatively lower quality than that of MPEG-2 is also actively provided, and mainly uses an encoded video bit stream of the H.264 standard. The IPTV service receiver made it possible to receive broadcasts through the Internet, and H.264 is also used here.</p><p>Meanwhile, with the development of computer technology and low-power technology, portable multimedia players (PMPs) are being distributed in various forms. The portable multimedia player has a small capacity memory device, a small display screen, low computing power, low network connection bandwidth, limited battery capacity, etc., so there are restrictions on the type and quality of contents that can be utilized.</p><p>The main existing multimedia information sources are a mixture of MPEG-2 and H.264 standards such as digital broadcasting, IPTV service, and DVD/Blueray, and the H.264 standard has been proven to have better compression efficiency than the MPEG-2 standard. It is expected that support of the H.264 standard will be generalized in mobile terminals such as media players. Accordingly, there is a need for a transcoding apparatus and method for converting multimedia contents of the existing MPEG-2 standard to H.264.</p><p>A basic operation of a conventional multimedia device is to decode a video bit stream existing in a storage device of the host system using a decoder in the host system and display it on the screen. Alternatively, a video bit stream received from a remote system through a network channel is decoded in the client system using a decoder and displayed on the screen.</p><p>Here, when the encoded and stored video bitstream standard is different from the bitstream standard that the decoder can decode, a transcoding technique for converting these standards is required. </p><p>Transcoding technology generates a compressed bit stream by decoding a video or audio bit stream compressed in a specific standard and encoding it again in another standard. Control functions such as video enlargement/reduction, screen rate increase/decrease, bit rate increase/decrease, audio sampling rate increase/decrease, frame size increase/decrease, bit rate increase/decrease, sound field filtering, etc. This can be added.</p><p>For example, Korean Patent Application Laid-Open No. 2008-12753 discloses a specific method for an efficient conversion technique of an encoded image. Specifically, it is a method of improving image quality by optimizing bit distribution using signal distribution for each video coding unit.</p><p>However, this does not mean that a dedicated transcoding system exists, and is limited to an efficient conversion technique for video transcoded inside a transcoder. </p><p>Meanwhile, Efficient Video Transcoding Technique for QoS-Based Home Gateway Service (J.-W. Kim, G.-R. Kwon, N.-H. Kim, A. Morales, S.-J. Ko, IEEE Trans. Consumer Electronics, Vol. 52, No. 1, pp. 129-137, Feb. 2006) reads video data from a video server in the home network and converts the bit rate according to the bandwidth of the transmission channel, and the screen size and screen A method of adjusting the rate is proposed. </p><p>On the other hand, a personal PC can be connected to various peripheral devices. Traditionally, devices such as a printer are connected using a parallel bus interface. However, such a parallel port is inconvenient to use and the size of the cable is also burdensome, so various methods have been used to replace it.</p><p>In particular, there are various interface standards using a serial bus, for example, a universal serial bus (USB), IEEE 1394, etc. are widely used.</p><p>In addition, the latest short-range wireless communication technology provides a more convenient and high-speed interface. For example, WiFi, RFID, Bluetooth, ZigBee, or IEEE 802.11 family of wireless communication protocols may be used.</p><p>These general-purpose host interfaces allow PC users to connect peripheral devices and PCs very easily, thereby reducing the inconvenience of using PC peripheral devices, and more multimedia devices are being easily connected to PCs. </p>

<solutionproblem><p>It is difficult to reproduce a multimedia data stream encoded with a high-definition video codec such as MPEG-2 in a small multimedia player such as a PMP or a mobile phone as it is. There is a limit to the memory capacity of a small device, and there is a limit to the CPU performance of the small device. Also, since small devices have a small screen size, it is possible to sufficiently reduce the resolution.</p><p>As mentioned above, H.264 is expected to be widely used in small portable multimedia devices for the time being. Therefore, individual users will need transcoding from MPEG-2 to H.264 in order to reproduce the MPEG-2 data stream that can be played on a general PC on a portable multimedia device.</p><p>A conventional transcoding device is implemented as hardware or software embedded in a host system. </p><p>Software-embedded transcoding devices are widely used and can be operated by being mounted on a host system having various types of hardware and operating systems. However, since the transcoding conversion speed may vary depending on the hardware arithmetic processing capability of the host system, high-cost hardware is required for high-speed conversion.</p><p>A hardware-embedded transcoding device can perform high-speed conversion regardless of the host system's arithmetic processing capability, but the transcoding hardware module must be designed to fit a specific bus standard and control structure inside the host system. That is, the hardware-embedded transcoding module is limited in its application to host systems of other standards, and there is a limitation in that it must be manufactured only as a dedicated device for a specific purpose including a transcoding function, not a general-purpose digital device.</p><p>The spread of portable multimedia players is rapidly increasing, and the demand for moving pictures to be played using the device is also increasing rapidly. However, in order to have a conventional software or hardware-embedded transcoding device, it is necessary to increase the performance of the host system that the user already owns, that is, a personal PC, or to purchase a device that performs a high-speed transcoding function separately, that is, a card for transcoding. There is a problem of having to pay a high cost.</p><p>To solve the above-mentioned issues, the present invention uses the structure described below. In addition, reference signs in parentheses, supplementary explanations, etc., to help the understanding of the present invention, indicate that they correspond to the embodiments described below, and do not impose any limitations on the present invention.</p></solutionproblem><meansproblemsolution><p>We propose a portable transcoding client device, method, and internal operation structure using a universal host interface that enables high-speed multimedia transcoding in combination with a low-spec host system. The present invention relates to an apparatus and method for reading video content stored in a host system through a universal host interface, converting it into video content having a different standard, and then storing it back in the host system through the same interface.</p><p>According to one aspect of the present invention, there is provided a portable transcoder device for transcoding first video/audio data stored in a host system using a universal host interface, the universal host interface used for transmitting and receiving data to and from the host system, the first video /transcoder for transcoding audio data into second video/audio data, first memory for storing all or part of first video/audio data, second for storing all or part of second video/audio data Receive and store all or part of the first video/audio data stored in the host system using the memory, and the general-purpose host interface, and control the transcoder to transcode the data stored in the first memory, , storing all or part of the transcoded second video/audio data in the second memory, There is provided a portable transcoding device including a controller for transmitting data stored in a second memory to a host system using the general-purpose host interface. </p><p>The transcoder includes a demultiplexer that separates the first video/audio data into a video signal of a first standard and an audio signal of a second standard, and a video signal transformer that transcodes the video signal of the first standard into a video signal of the third standard. A coder, an audio signal transcoder for transcoding an audio signal of the second standard into an audio signal of a fourth standard, and a video signal of one of the first and third standards and an audio signal of one of the second and fourth standards It may include a multiplexer for multiplexing. </p><p>According to another aspect of the present invention, there is provided a method comprising: transmitting first video/audio data stored in a host system to a transcoder device through a universal host interface; storing the transmitted first video/audio data in a first memory, transcoding the data in the first memory into second video/audio data, storing the second video/audio data in a second memory; and transmitting the data of the second memory to the host system through the universal host interface.</p><p>The transcoding step includes demultiplexing the first video/audio data into a video signal of a first standard and an audio signal of a second standard, and transcoding the video signal of the first standard into a video signal of a third standard. , transcoding an audio signal of the second standard into an audio signal of a fourth standard, and multiplexing a video signal of one of the first standard and the third standard with an audio signal of one of the second standard and the fourth standard may include. </p><p>The above and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention with reference to the accompanying drawings.</p></meansproblemsolution><effectiveness><p>The present invention enables transcoding using only the hardware and firmware inside the device regardless of the arithmetic processing capability of the host system, thereby enabling high-speed transcoding even when connected to a host system with low arithmetic processing capability. can Therefore, individual PC users do not need to purchase expensive PC equipment or dedicated hardware for transcoding built into the PC just for transcoding.</p><p>In addition, this device can be configured as an independent type transcoder client device having a universal host interface without being dependent on any host system. Therefore, it can be applied to any host system having the same general-purpose interface, enabling transcoding regardless of the bus standard and control structure inside the host system. Therefore, it can be applied to any host system having a general-purpose interface.</p></effectiveness>

<p>1 shows the configuration of a transcoder device of the present invention. </p><p>The transcoder device has a universal host interface and can be physically or logically connected to a host system supporting the same universal host interface standard. A device driver and firmware may be provided as necessary for use of the transcoder device. The firmware may be embedded in the transcoder device, and the device driver may be pre-installed on the host system.</p><p>For the operation of the transcoder device, the host system supplies the transcoding input video bit stream to the device, provides a user interface for setting video and audio transcoding control coefficients, sets the control registers inside the device, Receives the transcoded video bit stream and stores it in a storage medium inside the host system. </p><p>These operations are simple control functions that do not require high-speed arithmetic processing capability, and can be performed in real time even in a low-performance host system. The processing load required for transcoding is placed on the transcoder device of the present invention, which will be external to the host system.</p><p>A transcoding host unit resides in the memory of the host system, and it is possible to control transcoding through a general-purpose host interface. Such control may be realized through a user interface or the like. Installation of the user interface may be performed automatically upon connection of the transcoder device, or may be pre-installed.</p><p>In the host system, for example, first video/audio data according to a first encoding standard such as MPEG-2 is stored, and the present transcoder device converts the first video/audio data to a second video/audio data such as H.264, for example. It is transcoded into the second video/audio data according to the encoding standard. </p><p>The first video/audio data input bit string is transmitted to the transcoder device through the universal host interface and stored in the input bit string storage unit which is a temporary memory. The temporary memory may serve as a buffer before the data bit stream is input to the transcoder. Alternatively, a large-capacity memory may be provided to store files requiring transcoding in advance, and transcoding may be reserved.</p><p>2 shows a detailed configuration of a transcoder. </p><p>The transcoding apparatus includes a video/audio demultiplexer to extract a video signal encoded in the first standard and an audio signal encoded in the second standard from the data bit stream. This is to satisfy various needs of users by allowing the user to set the target of transcoding in detail. For example, in the case of a video material for a language course, it is possible to transcode a video signal in low quality and an audio signal in high quality.</p><p>The transcoding control unit receives the transcoding control coefficients from the host system, and adjusts the aspect ratio, screen size, and quality (or target bit rate) of the video signal to match the transcoding control coefficient to generate a transcoded video signal. Based on the video coding rate control coefficient set by the host system, it is possible to enlarge/reduce the screen size, increase/decrease the screen rate, or increase/decrease the bit rate when converting the video compression standard.</p><p>The aspect ratio/screen size adjusting unit adjusts the aspect ratio and screen size of the video signal of the first standard extracted according to the control coefficient received from the transcoding control unit. In addition, the bit rate control unit adjusts the bit rate according to the control coefficient received from the transcoding control unit.</p><p>The transcoding control unit also controls the bit rate while transcoding the audio signal with a value specified in the transcoding control coefficient. That is, based on the audio coding rate control coefficient set by the host system, when converting the audio compression standard, the sampling rate is increased/decreased, the audio frame size is increased/decreased, the bit rate is increased/decreased, or the sound field filtering is performed. it is possible to do The audio encoding rate control unit adjusts the encoding rate of the audio signal to be transcoded according to the control coefficient received from the transcoding control unit.</p><p>That is, the extracted video signal of the first standard is transcoded into a video signal of the third standard by the third standard video encoder after adjusting the aspect ratio, screen size, bit rate, etc., and then transmitted to the audio/video multiplexer. The audio signal of the second standard is transcoded into the audio signal of the fourth standard in the fourth standard audio encoder unit by adjusting the encoding rate, and is transmitted to the audio/video multiplexer. Both the audio signal and the video signal may be transcoded, and only one of the two signals may be transcoded.</p><p>The encoded audio and video signal bit streams are multiplexed and temporarily stored in an output bit stream storage unit, which is a temporary memory, and transmitted back to the host system. </p><p>Accordingly, the host system can store the transcoded video/audio data without using resources such as the CPU of the host system. </p><p>While the present invention has been particularly shown and described with reference to preferred embodiments, it will be appreciated by those skilled in the art that various modifications may be made within the spirit and scope of the appended claims in form and detail without departing from the spirit and scope of the invention. they must understand </p>

<p>According to the present invention, since high-speed conversion of MPEG-2 video to H.264 video is possible in a low-spec desktop/laptop computer, even users with low-end PCs can be included as service targets for high-definition video. </p><p>In addition, it is possible to reduce the cost of storing digital broadcasting received in the MPEG-2 standard by applying it to a digital broadcasting receiver, a personal video recorder (PVR), and the like. </p><p>Since it can become an essential device for securing content to be played on a portable multimedia player (PMP), it is expected that the market will rapidly expand worldwide along with the spread of the PMP market.</p>