Video codec technology knowledge summary
2020-06-06 05:15:16
With the increasing use of digital multimedia, video decoding becomes an essential element in the design of embedded systems. There are many video standards, depending on one or more standards that the product can implement. Of course, this is not all. Video is only part of the multimedia stream. In addition, audio or speech needs to be processed in parallel. Therefore, an accurate synchronization layer that handles storage or data flow is required. In addition, video decoding itself has high performance requirements and needs to be different from the previous system architecture based on voice and information applications; this poses special challenges for portable systems, and desktop applications also face these problems.
Video coding technology is the initial condition for the development of network television. Only efficient video coding can guarantee the provision of video services in the real Internet environment. In addition to the video coding standards developed by ITU-T and ISO/IEC, two international standardization organizations, Microsoft Corporation of America and Real Network have their own video coding standards. In fact, they are also commonly used Internet TV standards.
And a common video codec standard <br> <br> Joint Video Team (Joint Video Team, JVT) of the ITU Video Coding Experts Group (Video Coding Experts Group, VCEG) and ISO / IEC Moving Picture Experts Group (Moving Picture Experts Group, MPEG). VCEG develops voluntary standards for advanced mobile image coding for session and non-conversation audio/video applications. MPEG develops international standards for the compression, encoding, decompression, processing, etc. of moving images, audio and a combination of both to meet various applications. In summary, JVT has developed the most popular video standards including ITU H.262/MPEG2 and H.264/MPEG-4 AVC.
MPEG-2 Video/H.262: MPEG 2 (ISO/IEC 13818-2), also known as ITU-T H.262, is the most widely used video coding standard for consumer electronic video equipment. MPE2 video is used for digital television broadcasting: including terrestrial, cable and direct satellite broadcasting. It can achieve 720x576 pixel imaging at a fixed frame rate of 25 fps (Pal) or 30 fps (NTSC). In addition, it is also a necessary codec in DVD video.
MPEG-4-SP/ASP: ISO/IEC 14496-2 describes the MPEG4 Simple Profile (SP)/Advanced Simple Profile (ASP). Among them, SP is used for next generation portable terminal and narrow band Internet. While ASP has added several tools, the coding efficiency has increased by 1.5 to 2 times. Both of them have gained more and more acceptance in the market.
MPEG-4-AVC/ITU-TH.264: Advanced Video Coding (AVC) is a multimedia standard developed by the Joint Technical Committees of ISO/MPEG and ITU-T. AVC provides higher compression ratio, better video quality and higher fault tolerance than MPEG2, and is expected to be used for Internet broadcasting and mobile communication.
Windows Media Video (WVM)/SMPTEVC-1: WMV9 is Microsoft's multimedia standard. Its features include support for streaming, variable bit rate, and fault tolerance tools comparable to MPEG-4-AVC/H.264. In addition to its use in home computers, WMV9 is currently also used in digital cinema projections. The encoding used in the movie can be a constant bit rate CBR of 7 to 12 Mbps or a variable bit rate VBR and reaches a DVE resolution (720x480).
When used only for audio playback - such as a typical MP3 player, a single DSP solution can also be used. In this system, DSP performs audio decoding, file/stream data processing, and also controls the keyboard, display, and memory at the same time. Because DSPs handle audio decoding more efficiently, using a ZSP 400 DSP instead of a microcontroller can significantly reduce power consumption. In addition, DSP-based solutions can be software upgraded to support more intensive audio standards (such as aac Plus), where the microcontroller may not be able to handle the additional load.
Video mobile phone: The video size of this type of application is QCIF or CIF, and the frame rate is from 10 to 30 frames per second. The need to support multiple video/audio decoding standards depends on the functional requirements of the phone. The video will be streaming video or short video sequence playback. Software decoding without additional hardware can meet the performance requirements of these devices. And most phones integrate microcontrollers and DSPs, so video decoding can be done with DSPs, which also makes low power compact systems possible. Other phones may contain some features of PMPs or digital video cameras. A pure DSP design cannot meet the requirements. This requires additional hardware acceleration.
Video Desk Phone: This device provides video conferencing capabilities that require encoding and decoding under strong real-time restrictions. If the frame size and frame rate are limited, a single DSP solution is still feasible. However, most desktop phones have a QVGA or larger display; in addition, users generally expect better voice/video quality than wireless mobile devices. This means that the frame rate should be higher, the frame drop rate/card frame rate should be as low as possible, and a hardware solution may be needed to complete the video codec. The speech codec can be implemented by a low-cost DSP (such as ZS Pneo) or a microcontroller in the system.
Mobile Digital Video Camera (DVR): For this type of device, multi-standard codecs are not necessary, and most use only a single video codec standard. Due to the demanding requirements of large size, high frame rate and low power consumption, pure hardware solutions are usually preferred. Instead of a DSP, the system microcontroller is used to drive the video and audio hardware modules.
Set top box: The set top box needs to complete the processing of high quality video streams and the decoding of recorded video files. Like DVRs, the video quality requirements (frame size, frame rate, bit rate, and fault tolerance) make it almost impossible to do with hardware decoding. Of course, because unlike mobile devices, which are as demanding as power consumption requirements, multiple DSP cores can be used with some basic hardware acceleration schemes to design systems that can handle a variety of video codecs. Depending on the functional requirements, the set-top box may require some flexibility: in particular, it is used in the field of media players, digital VCRs or network streaming media. At this time, the software in DSP can be used to process audio. In order to realize this kind of flexibility, we must choose different codecs to complete the functions of playback, encoding, decoding and so on. At this time, the DSP used for audio processing will be a high-performance processor such as ZSP500 to meet the latest needs of home theater. The trend of the surrounding sound, sound processing and other functional requirements.
The design of an embedded system depends on the specific target application. Comprehensive considerations of software flexibility, power consumption, and performance determine the best configuration solution. The application is very extensive, and the solution reflects the needs of different applications. Some applications require low power consumption while others require flexibility and/or high performance. DSPs provide good performance and low power consumption while adding flexibility; they are perfectly suited for a variety of applications. Because the entire multimedia solution (audio/video codec and audio/video synchronization) can be easily integrated into existing and new systems as a single module; this will enable a large number of complex problems to be solved once and reused multiple times later, thus reducing The development costs and overall development time of systems using multimedia modules.
Video coding technology is the initial condition for the development of network television. Only efficient video coding can guarantee the provision of video services in the real Internet environment. In addition to the video coding standards developed by ITU-T and ISO/IEC, two international standardization organizations, Microsoft Corporation of America and Real Network have their own video coding standards. In fact, they are also commonly used Internet TV standards.
And a common video codec standard <br> <br> Joint Video Team (Joint Video Team, JVT) of the ITU Video Coding Experts Group (Video Coding Experts Group, VCEG) and ISO / IEC Moving Picture Experts Group (Moving Picture Experts Group, MPEG). VCEG develops voluntary standards for advanced mobile image coding for session and non-conversation audio/video applications. MPEG develops international standards for the compression, encoding, decompression, processing, etc. of moving images, audio and a combination of both to meet various applications. In summary, JVT has developed the most popular video standards including ITU H.262/MPEG2 and H.264/MPEG-4 AVC.
MPEG-2 Video/H.262: MPEG 2 (ISO/IEC 13818-2), also known as ITU-T H.262, is the most widely used video coding standard for consumer electronic video equipment. MPE2 video is used for digital television broadcasting: including terrestrial, cable and direct satellite broadcasting. It can achieve 720x576 pixel imaging at a fixed frame rate of 25 fps (Pal) or 30 fps (NTSC). In addition, it is also a necessary codec in DVD video.
MPEG-4-SP/ASP: ISO/IEC 14496-2 describes the MPEG4 Simple Profile (SP)/Advanced Simple Profile (ASP). Among them, SP is used for next generation portable terminal and narrow band Internet. While ASP has added several tools, the coding efficiency has increased by 1.5 to 2 times. Both of them have gained more and more acceptance in the market.
MPEG-4-AVC/ITU-TH.264: Advanced Video Coding (AVC) is a multimedia standard developed by the Joint Technical Committees of ISO/MPEG and ITU-T. AVC provides higher compression ratio, better video quality and higher fault tolerance than MPEG2, and is expected to be used for Internet broadcasting and mobile communication.
Windows Media Video (WVM)/SMPTEVC-1: WMV9 is Microsoft's multimedia standard. Its features include support for streaming, variable bit rate, and fault tolerance tools comparable to MPEG-4-AVC/H.264. In addition to its use in home computers, WMV9 is currently also used in digital cinema projections. The encoding used in the movie can be a constant bit rate CBR of 7 to 12 Mbps or a variable bit rate VBR and reaches a DVE resolution (720x480).
When used only for audio playback - such as a typical MP3 player, a single DSP solution can also be used. In this system, DSP performs audio decoding, file/stream data processing, and also controls the keyboard, display, and memory at the same time. Because DSPs handle audio decoding more efficiently, using a ZSP 400 DSP instead of a microcontroller can significantly reduce power consumption. In addition, DSP-based solutions can be software upgraded to support more intensive audio standards (such as aac Plus), where the microcontroller may not be able to handle the additional load.
Video mobile phone: The video size of this type of application is QCIF or CIF, and the frame rate is from 10 to 30 frames per second. The need to support multiple video/audio decoding standards depends on the functional requirements of the phone. The video will be streaming video or short video sequence playback. Software decoding without additional hardware can meet the performance requirements of these devices. And most phones integrate microcontrollers and DSPs, so video decoding can be done with DSPs, which also makes low power compact systems possible. Other phones may contain some features of PMPs or digital video cameras. A pure DSP design cannot meet the requirements. This requires additional hardware acceleration.
Video Desk Phone: This device provides video conferencing capabilities that require encoding and decoding under strong real-time restrictions. If the frame size and frame rate are limited, a single DSP solution is still feasible. However, most desktop phones have a QVGA or larger display; in addition, users generally expect better voice/video quality than wireless mobile devices. This means that the frame rate should be higher, the frame drop rate/card frame rate should be as low as possible, and a hardware solution may be needed to complete the video codec. The speech codec can be implemented by a low-cost DSP (such as ZS Pneo) or a microcontroller in the system.
Mobile Digital Video Camera (DVR): For this type of device, multi-standard codecs are not necessary, and most use only a single video codec standard. Due to the demanding requirements of large size, high frame rate and low power consumption, pure hardware solutions are usually preferred. Instead of a DSP, the system microcontroller is used to drive the video and audio hardware modules.
Set top box: The set top box needs to complete the processing of high quality video streams and the decoding of recorded video files. Like DVRs, the video quality requirements (frame size, frame rate, bit rate, and fault tolerance) make it almost impossible to do with hardware decoding. Of course, because unlike mobile devices, which are as demanding as power consumption requirements, multiple DSP cores can be used with some basic hardware acceleration schemes to design systems that can handle a variety of video codecs. Depending on the functional requirements, the set-top box may require some flexibility: in particular, it is used in the field of media players, digital VCRs or network streaming media. At this time, the software in DSP can be used to process audio. In order to realize this kind of flexibility, we must choose different codecs to complete the functions of playback, encoding, decoding and so on. At this time, the DSP used for audio processing will be a high-performance processor such as ZSP500 to meet the latest needs of home theater. The trend of the surrounding sound, sound processing and other functional requirements.
The design of an embedded system depends on the specific target application. Comprehensive considerations of software flexibility, power consumption, and performance determine the best configuration solution. The application is very extensive, and the solution reflects the needs of different applications. Some applications require low power consumption while others require flexibility and/or high performance. DSPs provide good performance and low power consumption while adding flexibility; they are perfectly suited for a variety of applications. Because the entire multimedia solution (audio/video codec and audio/video synchronization) can be easily integrated into existing and new systems as a single module; this will enable a large number of complex problems to be solved once and reused multiple times later, thus reducing The development costs and overall development time of systems using multimedia modules.
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