Research On Related Issues Of AVS Transport Stream Multiplexing

As the development of digital audio/video compression technology, network and communication technology, it has been applicable to transmit real-time A/V information on transmission media. And all these technologies are foundation of DTV (Digital television).Several signal processing and transmission standards for audio and video have been developed by different international organizations. The standardization of AVS, which is developed by Audio Video Coding Standard Working Group of China, indicates that the audio video coding technology of China has come up to an international advanced level.Transport Stream is designed to handle errors introduced in the transmission channel, and has been adopted in the current digital TV systems. For the purpose of supporting the national standard and the project need, this paper developed a single program transport stream multiplexer for AVS.After study the AVS system layer and the key techniques in the transport stream multiplexer, some algorithms in multiplexer were designed in this paper. A T-STD (Transport stream System Target Decoder) is established in the system layer to standardize the output of the multiplexer. But none of the former multiplexer algorithms took it into consideration. The T-STD is implemented in this paper, and a simplified buffer model is established to simplify its use. After the modification and simulation control, the output transport stream of the multiplexer can strictly satisfy the T-STD uniformity. Two multiplexer modes are implemented, which are called CBR (Constants Bits Rate) and VBR (Variable Bits Rate). A algorithm based on timing mode is adopted in the interleaved strategy of CBR mode, and the PCR time is bind to the audio ES (Elementary Stream). This algorithm is simple to implement and the generated PCR are accurate enough to set the clock recovery. The TD (Time Difference) algorithm is designed in the interleaved strategy of VBR mode. TD algorithm is based on the decoding time of audio and video frames, it has higher multiplex efficiency and is suitable for MPTS( Multiple Program Transport Stream ), the audio stream and video stream come to the decoder at the same time, and thus the smooth of the audio/video is solved.