Our client is a US based designer and developer of collaborative audio/ video computing systems. eInfochips has developed an audio/ video streaming application based on TI’s DM642 platform.

Application Overview

This application allows users to play video files on a PC browser or TV. The application finds selected video and audio files on local storage or from remote servers and transports it over PCI/ Ethernet to the set-top-box (Based on TI DM 642 Platform). The DSP decompresses and synchronizes the audio/ video files and plays it on a TV.

The application streams user specified H.264 encoded video files with MP3/ PCM audio to TI’s DM642 hardware for playback over the audio/ video ports. The PC application also provides an API interface for the web browser to pass the files to be played.

Features

• DSP application for live streaming of Audio/ Video data based on TI’s DM642 based hardware
• Integration of MP3 Audio Codec and H. 264 Video Codec
• Synchronization of audio and video at the time of play, separate audio and video files
• Well synchronized interfaces and applications for better utilization of CPU resources

The application is divided into 2 basic components, the host component and the DSP component

Host Component

The Host component exports an API to play, stop, pause, rewind & fast-forward. The host, after receiving the audio/ video files from the HTML application, reads one video frame of data from the video file and an equivalent audio data from audio file, and streams it over the PCI interface to the DSP component. It then waits for an acknowledgement from the DSP.

DSP Component

The DSP side application reads the audio/ video data over the PCI interface, decompresses it and passes it to the respective audio/ video drivers after synchronizing them.

The Challenges

One of the challenges was to transfer the video data (640X480 @24 fps) at the rate of 2.5 Mbps and audio data (48 KHz, stereo) at the rate of 1.5 Mbps, over the PCI interface and decompress (using H.264 decompression algorithm) it before it could be played. This large amount of data handling required an efficient design of the DSP application to make full utilization of CPU power and its peripherals, and reduction in number of data copies.

Since both the audio and video were available as two separate files without any synchronization stamps, the synchronization at the time of play was a big challenge. Not just the synchronization between audio and video but synchronization of audio/ video with time was also a challenge.

Conclusion

With proper synchronization between interfaces, application of various hardware devices and multiple audio / video algorithms, eInfochips’ team delivered the complete solution in time achieving the desired performance.