Dynamic Bit Allocation for Video Conferencing

Benjamin Pugliese <pugliese@andrew.cmu.edu>
Matthew Richey <mr6v@andrew.cmu.edu>
Mahesh Saptharishi <mahesh@andrew.cmu.edu>
 

Goals:

• Get H.263v2 decoder to work in real-time
• Add tunable parameters for audio
• Put audio over the network
• Add enhancements to control layers to accommodate user specified quality requirements
• Be able to specify a set of quality requirements so that the system automatically adapts to meet the demands of the user

Accomplishments:

• Frame grabbing using Video for Windows
• Raw audio inputted and outputted to sound card
• Datagram socket interface written
• H.263v2 encoder and decoder modified to take real-time video and work independantly
• ADPCM audio compression implemented (4:1 compression ratio)
• Compressed video remotely displayed
• Audio quantization implemented
• Quantized audio remotely played
• Real-time adjustment of video quantization and audio quantization enabled
• Remote control of video and audio parameters implemented

Shortcomings:

• Dynamic bit allocation not fully explored
• System not stable
• Audio is choppy when put over the network
• Adjustment of video and audio parameters not intuitive

Conclusions:

Software interfaces to hardware continued to be problematic throughout this project. Determining an appropriate way to trade off parameters was a difficult problem, which was not fully solved.

Code:

Find a compressed copy of our code here. All code was developed using Microsoft Visual C++ 6.0. Some bugs still exist, mostly when audio and video portions run simultaneously for a long duration.