A research MPEG-1 decoder written using Qt as the platform framework for portability by Darren R. Starr submux at gmail

This project contains an MPEG-1 decoder which was originally ported from the research project published at : http://www.developer.nokia.com/Community/Wiki/MPEG_decoder_in_Java_ME

The decoder presented by Nokia was originally written in Java, but I have ported to C++ as a step towards making a parallel decoder while writing an article on WebCL. I am using C++ in order to make use of encapsulation that will assist in identifying and classifying the scopes of the variables as they would be used in an OpenCL implementation.

I know that I still am experiencing several bugs in the decoder since when I compare my output to the output of other decoders, there are blocking artifacts. I have chosen to ignore them at this time as much of the code responsible for this will be rewritten to support floating point instead of fixed point as there is no benefit and possible disadvantages to using integer mathematics on the graphics card. OpenGL sees colors as floating point values and therefore using fixed point adds an unnecessary conversion step as well.

TODO short-term :

• Convert the image format to floating point
• Implement floating point DCT
• Redesign parser to be push based
• Isolate slice decoding from picture decoding
• Isolate block parsing from block processing
• Isolate all variable scopes from any point higher than where they're used
• Break motion vectors into a finer granularity of operations (separate functions for vertical half pel vs. horizontal half pel for example).
• Replace InputBitstream with a smaller buffer based model.
• Move start code based parsing into the application

TODO long-term :

• Replace each function (all of them) with an OpenCL kernel
• Use QOpenCL to make a test app for pushing OpenCL data to the kernels
• Queue each sequence decoder, Sequence header + GOP headers
• Queue each each picture decoder dependent on GOP header decoding
• Queue each slice decoder dependent on picture header decoding
• For each macroblock parsed, queue a block processor which performs motion-compensation, DCT and correction.
• For each DCT operation, implement in parallel using parallel vector operations in OpenCL-C (float4 for example).
• Upon completion of block decoding signal the slice decoder.
• Upon all blocks decoded, slice decoder should signal picture decoder
• Upon all slices decoded, picture decoder should signal OpenGL output queue
• Implement an OpenGL context for display. OpenCL would be ideal for color conversion, alternatively, I have used fragment shaders for this in the past in GLSL, they're fine so long as there's no need for interlace support.