README.tech
上传用户:jxp0626
上传日期:2007-01-08
资源大小:102k
文件大小:2k
- Technical notes:
- ---------------
- Video:
- -----
- - The decision intra/predicted macroblock is the algorithm suggested
- by the mpeg 1 specification.
- - only Huffman based H263 is supported, mainly because of patent
- issues.
- - MPEG4 is supported, as an extension of the H263 encoder. MPEG4 DC
- prediction is used, but not AC prediction. Specific VLC are used for
- intra pictures. The output format is compatible with Open DIVX
- version 47.
- - MJPEG is supported, but in the current version the huffman tables
- are not optimized. It could be interesting to add this feature for
- the flash format.
- - To increase speed, only motion vectors (0,0) are tested for real
- time compression.
- - In high quality mode, full search is used for motion
- vectors. Currently, only fcode = 1 is used for both H263/MPEG1. Half
- pel vectors are used.
- I also plan to improve the bitrate control which is too simplistic.
- Audio:
- -----
- - I rewrote the mpeg audio layer 2 compatible encoder from scratch. It
- is one of the simplest encoder you can imagine (800 lines of C code
- !). It is also one of the fastest because of its simplicity. There
- are still some problems of overflow. A minimal psycho acoustic model
- could be added. Currently, stereo is supported, but not joint
- stereo.
- - I rewrote the AC3 audio encoder from scratch. It is fairly naive,
- but the result are quiet interesting at 64 kbit/s. It includes
- extensions for low sampling rates used in some Internet
- formats. Differential and coupled stereo is not handled. Stereo
- channels are simply handled as two mono channels.