mirror of https://git.ffmpeg.org/ffmpeg.git
f359a5bed8
Originally committed as revision 456 to svn://svn.ffmpeg.org/ffmpeg/trunk |
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| FAQ | ||
| HOWTO-STREAM | ||
| README.dev | ||
| README.tech | ||
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| bench.txt | ||
| ffmpeg.txt | ||
| ffserver.conf | ||
| ffserver.txt | ||
README.tech
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. NEW: now motion compensation is done with several methods : none, full, log, and phods. The code is mmx/sse optimized. - 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.