ffmpeg/doc
François Revol 0147f19856 beos/mov/adpcm patch by François Revol <revol at free dot fr>
* Some BeOS fixes:
- errno stuff
- nanosleep() replacement
- added a doc/README.beos

* mov reader still has problems with most videos (skips many chunks),
- It should now read .mov files with zlib-compressed moov headers (aka cmov)
- added SVQ1 support.
- removed mapping 'raw ' and 'yuv2' to h263, was my mistake.
- added IMA4 support. (tested)
- fixed frame rate (it reported 0 fps or something before)
- extended file probing ('wide' and 'free' atoms)
- improved .mov/.mp4 detection (or so I think)

* adpcm
* added zlib support, with header file and lib check

Originally committed as revision 780 to svn://svn.ffmpeg.org/ffmpeg/trunk
2002-07-20 20:05:50 +00:00
..
FAQ
HOWTO-STREAM * Added a note that says that WMP cannot stream .mpg files. 2002-05-17 01:54:39 +00:00
README.beos beos/mov/adpcm patch by François Revol <revol at free dot fr> 2002-07-20 20:05:50 +00:00
README.dev added regression test mention 2002-05-20 16:21:46 +00:00
README.tech update 2002-05-25 22:26:48 +00:00
TODO update 2002-05-25 22:26:48 +00:00
bench.txt
ffmpeg.txt
ffserver.conf Add the copyright/comment/author/title keywords 2002-06-05 02:19:45 +00:00
ffserver.txt update 2002-05-20 16:22:05 +00:00

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.

Audio:
-----

- The mpeg audio layer 2 compatible encoder was rewritten 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.

- The AC3 audio encoder was rewritten 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.

- The mpeg audio layer 3 decoder was rewritten from scratch. It uses
  only integers and can be 16 bit precision for the synthesis filter
  at the expense of a slight precision loss. A slower bit exact mode
  is available too for compliance testing.