gecko-dev/media/ffvpx/README_MOZILLA

This directory contains files used in gecko builds from FFmpeg
(http://ffmpeg.org). The current files are from FFmpeg as of
revision n3.4-1-g587fadaef1
All source files match their path from the library's source archive.

Currently, we only use the vp8 and vp9 portion of the library, and only on x86
based platforms. If this changes, configuration files will most likely
need to be updated.

AVX2 must be disabled on Linux due to the use of yasm 1.1 on the build bots.
Once yasm is upgraded to 1.2 or later, AVX2 code could be re-enabled.
Add --disable-avx2 to configure on those platforms.

configuration files were generated as follow using the configure script:
./configure --disable-everything --disable-protocols --disable-demuxers --disable-muxers --disable-filters --disable-programs --disable-doc --disable-parsers --enable-parser=vp8 --enable-parser=vp9 --enable-decoder=vp8 --enable-decoder=vp9 --disable-static --enable-shared --disable-debug --disable-sdl2 --disable-libxcb --disable-securetransport --disable-iconv --disable-swresample --disable-swscale --disable-avdevice --disable-avfilter --disable-avformat --disable-d3d11va --disable-dxva2 --disable-vaapi --disable-vda --disable-vdpau --disable-videotoolbox --enable-decoder=flac --enable-asm --enable-yasm

config*:
replace: /HAVE_(MALLOC_H|ARC4RANDOM|LOCALTIME_R|MEMALIGN|POSIX_MEMALIGN)/d

config_darwin32.h:
add to configure command: --disable-asm --disable-yasm --cc='clang -m32'

config_unix32.h:
add to configure command: --disable-asm --disable-yasm --cc='clang -m32'
replace: s/HAVE_SYSCTL 1/HAVE_SYSCTL 0/ and s/HAVE_MEMALIGN 1/HAVE_MEMALIGN 0/ and s/HAVE_POSIX_MEMALIGN 1/HAVE_POSIX_MEMALIGN 0/


config_unix64.h/config_unix64.asm:
replace: s/HAVE_SYSCTL 1/HAVE_SYSCTL 0

config_win32/64.h/asm:
add to configure command: --toolchain=msvc

Regenerate defaults_disabled.{h,asm} with:
$ grep -E ".*_(INDEV|OUTDEV|DECODER|ENCODER|DEMUXER|MUXER|PARSER|FILTER|HWACCEL|PROTOCOL|ENCODERS|DECODERS|HWACCELS|INDEVS|OUTDEVS|FILTERS|DEMUXERS|MUXERS|PROTOCOLS) 0" config.h > ~/Work/Mozilla/mozilla-central/media/ffvpx/defaults_disabled.h
$ grep -E ".*_(INDEV|OUTDEV|DECODER|ENCODER|DEMUXER|MUXER|PARSER|FILTER|HWACCEL|PROTOCOL|ENCODERS|DECODERS|HWACCELS|INDEVS|OUTDEVS|FILTERS|DEMUXERS|MUXERS|PROTOCOLS) 0" config.asm > ~/Work/Mozilla/mozilla-central/media/ffvpx/defaults_disabled.asm

All new decoders/muxers/encoders/... should be added in the list of dummy functions found in libavcodec/dummy_funcs.c
otherwise linkage will fail on Windows. On other platforms they are optimised out and aren't necessary.
The GNU comm utility is a useful tool to compare and extract only the changes.

To update the source tree, perform a diff on the files listed in FILES.
The diffs should typically apply to the ffvpx tree.
e.g. something like this would do:
Run in the ffmpeg original tree:
$ for i in `cat $PATH_CENTRAL/media/ffvpx/FILES`; do diff $REV_LASTSYNC HEAD >> patch.diff; done
Then apply patch.diff on the ffvpx tree.

Compilation will reveal if any files are missing.