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diff --git a/media/ffvpx/README_MOZILLA b/media/ffvpx/README_MOZILLA new file mode 100644 index 0000000000..b90d6020b5 --- /dev/null +++ b/media/ffvpx/README_MOZILLA @@ -0,0 +1,147 @@ +# FFVPX + +This directory contains files used in gecko builds from FFmpeg +(http://ffmpeg.org). The current files are from FFmpeg as of +revision fed07efcde72824ac1ada80d4af4e91ac4fcfc14 +git clone https://git.ffmpeg.org/ffmpeg.git ffmpeg +git checkout fed07efcde72824ac1ada80d4af4e91ac4fcfc14 + +All source files match their path from the library's source archive. + +Currently, we only use the vp8, vp9, av1 (libdav1d), mp3, and flac portion of +the library. If this changes, configuration files will most likely need to be +updated. Decoding AV1 via libdav1d is supported, although the decoder +(libdav1d) is vendored separately, `ffvpx` only contains the code to use `libdav1d` through the `ffmpeg` API. + +The ffmpeg project recommends to use ffmpeg's tip, not a particular release. + +## Source files + +This library only use a small part of `ffmpeg`. To update the source tree, run: + +> rsync -av --existing ffmpeg-upstream ffmpeg-mozilla-dir + +Compilation will reveal if any files are missing. + +Then, make sure the files: + +- `libavcodec/codec_list.c` +- `libavcodec/bsf_list.c` +- `libavcodec/parser_list.c` + +include conditional compilation directives, by probably reverting them (or +reverting and adjusting them if new codecs are added). + +## `config.h` generation + +Configuration files are generated as follow using the configure script (here +for Linux desktop): + +> ./configure --disable-all --enable-avcodec --enable-decoder=vp8,vp9,mp3,flac,av1 \ + --enable-parser=vp8,vp9 --disable-static --enable-shared \ + --disable-autodetect --disable-iconv --enable-libdav1d --disable-linux-perf + +For Linux Desktop, there are a number of overrides in `config_common.h` for +VAAPI. We can't put them in `config_components.h` because this breaks the build. + +`config_components.h` is common to all platforms, and then a specific config +file is included, based on the platform and architecture. This needs to be +regenerated on all OSes. macOS is similar to Linux Desktop. For other OSes, +instructions below: + +# Linux 32-bits from a Linux 64-bits host: + +To produce `config_unix32.h` on a 64-bits machine, add to the configure command +above: `--disable-asm --disable-x86asm --cc='clang -m32'` + +Those files shouldn't be Linux-specific, and are included in e.g. various BSDs, +hence the `--disable-linux-perf` above. + +# macOS, x86 and aarch64 + +Similar to Linux Desktop in all aspects. + +# Android + +config_android32.h: Only mp3 and flac are enabled on this platform. Assuming +the standard toolchain location for a Firefox Developer, substitute with the +ndk version in use when updating: + +> ./configure --disable-all --enable-avcodec --enable-decoder=mp3,flac \ + --disable-static --enable-shared --disable-autodetect \ + --enable-small --target-os=linux --arch=arm --enable-cross-compile \ + --cc=$HOME/.mozbuild/android-ndk-r20/toolchains/llvm/prebuilt/darwin-x86_64/bin/armv7a-linux-androideabi16-clang + +config_android64.h, config_androidx86_64.h: substitute with aarch64 and the right compiler. + +For config_androidx86_64.h, enable vp8 and vp9. + +# Windows + +The general idea is to get an msys prompt with an msvc toolchain +configured, so that the configure script for ffmpeg can run successfully +with the thread flavor Gecko prefers on Windows (win32, not pthreads). + +- Open Visual Studio (2019 when writing this) +- Tools → Command Line → Developer command prompt +- Check that compiling a small C program with cl.exe works +- Install msys2 from https://www.msys2.org/ +- From the Visual Studio Developer Command Prompt, run the following: + > C:\msys64\msys_shell.cmd -mysy -use-full-path +- This pops up a new shell window, with a 32-bits build environment +- Check that compiling a small C program with `cl.exe` works +- Run ffmpeg's ./configure with the options needed: + +> ./configure --disable-all --enable-avcodec + --enable-decoder=vp8,vp9,mp3,flac --enable-parser=vp8,vp9 + --disable-static --enable-shared --disable-autodetect + --enable-w32threads --toolchain=msvc + +- Copy `config.h` and `config.asm` as `config_win32.h` and `config_win32.asm` + in this directory +- Close the `msys2` window, go back to the `cmd.exe` window +- Run this command, maybe substituting the Visual Studio version: + +> "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvarsall.bat" amd64 + +- This pops up a new shell window, now with a 64-bits build + environment +- Check that compiling a small C program with `cl.exe` works +- Run ffmpeg's `./configure` with the options needed: + +> ./configure --disable-all --enable-avcodec --enable-decoder=vp8,vp9,mp3,flac + --enable-parser=vp8,vp9 --disable-static --enable-shared + --disable-autodetect --enable-w32threads --toolchain=msvc + +- Copy `config.h` and `config.asm` as `config_win64.h` and `config_win64.asm`. + +config_aarch64_win64.h: You will need to install cpp (either using msys or +wsl), then: + +> ./configure --disable-all --enable-avcodec --enable-decoder=vp8,vp9,mp3,flac \ + --enable-parser=vp8,vp9 --disable-static --enable-shared \ + --disable-autodetect --toolchain=msvc --enable-cross-compile \ + --target-os=win32 --arch=arm64 + + +# Finally + +Run the following command on all config* file: + +> sed -i -E '/HAVE_(MALLOC_H|ARC4RANDOM|LOCALTIME_R|MEMALIGN|POSIX_MEMALIGN)/d' config.* + +to avoid redefined macros. + +# Build, fix errors + +Missing files need to be added, and the patch to rename `time.h` to `fftime.h` +might need to be reaplied or extended to other files including `time.h`. The +issue being that it's included instead of the system header, causing all sorts +of issues. + +`moz.build` files might need to be modified as well, in light of compilation +and link errors. + +There are going to be a lot of changes in terms of symbols exported. Adjust +`libavutil/avutil.symbols` and `libavcodec/avcodec.symbols` by removing and +adding symbols until the build passes. |