# FFmpeg Packaged for Zig

This is a fork of [ffmpeg](https://ffmpeg.org/), packaged for Zig. Unnecessary
files have been deleted, and the build system has been replaced with
`build.zig`.

There are no system dependencies; the only thing required to build this package
is [Zig](https://ziglang.org/download/).

Zig API bindings are also provided via the "av" module. See `doc/examples` for
API usage examples.

## Usage

```
zig fetch --save=ffmpeg https://github.com/allyourcodebase/ffmpeg/archive/refs/tags/7.0.1-5.tar.gz
```

```zig
// build.zig
const ffmpeg_dep = b.dependency("ffmpeg", .{.target = target, .optimize = optimize});
```

Choose one:

- Just link ffmpeg:

  ```zig
  exe.root_module.linkLibrary(ffmpeg_dep.artifact("ffmpeg"));
  ```
- Add zig bindings with `@import("ffmpeg")`
  
  ```zig
  exe.root_module.addImport("ffmpeg", ffmpeg_dep.module("av"));
  ```

## Differences from Upstream

* Only a single static library is produced. There is no option to create a
  dynamic library.
* The ffmpeg command line tool is not provided. Perhaps this could be added if
  desired.
* Documentation, tests, and tools are not provided.
* This package enables everything supported by the target; it does not expose
  configuration options to choose the set of supported codecs and formats.
* The set of external library integrations is fixed.

## External Libraries Included

* [x] libmp3lame
* [x] libvorbis
* [x] libogg

More can be added as desired.

## Update Process

These are the instructions to update this package when a new FFmpeg version is
released upstream.

1. Merge the new tag into main and resolve all conflicts by replacing the
   conflicting files with the files from upstream.
2. `find libavcodec/ libavdevice/ libavfilter/ libavformat libavutil/ libswscale/ libswresample/ -type f -name "*.asm" -o -name "*.c" -o -name "*.S"`
   * Edit to omit files ending in `_template.c` or `_tablegen.c`
   * Sort the list
   * Update the `all_sources` list in `build.zig`.
3. Inspect the git diff to keep some of the source files commented out like
   they were before. Some handy filtering rules apply:
   * `/L` prefix means Linux-only
   * `/W` prefix means Windows-only
4. Run `./configure --prefix=$HOME/local/ffmpeg --disable-doc --disable-htmlpages --disable-manpages --disable-podpages --disable-txtpages --disable-programs --enable-libmp3lame --enable-libvorbis --disable-shared --enable-static`
   against upstream and diff the generated `config.h` file to the one generated
   by this build script. Apply appropriate changes to `build.zig`.
   * `config.h`
   * `config_components.h`
   * `avconfig.h`
5. Update these files which are generated by the upstream configure script:
   * `libavfilter/filter_list.c`
   * `libavcodec/codec_list.c`
   * `libavcodec/parser_list.c`
   * `libavcodec/bsf_list.c`
   * `libavformat/demuxer_list.c`
   * `libavformat/muxer_list.c`
   * `libavdevice/indev_list.c`
   * `libavdevice/outdev_list.c`
   * `libavformat/protocol_list.c`
6. Update the `headers` list in `build.zig` based on what files are present in
   `$HOME/local/ffmpeg/include`.

## License

This package copies code from upstream ffmpeg project and therefore also copies
the original license files, unedited. All the Zig code added on top of this
(i.e. build.zig and av.zig) is MIT licensed:

Copyright (c) contributors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.