--- breadcrumbs: [] page_name: audio-video title: Audio/Video --- A starting point for becoming familiar with audio and video in the Chromium projects. ## Get Connected ### Slack For more real-time questions and collaboration, please consider joining the `#media` slack channel. See the main [Chromium Slack](/developers/slack) page for rules and instructions on signing up, as well as tips and tricks. ### Mailing Groups For more serious technical discussions or topics with potentially broader interest, it's still best practice to send to the [chromium-dev](https://groups.google.com/a/chromium.org/g/chromium-dev) discussion group ([chromium-dev@chromium.org](mailto:chromium-dev@chromium.org)) or, for media specific matters, the [media-dev](https://groups.google.com/a/chromium.org/forum/#!forum/media-dev) discussion group ([media-dev@chromium.org](mailto:media-dev@chromium.org)). See [Technical Discussion Groups](/developers/technical-discussion-groups) for an extensive list of available groups. ### Issue Tracking Issues are tracked in the [Chromium > Internals > Media](https://g-issues.chromium.org/components/1456190) component. See the [open issues](https://g-issues.chromium.org/issues?q=status:open%20componentid:1456190) query. ## Documentation The majority of the media documentation lives in the source tree, see [media/README.md](https://chromium.googlesource.com/chromium/src/+/HEAD/media/README.md). For historical reference, here's the original [design doc for HTML5 audio/video](/developers/design-documents/video). ## Codec and Container Support Chromium supports a variety of codecs and containers for content playback (decoding) and content capture (encoding), listed below. ### Container formats * MP4 (QuickTime/ MOV / ISO-BMFF / CMAF) * Ogg * WebM * WAV * Matroska * HLS ### Codec formats #### Audio * FLAC * MP3 * Opus * PCM 8-bit unsigned integer * PCM 16-bit signed integer little endian * PCM 32-bit float little endian * PCM μ-law * Vorbis ##### Proprietary Audio Codecs (Limited to Google Chrome) * AAC (Main, LC, HE profiles only) * xHE-AAC (requires native OS support, i.e. Android P+, macOS, Windows 11 22H2+) #### Video * AV1 * VP8 * VP9 ##### Proprietary Video Codecs (Limited to Google Chrome) * H.264 / AVC * H.265 / HEVC (Proprietary, limited to Google Chrome, requires hardware support) ## Code Locations ### Chromium * [`media/`](https://chromium.googlesource.com/chromium/src/+/HEAD/media/) - Home to all things media! * [`media/audio`](https://chromium.googlesource.com/chromium/src/+/HEAD/media/audio/) - OS audio input/output abstractions * [`media/video/capture`](https://chromium.googlesource.com/chromium/src/+/HEAD/media/video/capture/) - OS camera input abstraction * [`media/video`](https://chromium.googlesource.com/chromium/src/+/HEAD/media/video/) - software/hardware video decoder interfaces + implementations * [`third_party/ffmpeg`](https://chromium.googlesource.com/chromium/third_party/ffmpeg) - Chromium's copy of FFmpeg * [`third_party/libvpx`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/libvpx/) - Chromium's copy of libvpx ### Blink * [`third_party/blink/renderer/core/html/media/html_media_element.{cpp,h,idl}`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/renderer/core/html/media/html_media_element.h) - media element base class * [`third_party/blink/renderer/core/html/media/html_audio_element.{cpp,h,idl}`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/renderer/core/html/media/html_audio_element.h) - audio element implementation * [`third_party/blink/renderer/core/html/media/html_video_element.{cpp,h,idl}`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/renderer/core/html/media/html_video_element.h) - video element implementation ### Particularly Interesting Bits * [`media/base/mime_util.cc`](https://chromium.googlesource.com/chromium/src/+/HEAD/media/base/mime_util.cc) - defines `canPlayType()` behaviour and file extension mapping * [`third_party/blink/renderer/platform/media/multi_buffer_data_source.{cc,h}`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/renderer/platform/media/multi_buffer_data_source.h) - Chromium's main implementation of DataSource for the media pipeline * [`third_party/blink/renderer/platform/media/multi_buffer.{cc,h}`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/renderer/platform/media/multi_buffer.h) - Implements the sliding window buffering strategy (see below) * [`third_party/blink/public/platform/web_media_player.h`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/public/platform/web_media_player.h) - Blink's media player interface for providing HTML5 audio/video functionality * [`third_party/blink/renderer/platform/media/web_media_player_impl.{cc,h}`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/renderer/platform/media/web_media_player_impl.h) - Chromium's main implementation of WebMediaPlayer ## How does everything get instantiated? [`WebLocalFrameClient::CreateMediaPlayer()`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/public/web/web_local_frame_client.h) is the Blink embedder API for creating a [`WebMediaPlayer`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/public/platform/web_media_player.h) and passing it back to Blink. Every HTML5 audio/video element will ask the embedder to create a [`WebMediaPlayer`](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/public/platform/web_media_player.h). For Chromium this is handled in [`RenderFrameImpl`](https://chromium.googlesource.com/chromium/src/+/HEAD/content/renderer/render_frame_impl.h). ## Build Configuration & GN Flags Chromium currently uses the [GN](https://gn.googlesource.com/gn/) meta-build system for generating build files. With several exceptions, the majority of GN flags that alter the behavior of Chromium's HTML5 audio/video implementation are specified in the [media_options.gni](https://chromium.googlesource.com/chromium/src/+/HEAD/media/media_options.gni) file. ### `ffmpeg_branding` Overrides which version of FFmpeg to use. * Default: `$(branding)` - matches the build branding (see [is_chrome_branded](https://chromium.googlesource.com/chromium/src/+/HEAD/docs/google_chrome_branded_builds.md)) * Values: * `Chrome` - includes additional proprietary codecs (MP3, etc..) for use with Google Chrome * `Chromium` - builds default set of codecs ### `proprietary_codecs` Alters the list of codecs Chromium claims to support, which affects `` and `canPlayType()` behavior. * Default: `false` * Values: * `false` - `` and `canPlayType()` assume the default set of codecs * `true` - `` and `canPlayType()` assume they support additional proprietary codecs ## How buffering works Chromium uses a combination of range requests and an in-memory sliding window to buffer media. We have a low and high watermark that is used to determine when to purposely stall the HTTP request and when to resume the HTTP request. It's complicated, so here's a picture: ![Buffering Diagram](/audio-video/ChromiumMediaBuffering.png)