[webkit-changes] [WebKit/WebKit] 7926de: [GStreamer][MSE] Optional encoders for AppendPIpel...

[Vivienne]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 7926de4222132a135d84b4d4cc05d8f6738f9c6a
      https://github.com/WebKit/WebKit/commit/7926de4222132a135d84b4d4cc05d8f6738f9c6a
  Author: Vivienne Watermeier <vwatermeier at igalia.com>
  Date:   2025-02-19 (Wed, 19 Feb 2025)

  Changed paths:
    M Source/WebCore/platform/graphics/gstreamer/TrackPrivateBaseGStreamer.cpp
    M Source/WebCore/platform/graphics/gstreamer/mse/AppendPipeline.cpp
    M Source/WebCore/platform/graphics/gstreamer/mse/AppendPipeline.h

  Log Message:
  -----------
  [GStreamer][MSE] Optional encoders for AppendPIpeline streams
https://bugs.webkit.org/show_bug.cgi?id=287860

Reviewed by Philippe Normand.

Adds optional encoder elements, analogous to the optional parsers streams can have.
This is necessary for TextTrack support in MSE, where we need to re-encode any
subtitle or caption tracks to WebVTT, which is the format WebKit expects.

A stream in AppendPipeline now looks like this:
               __________    ___________    ___________
___________    |        |    |         |    |         |
|         | -> | parser | -> | encoder | -> | appsink |
| demuxer |    |________|    |_________|    |_________|
|_________| -> ...

Additionally, I've renamed parser elements, which previously tended to break pipeline dumps.
See: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7979
While this was backported to 1.24.10, the change also makes element names more descriptive.
(Take for example 0_parser, which might now be called parser_0_video.)

Finally, I've changed some logging in TrackPrivateBaseGStreamer, which didn't yet use track IDs.

* Source/WebCore/platform/graphics/gstreamer/TrackPrivateBaseGStreamer.cpp:
(WebCore::TrackPrivateBaseGStreamer::tagsChanged):
(WebCore::TrackPrivateBaseGStreamer::getLanguageCode):
(WebCore::TrackPrivateBaseGStreamer::getTag):
(WebCore::TrackPrivateBaseGStreamer::notifyTrackOfStreamChanged):
* Source/WebCore/platform/graphics/gstreamer/mse/AppendPipeline.cpp:
(WebCore::AppendPipeline::appsinkCapsChanged):
(WebCore::AppendPipeline::didReceiveInitializationSegment):
(WebCore::createOptionalParserForFormat):
  Just takes the new element's name as argument now.
(WebCore::createOptionalEncoderForFormat):
  Creates an encoder, analogous to its parser counterpart.
(WebCore::AppendPipeline::recycleTrackForPad):
(WebCore::AppendPipeline::makeWebKitTrack):
(WebCore::AppendPipeline::Track::emplaceOptionalParserForFormat):
  Creates parserName, and links the parser to the encoder, instead of the appsink.
(WebCore::AppendPipeline::Track::emplaceOptionalEncoderForFormat):
  Create an encoder and link it to the appsink, also set finalCaps here.
(WebCore::AppendPipeline::Track::initializeElements):
(WebCore::AppendPipeline::streamTypeToStringLower):
* Source/WebCore/platform/graphics/gstreamer/mse/AppendPipeline.h:
  Add fields to AppendPipeline::Track: finalCaps, encoder, and encoderPad.

Canonical link: https://commits.webkit.org/290605@main



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