WebCodecs: Per-frame quantizer in VideoEncoder

[Djuffin]

WebKittens

@youennf

Title of the spec

WebCodecs VideoEncoderBitrateMode

URL to the spec

https://www.w3.org/TR/webcodecs/#video-encoder-bitrate-mode

URL to the spec's repository

https://github.com/w3c/webcodecs

Issue Tracker URL

No response

Explainer URL

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TAG Design Review URL

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Mozilla standards-positions issue URL

No response

WebKit Bugzilla URL

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Radar URL

No response

Description

This change adds "quantizer" VideoEncoderBitrateMode for VideoEncoder.
This allows to specify quantizer parameter for each frame for AV1, VP9, and AVC video codecs.

Quantizer parameter is set via codec specific extensions for VideoEncoderEncodeOptions.

Controlling quantizer for every frame makes possible at least two new use cases for VideoEncoder:

1. Constant quality encoding when complex frames and parts get more bandwidth than less complex ones.
2. External rate control algorithms implemented by web developers. Such algorithms can take into account website's knowledge about contents of each frame or quick changes in available network bandwidth.

Work on the Chromium side is being tracked here.

[Djuffin]

Suggested labels:
topic: media
venue: W3C Media WG
from: Google