Video playbackRate not working when silent video is connected to AudioContext
Categories
(Core :: Audio/Video: Playback, defect)
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People
(Reporter: gismya, Unassigned)
References
Details
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/132.0.0.0 Safari/537.36
Steps to reproduce:
- Load a video file without audio tracks
- Create an AudioContext and connect the video element using createMediaElementSource
- Attempt to change the video's playbackRate
Minimal reproduction page: https://gismya.github.io/firefox-playbackrate-bug-report/
Github repo for the repro: https://github.com/gismya/firefox-playbackrate-bug-report/
Actual results:
- When a silent video is connected to an AudioContext via createMediaElementSource, the playbackRate property is ignored
- The video plays at 1x speed regardless of the playbackRate value
- The video.playbackRate property reports the correct set value, but the actual playback speed remains unchanged
Expected results:
- The video should play at the speed specified by the playbackRate property
- Changing playbackRate should affect the video playback speed, regardless of whether the video has audio or is connected to an AudioContext
Issue reported from multiple end users with, but I think all of them (Including me) is using it on MacOS. Unknown if the issue is in other operating systems.
Confirmed that it's an issue at least as far back as the ESR (v.128) and in the latest nightly (136.0a1 (2025-01-19))
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Comment 3•15 days ago
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Karl, would you mind taking a look here? Something related to audio context.
Comment 4•13 days ago
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Thank you for the nice testcase. Reproduces on Linux too.
Given this works in the other combinations of with sound and/or not connected to an AudioContext, I expect this shouldn't be hard to fix once the clock source choice for the no sound and connected to AudioContext case is identified.
Connecting a no sound video to an AudioContext is a combination that I wouldn't expect to be common.
Description
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