[Webkit-unassigned] [Bug 221553] Audio is sometimes distorted when using createMediaElementSource

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Mon Feb 8 09:10:53 PST 2021


https://bugs.webkit.org/show_bug.cgi?id=221553

Chris Dumez <cdumez at apple.com> changed:

           What    |Removed                     |Added
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                 CC|                            |eric.carlson at apple.com,
                   |                            |jer.noble at apple.com

--- Comment #1 from Chris Dumez <cdumez at apple.com> ---
The steps in the video did not reproduce an issue on my machine. I used the source at 44.1khz and used to Audio MIDI Setup tool to switch from 44.1KHz to 48Khz and all the way up to 96Khz. The audio seems alright.

http://trac.webkit.org/changeset/267014/webkit is indeed a patch where we added support for resampling in WebKit. This patch is recent. It got committed after we started getting bug reports about this issue so I doubt this is the source of the problem. Also, in the test case of the video, WebKit does not do any resampling to my knowledge because the source is 44.1 Khz is the AudioContext also uses 44.1Khz. I understand that the hardware's sample rate gets changed after that via the Audio MIDI tool. However, this does not impact the sample rate of the AudioContext AFAIK. The rate of the AudioContext is decided upon construction (it is either the sample rate being provided upon construction or the current hardware sample rate at the time of construction). Certainly some resampling must take place when we change the hardware sample rate with the Audio MIDI tool but I suspect this is happening in the Audio framework under us (I will double check).

It is also interesting that it is working in Chrome because we're using the same implementation of MultiChannelResampler as Chrome nowadays AFAIK. This seems to indicate that the bug is likely outside the MultiChannelResampler.

I will do more testing (maybe with bluetooth headphones since it seems they were used in the test video).

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