[Webkit-unassigned] [Bug 244203] recording audio using audioworklet produces corrupted data

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=244203

mkahlau at audeering.com changed:

           What    |Removed                     |Added
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                 CC|                            |mkahlau at audeering.com

--- Comment #3 from mkahlau at audeering.com ---
I have probably faced the same issue using Safari and Chrome on iOS 15.7.3 on an iPhone 7 Plus.

When recording with the built-in microphone using AudioWorklet (and latencyHint "playback") by pushing each sample of each audio block of channel 0 to an array as the audio blocks are coming into the AudioWorkletProcessor.process method, some samples are regularly missing. It's easy to notice if you count numbers, like 1 to 20 (about seconds apart). When playing back the recordings I noticed that every few numbers 1 to 3 numbers are missing or cut off, e.g.: 1, 2, 3, 4, 5, 8, 9, 10, 11, 12, (13), 15, 16, 17, 18, 19

Note: With Safari and Chrome on iOS, the sample rate mentioned in the track settings is 44.100 Hz. However, the sampleRate retrieved from the AudioContext is 48.000 Hz. I wonder why the settings are not the same.

The mentioned behavior unfortunately makes AudioWorklet-based recording unusable with Webkit-based browsers. On the other hand, if you record with ScriptProcessorNode, this problem does not occur. Unfortunately, ScriptProcessorNode has been deprecated for some time, and AudioWorklet would be state-of-the-art. 

On other operating systems like Ubuntu (Chrome, Firefox) and Android (Chrome) I could not reproduce the problem with AudioWorklet. I therefore assume that it is Webkit-specific. 

Any help highly appreciated. Let me know, if you need more info or another minimal test case.

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