[Webkit-unassigned] [Bug 196643] New: Audio stream dropping frames
bugzilla-daemon at webkit.org
bugzilla-daemon at webkit.org
Fri Apr 5 04:07:14 PDT 2019
https://bugs.webkit.org/show_bug.cgi?id=196643
Bug ID: 196643
Summary: Audio stream dropping frames
Product: WebKit
Version: Safari 12
Hardware: All
OS: macOS 10.14
Status: NEW
Severity: Major
Priority: P2
Component: WebRTC
Assignee: webkit-unassigned at lists.webkit.org
Reporter: alexosoft at gmail.com
CC: youennf at gmail.com
Created attachment 366806
--> https://bugs.webkit.org/attachment.cgi?id=366806&action=review
Recording test on top of a backing track
How to reproduce the issue:
1. Open https://developer.mozilla.org/en-US/docs/Web/API/Media_Streams_API/Constraints#Result with Safari 12.2.
2. Put on headphones and click on the "Start" button
3. Speak/sing a constant tone into the microphone
You'll hear that the resulting audio on the monitor is constantly dropping frames. This issue doesn't occur in Chrome or Firefox though.
Further observations:
- the same issue occurs when playing back another audio source in the background
- however, when setting the background audio source's volume to 1%, the getUserMedia audio stream seems to be (almost) fine
- also, the issue does not occur when concurrently playing back a track of silence
This makes e.g. recording audio while playing back a backing track impossible (despite using headphones).
In order to exclude any external factors, I've tested this with different mics, different computers, checked the mic's sample rate, bit rate etc. in "Audio Midi Setup" but to no avail.
I've also tested preloading the audio, as well as tested with a WebAudio API white-noise generator in order to exclude memory or buffering issues – no difference. The audio stream is constantly dropping frames while the other audio source was audible.
I've got a hunch that echo cancellation might be the culprit here. Even if turned off, like in the example above, it just seems to keep filtering the audio stream while another audio source was active.
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