[Webkit-unassigned] [Bug 208233] New: Audio crackling in WebRTC calls on iOS using Cisco Meeting WebRTC app

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=208233

            Bug ID: 208233
           Summary: Audio crackling in WebRTC calls on iOS using Cisco
                    Meeting WebRTC app
           Product: WebKit
           Version: Safari 13
          Hardware: iPhone / iPad
                OS: iOS 13
            Status: NEW
          Severity: Critical
          Priority: P2
         Component: WebRTC
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: mawojtcz at cisco.com
                CC: youennf at gmail.com

When joining calls using Cisco Meeting WebRTC app in Safari on iPhones the user can hear audio crackling. The crackling is heard on different iPhone models (for example: 7s, XR) and different iOS versions (both 12.x and 13.x)

Here at Cisco, we have created a temporary account in our product that should allow you to replicate the issue we are seeing. I can provide you a link to it if you message me privately, as we don't want this link to be available in public.

We've done some initial investigation on this and these are our findings:
- Audio plays fine in our product without any crackling in Chrome and Firefox on Windows and MacOS as well as Safari on MacOS and Chrome on Android
- The issue is intermittent. Sometimes the audio may work fine for a long period of time and on another occasion the crackling will be very frequent. It seems that the probability of crackling gets higher with longer time since the phone's reboot or when more apps have been used. Once it starts, it seems to be worse when the app is doing some UI transitions etc.
- When we capture the network traffic and recreate the audio from the pcap file, we don't hear the crackling in the resultant wav file
- When we've modified our werbtc app to not do any video encoding and decoding, we could still hear the audio crackling
- Audio crackling can be heard also when we tried other audio codecs

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