Hi Vladmir, thanks for reporting this audio bug & testing in the Beta and Nightly versions to make sure it was happening there as well. I have found at least 4 more reports of what you've seen and I don't think your phone is to blame.

One user who uses Firefox Nightly on Android said the Youtube audio bug first appeared for him on January 14 (link). So I think if you'd be willing to test some older Nightly builds we could start on the date of Jan 14 and work our way backwards until we found the last day that the Nightly builds weren't showing this audio bug.

I tracked down the issue to this bug: Bug 1944207 - youtube.com - The audio keeps stuttering at a playback speed of more than 1x

• Play the video
• Change the speed to more than 1x
• Observe

Expected Behavior: The audio is playing correctly

Actual Behavior: The audio keeps stuttering and crackling

If the description in that bug matches what you're seeing, please subscribe yourself to that bug report to track updates. If you happen to find which Nightly build is good (the audio works normally), that would a big help for the developers. They could investigate which new patch they added to the code created the Youtube audio bug.

The January Nightly builds are stored here: https://ftp.mozilla.org/pub/fenix/nightly/2025/01/

I'm not sure which architecture is the right one for your phone but I believe it's either of these: 2025-01-13-09-36-12-fenix-136.0a1-android-arm64-v8a/ 2025-01-13-09-36-12-fenix-136.0a1-android-armeabi-v7a/

If those don't work, there are other versions you can try: https://ftp.mozilla.org/pub/fenix/nightly/2025/01/2025-01-13-09-36-12-fenix-136.0a1-android-x86/ https://ftp.mozilla.org/pub/fenix/nightly/2025/01/2025-01-13-09-36-12-fenix-136.0a1-android-x86_64/

The issue first appears for me in this nightly version from January 10:

https://ftp.mozilla.org/pub/fenix/nightly/2025/01/2025-01-10-09-49-27-fenix-136.0a1-android-arm64-v8a/

In the nightly versions from January 9, there is no issue.

Thanks Vlad! That was a huge help. I'm going to report your findings to that bug. Hopefully they can quickly pinpoint which patch caused the audio regression. They might provide some test builds with the bad patch removed so that you all can test them to confirm they removed the right patch and that the audio is smooth again. I'll let you know if they create any test builds.

Hey the Firefox devs have found the problem & fixed it in the bug below: Bug 1947917 - Firefox android 135 audio crackling on any website while playing video or audio

Can you download the latest Firefox Nightly & see if the audio bug has been fixed? The audio fix is available in the Beta and Nightly versions right now. For anyone on the main Firefox for Android release, you have to wait until Firefox 136 is released. It will be released on March 4th.

Nightly version: https://ftp.mozilla.org/pub/fenix/nightly/2025/02/2025-02-23-09-38-28-fenix-137.0a1-android-arm64-v8a/

Installed the nightly version using your link, checked it — the issue is gone, sound is good everywhere. Thanks!

Awesome thanks! I'll let the devs know the good news. Thanks again for helping track down when it broke & for your extensive testing. It's very much appreciated.