macOS 14.1.1 on an M2 with FF 120. When going to sites such as nbcnews.com/now or https://toronto.ctvnews.ca, A/V sync is off by about a second. This appears to be due … (read more)
macOS 14.1.1 on an M2 with FF 120.
This appears to be due to the volume being muted when video playback starts. Unpausing the video leads to the video freezing for a very brief moment, then the A/V sync is clearly incorrect.
This can be replicated on YouTube by loading a video, muting the video (if not muted already), refreshing the page (F5), allowing the video to play, then unmuting the video. The sync will be incorrect.
If the audio is unmuted when the video play back starts, this does not appear to happen.
Following this article has no impact: https://support.mozilla.org/en-US/kb/performance-settings, nor does setting media.hardware-video-decoding.enabled to false.
This issue does not occur on Microsoft Edge.