1856998 - WebRTC h.264 stream displays in low frame rate

Status: RESOLVED DUPLICATE of bug 1855636

(Core :: WebRTC, defect)

Description

[Evan Sonderegger]

Steps to reproduce:

Visited a page that streams a video source using the WebRTC-HTTP Egress Protocol (WHEP). This page uses h.264 for the video stream and opus for the audio stream.

Unfortunately, this was a private stream, but I can generate a public link if that would be helpful.

I've only witnessed this issue on M1 macOS machines, but this post describes similar behavior on Ubuntu: https://www.reddit.com/r/firefox/comments/16zhpzc/terrible_webrtc_performance_on_11801/

Actual results:

Firefox 115 and earlier: video plays great

Firefox 116 and newer: audio plays fine, but video plays at about 1 frame per second

Expected results:

Video and audio play at their encoded frame rate.

Comment 2

[Andreas Pehrson [:pehrsons] (PTO; back in Aug)]

Wait, this started in 116? Could you run mozregression?

Comment 3

[Evan Sonderegger]

Attachment: Screenshot 2023-10-05 at 1.31.29 PM.png

mozregression is a super-cool tool! Thank you for suggesting it. Here are my results for this bug.

Comment 4

[Evan Sonderegger]

Also, my apologies. Yesterday (when I didn't yet know about mozregression) I was downloading the most recent patch of each recent major version, and I could have sworn this issue was in 116.0.3. However, I just tried it again and am no longer seeing it. It looks like https://bugzilla.mozilla.org/show_bug.cgi?id=1846796 being the cause of the regression makes sense.

We do an I-frame every 1.5 seconds in our WHEP streams, so P-frames not decoding would be an understandable cause of the symptoms described above.

Comment 5

[Andreas Pehrson [:pehrsons] (PTO; back in Aug)]

Cool, thanks for confirming!