Question / Help AV Sync issues

[jjjjjjjjjj]

Recordings of my video broadcast (captured with ffplay) show audio video sync issues when played back with VLC but not QuickTime player.

Are there any encoding settings that could cause playback sync issues of this nature?

Aside from the recording only some of the live viewers of my stream experience AV sync issues - even when they are all using the same player.

Any insight appreciated-- I am attaching the logs from my last broadcast.

 

[Narcogen]

You're using an old version. For your version of MacOS you should be using the latest, version 22.0.3. Download it from the main site, don't use the in-app updater, as it was broken in version 21.

You're using the faster CPU preset. Your machine is very likely not fast enough for this; most aren't. Use veryfast or even superfast.

You're using CBR rate control with a limit of 1000. Is this intentional? That is pretty low; there's no way you're going to get good looking 1080p30 footage at that bitrate. Twitch would suggest 3500-5000 for that. If you need to be as low as 1000 you probably need to be streaming at 480p30 to get decent quality. Those are Twitch's guidelines but they are broadly applicable to other services.

https://stream.twitch.tv/encoding/

1. 20:19:13.777: Output 'adv_stream': Number of lagged frames due to rendering lag/stalls: 4573 (3.4%)

The above line shows your GPU is overloaded. This will be alleviated if you set your canvas resolution to smaller dimensions (1280x720 or smaller).

1. 20:19:13.777: Output 'adv_stream': Number of dropped frames due to insufficient bandwidth/connection stalls: 1965 (1.4%)

The above indicates that your internet connection is unable to keep up even with the 1000 kbps stream. Are you streaming on wireless instead of a wired connection? Are you using a low speed DSL provider, or a cellular modem?

 

[jjjjjjjjjj]

The 1000kbps limit is intentional, I am rescaling output to 480x852 in Settings > Rescale Output
I am streaming over a wired gigabit connection, the network instability issue is as far as I am aware unrelated to the AV sync problem.
When I simulate a poor connection for the broadcaster I am unable to reproduce AV sync issues consistently.
Thanks so much for your help!

 

[Narcogen]

If you're rescaling that aggressively, reduce your canvas size until the GPU overload goes away. That means less load on the GPU for rendering each frame, and less load on the CPU to downscale them.