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Audio out of sync different amount depending on audio codec?

Posted: 08 Jun 2018, 03:23
by Soaringswine
My setup is MrMC (audio set to passthrough, change refresh rate on start / stop with a delay of 4 seconds, audio offset 0) -> Shield (audio offset 0) -> HDMI -> Denon AVR-S720W (7.1 surround, audio offset 0 and Auto Lipsync tried on and off).

I was noticing that the audio would be delayed or ahead depending on audio type: stereo, DD+, DTS and I'd constantly have to mess with audio offset options in MrMC, so I downloaded some AV sync test clips (https://sync-one2.harkwood.co.uk/suppor ... 080-files/) and installed an app designed for checking audio / video offsets on my iPhone (https://itunes.apple.com/us/app/catchin ... 41912?mt=8) and ran some tests:

It looks like MrMC will go out of audio sync +220ms to -120ms and some stops in between on if the audio track is 5.1 or stereo.

I don't seem to have this issue with the Netflix or Youtube app on Shield or with other HDMI devices connected to the Denon.

Re: Audio out of sync different amount depending on audio codec?

Posted: 17 Jun 2018, 17:16
by AlexBlomkvist
Hi,

Have you found out what the problem is and if there is any fix? I just recently switched from SPMC to MrMC on the Nvidia Shield and I am having a similar audio out of sync issue but apparently only on some video files.

Thank you.

Re: Audio out of sync different amount depending on audio codec?

Posted: 18 Jun 2018, 12:30
by Soaringswine
I set an audio ahead offset of 34 ms on my receiver and that seems to have fixed the issue with Dolby Digital+ (5.1) content. However, stereo content and Atmos have different offsets that I have to mess with every time to get lips synced :-(

Re: Audio out of sync different amount depending on audio codec?

Posted: 19 Jun 2018, 07:00
by koying
I'm surpised that an offset of 34ms would change anything.
That's less than a frame in 24p, and "Normal" people can't notice a delay less than 100ms.

Furthermore, I don't experience those symptoms myself.

Could it be bad encodes?
Did you try with Kodi, VLC, ...?
Which version is it? Are you on Testflight?

Re: Audio out of sync different amount depending on audio codec?

Posted: 20 Jun 2018, 00:13
by Soaringswine
Yes, the files play fine elsewhere.

In fact they even play in-sync on the Plex app on the Shield.

I am on MrMC 3.7-0 Git:2018-06-14-312a692.

Re: Audio out of sync different amount depending on audio codec?

Posted: 20 Jun 2018, 02:09
by Soaringswine
just tried clearing data / cache on the MrMC app and starting from scratch. only change I made was to enable passthrough audio settings.

I then played a Dolby Digital+ 5.1 video and the audio was out of sync. tried disabling refresh rate switching: same issue. playing the exact same video on the Shield Plex app has no sync issues (with audio passthrough enabled and refresh rate switching on even).

Re: Audio out of sync different amount depending on audio codec?

Posted: 20 Jun 2018, 06:23
by koying
Ok, will try to reproduce

Re: Audio out of sync different amount depending on audio codec?

Posted: 20 Jun 2018, 14:22
by Soaringswine
I can share privately some sample video files that require different offsets if you'd like. Or I'd be happy to do some testing / provide debug logs as well.

Re: Audio out of sync different amount depending on audio codec?

Posted: 20 Jun 2018, 21:03
by koying
Yep, samples that are positively wrong on your side would be great

Re: Audio out of sync different amount depending on audio codec?

Posted: 20 Jun 2018, 21:48
by Soaringswine
Sent you a PM with 3 samples.