FLAC A/V consistently out of sync

[hedgehog90 16]

I've just installed the latest version using the USB method, unfortunately I encountered a few issues that makes much of my blu-ray film collection unwatchable without re-encoding them, which I'd really like to avoid.

 

Every film I tried to play (using Direct Play) with FLAC audio was terribly out of sync by a second or more.
However, switching to an alternate audio stream during playback (to a DTS or DTS-HD audio stream) played perfectly. It was just FLAC streams that were out of sync with. Unfortunately when I converted my blu-ray collection to MKVs (losslessly) with makemkv, I used a profile that converted LCPM audio to FLAC to save space.

I tested 5 or 6 films and the issue was consistent. I think it may be made worse after repeatedly skipping forward 30 seconds.

 

PGS subtitles were also completely non-functional, but if I played the same videos though the TV's DLNA media streaming functionality (ie, not Emby), the PGS subtitles displayed fine, so it's definitely not an issue with the firmware / built-in video decoder.

 

I'm using a Samsung SmartTV (UE50MU6120) with the latest firmware updates.

 

Any chance of fixing these issues soon?

Edited July 21, 2019 by hedgehog90

[Luke 36999]

Hi there, as a test, if you use user permissions to force the video to direct play, do the subtitles play in the app?

 

My guess is they won't. Even though the TV can decode them in Samsung's apps, it does not seem to be available for third party apps to utilize. But please try that, perhaps it will be different for your model.

 

@@SamES

[SamES 890]

Correct, PGS subs seem to work (but not always?) through the native DLNA player, but it's not available for third party apps.

[hedgehog90 16]

Hi there, as a test, if you use user permissions to force the video to direct play, do the subtitles play in the app?

 

My guess is they won't. Even though the TV can decode them in Samsung's apps, it does not seem to be available for third party apps to utilize. But please try that, perhaps it will be different for your model.

 

@@SamES

 

I've already done this, and your assumption is correct.

[Luke 36999]

Ok then can we look at an example that is out of sync? Thanks.

[hedgehog90 16]

Ok then can we look at an example that is out of sync? Thanks.

 

They're bluray remuxes of films, so around 25-30 GB each, which makes obtaining a sample difficult, but I've remuxed a 90 second clip that you can check out:

 

https://drive.google.com/open?id=1l_u4XGpoIigiZ56c7lljdvf3xPVG6kn1

 

But like I said, it was the same for each MKV with a FLAC audio stream. I checked around 20 films, 6 of them had FLAC audio streams, each one with FLAC was out of sync, everything else appeared to be in sync.

While testing it was necessary to skip forward to find dialogue so I could check sync easily. The sync issue may be triggered by seeking, I'm not sure.

 

I know some people tend to exaggerate with AV sync issues by saying 'it was a second out of sync', when in reality it was more like 100ms... however in this case, it was really around 1 to 1.5 seconds out of sync, consistently.

Edited July 22, 2019 by hedgehog90

[Luke 36999]

Ok I just meant the usual logging information so that we can take a look at how it's playing. Thanks.

[hedgehog90 16]

Ok I just meant the usual logging information so that we can take a look at how it's playing. Thanks.

 

Oh right, here you go:

https://drive.google.com/open?id=1WfSNxbZdWBo97kIkgLxet379lmzXUnr7

 

I've looked through it, I'm not sure what you could gleam from it with regards to why FLAC audio is out of sync.

One of the videos in the log that I tested a few times was 'The Last Detail (1973) - Indicator BDRemux.mkv', which had 24 bit FLAC audio and was always out of sync.

[Luke 36999]

it is also direct playing which means there's really nothing we're going to be able to do about this, other than transcode it of course.

 

Why use flac? I'm going to go out on a limb and guess that even though it's technically supported, it probably hasn't been tested quite as much by Samsung engineers.

[FrostByte 5041]

You will probably get better results using one of the formats specified in your users manual.  

 

This chart should be somewhere in your manual.

 

https://developer.samsung.com/tv/develop/specifications/media-specifications/2017-tv-video-specifications

[rexerm 20]

Sorry to resurrect an old thread, but I just discovered the same issue. Other than demuxing / re-encoding the audio / remuxing all of the files I have with FLAC audio, is there anything else to try?

[hedgehog90 16]

It would be good if there were options in the profile to convert FLAC to LCPM on the host before serving to the viewer device.

Similarly, a profile option for converting PGS subs (not compatible with Samsung TVs) to VobSub (as suggested in a feature request some months ago):

Basically the host should provide some options for transcoding specific streams with Direct Play, instead of unnecessarily having to convert all streams (video, audio & subs).

I have a library of lossless blu-ray + 4K blu-ray films, to play them on my TV they have to be fully transcoded which uses a ton of processing power and reduces picture quality... when all I need to transcode often are the subtitle or audio streams, which only require a tiny fraction of the processing power.

2 toggles in the profile option is all I need, and the additional code to handle conversion with ffmpeg is trivial.

If Emby was opensource I would happily implement this myself.

Edited August 30, 2021 by hedgehog90