MKV video file - Only one audio tracks showing since updated to tvOS 14

[RoscoMoss89]

Hi,

First of, thanks for the VLC player. I have used it for a very long time and I would not change it for any other player. Now, here is the description of my problem... I couldn't find something similar in the forum or anywhere else over the web. I hope it's not a too long post (nor too short )

I have been using VLC on my Apple TV 4K to read MKV video files via DLNA on my NAS. Some of the MKV files have multiple audio tracks (AC3, DTS, and other types). Since I updated my Apple TV 4K to tvOS 14 (it was updated automatically since I forgot to disable auto-update), only one audio track is appearing in the audio track selection for each of my MKV video files. The audio track is showed as the "Track 1" even though it is sometime another track number in the MKV file. The mutiple audio tracks were available when the Apple TV was on tvOS 13, there were no problem, I could choose each of them. Now that the VLC app only shows one audio track, it seems to show (and play) the first AC3 track found in all the audio tracks available. Even the "default" track tagged in the MKV file is not shown when it is not the first AC3 track available.

Since the problem appeared, I waited for a VLC and tvOS update wishing it could adress the problem, but it wasn't the case with the last updates. Unfortunately, Apple doesn't allow to roll back to a previous tvOS version (modern way to do business, I guess...).

I think the problem points towars the VLC app for tvOS or the way VLC depends on the tvOS. I have the VLC app on my iPhone which is still running iOS 13 (13.6 to be more specific) and I can still select all the available audio tracks of the same MKV files.


Here are the informations to summarize a little bit:

Apple TV 4K
tvOS 14.2
VLC 3.0.12 (414)
NOT OK: Shows only one audio track (always the first AC3 track, shown as "Track 1")

Apple TV 4K
tvOS 13.something (can't remember the specific version before updating)
VLC 3.something (can't remember the specific version before updating)
OK: All tracks were shown and could be chosen, they were playing nicely

iPhone SE 1st gen
iOS 13.6
VLC 3.0.2 (312)
OK: All tracks are shown and can be chosen, they play nicely

MKV video files (audio tracks example)
Track 1
Codec: DTS Audio (dts)
Description: Surround 5.1
Type: Audio
Channels: 3F2M/LFE
Sample rate: 48000 Hz
Bits per sample: 32
Track 2
Codec: DTS Audio (dts)
Description: Surround 5.1
Type: Audio
Sample rate: 48000 Hz
Track 3
Codec: A52 Audio (aka AC3) (A52)
Description: Surround 5.1
Type: Audio
Sample rate: 48000 Hz
Track 4
Codec: A52 Audio (aka AC3) (A52)
Description: Surround 5.1
Type: Audio
Channels: 3F2M/LFE
Sample rate: 48000 Hz
Bits per sample: 32



Thanks to all of you developping such a great media player. I hope you will find the way to fix that

[ajmas]

Can you indicate whether you see this issue with MP4 files? If you don't have any, you could try converting one with Handbrake (just remember to include the subtitles). Also, what is the size of the smallest MKV file?

Unfortunately VLC for tvOS doesn't seem to have any message logs that I am aware of, so that doesn't seem to be an option for investigation.

[RoscoMoss89]

Thank you for your reply. I could find a MKV file as small as 31 MB. It doesn't have multiple audio tracks though. For multiple audio tracks, I found a file of 3.8 GB being one of smallest in my library. I tried SD and HD files with multiple audio tracks, ranging from 3.8 to 30 GB approx., and they all only show one audio track in VLC on the AppleTV.

I forgot to mention in the original post that in addition to the audio tracks problem with the MKV files, the list of subtitle tracks doesn't appear at all in VLC on the Apple TV. Though, the subtitle tracks list appears very well on the iPhone iOS 13.6 using VLC.

So, I did what you suggested, I tried a MP4 file. I transcoded with Handbrake the MKV file I gave as an example in my original post. It was the first time I was using Handbrake, so I chose the parameters that seem the best suited for the test. While reading on Handbrake, I understood that it cannot just change the wrapper from MKV to MP4 (passthrough), the video has to be transcoded. Concerning the audio tracks, I chose the passthrough parameter for each audio track. For the subtitles, beside adding all the subtitles tracks, nothing else was set.

Conclusion to the test: VLC on the AppleTV under tvOS 14 could finally see all the audio and subtitle tracks of the MP4 file. VLC could play all of them without any issue. Since all the audio tracks were set to passthough in Handbrake and that they play nicely with the MP4 file but don't appear with the MKV file, it really make me think that it has something to do with VLC, tvOS 14 and MKV files.

I am happy to see that the MP4 file can play nicely with all the audio and subtitle tracks. On the other hand, I am not really interested in transcoding all of my library's MKV files to MP4. In my situation, it would be a lot of time.

Let me know what you think about the result. Thank you!

[ajmas]

You can repackage your MKVs, without transcoding, but it will need user of the command line:

https://superuser.com/questions/472420/ ... al-quality

Without access to a problematic MKV it will be hard to investigate the issue.

[RoscoMoss89]

Here's an update on the problem which is now solved! Since this post will finally be about the Synology NAS settings that caused the problem, I'm not sure if this is allowed here.To moderators, feel free to delete my post. I just hope it may help others in a similar situation.

So here is why it wasn't working. The fault is on me, not Apple nor VLC. While I did the update of the Apple TV, I forgot that I played around settings in the Media Server package of my Synology NAS, under the DMA Compatibility section (DMA standing for Digital Media Adapter, like the Apple TV). The problem is that I enabled the transcoding of some video files with specific extensions when they are played to a Digital Media Adaptor (written DMA in the Synology settings) through DLNA. The checkbox says "Enable converter to play files with the below formats if they are not supported on your DMA.", and "mkv" extension was listed there. However, it seems that even though the Apple TV with VLC app is good for reading the MKV files without transcoding on the NAS, the video were certainly transcoded since I was loosing the ability to change the language, the subtitles and choosing chapters. Or at least it was somehow "re-wrapped" in a new container for streaming to the Apple TV.

I'm not a network or coding professionnal, so I hope that my explanations are understandable.

Finally, thanks ajmas for helping me with the problem and for your suggestion of repackaging the MKVs. I know I can sometimes find my way through command line, but it's not natural for me. I put the problem aside while I didn't have time.


TL;DR
Problem: In the VLC app on the Apple TV, while playing MKV video files (streaming) coming from Synology NAS through DLNA, I lost the ability to change the language, subtitles and choosing the chapter.

Resolution: The problem wasn't about VLC or Apple TV version. In the Synology Media Server package, go to the section DMA Compatibility, then uncheck "Enable converter to play files with the below formats if they are not supported on your DMA.".