opus 5.1 and 7.1 channel order is incorrect

[Tupsi]

Describe how the issue can be reproduced, ideally using the ExoPlayer demo app
or a small sample app that you’re able to share as source code on GitHub. To
increase the chance of your issue getting attention, please also include:

• Clear reproduction steps including observed and expected behavior

1. Create a mkv with video and opus 5.1 or 7.1 audio
   (I use ffmpeg, with the releveant audio part as -c:a libopus -b:a 256000 -mapping_family 1 -af aformat=channel_layout=5.1 (or 7.1 respectively))
2. Playback on FireTV Stick
   (I am using emby app with my emby server, nerd stats inside showing native opus playback (no transcoding)

Observed behavior:
Playback works but channels are somehow mixed up. The dialogs which should be on center are now ONLY on the right channel and the center only plays back some surround channels ambient music/sound.

Expected behavior:
Channels should be where there are suppose to be. I can force that by enabling transcoding in the emby app (server side), so the server transcodes the audio from opus to dd+, resulting the dialog gets played at the center speaker).

You will NOT hear the problem with 2.0 stereo sets as the downmixing seems to work in the sense, that the original center gets mixed into both channels.

I also isolated only the center channel on my computer from the audio to verify that this is indeed the original center audio.

• ExoPlayer version number: 2.12.2
• Android version: API Level 25 (Android 7.1) (according to amazon dev specs)
• Android device: Amazon Fire TV 4k Stick

For reference, I already talked about this problem in detail over at the emby forum over a year ago and provided a sample file (in case you need one)
https://emby.media/community/index.php?/topic/71360-playing-back-opus-5171-does-not-work-center-channel-is-missing/

[marcbaechinger]

Thanks! Can you provide us with a sample stream? I know you said it's in the thread you are referencing, but besides the thread being huge, I seem to not have access to the sample.zip that might be what you say is the sample stream.

[Tupsi]

Yeah sorry, just now realized I password protected that file because of the overzealous german laws when it comes to copyright stuff. Does github offer any form of private upload?

[marcbaechinger]

Please send an email to dev.exoplayer@gmail.com using a subject in the format "Issue #8396". Please also update this issue to indicate you’ve done this.

Many thanks!

[Tupsi]

Please send an email to dev.exoplayer@gmail.com using a subject in the format "Issue #8396". Please also update this issue to indicate you’ve done this.

Many thanks!

done.

[krocard]

I though at first that your channels where in a different order than what Android was expected. It does not seem to be the case as ffmpeg and android have the same channel order. I also looked at the sample and it has the expected channel order.

I then thought that maybe the format was played in passthrough and the tv/av receiver was decoding this incorrectly, but it unlikely that your setup supports Opus passthrough.

The channels also seems to be correctly mapped post decoding as dd+ is correctly played.

So the audio is most probably decoded on your FireTV Stick, and the channel incorrectly mapped there.

Unfortunately, I don't have access to a FireTV, nor a 5.1 setup.

In order to isolate variables and confirm the issue, could you play your sample with our DemoApplication?
If our demo app also exhibits the issue, then it is most probably a platform decoder issue, and you could block this decoder, if there is an other one on the platform supporting Opus or use the ffmpeg extension.
If our demo app does not exhibit the issue, then something else in your setup is causing the problem and I don't think we can help you figuring out what it is.