Audio mixing is bad from 5.1 to stereo while streaming

[tal 0]

I've tested with the web-app and in emby theatre for now. The audio mixing is pretty bad from 5.1 to stereo, the right and left chanels, along with the rear right and rear left channels are loud, the surround channels actually seem especially loud, meanwhile the center channel is quiet and is easily drowned out by everything else.  Is there a way to change the default down-mixing channel mix settings?

[Luke 37196]

What browser?

[tal 0]

I've tried firefox and chrome so far, it's been identical across the two

[Luke 37196]

Ok, i really haven't seen this in my testing. One thing you can play with the audio boost when downmixing setting under the server's transcoding menu. That only applies if transcoding is occurring.

 

If the file is direct playing then the downmixing is handled by the browser video player and we don't have any control over it.

[tal 0]

It works fine when direct playing, it's only when transcoding that I experience this at all, it works fine on chromecast, works fine when playing to a 5.1 source, it's only when streaming and down mixing to stereo.

[Luke 37196]

Can you provide a sample video for testing? thanks.

[tal 0]

I can pm you a download link to a couple of the files I'm experiencing this in in a couple hours here if that's okay?

[Luke 37196]

Thanks for the links. @ i know you like testing audio so i added you to the conversation in case you'd like to try them in Theater. Thanks.

[Guest asrequested]

You said you also get this in Theater? Which version?

[Guest asrequested]

Ok, so I've been testing the Rick and Morty episode. I forced down-mixing in theater desktop, and it played correctly. But you stated that this only happens when transcoding. So I tested in chrome. Down-mixing also played correctly when direct streaming and the audio is converted to MP3.

Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (eac3 (native) -> mp3 (libmp3lame))
Press [q] to stop, [?] for help
[segment @ 000002bbbfd3e160] Opening 'C:\Users\Peter\AppData\Roaming\Emby-Server\programdata\transcoding-temp\9369f1efbc688e5cb483bd68fe5dd4070.ts' for writing
Output #0, segment, to 'C:\Users\Peter\AppData\Roaming\Emby-Server\programdata\transcoding-temp\9369f1efbc688e5cb483bd68fe5dd407%d.ts':
  Metadata:
    encoder         : Lavf57.83.100
    Stream #0:0: Video: h264 (High), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 23.98 fps, 23.98 tbr, 90k tbn, 23.98 tbc (default)
    Stream #0:1: Audio: mp3 (libmp3lame), 48000 Hz, stereo, fltp, 384 kb/s (default)
    Metadata:
      encoder         : Lavc57.107.100 libmp3lame

Forcing a full transcode, I still had correct down-mixing.

Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (eac3 (native) -> mp3 (libmp3lame))

  Metadata:
    encoder         : Lavf57.83.100
    Stream #0:0: Video: h264 (libx264), yuv420p, 720x404 [SAR 404:405 DAR 16:9], q=-1--1, 23.98 fps, 90k tbn, 23.98 tbc (default)
    Metadata:
      encoder         : Lavc57.107.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 1616000/0/0 buffer size: 3232000 vbv_delay: -1
    Stream #0:1: Audio: mp3 (libmp3lame), 48000 Hz, stereo, fltp, 384 kb/s (default)

The one thing that might be causing an issue is that the audio is EAC3. I'm running windows 10 so I don't know if EAC3 has good support on Linux.

Edited November 15, 2017 by Doofus

[Luke 37196]

thanks @ !