FLAC 5.1 sends DD 2.0 via Direct Playing

[Xorp 47]

I believe I've encountered this bug on other platforms like the Android version, but I only have access to test with a Roku device at the moment.

 

Anyway, if I play content that has FLAC 5.1 audio, the receiver gets the audio as Dolby 2.0. Playback mode is "direct playing". Interestingly, if I play something with FLAC 7.1 or FLAC 6.1, the receiver gets audio as re-encoded Dolby 5.1, which is what I want. Playback mode in that case is "direct streaming". Container, video and subtitle formats are identical between FLAC 5.1 and FLAC 7.1 tests.

 

I'm playing over the internet using a manual direct connection to the remote Emby server. Remote server has 1 gig upload so not a bandwidth issue.

Edited December 28, 2018 by Xorp

[Luke 37046]

Hi, sounds to me like the Roku is doing this.

 

Can you attach the Emby server log? thanks.

[Xorp 47]

This is weird, there are no individual log entries for the FLAC 5.1 plays. They show in activity history, but no individual logs if it's remuxed. I see individual log entries for FLAC 5.1 content if it's transcoded (still sent as DD 2.0)

 

Found the FLAC 5.1 play attempts in the embyserver logs: https://pastebin.com/4TsNHPmE

Here's the individual log for the 7.1 file: https://pastebin.com/nqH4v46U

[Luke 37046]

Is this the flac 5.1 file?

\\SAN1\media\Movies\Children of Men (2006)\Children of Men (2006).mkv

[Xorp 47]

Yes, also True Grit, Munich. I think all the files in there are 5.1

[Luke 37046]

Ok, that is direct playing, therefore the Roku is responsible for the downmixing to stereo.

 

There's nothing the Emby app can about this, other than of course consider transcoding. But if you want to keep the direct play, you might have to live with this. You can also check Roku system audio settings to see if there's anything that might affect this. Thanks.

[Xorp 47]

Ok, that's makes sense the Roku is not liking the audio in this situation. With Direct Playing the means Emby will send FLAC 5.1, and since this particular setup uses SPDIF and not HDMI for audio, the bandwidth limits of SPDIF require something to convert it to DD 2.0?

 

If the video gets transcoded, then Emby converts the audio to DD 5.1. Why doesn't Emby try to send transcoded video and FLAC 5.1?

With FLAC 6.1/7.1, Emby converts the audio DD 5.1 with Direct Streaming (EnableAudioPlaybackTranscoding: True) but it's not really direct streaming since the audio is converted.

[Luke 37046]

That might just be what Roku does with flac 5.1, it's really hard to say. 

 

 

Why doesn't Emby try to send transcoded video and FLAC 5.1?

With FLAC 6.1/7.1, Emby converts the audio DD 5.1 with Direct Streaming (EnableAudioPlaybackTranscoding: True) but it's not really direct streaming since the audio is converted.

 

I'm afraid I don't understand what you're asking here. Why would we do this?

[majorsl 20]

I've seen this often with the Roku and my SPDIF receivers, same as you.  For situations like this, I use ffmpeg to convert the file so the audio is ac3 (eac3 works too).  It then plays audio as expected on every device including those with HDMI audio.