Cannot get sound on playback without using conversion option

[george.smathers 1]

I attempted to put my media library into a format that requires no conversion or re-encoding. After a lot of effort, I failed.This example illustrates my difficulty:

 

1.  When file played with settings shown in attachment 1 Emby passes file thru ffmpeg copying video and audio streams and after a brief pause(for ffmpeg I suppose) everything plays beautifully.

2.  When the file is played without the   "Allow video playback that requires conversion

     without re-encoding" unchecked(I assume that is the direct play setting) the video plays with no sound.

 

Why will this file not play audio unless Emby passes it through ffmpeg? Can I somehow pr-encode in some manner and avoid this? 

 

Any guidance is appreciated.

 

Other documents that might be helpful are attached including an ffprobe dump from a typical encoded ".ts" file

 

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My set up is:

Windows 10 server

Roku streaming stick client set to Dolby Digital audio 20 Mbps

TV & Audio equipment with Dolby Digital capability 

 

 

 

 

 

 

 

 

 

 

embyserver.txt

ffmpeg log.txt

typical .ts file ffprobed.txt

[Luke 37057]

Hi, are you trying to play from Roku, or is this the web app? What app are you playing from? Thanks.

[george.smathers 1]

I'm trying to play from Roku.  I concluded that since my pc has only 2  channels, direct play should fail. I expected it to work on the ROKU, however, which advertises Dolby Digital capability. 

[george.smathers 1]

Amend ..since my pc has only 2 channels, direct play by the web app should fail and, in fact, the server did convert to 2 channel mp3 when asked to play with the transcode video option enabled.

[Luke 37057]

Ok, the Roku has only Dolby pass-through support, but not Dolby decoding support. What that means is that it passes the audio directly to your audio equipment, and that equipment needs to be able to support Dolby. If it doesn't, then the Roku doesn't have any Dolby decoding support to convert it to PCM. That's why when you force the direct play, you don't get any audio.

 

The Roku is just passing it straight through, and whoever processes it next (your audio equipment), has to support Dolby decoding or you won't get any sound. 

 

Dolby decoding and Dolby pass-through are two different things. Some devices support one or the other, and some will support both. 

 

@@ebr and @@speechles can elaborate more on Roku decoding capabilities. Thanks !

[Luke 37057]

Amend ..since my pc has only 2 channels, direct play by the web app should fail and, in fact, the server did convert to 2 channel mp3 when asked to play with the transcode video option enabled.

 

Correct, there is currently no web browser that can direct play that mkv. Chrome supports the mkv container but not the AC3 audio. MS Edge supports the AC3 audio, but not the mkv container.

[george.smathers 1]

Thanks for the thoughtful and timely response.  I'll check the link you provided.

[george.smathers 1]

Apologies for dragging this topic on, but I'm still baffled.  My objective seems straightforward:  I want to trans-code my videos so that the will play directly thru my Roku without  conversion by the Emby server.   Is this possible?  If so, what options for ffmpeg are needed? I tried to duplicate what I thought were the essential ffmpeg settings that the server appears to be using(e.g.,from the ffmpeg.log -c:v copy  -c:a copy) and that doesn't work.

 

If the Emby server can convert a stream so that Roku and my a/v equipment plays, should I not be able to do the conversion beforehand and eliminate that step from the process? 

[PenkethBoy 2063]

I think you are not understanding what "-c:v copy  -c:a copy" means - that just copies the video and audio as is to the new file - its not converting anything

 

you need to actually change the video or audio or both depending whats not supported by your Roku

 

One option is to search for Handbrake on google - has a gui so easier to use than the command line

[george.smathers 1]

Thanks PenkethBoy  for your comment.  I do understand what  "-c:v copy  -c:a copy"  means.  Perhaps my description of the problem is unclear.  If you examine the ffmpeg log you will see that is exactly what Emby does and everything works.  If I let get Emby play with conversion it runs ffmpeg with a  "-c:v copy  -c:a copy"  setting and everything.  Play the same file directly(e.g. without conversion) and it fails.  I am baffled.

[speechles 1917]

ffmpeg.exe -i input.mkv -map 0:0 -map 0:1 -map 0:1 -c:v copy -c:a:0 ac3 -c:a:1 libfdk_aac -ac 2 output.mkv

 

If it is indeed dolby, you need to decode it. If you hear silence the trick is have 2 audio streams. The secondary is aac 2 channel. Best of both worlds. The line above can generate this while copying the video stream. Enjoy.