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can't hear sound with some AC3 5.1 files on Shield


justinrh

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justinrh

It seems like every Disney movie on TV (or is it the local channel 31 that broadcasts them??) has AC3 5.1 but there is no sound when I play the recording.  I have to switch to the stereo track or turn on the Shield's Dolby processing (I normally leave have it off).  Any ideas as to why this would be a problem for some AC3 5.1 files?

Sent ATV app logs @ 3:52 CT, user home.

embyserver.txt

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rbjtech

Probably need an example of the file itself to determine - but I suspect they are not properly formatted AC3 or not AC3 at all, but that's what's it is being reported as - and thus need to be further processed by the Shield.

What does Mediainfo say about the Audio track ?

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Hi.  The major difference I see is the bitrate of the audio track (as well as channel content).  384k vs. 192k.

What happens with the same recording in the web app?

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justinrh

MediaInfo says:

Audio #1
ID                                       : 52 (0x34)
Menu ID                                  : 1 (0x1)
Format                                   : AC-3
Format/Info                              : Audio Coding 3
Commercial name                          : Dolby Digital
Codec ID                                 : 129
Duration                                 : 31 min 58 s
Bit rate mode                            : Constant
Bit rate                                 : 384 kb/s
Channel(s)                               : 6 channels
Channel layout                           : L R C LFE Ls Rs
Sampling rate                            : 48.0 kHz
Frame rate                               : 31.250 FPS (1536 SPF)
Compression mode                         : Lossy
Delay relative to video                  : -305 ms
Stream size                              : 87.8 MiB (6%)
Language                                 : English
Service kind                             : Complete Main

 

Web app direct plays the 5.1 w/o issue in Edge (has to transcode in Fx), but the video has to transcode, of course.

If Emby would divulge how to share video files I would.

 

Edited by justinrh
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rbjtech
11 hours ago, justinrh said:

MediaInfo says:

Audio #1
ID                                       : 52 (0x34)
Menu ID                                  : 1 (0x1)
Format                                   : AC-3
Format/Info                              : Audio Coding 3
Commercial name                          : Dolby Digital
Codec ID                                 : 129
Duration                                 : 31 min 58 s
Bit rate mode                            : Constant
Bit rate                                 : 384 kb/s
Channel(s)                               : 6 channels
Channel layout                           : L R C LFE Ls Rs
Sampling rate                            : 48.0 kHz
Frame rate                               : 31.250 FPS (1536 SPF)
Compression mode                         : Lossy
Delay relative to video                  : -305 ms
Stream size                              : 87.8 MiB (6%)
Language                                 : English
Service kind                             : Complete Main

 

Web app direct plays the 5.1 w/o issue in Edge (has to transcode in Fx), but the video has to transcode, of course.

If Emby would divulge how to share video files I would.

 

Looks fairly typical, so nothing obvious.

re - sharing the file, then trim a sample in mkvtoolnix (use the output tab, split mode, by parts based on timestamps - then use '00:01:00-00:02:00' (for example) to create an extractt of 60 seconds worth of video starting after 60 seconds. (format is HH:MM:SS)

 

 

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seanbuff
On 01/11/2023 at 08:21, justinrh said:

If Emby would divulge how to share video files I would.

 

3 minutes ago, justinrh said:

??

 

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justinrh

But, how about this?  😉

ffmpeg.exe -i "Toy Story of Terror! 2013-10-16.ts" -t 30 -codec copy out.ts

BUT, if I trim it the problem is not seen.

@LukeI PM'd you a link to the uncut file, even though you didn't ask for it.  The std app is worser (even the trimmed file won't play audio).
The link expires in ONE WEEK!

Edited by justinrh
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rbjtech
7 hours ago, justinrh said:

But, how about this?  😉

ffmpeg.exe -i "Toy Story of Terror! 2013-10-16.ts" -t 30 -codec copy out.ts

 

Sure - you can use ffmpeg to trim if you like as this a transport stream (TS) - but as you've seen, there is a chance the 'timing' is corrected if you do this - which is probably the original problem.

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rbjtech
11 hours ago, justinrh said:

So maybe I just need to trim off a couple of seconds of each channel 31 recording  😀

Possible just do a post recording processing script - probably better to just write to an MKV rather than keep as a TS.  

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rbjtech
Just now, rbjtech said:

Possible just do a post recording processing script - probably better to just write to an MKV rather than keep as a TS.  

I don't know what OS Emby is running on - but some examples of a post processing script in this thread, but plenty more if you search the TV forum.

https://emby.media/community/index.php?/topic/118947-scheduled-mp4-conversion-after-recording-is-done/#comment-1293923

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pwhodges

Because MKV has a much more flexible structure, which makes it easier to handle.

Paul

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rbjtech
9 hours ago, justinrh said:

Why prefer MKV?  The video track would still be MPEG, right?

Yes, MKV is just a container - but the key issues with some TS files is timing - by putting the mpeg2 in an MKV container, it adds timing into the stream, making ffwd/rwd, jump to a time etc possible.   With the native TS, it's likely to have sync issues.

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As others have said, the container can be very important/helpful.  TS is a Transport Stream which is something that is not indexed and not intended to be seekable.

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  • 2 weeks later...
justinrh

I've been converting all my recordings to MKV.  It does seek faster, but it doesn't fix the audio out-of-sync issue or the freeze issue.

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