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Transcoding when not necessary?

PostPosted: Sat Aug 18, 2018 10:08 am
by Ramrunner
How do I fix the following:

A Movie has 8 audio streams. The second and third streams are DTS and AC-3. The FIRST (default) stream is TrueHD.

My Samsung TV is NOT capable of any of the newer formats. It plays back DTS and AC-3 just fine though. The Video track is also OK to be played back natively.

However, for some reason Serviio decides to TRANSCODE everything. I think it's because it realises the TV cannot handle the TrueHD track.

The video becomes more choppy, and the audio is simply terrible. Very muffled.

How can I stop Serviio transcoding and simply feeding the whole thing through to the TV with one of the DTS or AC-3 tracks?? If I choose not to transcode it says codec not supported on the TV (which I'm sure is caused by the TrueHD track), so Serviio can't leave the file alone, but instead of transcoding, a simple remuxing with another supported audio track should do the trick and lose NO QUALITY.

I need Serviio to be smarter. Obviously if there's DTS or AC-3 tracks available, can we not simply send those through instead of the default track? There really should be no need at all to transcode if the tracks are available, just not as track 1 or marked as default...

Any way to get around this?

Re: Transcoding when not necessary?

PostPosted: Sat Aug 18, 2018 5:28 pm
by atc98092
Transcoding is controlled by the profile used. Serviio makes a best attempt to select the proper profile, but it doesn't always choose the best one. What model Samsung do you have, and what profile is shown on the Status tab of the console?

Re: Transcoding when not necessary?

PostPosted: Sun Aug 26, 2018 8:46 am
by DenyAll
You are correct - Serviio makes it's Trascoding decisions based the first video and first audio track.

There are no plans for Serviio to take into account all audio tracks that I have seen (I suspect this would be a considerable undertaking as it would require Serviio to know the formats your TV supports - the way transcoding profiles currently work is that they know what your TV doesn't support. So Serviio would need to be re-worked considerably, almost a complete revamp would be my guess). Even if it was done, I'm not so certain that your TV wouldn't reject the file anyway (I suspect TV's don't look too deeply into the file)....

The simplest way to achieve what you want is to remux the file and move the supported audio track to being the first stream. Remuxing is non-destructive with no loss in quality. ffmpeg that comes with Serviio will do this, but you'll need to do some research to get the command line correct (hint: look at the map: statement - or XMedia Recode is another program than will do it, and has a gui to make life easier.