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C9 audio transcode whole video


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#1 nodiaque OFFLINE  

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Posted 20 February 2020 - 10:38 PM

Hello

 

I found out that using the lg c9 tv, if the soundtrack is 7.1 or more, it will transcode instead of direct play. But C9 does support the codec. I can only think it's because I'm using arc which from the c9, isn't earc meaning no supporte for atmos and such. But the thing is everything is transcoded, including video. Because of that, 4K hdr video get washed out since the transcoding doesn't account for the hdr.

 

Could it only transcode the audio? Or if I recall, the tv can itself downmix to supported codec for arc anyway. If xbox one could directplay I'd used that instead since it's 4k hdr with atmos.

 

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#2 Happy2Play OFFLINE  

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Posted 20 February 2020 - 11:03 PM

Pretty sure this is the same as all the other 4K topics.  If any transcoding is needed the video stream gets transcoded do the HLS streaming method.

 

But a dev will have to comment more.  You will probably have to post server and ffmpeg logs.

 

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#3 Luke OFFLINE  

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Posted 21 February 2020 - 12:55 AM

Hi there, can we please look at an example?



#4 SamES OFFLINE  

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Posted 21 February 2020 - 05:38 AM

If you turn off the user options on the server that allow transcoding, does the file now DirectPlay correctly on the TV without a connected receiver?  If it does, then 'your' TV supports the higher channel counts, but if it's not supported by older models then that adds some additional challenges to support this.

 

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#5 nodiaque OFFLINE  

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Posted 21 February 2020 - 11:34 AM

Ok I just tried many things.

 

With everything has it is, a movie with Dolby TrueHD 7.1 audio track (show in emby real one is Dolby Atmos - Dolby TrueHD). Playing through LG Emby Apps (the version released today 1.0.24) on server 4.3.1.0.

 

I start the moving, I see "direct streaming" with transcoding position and buffer. My Sony STR-DN1080 show "Dolby Digital 5.1(3/2)". It is connected through the Arc port (and earc on the sony).

 

If I disable all 3 transcoding, it now show direct play, and the sony display "Dolby Digital 5.1(3/2)".

 

Both of them display "HDR" on startup, but the image isn't the same.

 

If I check one or two configuration in any order, I always receive the message "there is no compatible stream", thus it's working when everything is checked or none are checked. But in the event that all are checked, it's transcoding.

 

Now, here, everything shows has Dobly Digital 5.1(3/2)" on my receiver, while it's Dolby Digital TrueHD 7.1. THat's because ARC cannot do lossless TrueHD 7.1, only earc can.

 

If I play from my PC directly the 4k video, which is connected directly in my sony amp through HDMI, my amp display "Dolby Atmos - Dolby TrueHD". My computer isn't able to play 4k so that's why I'm using the emby app.

 

Aside from having a more powerfull pc, the best case scenario for me would be to have the xbox one app do direct streaming since it can play 4k hdr/dv and dolby atmos because it's connected directly to my amp, not through arc. But for now, it's the LG TV App that is doing some transcoding that isn't needing since my TV does it anyway (has showed by the amp).


Edited by nodiaque, 21 February 2020 - 11:34 AM.


#6 Luke OFFLINE  

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Posted 21 February 2020 - 03:10 PM

 

 

But for now, it's the LG TV App that is doing some transcoding that isn't needing since my TV does it anyway (has showed by the amp).

Yea but we don't have any control over this as we're simply using the LG video player.



#7 SamES OFFLINE  

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Posted 21 February 2020 - 04:23 PM

Does your file have multiple audio tracks?  Just be careful as the LG player will switch to a secondary track if the first one is not playable.  It does this in a way that the Emby client is not aware of, so it will report the wrong track.  This is why you might be seeing Dobly Digital 5.1(3/2)" on your receiver.

 

There has been a lot of discussion and comments on this LG thread.  No one has confirmed yet that TrueHD/Atmos is playable via eArc, even on a C9.  Therefore, it must convert the file by some form of transcoding or remuxing


Edited by SamES, 21 February 2020 - 04:23 PM.


#8 nodiaque OFFLINE  

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Posted 21 February 2020 - 05:58 PM

Sorry my english isn't my principal language so I might badly explain myself.

 

ARC doesn't support TrueHD Atmos 7.1. But, the TV does support it. What isn't support is the transport link through Arc, this require a downmix of some sort and the TV itself does it, regardless of the source used. It is part of the software/hardware.

 

As for the sound track, it did had many soundtrack, so I checked with another one that have 2 track, but in different language. and you're right, I cannot select the english Atmos, it only play the french 5.1. I know TrueHD or Dolby DTS-MA 7.1 work, but not TrueHD/Dolby Atmos (this doesn't support ARC, it require EARC which the C9 doesn't have but there's rumor it could be software implement).

 

Thus, my previous test wasn't perfer.

 

But, in regards to this, could we only have the audio transcode and not the whole video data? This would reduce CPU strain with keeping the original quality. Right now, I'm simply converting each movie to have a 5.1 audio track (which is kind of sad since I have a 7.1 atmos system) and seeing the video quality difference with the transcode in x264 isn't nice, specially since it's not needed for the video part.



#9 SamES OFFLINE  

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Posted 23 February 2020 - 06:32 AM

But, in regards to this, could we only have the audio transcode and not the whole video data? This would reduce CPU strain with keeping the original quality. Right now, I'm simply converting each movie to have a 5.1 audio track (which is kind of sad since I have a 7.1 atmos system) and seeing the video quality difference with the transcode in x264 isn't nice, specially since it's not needed for the video part.

 

 

Actually, this is exactly what is happening when you see DirectStream

 

There are three playback modes:

  • DirectPlay - File is payed exactly as it stored - there is not conversion
  • DirectStream - The audio is being converted, but the original video stream is used.  To perform this, the original video stream must be cut into segments and streamed using an m3u8 container instead of the original video container.  Note that the original video stream is not converted, it is just cut into small segments for streaming, however you will see a buffer during playback due to the streaming.
  • Transcoding - The video is now being converted to a different format, and possibly the audio as well.  This is the specific case where you will start to lose HDR. 

I start the moving, I see "direct streaming" with transcoding position and buffer. My Sony STR-DN1080 show "Dolby Digital 5.1(3/2)". It is connected through the Arc port (and earc on the sony).


Edited by SamES, 23 February 2020 - 06:33 AM.


#10 rbjtech OFFLINE  

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Posted 10 March 2020 - 01:42 PM

The limitation is the LG Media Player - even with eARC (the latest C9 does have this interface) the LG Player is NOT passing eARC uncompressed signals to an eARC Receiver for TrueHD/Atmos sound.

 

Currently, the only way to get TrueHD/Atmos sound is to use an External Player direct to your Receiver and passthrough the video to the LG TV.

 

If you insist on using the LG Player, then you can insert a pre-converted 5.1 AAC, AC3 or DTS sound track into your source as the default sound track.  That way you get untouched direct play 4K HDR along with decent 5.1 (albeit compressed) sound, with zero transcoding.

 

ie ffmpeg.exe -i input.mkv -map 0:v -map 0:a:0 -map 0:a  -c:v copy -c:a copy -c:a:0 ac3 -disposition:a:0 default -disposition:a:1 0 output.mkv

 

This will use ffmpeg to convert the current primary track (assumed to be TrueHD) to AC3 and insert the new track as the first Audio track 0 (while maintaining the TrueHD which now becomes track 1) and then set track 0 as the default.


Edited by rbjtech, 10 March 2020 - 01:54 PM.

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