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Pass through SDR video from Dolby Vision instead of tonemapping


lolque
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Some Dolby Vision profiles (eg 8.2) have SDR video for backwards compatibility SDR TV/players.

 

It would be nice if Emby could directly transcode or stream the SDR video instead of tonemapping when playing on SDR clients. This generally ends up with superior video quality as the SDR video was mastered for SDR displays, and can possibly prevent a transcode for SDR players.

 

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It may well do - I have never seen a DV media file with a .2 BL with SDR.

Have you tested this ?

Emby uses the .1 (HDR10) BL now when tonemapping (if available) - so it may just passthough the SDR if it is available with no tonemapping.

A lot of the capabilities depend on what ffmpeg supports.  Emby (beta) recent upgraded to ffmpeg 5+ which has Dovi support - so if it doesn't fully support this now, the capability to is now a possibility.

Edited by rbjtech
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FrostByte
3 hours ago, lolque said:

 

It would be nice if Emby could directly transcode or stream the SDR video instead of tonemapping when playing on SDR clients. 

 

You mean direct play?  That should be the goal unless it needs to transcode for another reason.  Then if it still needs to transcode then it should do so without TM on any TV because even HDR TVs can display SDR.

I'm surprised it wants to transcode DV 8.2 because I can direct play/passthrough DV5/7/8.1 to my HDR Samsung all the time without it transcoding.  Though DV5 looks funny :)  

If it wants to transcode now, try turning video transcoding off on the server as a test and see what happens.  

As rbjtech mentioned, some things will require the DV information be added to Emby first before it will know how to deal with a lot of other things.

 

 

 

 

 

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On Emby Web (on an SDR display), I can play this HDR video fine with direct play. If I decrease the bitrate to force transcoding, it will tonemap instead of just transcoding the video as is.

 

image.png.b498a00af077e161eed8741833ae3fe8.png

image.png.48c5d9d3bf5b807724e07466b4e3c840.png

I see these 4 situations occurring.

Video is SDR, Client supports HDR: Play as SDR. Transcode if bitrate exceeded.

Video is HDR, Client supports HDR: Play as HDR. Transcode with HDR if bitrate exceeded.

Video is SDR, Client is SDR: Play as SDR. Transcode if bitrate exceeded.

Video is HDR, Client is SDR: Always transcode and tone map.

 

However in this case, the client is clearly either playing the SDR video from Dolby Vision 8.2, or playing the HDR natively. However Emby is still tonemapping.

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7 hours ago, lolque said:

On Emby Web (on an SDR display), I can play this HDR video fine with direct play. If I decrease the bitrate to force transcoding, it will tonemap instead of just transcoding the video as is.

 

image.png.b498a00af077e161eed8741833ae3fe8.png

image.png.48c5d9d3bf5b807724e07466b4e3c840.png

I see these 4 situations occurring.

Video is SDR, Client supports HDR: Play as SDR. Transcode if bitrate exceeded.

Video is HDR, Client supports HDR: Play as HDR. Transcode with HDR if bitrate exceeded.

Video is SDR, Client is SDR: Play as SDR. Transcode if bitrate exceeded.

Video is HDR, Client is SDR: Always transcode and tone map.

 

However in this case, the client is clearly either playing the SDR video from Dolby Vision 8.2, or playing the HDR natively. However Emby is still tonemapping.

If it transcodes the video at all, it is going to have to tone map. There is no way right now to transcode and keep it as hdr.

There are situations though where we can transcode only the audio and keep the original video, but this is not one of them (due to quality setting).

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FrostByte
49 minutes ago, Luke said:

If it transcodes the video at all, it is going to have to tone map. There is no way right now to transcode and keep it as hdr.

There are situations though where we can transcode only the audio and keep the original video, but this is not one of them (due to quality setting).

Luke, I think the file he is playing is DV profile 8.2 though which isn't HDR.  So, it shouldn't need TMing on any TV

 

  • DV 8.2 is SDR BL + RPU.
  • DV 8.1 is HDR10 BL + RPU
  • and I believe 8.3 is HLG BL + RPU
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Right, but this comes down to detection as well.  We are seeing the item as HDR10.  I'm not sure if we could discover that it is a flavor of DV that actually has an SDR layer at this point - but that is what this request is about.

As long as the item direct plays, I think it will work fine.

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FrostByte

Roger, that's what @rbjtech and I figured may be the case.  I've added it to the list of things the other FR will enable since they're related, and this may depend on the other one

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