HDR -> SDR transcoding - washed out colors

[Paul77nz 8]

I am getting more 4K HDR files, and they look great when direct playing via the Emby app on my LG TV.

 

However, when I transcode these for remote viewing on my iPhone X or Emby Theater (on Surface 5 Pro) the colours are very dull and washed out looking. The same happens if I transcode to the LG TV rather than direct-play (this is the same TV that they look great on when direct playing).

 

The transcoded colours don't just look dull compared to the direct played HDR file, but also when compared to a native SDR version of the same movie.

 

I assume that when transcoding it is outputting SDR (which is fine), but is there any way to make the output colours look better (i.e. more like the native SDR version)?

 

At the moment I am having to keep two copies of each file (HDR and SDR), and this obviously takes up a lot more disk space, so I'd be keen to hear if there is a solution to this.

 

Thanks

Edited November 26, 2018 by Paul77nz

[CBers 7121]

When transcoding, HDR is lost.

 

FFMPEG, which performs the transcoding, doesn't currently support HDR.

[Paul77nz 8]

When transcoding, HDR is lost.

 

FFMPEG, which performs the transcoding, doesn't currently support HDR.

 

Thanks for the quick reply. Do you have any knowledge if support is planned to be added, and whether that would be likely to improve the transcoding from HDR to SDR?

[Paul77nz 8]

Just did a little Googling, and apparently what I'm after is tonemapping of HDR to SDR.

 

Is there already a feature request in place for this?

Edited November 26, 2018 by Paul77nz

[CBers 7121]

Not sure about that.

 

@@Luke @

[ebr 15672]

Yes there is.  Thanks.

[Guest asrequested]

Ffmpeg has the potential, but transcoding 4k takes a lot of processing, and then add tone mapping to that. Here's one person trying to figure it out.

 

https://emby.media/community/index.php?/topic/65265-tonemapping-filter-pull-request/

[Luke 40121]

We plan to look at tone mapping with transcoding in a future update. Thanks.

[Paul77nz 8]

We plan to look at tone mapping with transcoding in a future update. Thanks.

 

Thanks @@Luke

[Gerrit507 24]

Hi,

 

I have gathered quite a lot of hevc hdr videos in my library now. When they are getting transcoded, for example because I watch them over a webbrowser, the colors look washed out. I've searched around and found this blog post, which exactly describes the issue:

 

https://stevens.li/guides/video/converting-hdr-to-sdr-with-ffmpeg/

 

When transcoding hevc 10bit hdr content to avc, emby (or ffmpeg) just cuts off the additional colorspace. The blog also describes a method to convert BT.2020 to BT.709. It basically scales down the colors to the smaller colorspace.

 

Is there a way that you can implement this into emby?  I'd love to have that feature.

[Guest asrequested]

It's planned

 

https://github.com/MediaBrowser/Emby/issues/3480

[Gerrit507 24]

Well, is there any possibility that this gets implemented in the near future? Are pull requests required? I could try to implement it.

[Guest asrequested]

That's up to the Emby gods

[Luke 40121]

I would think within the next 2-3 releases is realistic for this.

[vlix 1]

Hi Luke & ebr,

 

Can you perhaps give us an update on progress (if any) on this feature? I for one have more and more UHD Bluray material on my Emby server, and it sucks that all that material is unwatchable on remote devices because of the washed out colours.

 

Thanks!!!

[Guest asrequested]

Hi Luke & ebr,

 

Can you perhaps give us an update on progress (if any) on this feature? I for one have more and more UHD Bluray material on my Emby server, and it sucks that all that material is unwatchable on remote devices because of the washed out colours.

 

Thanks!!!

https://emby.media/community/index.php?/topic/72233-hdr-sdr-transcoding-washed-out-colors/

[lightsout 156]

double

Edited August 16, 2019 by lightsout

[lightsout 156]

I would think within the next 2-3 releases is realistic for this.

Any updates on this Luke?

[Luke 40121]

We haven't gotten to it yet, but it's on our list.

[lightsout 156]

We haven't gotten to it yet, but it's on our list.

Ok thanks for the quick reply.

[vdatanet 1586]

I am also interested in this. My server has enough power to transcode 4K HDR, but since HDR is lost in this operation, I am required to keep two versions of my movies (1080p SDR and 4K HDR) for clients that do not support 4K HDR. As long as I have enough disk space, it's not a problem, and if my space runs out, I'll have to expand it. 

[MagicDoubleM 116]

I'd want to add, that not always a full transcode from 4kHDR->SDR is the necessary way. Transcoding to lower resolution (or just lower bitrate 4k) while staying with HDR10 works nicely and keeps color-data intact. Leaving it to the client to convert to 8bit and do the tone-mapping, which most modern stuff can do (or just enjoying HDR even on a lower-res transcode!). Sure, some older clients might still not like 10bit HDR hevc and that needs a full conversation with tone-mapping on the other side, but i bet in lots of scenarios this isn't the case anymore (or easy to fix with a 4k firetv-stick when it's on sale again ;-) ).

Edited October 8, 2019 by MagicDoubleM

[raudraido 44]

I'm also waiting for this!

[SLMK 15]

I also hope this isn't too far off, its literally the only feature I'm waiting on.

4K HDR is getting increasingly common in my collection and Ive got plenty of power for transcoding.

[hooj1981 5]

Same here. I'm having to keep two versions of HDR media for transcoding clients. This would be of great benefit.

 

Any update Luke?