Chromecast HD not requesting transcoding for a 4K video, IF it has HDR10

[slothonastick]

1. I play a 4K non HDR10 file, and it plays successfully.
   
2. The dashboard shows it is being transcoded due to a non supported resolution.
   
3. I then try play a 4K HDR10 file, which repeats a playback error until giving up.
   
4. The dashboard reports it is direct playing the file.
   
5. I can force a transcode of the 4K HDR10 file by lowering my max bitrate to under 5mbps
   
6. This issue can be replicated with any 4K HDR10 file.
   
   This reminds me of a recently fixed issue with the GoogleTV app wherein any 4K file would not request to be transcoded, perhaps the recent fix is not working with files that are both 4K and HDR?
   
   Any help would be appreciated,thank you!
   
   I have attached ffmpeg logs for both an HDR and non HDR 4K file.
   
   
   
   Application version
   0.17.5 release
   Device information
   Google Chromecast HD
   Android version
   STTL.240615.007
   Jellyfin server version
   10.9.11 (Windows)
   

[TheDreadPirate]

Can you attach the full jellyfin log and provide a file name that is not playing?

[slothonastick]

Thank you for your response, I have attached my jellyfin log and a MediaInfo export for two files that will not play.

[TheDreadPirate]

Not entirely sure what the problem is. It is tone mapping the HDR video and downscaling to 1080P. Both are getting AAC 7.1 audio.

Can you share the ffmpeg log from when you got the HDR video to work by setting the bit rate really low?

[theguymadmax]

The 2160p HDR file is getting transcoded to the correct resolution, so I don't think that's the issue.

Code:

Stream mapping:
  Stream #0:0 -> #0:0 (hevc (hevc_cuvid) -> hevc (hevc_nvenc))
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
Output #0, hls, to 'C:\ProgramData\Jellyfin\Server\cache\transcodes\226fc907ecbfc9556101cf1decd22cfd.m3u8':
  Metadata:
    encoder        : Lavf60.3.100
  Stream #0:0: Video: hevc (Main) (hvc1 / 0x31637668), cuda(tv, bt709, progressive), 1920x804 [SAR 1:1 DAR 160:67], q=2-31, 15946 kb/s, 23.98 fps, 90k tbn (default)

I think it might be an issue with 7.1 AAC audio. Can you also share the media info for Stepbrothers? It would be helpful to compare the differences. 

Does a 2160p HDR file with 5.1 AAC or AC3 audio play correctly?

[slothonastick]

Thank you both, I have attached media info for stepbrothers, as well has the ffmpeg transcode log for when I get it to play by setting a low max bitrate.

I cannot find a 2160p HDR 5.1 file. However I am now noticing that any 4k HDR file I own is also 7.1, wheras the non HDR 4K files tend to be 5.1

Because of this I definitely think you're right, it must be the audio causing the issue and not whether it is HDR or not!

---

It was the audio! I've checked "Downmix to stereo" in the playback settings of the Chromecast app and everything is playing perfectly. This is fine for me as I use the chromecast in the bedroom with a soundbar.

Thank you very much to the both of you for helping me get to the bottom of this. The Jellyfin community is amazing!