Chromecast Ultra wrongly transcodes HEVC 10-bit HDR MKV instead of Direct Play

[Usak]

Describe the bug:

When casting 4K HEVC Main10 HDR MKV files (with EAC3/AC3 audio) from Jellyfin to a Chromecast Ultra, the server always transcodes video and audio, even though the device natively supports these formats.

This results in massive CPU usage on low-power servers (Raspberry Pi 5 in my case) and unplayable performance, despite the media being fully compatible with the Chromecast Ultra.

Plex on the same setup (same file, same Chromecast Ultra) direct plays without transcoding, confirming that the issue is with Jellyfin’s Chromecast profile being too restrictive.

Reproduction steps

1. Use Jellyfin 10.10.7 with Docker on Raspberry Pi 5
2. Add a 4K HEVC Main10 HDR MKV (BT.2020, SMPTE2084, 10-bit) with AC3/EAC3 audio
3. Cast it to a Chromecast Ultra (2016 model, HDMI)
4. Observe transcoding (video → H.264, audio → AAC stereo) instead of direct play

Expected behavior

Jellyfin should allow Direct Play of HEVC Main10 HDR MKV with AC3/EAC3 audio on Chromecast Ultra, since the device supports:

• HEVC (H.265) up to 4K
• 10-bit color depth
• HDR10
• EAC3 / AC3 passthrough

Actual behavior

Jellyfin forces transcoding of video (HEVC → H.264)
Jellyfin forces downmixing audio (EAC3/AC3 → AAC stereo)
This creates unnecessary CPU load and poor playback on servers without hardware transcoding

Logs / FFmpeg command

Jellyfin launches ffmpeg with:
/usr/lib/jellyfin-ffmpeg/ffmpeg -i "FileName.mkv" -codec:v libx264 ...
Even though the file is fully playable on Chromecast Ultra if streamed directly.

Environment

• Jellyfin Server 10.10.7
• Docker on Raspberry Pi 5 (Debian 12 arm64)
• Chromecast Ultra (2016 HDMI model, firmware up to date)
• Jellyfin webOS / Android app → Cast to Chromecast Ultra

Additional context

This looks like a Chromecast profile issue: the Jellyfin Chromecast profile is too strict, disallowing HEVC/HDR10 for Ultra devices, and forcing transcoding unnecessarily.

👉 Plex demonstrates this exact file can be Direct Played on Chromecast Ultra without any transcoding, so the limitation comes from Jellyfin’s implementation, not from the device itself.

It would be very useful if Jellyfin could align Chromecast profiles with actual device capabilities, similar to Plex’s behavior, to avoid wasteful transcoding and make Raspberry Pi setups viable.

[stanelie]

I am experiencing similar issues, on an older Chromecast 3rd gen. My video files are being transcoded. The info says "The audio codec is not supported" and "the video's resolution is not supported". It is regular 1080p resolution.

The same video files are NOT transcoded when they are served from Emby from the same physical server (so, the only variable is the software serving the file).

[GodTamIt]

@Usak @stanelie are y'all on the stable or unstable channel for Chromecast?

I addressed a lot of these issues in #744 but that's only on the unstable channel.

[stanelie]

I think I have the stable release since I installed jellyfin with apt on my Ubuntu system.

How do I switch to unstable?

[GodTamIt]

I think I have the stable release since I installed jellyfin with apt on my Ubuntu system.

How do I switch to unstable?

@stanelie it's in your settings of your client. Profile picture -> Playback -> Advanced

[stanelie]

Thanks,
I will test next week when I come back to my Chromecast.

[3flex]

@stanelie @Usak have you tested on unstable?

[GodTamIt]

@Usak @stanelie were you able to test the latest unstable builds by chance?

I believe that #744, #820, and #822 should have addressed all of the issues, so this issue can be closed.

[clarkent86]

I still seem to be experiencing this on latest builds. are we sure this is fixed?

Update: I just swapped to the unstable Google Cast Version (wasn't expecting the fixes to still be there as these have been merged for awhile). It crashed the first time. 2nd time it took awhile and played on my phone for a bit at first, and seems to be working now.