[Playback] Failed to initialize a decoder for codec 'truehd' on iOS

[userobvixus]

Moonfin version

2.1.0

Platform

iOS

OS version

26.5

Device model

iPhone 12 Pro Max

Input method

Touch

Server type and version

Jellyfin 10.11.11

Content type

Episode

Media details (as much as you know, check the info button at the bottom right of the player)

• File: Game of Thrones - S05E07 - The Gift Bluray-2160p MULTI [x265]-QTZ.mkv
• Container: MKV
• Resolution: 3840x2160 @ 24fps
• HDR: HDR10
• Video: HEVC (H.265) Main 10@L150
• Audio causing issue: TrueHD (Note: AC3 5.1 track works fine)
• HD Audio Support: Reported as "No" in playback info

Playback path

Direct Play

Symptoms (check all that apply)

• Black screen / endless spinner
• Audio only (no video)
• Stuttering / frame drops
• A/V sync issues
• Seeking/scrubbing broken
• Subtitles missing or incorrect
• Unexpected forced transcode
• App crashes / exits

Steps to reproduce

1. Play the 4K HDR MKV file containing a TrueHD audio track on iOS.
2. Select the TrueHD audio track.
3. Observe the bottom of the screen: an error message immediately appears stating "Failed to initialize a decoder for codec 'truehd'."
4. The video plays, but there is absolutely no audio output.
5. Switching to the AC3 5.1 track restores the audio.

Frequency

Always

Logs / errors (optional)

It seems media_kit on iOS is failing to software-decode the TrueHD stream, returning a decoder initialization error instead of playing the audio or requesting an audio transcode from the server.