Hardware encoder fails transcoding HEVC to AVC (burned in subtitles)

[st3iny 1]

Hello emby community and staff,

I'm using hardware transcoding on a rather old Skylake GT2 HD Graphics 520 chip. It works well for most videos. However, emby fails to transcode one HEVC movie when it tries to burn in PGS subtitles. It works fine when I disable subtitles. I can reproduce the error consistently (100%). When I disable hardware encoding (but keep decoding enabled) it also works flawlessly.

I'm running emby 4.7.14.0 on Arch Linux 6.1.53-1-lts (installed via pacman). I'm using the custom ffmpeg build emby-ffmpeg-bin-2022_05_07-1-x86_64 (although it doesn't make a difference when not using it).

For privacy reasons I'd rather not attach the full server log. If you still require it, I'd be willing to share it privately. Please let me know if you need more information. I'd be glad to aid debugging this further.

An excerpt from the ffmpeg log file just before the crash:

18:20:51.808 subtitle input filter: decoding size 1920x1080
18:20:51.809 Auto-inserting subfeed filter
18:20:51.809 Auto-inserting graphicsub2video filter
18:20:51.809 Impossible to convert between the formats supported by the filter 'hwupload@f5' and the filter 'auto_scale_2'
18:20:51.809 Error reinitializing filters!
18:20:51.809 Failed to inject frame into filter network: Function not implemented
18:20:51.809 Error while processing the decoded data for stream #0:3

Best regards, st3iny

ffmpeg-transcode-5adbdbe3-3c44-4328-b2bc-0c0a48b474fd_1.txt

Edited September 23, 2023 by st3iny

[Luke 37253]

HI, are you able to try the 4.8 beta channel and see how that compares? 

[st3iny 1]

Hey Luke, it works again on the latest beta docker image (4.8.0.47). This thread can be closed.

Thank you very much for the fast response.