[FFmpeg-devel] avfilter/hwupload: Did `-init_hw_device` become required with ffmpeg 8?

[Wladislav Artsimovich via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

Dear ffmpeg devs,
 
With the update of FFMPEG 7 to FFMPEG 8, I stumbled on an issue and wonder whether `hwupload` became more strict, requiring a device to be specified in ffmpeg 8 as opposed with ffmpeg 7, where it worked implicitly:
 
When enabling VA-API Hardware decode (AMD Graphics Card) on Nextcloud App Memories, playing a video errors out. I traced this to ffmpeg erroring out due to `hwupload` complaining about  `A hardware device reference is required to upload frames to.`, which is documented in https://github.com/NixOS/nixpkgs/issues/473008 and https://github.com/pulsejet/memories/issues/1591 as issues.
 
Nextcloud Memories calls ffmpeg like so: `ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -hwaccel_output_format vaapi -i 'sample.mp4' -vf "format=nv12|vaapi,hwupload,scale_vaapi=w=854:h=854:format=nv12" -vcodec h264_vaapi EncodeTest/output-www-data2.mp4`
 
This works with FFMPEG 7, but does not work with FFMPEG 8, which errors out with `[hwupload @ 0x55d77ee7d240] A hardware device reference is required to upload frames to.`
 
Nextcloud's memories does not specify `init_hw_device`, so when my server's system packages updated ffmpeg 7 to ffmpeg 8, it broke video playback for all users. Forcing dependency ffmpeg down to version 7 fixes this.
 
Reading the docs: https://trac.ffmpeg.org/wiki/Hardware/VAAPI#DeviceSelection and specifying a device fixes the above example in ffmpeg 8 and no more error occurs:
`ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -hwaccel_output_format vaapi -i 'sample.mp4' -init_hw_device vaapi=foo:/dev/dri/renderD128 -filter_hw_device foo -vf "format=nv12|vaapi,hwupload,scale_vaapi=w=854:h=854:format=nv12" -vcodec h264_vaapi EncodeTest/output-www-data2.mp4`
 
So this makes me wonder, was this changed on purpose going to ffmpeg 8? Is `init_hw_device` a requirement now, whereas in ffmpeg 7 it was done implicitly?
 
Best regards,
 
-- 
 
Wladislav Artsimovich 🇩🇪 🇷🇺 🇬🇧 🇯🇵
✍ TechBlog: https://blog.frost.kiwi/ 
▶ YouTube Channel: https://www.youtube.com/@FrostKiwi/
 
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