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Transcoding - VAAPI - quality control #6128

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Gronis asked this question in Ideas
Transcoding - VAAPI - quality control #6128
May 29, 2021 · 0 answers

When using vaapi for transcoding, changing CRF value does not do anything. From the documentation at https://trac.ffmpeg.org/wiki/Hardware/VAAPI

"No CRF-like mode is currently supported. The only constant-quality mode is CQP (constant quantisation parameter), which has no adaptivity to scene content. It does, however, allow different quality settings for different frame types, to improve compression by spending fewer bits on unreferenced B-frames - see the (i|b)_q(factor|offset) options. CQP mode cannot be combined with a maximum bitrate or buffer size."

It seams that quality control can be achieved with "-qp" flag instead of using CRF.

Would it be possible to be able to tweak with this value in jellyfin (in http://my-jellyfin-server.local/web/index.html#!/encodingsettings.html) instead of CRF (which is unsupported) to achieve quality control when using VAAPI?

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