Hevc_vaapi vs. hevc_qsv

Hello everybody!

I’ve been using Shotcut for quite some time now but there’s one thing I just can’t figure out so I have to ask.

I usually export my videos in HEVC using hardware acceleration. CPU is Intel i5 and I’m on Linux, so I have to use VAAPI.
Now, when choosing the encoder, there are two options available, hevc_vaapi and hevc_qsv:


Both work fine, both give about the same speed and at the settings I use I can’t see any difference in quality.
So I’m really curious: What’s the difference between those two encoder options?

Simply put, they are one and the same.
QSV - QuickSync. VAAPI - Video Acceleration API.
Both terms belong to Intel, both are responsible for access to the hardware encoder. On Windows, QSV is more common, on LINUX, VAAPI is more common.

That’s what I thought also. But: The settings are different. One achives what I believe is CRF14 (not sure; it’s labeled as “qscale” for qsv and “vglobal_quality” for vaapi) at a setting of 72%, the other one at 74%. And the output also differs. Usually vaapi gives me a lower bitrate.

Yes, they are slightly different, until I figured out what exactly, but the player in my old TV does not want to read files that were made using vaapi, but qsv reads fine. I am also looking for a difference, but for most users it will not be significant.

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