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Comment by cm2187 | Hacker News Reader

Maybe I am doing it wrong. But I tried the following commands to test it on h264/h265 and 1080p/4k sources:

  Soft: ffmpeg -i {src}  -map 0:v -f null - 
  Hard: ffmpeg -hwaccel cuda -i {src}  -map 0:v -f null -

the result I get is:

  Source       Hard  Soft
  1080p-h264  25.1x 37.1x
  1080p-h265  26.4x 36.5x
  4k-h264      5.5x  7.1x
  4k-h265      5.5x  6.5x

this is on an old CPU (i7-6700K) and a somewhat recent GPU (RTX 2060) and with ffmpeg 6

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You are using cuda for some reason? cuda is for general gpu computing, not the same as using the dedicated hardware enc/dec engines.

See ffmpeg docs for the hw decoding name, like nvdec iirc for nvidia cards.

I am pretty sure that does not activate the hardware encoder. https://trac.ffmpeg.org/wiki/HWAccelIntro

We are talking about decoding here. You meant decoder? I can certainly see the hardware decoder being busy in task manager.

I think you should use nvdec instead of cuda. GPU itself is not a hardware decoder, the special decoder unit inside of it is.

I barely know what I'm talking about, but in my experience to use software I had to explicitly enable it with "-allow_sw" but this may have only been necessary due to videotoolbox

Cuda is not a normal hardware decoding API. Look for VA-API and VDPAU.

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