[Libav-user] Nvenc_H264 very slow compared to Libx264

Jodon Karlik jodonk at gmail.com
Fri Jan 17 07:01:32 EET 2020

On Thu, Jan 16, 2020 at 5:28 PM Philippe Noël <
philippe_noel at college.harvard.edu> wrote:

> Hi,
> I was using libx264 to encode a video file using libav from a C file and
> switched to nvenc_h264 and now the encode is very slow. It appears
> nvenc_h264 does not have a "ultrafast" setting.
> With nvenc_h264 I am using preset "llhq" and tune "zerolatency". Am I
> using the wrong settings?
> Cheers,
> Philippe
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In my experience, x264 is very fast and you may not be able to beat it at
low quality.  That said, there are a lot of possibilities for why it may be
slow.  Look at:
https://devblogs.nvidia.com/nvidia-ffmpeg-transcoding-guide/ which will
give you some tips for minimizing PCIe transfers to keep it fast.

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