[FFmpeg-user] A question about video encoding.

Andrew Randrianasulu randrianasulu at gmail.com
Sun Nov 12 19:45:26 EET 2023

вс, 12 нояб. 2023 г., 20:23 Aditya Dandavate <adityadandavate04 at gmail.com>:

> I have an Intel Pentium G3240 processor.
> This is a quite a low end processor and even x264 etc is cpu-intensive and
> even encoding with this encoder is really slow. (6.0 to 6.5 fps with medium
> preset).
> I encoded some videos with mpeg4 video encoder and h264_qsv encoder. The
> results I got was the speed of h264_qsv with preset veryslow, is almost the
> same to mpeg4 -q:v 5, with 15000k bitrate for both encoders. libopus was
> audio encoder with 320kbps bitrate for both encoding settings.
> (h264_qsv = 16-17 fps, mpeg4 = 18-19 fps).

well, isn't it depend on frame size and fps too?

15 Mbit/s  * h264 sounds quite good bitrate for say, 1080p30, but h264 in
general allows for less bitrate at similar quality. So watch them both and
decide? I think at 25+ MB/s even old standby like mpeg2 can deliver not so
bad quality at full hd? I used to think that empirically mpeg4 compress 1/3
better than mpeg2, then h264 shaves thid more, and so on, at progressively
highr cpu usage on both decode and encode. Of course there is plenty of
knobs to tune, vbr vs cbr vs two-pass vbr ... this rabbit hole goes deep!

> So, Should I stick to h264_qsv or mpeg4 ? In general, which encoder gives
> higher quality at the same bitrate ?

Hardware encoders used to be not good at 2-4-6 Mbs range for live
streaming, but from existence of some bluray compat option in nvenc wrapper
I can guess at BluRay bitrates they might be quite good?

watch water/fire scene - usually they hard to encode.

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