[FFmpeg-user] Using Hardware Accelerated Encoder Produce Bigger File

[Moritz Barsnick]

On Tue, Sep 11, 2018 at 16:38:37 +0430, Ali Shirvani wrote:
> Is this variation in output size normal? or should I tune some settings?

Yes, it's normal - different encoders use different default settings.

Yes, you should tune your settings.

If you want to achieve similar size, use the "-b:v" (video bitrate)
command line parameter. Yet quality may differ significantly, depending
on the effort and the encoding methods used by the encoder. (Even at
somewhat constant quality, you can vary the size of the libx264
encoding significantly by using different "-preset" options.)

If you want to achieve identical quality, you need to fiddle with the
available options. libx264 offers "-crf" for its (default) variable
bitrate encoding (also for fixed). Other H.264 encoders probably use
other options (such as "-q:v", but its impact may differ depending on
encoder) and may even default to constant bitrate. Check in the manual
or with:

$ ffmpeg -h encoder=encoder_name

Cheers,
Moritz