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

Ali Shirvani aj.shirvani at gmail.com
Wed Sep 12 08:13:17 EEST 2018


Hi Moritz,

Thanks for your helpful reply. I change the encoders settings and the file
size now similar.

Cheers,
Ali

On Tue, Sep 11, 2018 at 5:32 PM Moritz Barsnick <barsnick at gmx.net> wrote:

> 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
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