[FFmpeg-user] libx264 very bad scaling with 4 real CPU cores (no HT)

[Jim Worrall]

On Fri, Dec 4, 2015 at 4:06 AM, D <dcmhoybdpzkh at web.de> wrote:

> On 03.12.2015 22:22, Lou wrote:
>
>> On Thu, 3 Dec 2015 16:43:28 +0100
>> D <dcmhoybdpzkh at web.de> wrote:
>>
> The other thing I find weird with -preset is that one can use -crf setting
> with it. I thought a preset would cover this and no -crf setting would be
> needed/allowed. But because it is, the question is what other settings are
> allowed/needed? Confusing.
>
> I would suggest you read a bit on x264 to reduce the confusion.  Here is a
good place to start:
https://trac.ffmpeg.org/wiki/x264EncodingGuide

When using presets, there are essentially three things you can vary:
encoding speed, quality, and bitrate.
You specify relative encoding speed with the choice of preset, then specify
either quality or bitrate.
You can't specify all three in one encode.

At a given quality level (crf), you will get lower bitrate with a slower
preset.
At a given bitrate level, you will get better quality with a slower preset.