manpage: add some blabla about zimg speed vs. libswscale

Of course nobody will read this. I'm just putting it there so I can
blame users, who run into problems, for not having read it.
This commit is contained in:
wm4 2020-02-10 18:11:42 +01:00
parent 83f070dfb8
commit a8404ed0a0
1 changed files with 10 additions and 1 deletions

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@ -4022,7 +4022,7 @@ Software Scaler
VOs like ``drm`` and ``x11`` will benefit a lot from using ``--sws-fast``.
You may need to set other options, like ``--sws-scaler``. The builtin
``sws-fast`` profile sets this option and some others to gain performance
for reduced quality.
for reduced quality. Also see ``--sws-allow-zimg``.
``--sws-allow-zimg=<yes|no>``
Allow using zimg (if the component using the internal swscale wrapper
@ -4039,6 +4039,15 @@ Software Scaler
Most things which need software conversion can make use of this.
.. note::
The builtin ``sws-fast`` profile (which you are supposed to use when you
use a VO that uses software conversion on weak hardware) sets this
option. But do note that zimg *may* be slower than libswscale. Usually,
it's faster on x86 platforms, but slower on ARM (due to lack of ARM
specific optimizations). The mpv zimg wrapper uses unoptimized repacking
for some formats, for which zimg cannot be blamed.
``--zimg-scaler=<point|bilinear|bicubic|spline16|spline36|lanczos>``
Zimg luma scaler to use (default: lanczos).