[x264-devel] [x264] quality of first I frame is very poor

[Jason Garrett-Glaser]

2008/8/7 Sandip Ray <sandip.ray at einfochips.com>:
>
> Dear Experts,
>
> I downloaded x264 source code from git://git.videolan.org/x264.git and built
> x264.exe in Visual Studio. I set command line parameters as follows.
>
> -v --frames 300 -B 128 -o D:/output/foreman.264 D:/output/foreman_cif.yuv
> 352x288
>
> I observe that QP in the first I frame is very high, resulting in poor
> quality. The output from the code is as follows.

In 1-pass bitrate mode, x264 has to guess the correct quantizer to use
for the first frame.  This guess isn't always very good.

If you want better quality, run a second pass.

Dark Shikari