[x264-devel] Default value for the --scenecut option causes heavy undesirable flood of I slices in active scenes

[Jason Garrett-Glaser]

On Tue, Nov 4, 2008 at 1:24 AM, Vladimir Chernyshov <vchernys at welho.com> wrote:
> I repeat the point of my posts: it is counterproductive to insert I-frames
> and suppress B-frames in highly active scenes - the bitrate would be
> inflated, and the quality improvement not noticed, and the default value for
> the scenecut could be changed from 40 to 0.

And I repeat my point that you still do not understand the purpose of
B-frames.  The purpose of B-frames is not to raise the quantizer, and
the purpose of I-frames is not to lower the quantizer.  These are
ratecontrol choices, which you can adjust as commandline options, and
have basically nothing to do with the reason why B-frames are useful
in the first place.

In such a scene as you have described, B-frames are suboptimal:
period.  No ifs, ands, or buts.  I-frames are relatively optimal,
because if a frame is nearly entirely I-blocks, there is little point
to having inter prediction anyways.  I am not going to change encoder
defaults because clueless people on the mailing list manage to
convince themselves of falsehoods and then proceed to ignore people
with enormously more experience in the field than they do and
completely disregard all responses that don't explicitly agree with
them.

End of story.  I am not going to waste any more of my time on this
unless someone starts paying me, or you submit a usable patch that not
only solves your supposed "problem" but also consistently improves
PSNR on every single test clip in my repertoire.

Also, stop top-posting, or others will likely proceed to ignore you as well.

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