[x264-devel] lossless I-slices inside I,P,B lossy frames

[Jason Garrett-Glaser]

On Sun, Oct 21, 2012 at 4:40 PM, Amin Zia <amin.zia at utoronto.ca> wrote:
> Hi List,
>
> I am trying to encode a h264 stream video with "lossless "I-slices that are
> inside some lossy encoded frames (I, P, and/or B) to allocate more bits to
> those slices.

Have you tried using quant_offsets to give more bits to one section of
the frame?  That might be a lot easier.

> This can also be done by some sporadic I-frames in my GOPs.
>
> Would you please let me know if this can be done by x264 encoder? I
> have tried to enable loss-less encoding but it seems that the transform is
> applied to the frames irrespective of whether I've enable lossless mode or
> not.

x264 doesn't currently support mixed lossy/lossless, but it wouldn't
be too difficult to do if there was a relevant use case.  Keep in mind
that using actual lossless mode would force the stream to High 4:4:4
Predictive profile.

Jason