[FFmpeg-devel] [PATCH 3/4] avcodec/jpeg2000: Simplify exp2fi for numbers used here

Tomas Härdin git at haerdin.se
Mon Feb 19 16:51:28 EET 2024


mån 2024-02-19 klockan 15:14 +0100 skrev Andreas Rheinhardt:
> Tomas Härdin:
> > lör 2024-02-17 klockan 21:05 +0100 skrev Andreas Rheinhardt:
> > > The call to ff_exp2fi() here always uses arguments in the normal
> > > range, so that the branches in ff_exp2fi() are unnecessary.
> > > This is so because JPEG2000 itself only supports up to
> > > 128 bits per component per pixel (we only support far less);
> > > furthermore, expn is always 0..31 for the decoder and also
> > > sane for the encoder, so that the difference between these
> > > two values is always in the normal range of -126..128.
> > 
> > Any measurable improvement in decode speed?
> > 
> 
> I don't think it is measurable; my aim was to move ff_exp2fi() out of
> internal.h (where it does not belong).

Ah. Well, fewer branches is almost always good so, looks good to me.
Maybe pal has an opinion?

/Tomas


More information about the ffmpeg-devel mailing list