[FFmpeg-devel] [PATCH] jpeg2000: split off inverse MCT decoding as Jpeg2000DSP

[Michael Niedermayer]

On Wed, Oct 01, 2014 at 08:08:18PM -0300, James Almer wrote:
> On 01/10/14 8:04 PM, Michael Niedermayer wrote:
> > On Wed, Oct 01, 2014 at 05:14:38PM -0300, James Almer wrote:
> >> This makes the addition of arch optimized functions easier.
> >>
> >> Signed-off-by: James Almer <jamrial at gmail.com>
> >> ---
> >>  libavcodec/Makefile      |  2 +-
> >>  libavcodec/jpeg2000dec.c | 71 +++++++++--------------------------
> >>  libavcodec/jpeg2000dsp.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++
> >>  libavcodec/jpeg2000dsp.h | 35 +++++++++++++++++
> >>  libavcodec/jpeg2000dwt.h |  3 +-
> >>  5 files changed, 153 insertions(+), 56 deletions(-)
> >>  create mode 100644 libavcodec/jpeg2000dsp.c
> >>  create mode 100644 libavcodec/jpeg2000dsp.h
> > [...]
> >> +static void mct_decode97_float(void *_src0, void *_src1, void *_src2, int csize)
> >> +{
> >> +    float *src0 = _src0, *src1 = _src1, *src2 = _src2;
> >> +    float i0f, i1f, i2f;
> >> +    int i;
> >> +
> >> +    for (i = 0; i < csize; i++) {
> >> +        i0f = *src0 + (f_ict_params[0] * *src2);
> >> +        i1f = *src0 - (f_ict_params[1] * *src1)
> >> +                    - (f_ict_params[2] * *src2);
> >> +        i2f = *src0 + (f_ict_params[3] * *src1);
> >> +        *src0++ = i0f;
> >> +        *src1++ = i1f;
> >> +        *src2++ = i2f;
> >> +    }
> >> +}
> >> +
> >> +static void mct_decode97_int(void *_src0, void *_src1, void *_src2, int csize)
> >> +{
> >> +    int32_t *src0 = _src0, *src1 = _src1, *src2 = _src2;
> >> +    int32_t i0, i1, i2;
> >> +    int i;
> >> +
> >> +    for (i = 0; i < csize; i++) {
> >> +        i0 = *src0 + (((i_ict_params[0] * *src2) + (1 << 15)) >> 16);
> >> +        i1 = *src0 - (((i_ict_params[1] * *src1) + (1 << 15)) >> 16)
> >> +                   - (((i_ict_params[2] * *src2) + (1 << 15)) >> 16);
> >> +        i2 = *src0 + (((i_ict_params[3] * *src1) + (1 << 15)) >> 16);
> >> +        *src0++ = i0;
> >> +        *src1++ = i1;
> >> +        *src2++ = i2;
> >> +    }
> >> +}
> >> +
> >> +static void mct_decode53(void *_src0, void *_src1, void *_src2, int csize)
> > 
> > the function names are not good
> > the code is not related to the 5/3 and 9/7 wavelets
> 
> Well, the code checks for one of the three DWTType values (FF_DWT97, FF_DWT97_INT and
> FF_DWT53) to choose what to run, so these names seemed adequate to me.
> 
> What names do you suggest then?

the terms used by jpeg2000 are rct and ict, for
Reversible multiple component transformation (RCT)
and
Irreversible multiple component transformation (ICT)

we have 2 implementations of the ICT, one float and one int
so id suggest

ict_float, ict_int, rct_int

maybe throwing a f/i in for forward and inverse, maybe instead not
abbreviating something, i dunno, pick what you prefer

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Republics decline into democracies and democracies degenerate into
despotisms. -- Aristotle
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