On Tue, Mar 03, 2015 at 10:50:09PM +0530, arwa arif wrote:
> On Tue, Mar 3, 2015 at 6:11 PM, Michael Niedermayer <michae...@gmx.at>
> wrote:
>
> > On Tue, Mar 03, 2015 at 12:06:09PM +0530, arwa arif wrote:
> > > I tried to change the name to fft, but it is conflicting with
> > > libavcodec/fft. So, I am unable to change that. I have updated the patch,
> > > adding support to coloured images.
> >
> > yes, the names could conflict in configure indeed
> >
> >
> > [...]
> > > +
> > > +#include "libavfilter/internal.h"
> > > +#include "libavutil/common.h"
> > > +#include "libavutil/imgutils.h"
> > > +#include "libavutil/opt.h"
> > > +#include "libavutil/pixdesc.h"
> > > +#include "libavcodec/avfft.h"
> > > +#include "libavutil/eval.h"
> > > +
> > > +typedef struct {
> > > + const AVClass *class;
> > > +
> > > + RDFTContext *rdft;
> > > + int rdft_hbits[3];
> > > + int rdft_vbits[3];
> > > + size_t rdft_hlen[3];
> > > + size_t rdft_vlen[3];
> > > + FFTSample *rdft_hdata[3];
> > > + FFTSample *rdft_vdata[3];
> > > +
> > > + int dc;
> > > + char *lum_str;
> > > + AVExpr *lum_expr;
> > > + double *lum_data;
> > > +
> > > +} FFTFILTContext;
> > > +
> > > +static const char *const var_names[] = { "X", "Y", "W", "H",
> > NULL };
> > > +enum { VAR_X, VAR_Y, VAR_W, VAR_H,
> > VAR_VARS_NB };
> > > +
> > > +#define OFFSET(x) offsetof(FFTFILTContext, x)
> > > +#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
> > > +
> >
> > > +static const AVOption fftfilt_options[] = {
> > > + { "dc", "adjust gain", OFFSET(dc),
> > AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1000, FLAGS },
> > > + { "lum", "set luminance expression", OFFSET(lum_str),
> > AV_OPT_TYPE_STRING, {.str = "1"}, CHAR_MIN, CHAR_MAX, FLAGS },
> > > + {NULL},
> >
> > The user should be able to set seperate dc / "lum" for teh 3 planes
> > that is if only the first dc and first exression is set then they
> > should be used for all 3 planes
> > otherwise, if teh user set 3 dc values and 3 expressions then each
> > plane should use the specific expression
> >
> >
> >
> > [...]
> > > +
> > > + memset(fftfilt->rdft_hdata[plane] + i *
> > fftfilt->rdft_hlen[plane], 0,
> > > + fftfilt->rdft_hlen[plane] *
> > sizeof(*fftfilt->rdft_hdata[plane]));
> >
> > the memseting should ideally be replaced by mirroring, this leads
> > to better quality
> >
> > for example
> > matrixbench_mpeg2.mpg -vf fftfilt=dc=128:lum="'(1 / (1 +
> > exp(-(Y+X)/10.0+H/100.0)))'"
> > results in a pink border due to this
> >
> > that is instead of for each line
> > 1 2 3 3 7 9 10 11 23
> > it should not be changed to:
> > 1 2 3 3 7 9 10 11 23 0 0 0 0 0 0 0
> > but
> > 1 2 3 3 7 9 10 11 23 23 11 10 x 3 2 1
> >
> >
> But, we want to clear the block of memory. Why do we want to mirror it?The idea is to clear it with the same data as is in the input picture not with 0 bytes so instead of 9999999999999999999000000 99999........999999000000 99999..9..9..999999000000 99999........999999000000 99999.9....9.999999000000 99999..9999..999999000000 99999........999999000000 9999999999999999999000000 it is 9999999999999999999999999 99999........999999999999 99999..9..9..999999999999 99999........999999999999 99999.9....9.999999999999 99999..9999..999999999999 99999........999999999999 9999999999999999999999999 because when the image is filtered the additional outside padding will affect the vissible area consider: 999999000000 -> 9999865100 vs 999999999999 -> 9999999999 the vissible part is: 999986 vs 999999 or said differently the 0 padding gets "smeared" into the vissible image, so the more similar it is to the input image the less artifacts this creates [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Rewriting code that is poorly written but fully understood is good. Rewriting code that one doesnt understand is a sign that one is less smart then the original author, trying to rewrite it will not make it better.
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