[FFmpeg-devel] [PATCH] avfilter/delogo: Set default band to 1

Jean Delvare jdelvare at suse.de
Wed Oct 7 13:57:46 CEST 2015


Hi Stefano,

On Wed, 7 Oct 2015 11:21:45 +0200, Stefano Sabatini wrote:
> On date Wednesday 2015-10-07 08:54:59 +0200, Jean Delvare encoded:
> > The original interpolation algorithm behaved poorly on the borders and
> > did not even guarantee continuity at the borders. For this reason, a
> > second interpolation/blending pass was required on the borders to make
> > them seamless.
> > 
> > However, since the interpolation algorithm was improved in June 2013,
> > the border issues no longer exist. The new algorithm does guarantee
> > continuity at the borders, making the second pass useless. A larger
> > band always increases the cumulated interpolation error. In most cases
> > it also increases the average interpolation error, even though the
> > samples in the band are only partially interpolated.
> > 
> > For this reason I would like to get rid of the "band" parameter. As a
> > first step, let's change its default value from 4 to 1 and document it
> > as deprecated.
> > 
> > I have benchmarked this change on a combination of input sources and
> > realistic logo areas. Lowering the band value from 4 to 1 resulted in
> > 8 to 39 % less interpolation error per frame (or 1 to 34 % less
> > interpolation error per luma sample.)
> > 
> > Signed-off-by: Jean Delvare <jdelvare at suse.de>
> > ---
> >  doc/filters.texi        |    4 +++-
> >  libavfilter/vf_delogo.c |   11 +++++++++--
> >  2 files changed, 12 insertions(+), 3 deletions(-)
> > 
> > --- ffmpeg.orig/doc/filters.texi	2015-10-02 11:41:24.035943770 +0200
> > +++ ffmpeg/doc/filters.texi	2015-10-02 12:02:08.231484828 +0200
> > @@ -4590,7 +4590,9 @@ specified.
> >  
> >  @item band, t
> >  Specify the thickness of the fuzzy edge of the rectangle (added to
> > - at var{w} and @var{h}). The default value is 4.
> > + at var{w} and @var{h}). The default value is 1. This option is
> > +deprecated, setting higher values should no longer be necessary and
> > +is not recommended.
> >  
> >  @item show
> >  When set to 1, a green rectangle is drawn on the screen to simplify
> > --- ffmpeg.orig/libavfilter/vf_delogo.c	2015-10-02 11:41:24.035943770 +0200
> > +++ ffmpeg/libavfilter/vf_delogo.c	2015-10-07 08:45:39.037203764 +0200
> > @@ -165,8 +165,9 @@ static const AVOption delogo_options[]=
> >      { "y",    "set logo y position",       OFFSET(y),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },
> >      { "w",    "set logo width",            OFFSET(w),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },
> >      { "h",    "set logo height",           OFFSET(h),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },
> > -    { "band", "set delogo area band size", OFFSET(band), AV_OPT_TYPE_INT, { .i64 =  4 },  1, INT_MAX, FLAGS },
> > -    { "t",    "set delogo area band size", OFFSET(band), AV_OPT_TYPE_INT, { .i64 =  4 },  1, INT_MAX, FLAGS },
> > +    /* Actual default value for band/t is 1, set in init */
> > +    { "band", "set delogo area band size", OFFSET(band), AV_OPT_TYPE_INT, { .i64 =  0 },  0, INT_MAX, FLAGS },
> > +    { "t",    "set delogo area band size", OFFSET(band), AV_OPT_TYPE_INT, { .i64 =  0 },  0, INT_MAX, FLAGS },
> >      { "show", "show delogo area",          OFFSET(show), AV_OPT_TYPE_BOOL,{ .i64 =  0 },  0, 1,       FLAGS },
> >      { NULL }
> >  };
> > @@ -201,6 +202,12 @@ static av_cold int init(AVFilterContext
> >      CHECK_UNSET_OPT(w);
> >      CHECK_UNSET_OPT(h);
> >  
> > +    if (s->band == 0) { /* Unset, use default */
> > +        av_log(ctx, AV_LOG_WARNING, "Note: default band value was changed from 4 to 1.\n");
> > +        s->band = 1;
> > +    } else if (s->band != 1) {
> > +        av_log(ctx, AV_LOG_WARNING, "Option band is deprecated.\n");
> > +    }
> >      av_log(ctx, AV_LOG_VERBOSE, "x:%d y:%d, w:%d h:%d band:%d show:%d\n",
> >             s->x, s->y, s->w, s->h, s->band, s->show);
> 
> LGTM. BTW, if you want to drop the band option, you could ifdef it so
> that it will be dropt at the next lavfi major bump.

Good idea. Something like this?

---
 libavfilter/vf_delogo.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- ffmpeg.orig/libavfilter/vf_delogo.c	2015-10-07 08:45:39.037203764 +0200
+++ ffmpeg/libavfilter/vf_delogo.c	2015-10-07 13:52:43.716487733 +0200
@@ -165,9 +165,11 @@ static const AVOption delogo_options[]=
     { "y",    "set logo y position",       OFFSET(y),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },
     { "w",    "set logo width",            OFFSET(w),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },
     { "h",    "set logo height",           OFFSET(h),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },
+#if LIBAVFILTER_VERSION_MAJOR < 7
     /* Actual default value for band/t is 1, set in init */
     { "band", "set delogo area band size", OFFSET(band), AV_OPT_TYPE_INT, { .i64 =  0 },  0, INT_MAX, FLAGS },
     { "t",    "set delogo area band size", OFFSET(band), AV_OPT_TYPE_INT, { .i64 =  0 },  0, INT_MAX, FLAGS },
+#endif
     { "show", "show delogo area",          OFFSET(show), AV_OPT_TYPE_BOOL,{ .i64 =  0 },  0, 1,       FLAGS },
     { NULL }
 };
@@ -202,12 +204,16 @@ static av_cold int init(AVFilterContext
     CHECK_UNSET_OPT(w);
     CHECK_UNSET_OPT(h);
 
+#if LIBAVFILTER_VERSION_MAJOR < 7
     if (s->band == 0) { /* Unset, use default */
         av_log(ctx, AV_LOG_WARNING, "Note: default band value was changed from 4 to 1.\n");
         s->band = 1;
     } else if (s->band != 1) {
         av_log(ctx, AV_LOG_WARNING, "Option band is deprecated.\n");
     }
+#else
+    s->band = 1;
+#endif
     av_log(ctx, AV_LOG_VERBOSE, "x:%d y:%d, w:%d h:%d band:%d show:%d\n",
            s->x, s->y, s->w, s->h, s->band, s->show);
 
Or should I use FF_API_OLD_FILTER_OPTS?

Assuming this is what you had in mind, would it go as a separate patch,
or should this be folded in the patch I just sent?

Thanks,
-- 
Jean Delvare
SUSE L3 Support


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