avfilter: add roberts cross operator

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Changelog

@@ -21,6 +21,7 @@ version <next>:
 - Gremlin Digital Video demuxer and decoder
 - headphone audio filter
 - superequalizer audio filter
+- roberts video filter
 
 version 3.3:
 - CrystalHD decoder moved to new decode API

doc/filters.texi

@@ -12118,6 +12118,23 @@ trim=end=5,reverse
 @end example
 @end itemize
 
+@section roberts
+Apply roberts cross operator to input video stream.
+
+The filter accepts the following option:
+
+@table @option
+@item planes
+Set which planes will be processed, unprocessed planes will be copied.
+By default value 0xf, all planes will be processed.
+
+@item scale
+Set value which will be multiplied with filtered result.
+
+@item delta
+Set value which will be added to filtered result.
+@end table
+
 @section rotate
 
 Rotate video by an arbitrary angle expressed in radians.

libavfilter/Makefile

@@ -268,6 +268,7 @@ OBJS-$(CONFIG_REMOVEGRAIN_FILTER)            += vf_removegrain.o
 OBJS-$(CONFIG_REMOVELOGO_FILTER)             += bbox.o lswsutils.o lavfutils.o vf_removelogo.o
 OBJS-$(CONFIG_REPEATFIELDS_FILTER)           += vf_repeatfields.o
 OBJS-$(CONFIG_REVERSE_FILTER)                += f_reverse.o
+OBJS-$(CONFIG_ROBERTS_FILTER)                += vf_convolution.o
 OBJS-$(CONFIG_ROTATE_FILTER)                 += vf_rotate.o
 OBJS-$(CONFIG_SAB_FILTER)                    += vf_sab.o
 OBJS-$(CONFIG_SCALE_FILTER)                  += vf_scale.o scale.o

libavfilter/allfilters.c

@@ -279,6 +279,7 @@ static void register_all(void)
     REGISTER_FILTER(REMOVELOGO,     removelogo,     vf);
     REGISTER_FILTER(REPEATFIELDS,   repeatfields,   vf);
     REGISTER_FILTER(REVERSE,        reverse,        vf);
+    REGISTER_FILTER(ROBERTS,        roberts,        vf);
     REGISTER_FILTER(ROTATE,         rotate,         vf);
     REGISTER_FILTER(SAB,            sab,            vf);
     REGISTER_FILTER(SCALE,          scale,          vf);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   6
-#define LIBAVFILTER_VERSION_MINOR  93
+#define LIBAVFILTER_VERSION_MINOR  94
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

libavfilter/vf_convolution.c

@@ -198,6 +198,55 @@ static int filter16_prewitt(AVFilterContext *ctx, void *arg, int jobnr, int nb_j
     return 0;
 }
 
+static int filter16_roberts(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
+{
+    ConvolutionContext *s = ctx->priv;
+    ThreadData *td = arg;
+    AVFrame *in = td->in;
+    AVFrame *out = td->out;
+    const int plane = td->plane;
+    const int peak = (1 << s->depth) - 1;
+    const int stride = in->linesize[plane] / 2;
+    const int bstride = s->bstride;
+    const int height = s->planeheight[plane];
+    const int width  = s->planewidth[plane];
+    const int slice_start = (height * jobnr) / nb_jobs;
+    const int slice_end = (height * (jobnr+1)) / nb_jobs;
+    const uint16_t *src = (const uint16_t *)in->data[plane] + slice_start * stride;
+    uint16_t *dst = (uint16_t *)out->data[plane] + slice_start * (out->linesize[plane] / 2);
+    const float scale = s->scale;
+    const float delta = s->delta;
+    uint16_t *p0 = (uint16_t *)s->bptrs[jobnr] + 16;
+    uint16_t *p1 = p0 + bstride;
+    uint16_t *p2 = p1 + bstride;
+    uint16_t *orig = p0, *end = p2;
+    int y, x;
+
+    line_copy16(p0, src + stride * (slice_start == 0 ? 1 : -1), width, 1);
+    line_copy16(p1, src, width, 1);
+
+    for (y = slice_start; y < slice_end; y++) {
+        src += stride * (y < height - 1 ? 1 : -1);
+        line_copy16(p2, src, width, 1);
+
+        for (x = 0; x < width; x++) {
+            int suma = p0[x - 1] *  1 +
+                       p1[x    ] * -1;
+            int sumb = p0[x    ] *  1 +
+                       p1[x - 1] * -1;
+
+            dst[x] = av_clip(sqrt(suma*suma + sumb*sumb) * scale + delta, 0, peak);
+        }
+
+        p0 = p1;
+        p1 = p2;
+        p2 = (p2 == end) ? orig: p2 + bstride;
+        dst += out->linesize[plane] / 2;
+    }
+
+    return 0;
+}
+
 static int filter16_sobel(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
 {
     ConvolutionContext *s = ctx->priv;
@@ -311,6 +360,54 @@ static int filter_prewitt(AVFilterContext *ctx, void *arg, int jobnr, int nb_job
     return 0;
 }
 
+static int filter_roberts(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
+{
+    ConvolutionContext *s = ctx->priv;
+    ThreadData *td = arg;
+    AVFrame *in = td->in;
+    AVFrame *out = td->out;
+    const int plane = td->plane;
+    const int stride = in->linesize[plane];
+    const int bstride = s->bstride;
+    const int height = s->planeheight[plane];
+    const int width  = s->planewidth[plane];
+    const int slice_start = (height * jobnr) / nb_jobs;
+    const int slice_end = (height * (jobnr+1)) / nb_jobs;
+    const uint8_t *src = in->data[plane] + slice_start * stride;
+    uint8_t *dst = out->data[plane] + slice_start * out->linesize[plane];
+    const float scale = s->scale;
+    const float delta = s->delta;
+    uint8_t *p0 = s->bptrs[jobnr] + 16;
+    uint8_t *p1 = p0 + bstride;
+    uint8_t *p2 = p1 + bstride;
+    uint8_t *orig = p0, *end = p2;
+    int y, x;
+
+    line_copy8(p0, src + stride * (slice_start == 0 ? 1 : -1), width, 1);
+    line_copy8(p1, src, width, 1);
+
+    for (y = slice_start; y < slice_end; y++) {
+        src += stride * (y < height - 1 ? 1 : -1);
+        line_copy8(p2, src, width, 1);
+
+        for (x = 0; x < width; x++) {
+            int suma = p0[x - 1] *  1 +
+                       p1[x    ] * -1;
+            int sumb = p0[x    ] *  1 +
+                       p1[x - 1] * -1;
+
+            dst[x] = av_clip_uint8(sqrt(suma*suma + sumb*sumb) * scale + delta);
+        }
+
+        p0 = p1;
+        p1 = p2;
+        p2 = (p2 == end) ? orig: p2 + bstride;
+        dst += out->linesize[plane];
+    }
+
+    return 0;
+}
+
 static int filter_sobel(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
 {
     ConvolutionContext *s = ctx->priv;
@@ -651,6 +748,10 @@ static int config_input(AVFilterLink *inlink)
         if (s->depth > 8)
             for (p = 0; p < s->nb_planes; p++)
                 s->filter[p] = filter16_prewitt;
+    } else if (!strcmp(ctx->filter->name, "roberts")) {
+        if (s->depth > 8)
+            for (p = 0; p < s->nb_planes; p++)
+                s->filter[p] = filter16_roberts;
     } else if (!strcmp(ctx->filter->name, "sobel")) {
         if (s->depth > 8)
             for (p = 0; p < s->nb_planes; p++)
@@ -739,6 +840,13 @@ static av_cold int init(AVFilterContext *ctx)
             else
                 s->copy[i] = 1;
         }
+    } else if (!strcmp(ctx->filter->name, "roberts")) {
+        for (i = 0; i < 4; i++) {
+            if ((1 << i) & s->planes)
+                s->filter[i] = filter_roberts;
+            else
+                s->copy[i] = 1;
+        }
     } else if (!strcmp(ctx->filter->name, "sobel")) {
         for (i = 0; i < 4; i++) {
             if ((1 << i) & s->planes)
@@ -845,3 +953,29 @@ AVFilter ff_vf_sobel = {
 };
 
 #endif /* CONFIG_SOBEL_FILTER */
+
+#if CONFIG_ROBERTS_FILTER
+
+static const AVOption roberts_options[] = {
+    { "planes", "set planes to filter", OFFSET(planes), AV_OPT_TYPE_INT,  {.i64=15}, 0, 15, FLAGS},
+    { "scale",  "set scale",            OFFSET(scale), AV_OPT_TYPE_FLOAT, {.dbl=1.0}, 0.0,  65535, FLAGS},
+    { "delta",  "set delta",            OFFSET(delta), AV_OPT_TYPE_FLOAT, {.dbl=0}, -65535, 65535, FLAGS},
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(roberts);
+
+AVFilter ff_vf_roberts = {
+    .name          = "roberts",
+    .description   = NULL_IF_CONFIG_SMALL("Apply roberts cross operator."),
+    .priv_size     = sizeof(ConvolutionContext),
+    .priv_class    = &roberts_class,
+    .init          = init,
+    .uninit        = uninit,
+    .query_formats = query_formats,
+    .inputs        = convolution_inputs,
+    .outputs       = convolution_outputs,
+    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
+};
+
+#endif /* CONFIG_ROBERTS_FILTER */