avfilter/fade: add color option.

Fixes Ticket #1822.

doc/filters.texi

@@ -3809,7 +3809,8 @@ effect. Default is 0.
 @item nb_frames, n
 The number of frames for which the fade effect has to last. At the end of the
 fade-in effect the output video will have the same intensity as the input video,
-at the end of the fade-out transition the output video will be completely black.
+at the end of the fade-out transition the output video will be filled with the
+selected @option{color}.
 Default is 25.
 
 @item alpha
@@ -3824,8 +3825,12 @@ whichever comes last.  Default is 0.
 @item duration, d
 The number of seconds for which the fade effect has to last. At the end of the
 fade-in effect the output video will have the same intensity as the input video,
-at the end of the fade-out transition the output video will be completely black.
+at the end of the fade-out transition the output video will be filled with the
+selected @option{color}.
 If both duration and nb_frames are specified, duration is used. Default is 0.
+
+@item color, c
+Specify the color of the fade. Default is "black".
 @end table
 
 @subsection Examples
@@ -3856,9 +3861,9 @@ fade=in:0:25, fade=out:975:25
 @end example
 
 @item
-Make first 5 frames black, then fade in from frame 5-24:
+Make first 5 frames yellow, then fade in from frame 5-24:
 @example
-fade=in:5:20
+fade=in:5:20:color=yellow
 @end example
 
 @item

libavfilter/vf_fade.c

@@ -25,6 +25,7 @@
  * based heavily on vf_negate.c by Bobby Bingham
  */
 
+#include "libavutil/avassert.h"
 #include "libavutil/avstring.h"
 #include "libavutil/common.h"
 #include "libavutil/eval.h"
@@ -61,6 +62,8 @@ typedef struct {
     int alpha;
     uint64_t start_time, duration;
     enum {VF_FADE_WAITING=0, VF_FADE_FADING, VF_FADE_DONE} fade_state;
+    uint8_t color_rgba[4];  ///< fade color
+    int black_fade;         ///< if color_rgba is black
 } FadeContext;
 
 static av_cold int init(AVFilterContext *ctx)
@@ -89,11 +92,13 @@ static av_cold int init(AVFilterContext *ctx)
                (s->duration / (double)AV_TIME_BASE),s->alpha);
     }
 
+    s->black_fade = !memcmp(s->color_rgba, "\x00\x00\x00\xff", 4);
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
+    const FadeContext *s = ctx->priv;
     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUV444P,  AV_PIX_FMT_YUV422P,  AV_PIX_FMT_YUV420P,
         AV_PIX_FMT_YUV411P,  AV_PIX_FMT_YUV410P,
@@ -105,8 +110,17 @@ static int query_formats(AVFilterContext *ctx)
         AV_PIX_FMT_RGBA,     AV_PIX_FMT_BGRA,
         AV_PIX_FMT_NONE
     };
+    static const enum AVPixelFormat pix_fmts_rgb[] = {
+        AV_PIX_FMT_RGB24,    AV_PIX_FMT_BGR24,
+        AV_PIX_FMT_ARGB,     AV_PIX_FMT_ABGR,
+        AV_PIX_FMT_RGBA,     AV_PIX_FMT_BGRA,
+        AV_PIX_FMT_NONE
+    };
 
-    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+    if (s->black_fade)
+        ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+    else
+        ff_set_common_formats(ctx, ff_make_format_list(pix_fmts_rgb));
     return 0;
 }
 
@@ -138,6 +152,47 @@ static int config_props(AVFilterLink *inlink)
     return 0;
 }
 
+static av_always_inline void filter_rgb(FadeContext *s, const AVFrame *frame,
+                                        int slice_start, int slice_end,
+                                        int do_alpha, int step)
+{
+    int i, j;
+    const uint8_t r_idx  = s->rgba_map[R];
+    const uint8_t g_idx  = s->rgba_map[G];
+    const uint8_t b_idx  = s->rgba_map[B];
+    const uint8_t a_idx  = s->rgba_map[A];
+    const uint8_t *c = s->color_rgba;
+
+    for (i = slice_start; i < slice_end; i++) {
+        uint8_t *p = frame->data[0] + i * frame->linesize[0];
+        for (j = 0; j < frame->width; j++) {
+#define INTERP(c_name, c_idx) av_clip_uint8(((c[c_idx]<<16) + ((int)p[c_name] - (int)c[c_idx]) * s->factor + (1<<15)) >> 16)
+            p[r_idx] = INTERP(r_idx, 0);
+            p[g_idx] = INTERP(g_idx, 1);
+            p[b_idx] = INTERP(b_idx, 2);
+            if (do_alpha)
+                p[a_idx] = INTERP(a_idx, 3);
+            p += step;
+        }
+    }
+}
+
+static int filter_slice_rgb(AVFilterContext *ctx, void *arg, int jobnr,
+                            int nb_jobs)
+{
+    FadeContext *s = ctx->priv;
+    AVFrame *frame = arg;
+    int slice_start = (frame->height *  jobnr   ) / nb_jobs;
+    int slice_end   = (frame->height * (jobnr+1)) / nb_jobs;
+
+    if      (s->alpha)    filter_rgb(s, frame, slice_start, slice_end, 1, 4);
+    else if (s->bpp == 3) filter_rgb(s, frame, slice_start, slice_end, 0, 3);
+    else if (s->bpp == 4) filter_rgb(s, frame, slice_start, slice_end, 0, 4);
+    else                  av_assert0(0);
+
+    return 0;
+}
+
 static int filter_slice_luma(AVFilterContext *ctx, void *arg, int jobnr,
                              int nb_jobs)
 {
@@ -271,8 +326,11 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
         if (s->alpha) {
             ctx->internal->execute(ctx, filter_slice_alpha, frame, NULL,
                                 FFMIN(frame->height, ctx->graph->nb_threads));
+        } else if (s->is_packed_rgb && !s->black_fade) {
+            ctx->internal->execute(ctx, filter_slice_rgb, frame, NULL,
+                                   FFMIN(frame->height, ctx->graph->nb_threads));
         } else {
-            /* luma or rgb plane */
+            /* luma, or rgb plane in case of black */
             ctx->internal->execute(ctx, filter_slice_luma, frame, NULL,
                                 FFMIN(frame->height, ctx->graph->nb_threads));
 
@@ -315,6 +373,8 @@ static const AVOption fade_options[] = {
                                                     OFFSET(duration),    AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT32_MAX, FLAGS },
     { "d",           "Duration of the effect in seconds.",
                                                     OFFSET(duration),    AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT32_MAX, FLAGS },
+    { "color",       "set color",                   OFFSET(color_rgba),  AV_OPT_TYPE_COLOR,    {.str = "black"}, CHAR_MIN, CHAR_MAX, FLAGS },
+    { "c",           "set color",                   OFFSET(color_rgba),  AV_OPT_TYPE_COLOR,    {.str = "black"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { NULL }
 };