Add a slice_dir parameter to avfilter_draw_slice().

Avoid the need to implement slice direction detection code, thus
reducing code duplication.

See the thread:
"[FFmpeg-devel] [PATCH] Add a slice_dir parameter to avfilter_start_frame()".

Originally committed as revision 20734 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavfilter/avfilter.c

@@ -287,13 +287,13 @@ void avfilter_end_frame(AVFilterLink *link)
 
 }
 
-void avfilter_draw_slice(AVFilterLink *link, int y, int h)
+void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
 {
     uint8_t *src[4], *dst[4];
     int i, j, hsub, vsub;
-    void (*draw_slice)(AVFilterLink *, int, int);
+    void (*draw_slice)(AVFilterLink *, int, int, int);
 
-    DPRINTF_START(NULL, draw_slice); dprintf_link(NULL, link, 0); dprintf(NULL, " y:%d h:%d\n", y, h);
+    DPRINTF_START(NULL, draw_slice); dprintf_link(NULL, link, 0); dprintf(NULL, " y:%d h:%d dir:%d\n", y, h, slice_dir);
 
     /* copy the slice if needed for permission reasons */
     if(link->srcpic) {
@@ -325,7 +325,7 @@ void avfilter_draw_slice(AVFilterLink *link, int y, int h)
 
     if(!(draw_slice = link_dpad(link).draw_slice))
         draw_slice = avfilter_default_draw_slice;
-    draw_slice(link, y, h);
+    draw_slice(link, y, h, slice_dir);
 }
 
 #define MAX_REGISTERED_AVFILTERS_NB 64

libavfilter/avfilter.h

@@ -25,7 +25,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  1
-#define LIBAVFILTER_VERSION_MINOR 11
+#define LIBAVFILTER_VERSION_MINOR 12
 #define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
@@ -322,7 +322,7 @@ struct AVFilterPad
      *
      * Input video pads only.
      */
-    void (*draw_slice)(AVFilterLink *link, int y, int height);
+    void (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);
 
     /**
      * Frame poll callback. This returns the number of immediately available
@@ -364,7 +364,7 @@ struct AVFilterPad
 /** default handler for start_frame() for video inputs */
 void avfilter_default_start_frame(AVFilterLink *link, AVFilterPicRef *picref);
 /** default handler for draw_slice() for video inputs */
-void avfilter_default_draw_slice(AVFilterLink *link, int y, int h);
+void avfilter_default_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
 /** default handler for end_frame() for video inputs */
 void avfilter_default_end_frame(AVFilterLink *link);
 /** default handler for config_props() for video outputs */
@@ -566,8 +566,12 @@ void avfilter_end_frame(AVFilterLink *link);
  * @param link the output link over which the frame is being sent
  * @param y    offset in pixels from the top of the image for this slice
  * @param h    height of this slice in pixels
+ * @param slice_dir the assumed direction for sending slices,
+ *             from the top slice to the bottom slice if the value is 1,
+ *             from the bottom slice to the top slice if the value is -1,
+ *             for other values the behavior of the function is undefined.
  */
-void avfilter_draw_slice(AVFilterLink *link, int y, int h);
+void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
 
 /** Initializes the filter system. Registers all builtin filters. */
 void avfilter_register_all(void);

libavfilter/defaults.c

@@ -78,7 +78,7 @@ void avfilter_default_start_frame(AVFilterLink *link, AVFilterPicRef *picref)
     }
 }
 
-void avfilter_default_draw_slice(AVFilterLink *link, int y, int h)
+void avfilter_default_draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
 {
     AVFilterLink *out = NULL;
 
@@ -86,7 +86,7 @@ void avfilter_default_draw_slice(AVFilterLink *link, int y, int h)
         out = link->dst->outputs[0];
 
     if(out)
-        avfilter_draw_slice(out, y, h);
+        avfilter_draw_slice(out, y, h, slice_dir);
 }
 
 void avfilter_default_end_frame(AVFilterLink *link)

libavfilter/vf_crop.c

@@ -195,7 +195,7 @@ static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
     avfilter_start_frame(link->dst->outputs[0], ref2);
 }
 
-static void draw_slice(AVFilterLink *link, int y, int h)
+static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
 {
     AVFilterContext *ctx = link->dst;
     CropContext *crop = ctx->priv;
@@ -210,7 +210,7 @@ static void draw_slice(AVFilterLink *link, int y, int h)
     if (y + h > crop->y + crop->h)
         h = crop->y + crop->h - y;
 
-    avfilter_draw_slice(ctx->outputs[0], y - crop->y, h);
+    avfilter_draw_slice(ctx->outputs[0], y - crop->y, h, slice_dir);
 }
 
 AVFilter avfilter_vf_crop = {

libavfilter/vf_format.c

@@ -112,9 +112,9 @@ static void end_frame(AVFilterLink *link)
     avfilter_end_frame(link->dst->outputs[0]);
 }
 
-static void draw_slice(AVFilterLink *link, int y, int h)
+static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
 {
-    avfilter_draw_slice(link->dst->outputs[0], y, h);
+    avfilter_draw_slice(link->dst->outputs[0], y, h, slice_dir);
 }
 
 AVFilter avfilter_vf_format = {

libavfilter/vf_scale.c

@@ -38,7 +38,6 @@ typedef struct {
 
     int hsub, vsub;             ///< chroma subsampling
     int slice_y;                ///< top of current output slice
-    int slice_dir;              ///< detected slice direction order for the current frame
     int input_is_pal;           ///< set to 1 if the input format is paletted
 } ScaleContext;
 
@@ -141,25 +140,19 @@ static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
               (int64_t)picref->pixel_aspect.den * outlink->w * link->h,
               INT_MAX);
 
-    scale->slice_dir = 0;
+    scale->slice_y = 0;
     avfilter_start_frame(outlink, avfilter_ref_pic(outpicref, ~0));
 }
 
-static void draw_slice(AVFilterLink *link, int y, int h)
+static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
 {
     ScaleContext *scale = link->dst->priv;
     int out_h;
     AVFilterPicRef *cur_pic = link->cur_pic;
     uint8_t *data[4];
 
-    if (!scale->slice_dir) {
-        if (y != 0 && y + h != link->h) {
-            av_log(link->dst, AV_LOG_ERROR, "Slices start in the middle!\n");
-            return;
-        }
-        scale->slice_dir = y ?                       -1 : 1;
-        scale->slice_y   = y ? link->dst->outputs[0]->h : y;
-    }
+    if (scale->slice_y == 0 && slice_dir == -1)
+        scale->slice_y = link->dst->outputs[0]->h;
 
     data[0] = cur_pic->data[0] +  y               * cur_pic->linesize[0];
     data[1] = scale->input_is_pal ?
@@ -172,10 +165,10 @@ static void draw_slice(AVFilterLink *link, int y, int h)
                       link->dst->outputs[0]->outpic->data,
                       link->dst->outputs[0]->outpic->linesize);
 
-    if (scale->slice_dir == -1)
+    if (slice_dir == -1)
         scale->slice_y -= out_h;
-    avfilter_draw_slice(link->dst->outputs[0], scale->slice_y, out_h);
-    if (scale->slice_dir == 1)
+    avfilter_draw_slice(link->dst->outputs[0], scale->slice_y, out_h, slice_dir);
+    if (slice_dir == 1)
         scale->slice_y += out_h;
 }
 

libavfilter/vf_slicify.c

@@ -73,16 +73,16 @@ static void end_frame(AVFilterLink *link)
     avfilter_end_frame(link->dst->outputs[0]);
 }
 
-static void draw_slice(AVFilterLink *link, int y, int h)
+static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
 {
     SliceContext *slice = link->dst->priv;
     int y2;
 
     for (y2 = y; y2 + slice->h <= y + h; y2 += slice->h)
-        avfilter_draw_slice(link->dst->outputs[0], y2, slice->h);
+        avfilter_draw_slice(link->dst->outputs[0], y2, slice->h, slice_dir);
 
     if (y2 < y + h)
-        avfilter_draw_slice(link->dst->outputs[0], y2, y + h - y2);
+        avfilter_draw_slice(link->dst->outputs[0], y2, y + h - y2, slice_dir);
 }
 
 AVFilter avfilter_vf_slicify = {

libavfilter/vf_vflip.c

@@ -78,11 +78,11 @@ static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
     avfilter_start_frame(link->dst->outputs[0], ref2);
 }
 
-static void draw_slice(AVFilterLink *link, int y, int h)
+static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
 {
     AVFilterContext *ctx = link->dst;
 
-    avfilter_draw_slice(ctx->outputs[0], link->h - (y+h), h);
+    avfilter_draw_slice(ctx->outputs[0], link->h - (y+h), h, -1 * slice_dir);
 }
 
 AVFilter avfilter_vf_vflip = {