Add mode to yadif to enable/disable deinterlacing based on src frame "interlaced" flag

Signed-off-by: Joakim Plate <elupus@ecce.se>

doc/filters.texi

@@ -1737,7 +1737,7 @@ Flip the input video vertically.
 Deinterlace the input video ("yadif" means "yet another deinterlacing
 filter").
 
-It accepts the optional parameters: @var{mode}:@var{parity}.
+It accepts the optional parameters: @var{mode}:@var{parity}:@var(auto).
 
 @var{mode} specifies the interlacing mode to adopt, accepts one of the
 following values:
@@ -1771,6 +1771,18 @@ Default value is -1.
 If interlacing is unknown or decoder does not export this information,
 top field first will be assumed.
 
+@var{auto] specifies if deinterlacer should trust the interlaced flag
+and only deinterlace frames marked as interlaced
+
+@table @option
+@item 0
+deinterlace all frames
+@item 1
+only deinterlace frames marked as interlaced
+@end table
+
+Default value is 0.
+
 @c man end VIDEO FILTERS
 
 @chapter Video Sources

libavfilter/vf_yadif.c

@@ -44,6 +44,12 @@ typedef struct {
 
     int frame_pending;
 
+    /**
+     *  0: deinterlace all frames
+     *  1: only deinterlace frames marked as interlaced
+     */
+    int auto_enable;
+
     AVFilterBufferRef *cur;
     AVFilterBufferRef *next;
     AVFilterBufferRef *prev;
@@ -240,6 +246,14 @@ static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
     if (!yadif->cur)
         return;
 
+    if (yadif->auto_enable && !yadif->cur->video->interlaced) {
+        yadif->out  = avfilter_ref_buffer(yadif->cur, AV_PERM_READ);
+        avfilter_unref_buffer(yadif->prev);
+        yadif->prev = NULL;
+        avfilter_start_frame(ctx->outputs[0], yadif->out);
+        return;
+    }
+
     if (!yadif->prev)
         yadif->prev = avfilter_ref_buffer(yadif->cur, AV_PERM_READ);
 
@@ -259,6 +273,12 @@ static void end_frame(AVFilterLink *link)
     if (!yadif->out)
         return;
 
+    if (yadif->auto_enable && !yadif->cur->video->interlaced) {
+        avfilter_draw_slice(ctx->outputs[0], 0, link->h, 1);
+        avfilter_end_frame(ctx->outputs[0]);
+        return;
+    }
+
     return_frame(ctx, 0);
 }
 
@@ -299,6 +319,9 @@ static int poll_frame(AVFilterLink *link)
     }
     assert(yadif->next || !val);
 
+    if (yadif->auto_enable && yadif->next && !yadif->next->video->interlaced)
+        return val;
+
     return val * ((yadif->mode&1)+1);
 }
 
@@ -344,9 +367,10 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 
     yadif->mode = 0;
     yadif->parity = -1;
+    yadif->auto_enable = 0;
     yadif->csp = NULL;
 
-    if (args) sscanf(args, "%d:%d", &yadif->mode, &yadif->parity);
+    if (args) sscanf(args, "%d:%d:%d", &yadif->mode, &yadif->parity, &yadif->auto_enable);
 
     yadif->filter_line = filter_line_c;
     if (HAVE_SSSE3 && cpu_flags & AV_CPU_FLAG_SSSE3)
@@ -356,7 +380,7 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
     else if (HAVE_MMX && cpu_flags & AV_CPU_FLAG_MMX)
         yadif->filter_line = ff_yadif_filter_line_mmx;
 
-    av_log(ctx, AV_LOG_INFO, "mode:%d parity:%d\n", yadif->mode, yadif->parity);
+    av_log(ctx, AV_LOG_INFO, "mode:%d parity:%d auto_enable:%d\n", yadif->mode, yadif->parity, yadif->auto_enable);
 
     return 0;
 }