lavfi: drop ff_null_start_frame/end_frame/draw_slice.

The functions have become unused
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/video.c

@@ -159,14 +159,6 @@ AVFilterBufferRef *ff_get_video_buffer(AVFilterLink *link, int perms, int w, int
     return ret;
 }
 
-int ff_null_start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
-{
-    AVFilterBufferRef *buf_out = avfilter_ref_buffer(picref, ~0);
-    if (!buf_out)
-        return AVERROR(ENOMEM);
-    return ff_start_frame(link->dst->outputs[0], buf_out);
-}
-
 // for filters that support (but don't require) outpic==inpic
 int ff_inplace_start_frame(AVFilterLink *inlink, AVFilterBufferRef *inpicref)
 {
@@ -315,11 +307,6 @@ int ff_start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
     return ret;
 }
 
-int ff_null_end_frame(AVFilterLink *link)
-{
-    return ff_end_frame(link->dst->outputs[0]);
-}
-
 static int default_end_frame(AVFilterLink *inlink)
 {
     AVFilterLink *outlink = NULL;
@@ -358,11 +345,6 @@ int ff_end_frame(AVFilterLink *link)
     return ret;
 }
 
-int ff_null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
-{
-    return ff_draw_slice(link->dst->outputs[0], y, h, slice_dir);
-}
-
 static int default_draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
 {
     AVFilterLink *outlink = NULL;

libavfilter/video.h

@@ -43,9 +43,6 @@ AVFilterBufferRef *ff_get_video_buffer(AVFilterLink *link, int perms,
                                        int w, int h);
 
 int ff_inplace_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);
-int ff_null_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);
-int ff_null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
-int ff_null_end_frame(AVFilterLink *link);
 
 /**
  * Notify the next filter of the start of a frame.
@@ -61,11 +58,6 @@ int ff_null_end_frame(AVFilterLink *link);
  */
 int ff_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);
 
-/**
- * Pass video frame along and keep an internal reference for later use.
- */
-int ff_null_start_frame_keep_ref(AVFilterLink *inlink, AVFilterBufferRef *picref);
-
 /**
  * Notify the next filter that the current frame has finished.
  *