lavfi/buffersink: add accessors for the stream properties.

av_buffersink_get_frame_rate() did already exist; its argument becomes const.

doc/APIchanges

@@ -15,6 +15,9 @@ libavutil:     2015-08-28
 
 API changes, most recent first:
 
+2017-01-12 - xxxxxxx - lavfi 6.69.100- buffersink.h
+  Add av_buffersink_get_*() functions.
+
 2017-01-06 - xxxxxxx - lavf 57.62.100- avio.h
   Add avio_get_dyn_buf()
 

libavfilter/buffersink.c

@@ -279,14 +279,27 @@ void av_buffersink_set_frame_size(AVFilterContext *ctx, unsigned frame_size)
     inlink->partial_buf_size = frame_size;
 }
 
-AVRational av_buffersink_get_frame_rate(AVFilterContext *ctx)
-{
-    av_assert0(   !strcmp(ctx->filter->name, "buffersink")
-               || !strcmp(ctx->filter->name, "ffbuffersink"));
-
-    return ctx->inputs[0]->frame_rate;
+#define MAKE_AVFILTERLINK_ACCESSOR(type, field) \
+type av_buffersink_get_##field(const AVFilterContext *ctx) { \
+    av_assert0(ctx->filter->uninit == uninit); \
+    return ctx->inputs[0]->field; \
 }
 
+MAKE_AVFILTERLINK_ACCESSOR(enum AVMediaType , type               );
+MAKE_AVFILTERLINK_ACCESSOR(AVRational       , time_base          );
+MAKE_AVFILTERLINK_ACCESSOR(int              , format             );
+
+MAKE_AVFILTERLINK_ACCESSOR(AVRational       , frame_rate         );
+MAKE_AVFILTERLINK_ACCESSOR(int              , w                  );
+MAKE_AVFILTERLINK_ACCESSOR(int              , h                  );
+MAKE_AVFILTERLINK_ACCESSOR(AVRational       , sample_aspect_ratio);
+
+MAKE_AVFILTERLINK_ACCESSOR(int              , channels           );
+MAKE_AVFILTERLINK_ACCESSOR(uint64_t         , channel_layout     );
+MAKE_AVFILTERLINK_ACCESSOR(int              , sample_rate        );
+
+MAKE_AVFILTERLINK_ACCESSOR(AVBufferRef *    , hw_frames_ctx      );
+
 static av_cold int vsink_init(AVFilterContext *ctx, void *opaque)
 {
     BufferSinkContext *buf = ctx->priv;

libavfilter/buffersink.h

@@ -101,9 +101,27 @@ AVABufferSinkParams *av_abuffersink_params_alloc(void);
 void av_buffersink_set_frame_size(AVFilterContext *ctx, unsigned frame_size);
 
 /**
- * Get the frame rate of the input.
+ * @defgroup lavfi_buffersink_accessors Buffer sink accessors
+ * Get the properties of the stream
+ * @{
  */
-AVRational av_buffersink_get_frame_rate(AVFilterContext *ctx);
+
+enum AVMediaType av_buffersink_get_type                (const AVFilterContext *ctx);
+AVRational       av_buffersink_get_time_base           (const AVFilterContext *ctx);
+int              av_buffersink_get_format              (const AVFilterContext *ctx);
+
+AVRational       av_buffersink_get_frame_rate          (const AVFilterContext *ctx);
+int              av_buffersink_get_w                   (const AVFilterContext *ctx);
+int              av_buffersink_get_h                   (const AVFilterContext *ctx);
+AVRational       av_buffersink_get_sample_aspect_ratio (const AVFilterContext *ctx);
+
+int              av_buffersink_get_channels            (const AVFilterContext *ctx);
+uint64_t         av_buffersink_get_channel_layout      (const AVFilterContext *ctx);
+int              av_buffersink_get_sample_rate         (const AVFilterContext *ctx);
+
+AVBufferRef *    av_buffersink_get_hw_frames_ctx       (const AVFilterContext *ctx);
+
+/** @} */
 
 /**
  * Get a frame with filtered data from sink and put it in frame.

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   6
-#define LIBAVFILTER_VERSION_MINOR  68
+#define LIBAVFILTER_VERSION_MINOR  69
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \