[FFmpeg-devel] [PATCH v3 1/1] avfilter/buffersink: Add video frame allocation callback

[John Cox]

Add a callback to enable user allocation of video frames on the final
stage of a filter chain.

Signed-off-by: John Cox <j...@kynesim.co.uk>
---
 libavfilter/buffersink.c | 21 +++++++++++++++++++++
 libavfilter/buffersink.h | 27 +++++++++++++++++++++++++++
 libavfilter/version.h    |  2 +-
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/libavfilter/buffersink.c b/libavfilter/buffersink.c
index 306c283f77..e99d444530 100644
--- a/libavfilter/buffersink.c
+++ b/libavfilter/buffersink.c
@@ -62,6 +62,11 @@ typedef struct BufferSinkContext {
     int sample_rates_size;
 
     AVFrame *peeked_frame;
+
+    union {
+        AVBuffersinkAllocVideoFrameFunc video;
+    } alloc_cb;
+    void * alloc_v;
 } BufferSinkContext;
 
 #define NB_ITEMS(list) (list ## _size / sizeof(*list))
@@ -154,6 +159,21 @@ int attribute_align_arg 
av_buffersink_get_samples(AVFilterContext *ctx,
     return get_frame_internal(ctx, frame, 0, nb_samples);
 }
 
+static AVFrame *alloc_video_buffer(AVFilterLink *link, int w, int h)
+{
+    AVFilterContext *const ctx = link->dst;
+    BufferSinkContext *const buf = ctx->priv;
+    return buf->alloc_cb.video ? buf->alloc_cb.video(ctx, buf->alloc_v, w, h) :
+                                 ff_default_get_video_buffer(link, w, h);
+}
+
+void av_buffersink_set_alloc_video_frame(AVFilterContext *ctx, 
AVBuffersinkAllocVideoFrameFunc cb, void *v)
+{
+    BufferSinkContext *const buf = ctx->priv;
+    buf->alloc_cb.video = cb;
+    buf->alloc_v = v;
+}
+
 static av_cold int common_init(AVFilterContext *ctx)
 {
     BufferSinkContext *buf = ctx->priv;
@@ -381,6 +401,7 @@ static const AVFilterPad avfilter_vsink_buffer_inputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
+        .get_buffer = {.video = alloc_video_buffer},
     },
 };
 
diff --git a/libavfilter/buffersink.h b/libavfilter/buffersink.h
index 64e08de53e..2419d1bd80 100644
--- a/libavfilter/buffersink.h
+++ b/libavfilter/buffersink.h
@@ -166,6 +166,33 @@ int av_buffersink_get_frame(AVFilterContext *ctx, AVFrame 
*frame);
  */
 int av_buffersink_get_samples(AVFilterContext *ctx, AVFrame *frame, int 
nb_samples);
 
+/**
+ * Callback from av_buffersink_set_alloc_video_frame to allocate 
+ * a frame 
+ *  
+ * @param ctx pointer to a context of the abuffersink AVFilter.
+ * @param v opaque pointer passed to 
+ *          av_buffersink_set_alloc_video_frame
+ * @param w width of frame to allocate 
+ * @param height of frame to allocate 
+ *  
+ * @return 
+ *         - The newly allocated frame
+ *         - NULL if error
+ */
+typedef AVFrame *(*AVBuffersinkAllocVideoFrameFunc)(AVFilterContext * ctx, 
void * v, int w, int h);
+
+/**
+ * Set a video frame allocation method for buffersink
+ *
+ * @param ctx pointer to a context of the abuffersink AVFilter.
+ * @param cb Callback to the allocation function. If set to NULL 
+ *           then the default avfilter allocation function will
+ *           be used.
+ * @param v  Opaque to pass to the allocation function
+ */
+void av_buffersink_set_alloc_video_frame(AVFilterContext *ctx, 
AVBuffersinkAllocVideoFrameFunc cb, void * v);
+
 /**
  * @}
  */
diff --git a/libavfilter/version.h b/libavfilter/version.h
index c001693e3c..54950497be 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -31,7 +31,7 @@
 
 #include "version_major.h"
 
-#define LIBAVFILTER_VERSION_MINOR   8
+#define LIBAVFILTER_VERSION_MINOR   9
 #define LIBAVFILTER_VERSION_MICRO 102
 
 
-- 
2.39.2

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