[FFmpeg-devel] [PATCH] vsrc_buffer: add flags param to av_vsrc_buffer_add_video_buffer_ref

[Stefano Sabatini]

The new flags parameter allow to specify if the video ref to add
should overwrite the cache, if the flag is not set vsrc_buffer will
complain and abort; otherwise it will clean the already cached video
ref before to overwrite it, thus avoiding a leak.

In particular, fix a massive leak occurring with ffmpeg -ss TIME -i
INPUT OUTPUT.
---
 ffmpeg.c                  |    3 ++-
 libavfilter/avcodec.h     |    5 ++++-
 libavfilter/vsrc_buffer.c |   22 ++++++++++++++--------
 libavfilter/vsrc_buffer.h |   11 ++++++++++-
 4 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/ffmpeg.c b/ffmpeg.c
index e5986a6..bbf8a41 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -1665,7 +1665,8 @@ static int output_packet(AVInputStream *ist, int ist_index,
                         picture.sample_aspect_ratio = ist->st->sample_aspect_ratio;
                     picture.pts = ist->pts;
 
-                    av_vsrc_buffer_add_frame(ost->input_video_filter, &picture);
+                    av_vsrc_buffer_add_frame(ost->input_video_filter,
+                                             &picture, AV_VSRC_BUF_FLAG_OVERWRITE);
                 }
             }
         }
diff --git a/libavfilter/avcodec.h b/libavfilter/avcodec.h
index 74434e8..4eed6b2 100644
--- a/libavfilter/avcodec.h
+++ b/libavfilter/avcodec.h
@@ -30,6 +30,7 @@
 
 #include "libavcodec/avcodec.h" // AVFrame
 #include "avfilter.h"
+#include "vsrc_buffer.h"
 
 /**
  * Copy the frame properties of src to dst, without copying the actual
@@ -49,9 +50,11 @@ AVFilterBufferRef *avfilter_get_video_buffer_ref_from_frame(const AVFrame *frame
  * Add frame data to buffer_src.
  *
  * @param buffer_src pointer to a buffer source context
+ * @param flags a combination of AV_VSRC_BUF_FLAG_* flags
  * @return >= 0 in case of success, a negative AVERROR code in case of
  * failure
  */
-int av_vsrc_buffer_add_frame(AVFilterContext *buffer_src, const AVFrame *frame);
+int av_vsrc_buffer_add_frame(AVFilterContext *buffer_src,
+                             const AVFrame *frame, int flags);
 
 #endif /* AVFILTER_AVCODEC_H */
diff --git a/libavfilter/vsrc_buffer.c b/libavfilter/vsrc_buffer.c
index 9ba7d4e..246444b 100644
--- a/libavfilter/vsrc_buffer.c
+++ b/libavfilter/vsrc_buffer.c
@@ -37,18 +37,23 @@ typedef struct {
     char              sws_param[256];
 } BufferSourceContext;
 
-int av_vsrc_buffer_add_video_buffer_ref(AVFilterContext *buffer_filter, AVFilterBufferRef *picref)
+int av_vsrc_buffer_add_video_buffer_ref(AVFilterContext *buffer_filter,
+                                        AVFilterBufferRef *picref, int flags)
 {
     BufferSourceContext *c = buffer_filter->priv;
     AVFilterLink *outlink = buffer_filter->outputs[0];
     int ret;
 
     if (c->picref) {
-        av_log(buffer_filter, AV_LOG_ERROR,
-               "Buffering several frames is not supported. "
-               "Please consume all available frames before adding a new one.\n"
-            );
-        //return -1;
+        if (flags & AV_VSRC_BUF_FLAG_OVERWRITE) {
+            avfilter_unref_buffer(c->picref);
+            c->picref = NULL;
+        } else {
+            av_log(buffer_filter, AV_LOG_ERROR,
+                   "Buffering several frames is not supported. "
+                   "Please consume all available frames before adding a new one.\n");
+            return AVERROR(EINVAL);
+        }
     }
 
     if (picref->video->w != c->w || picref->video->h != c->h || picref->format != c->pix_fmt) {
@@ -109,14 +114,15 @@ int av_vsrc_buffer_add_video_buffer_ref(AVFilterContext *buffer_filter, AVFilter
 #if CONFIG_AVCODEC
 #include "avcodec.h"
 
-int av_vsrc_buffer_add_frame(AVFilterContext *buffer_src, const AVFrame *frame)
+int av_vsrc_buffer_add_frame(AVFilterContext *buffer_src,
+                             const AVFrame *frame, int flags)
 {
     int ret;
     AVFilterBufferRef *picref =
         avfilter_get_video_buffer_ref_from_frame(frame, AV_PERM_WRITE);
     if (!picref)
         return AVERROR(ENOMEM);
-    ret = av_vsrc_buffer_add_video_buffer_ref(buffer_src, picref);
+    ret = av_vsrc_buffer_add_video_buffer_ref(buffer_src, picref, flags);
     picref->buf->data[0] = NULL;
     avfilter_unref_buffer(picref);
 
diff --git a/libavfilter/vsrc_buffer.h b/libavfilter/vsrc_buffer.h
index c717f3d..b661d41 100644
--- a/libavfilter/vsrc_buffer.h
+++ b/libavfilter/vsrc_buffer.h
@@ -29,12 +29,21 @@
 #include "avfilter.h"
 
 /**
+ * Tell av_vsrc_buffer_add_video_buffer_ref() to overwrite the already
+ * cached video buffer with the new added one, otherwise the function
+ * will complain and exit.
+ */
+#define AV_VSRC_BUF_FLAG_OVERWRITE 1
+
+/**
  * Add video buffer data in picref to buffer_src.
  *
  * @param buffer_src pointer to a buffer source context
+ * @param flags a combination of AV_VSRC_BUF_FLAG_* flags
  * @return >= 0 in case of success, a negative AVERROR code in case of
  * failure
  */
-int av_vsrc_buffer_add_video_buffer_ref(AVFilterContext *buffer_src, AVFilterBufferRef *picref);
+int av_vsrc_buffer_add_video_buffer_ref(AVFilterContext *buffer_src,
+                                        AVFilterBufferRef *picref, int flags);
 
 #endif /* AVFILTER_VSRC_BUFFER_H */
-- 
1.7.2.3