From f7db63f1b86f72deacb100a6fba97af5e835e1be Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian.droege@collabora.co.uk>
Date: Thu, 25 Apr 2013 16:23:14 +0200
Subject: [PATCH] videoencoder: Try harder to push writable buffers downstream

For this release the corresponding GstVideoCodecFrame before
pushing the buffer. The buffer will now be writable unless
the subclass still holds another reference to the buffer or
the frame.
---
 gst-libs/gst/video/gstvideoencoder.c | 49 ++++++++++++++++++----------
 1 file changed, 32 insertions(+), 17 deletions(-)

diff --git a/gst-libs/gst/video/gstvideoencoder.c b/gst-libs/gst/video/gstvideoencoder.c
index 4a8b6dd76a..46ecd7fbbd 100644
--- a/gst-libs/gst/video/gstvideoencoder.c
+++ b/gst-libs/gst/video/gstvideoencoder.c
@@ -1621,6 +1621,22 @@ gst_video_encoder_allocate_output_frame (GstVideoEncoder *
   return frame->output_buffer ? GST_FLOW_OK : GST_FLOW_ERROR;
 }
 
+static void
+gst_video_encoder_release_frame (GstVideoEncoder * enc,
+    GstVideoCodecFrame * frame)
+{
+  GList *link;
+
+  /* unref once from the list */
+  link = g_list_find (enc->priv->frames, frame);
+  if (link) {
+    gst_video_codec_frame_unref (frame);
+    enc->priv->frames = g_list_delete_link (enc->priv->frames, link);
+  }
+  /* unref because this function takes ownership */
+  gst_video_codec_frame_unref (frame);
+}
+
 /**
  * gst_video_encoder_finish_frame:
  * @encoder: a #GstVideoEncoder
@@ -1648,6 +1664,7 @@ gst_video_encoder_finish_frame (GstVideoEncoder * encoder,
   GList *l;
   gboolean send_headers = FALSE;
   gboolean discont = (frame->presentation_frame_number == 0);
+  GstBuffer *buffer;
 
   encoder_class = GST_VIDEO_ENCODER_GET_CLASS (encoder);
 
@@ -1837,7 +1854,6 @@ gst_video_encoder_finish_frame (GstVideoEncoder * encoder,
     for (tmp = priv->headers; tmp; tmp = tmp->next) {
       GstBuffer *tmpbuf = GST_BUFFER (tmp->data);
 
-      gst_buffer_ref (tmpbuf);
       priv->bytes += gst_buffer_get_size (tmpbuf);
       if (G_UNLIKELY (discont)) {
         GST_LOG_OBJECT (encoder, "marking discont");
@@ -1845,7 +1861,7 @@ gst_video_encoder_finish_frame (GstVideoEncoder * encoder,
         discont = FALSE;
       }
 
-      gst_pad_push (encoder->srcpad, tmpbuf);
+      gst_pad_push (encoder->srcpad, gst_buffer_ref (tmpbuf));
     }
     priv->new_headers = FALSE;
   }
@@ -1858,25 +1874,24 @@ gst_video_encoder_finish_frame (GstVideoEncoder * encoder,
   if (encoder_class->pre_push)
     ret = encoder_class->pre_push (encoder, frame);
 
-  /* A reference always needs to be owned by the frame on the buffer.
-   * For that reason, we use a complete sub-buffer (zero-cost) to push
-   * downstream.
-   * The original buffer will be free-ed only when downstream AND the
-   * current implementation are done with the frame. */
+  /* Get an additional ref to the buffer, which is going to be pushed
+   * downstream, the original ref is owned by the frame */
+  buffer = gst_buffer_ref (frame->output_buffer);
+
+  /* Release frame so the buffer is writable when we push it downstream
+   * if possible, i.e. if the subclass does not hold additional references
+   * to the frame
+   */
+  gst_video_encoder_release_frame (encoder, frame);
+  frame = NULL;
+
   if (ret == GST_FLOW_OK)
-    ret = gst_pad_push (encoder->srcpad, gst_buffer_ref (frame->output_buffer));
+    ret = gst_pad_push (encoder->srcpad, buffer);
 
 done:
   /* handed out */
-
-  /* unref once from the list */
-  l = g_list_find (priv->frames, frame);
-  if (l) {
-    gst_video_codec_frame_unref (frame);
-    priv->frames = g_list_delete_link (priv->frames, l);
-  }
-  /* unref because this function takes ownership */
-  gst_video_codec_frame_unref (frame);
+  if (frame)
+    gst_video_encoder_release_frame (encoder, frame);
 
   GST_VIDEO_ENCODER_STREAM_UNLOCK (encoder);