commit e4c5f7e2b6b51417cce2e5acb3fc286a6fc32d24
author hkuang <hkuang@google.com> Tue Jun 10 14:48:16 2014 -0700
committer hkuang <hkuang@google.com> Fri Jun 13 10:53:33 2014 -0700
tree a93e63c69ca4c3dca34ea9f5d908915d7a4e4162
parent c49fda26155c46a5e1110e413f89c631bdead8d7

Delay decreasing reference count in frame-parallel decoding.

The current decoding scheme will decrease the reference count
of the output frame when finish decoding. Then the application
could copy the frame from the decoder buffer to application buffer.
In frame-parallel decoding, a decoded frame will not be outputted
until several frames later which depends on thread numbers. So
the decoded frame's reference count should be decreased only
after application finish copying the frame out. But due to the
limitation of vpx_codec_get_frame, decoder could not know when
application finish decoding. So use a index last_show_frame to
release the last output frame's reference count.

Change-Id: I403ee0d01148ac1182e5a2d87cf7dcc302b51e63

vp9/decoder/vp9_decoder.c

diff --git a/vp9/decoder/vp9_decoder.c b/vp9/decoder/vp9_decoder.c
index 13d79ff..5859859 100644
--- a/vp9/decoder/vp9_decoder.c
+++ b/vp9/decoder/vp9_decoder.c
@@ -211,7 +211,10 @@
   }
 
   cm->frame_to_show = get_frame_new_buffer(cm);
-  cm->frame_bufs[cm->new_fb_idx].ref_count--;
+
+  if (!pbi->frame_parallel_decode || !cm->show_frame) {
+    --cm->frame_bufs[cm->new_fb_idx].ref_count;
+  }
 
   // Invalidate these references until the next frame starts.
   for (ref_index = 0; ref_index < 3; ref_index++)
@@ -240,7 +243,9 @@
   }
 
   // Check if the previous frame was a frame without any references to it.
-  if (cm->new_fb_idx >= 0 && cm->frame_bufs[cm->new_fb_idx].ref_count == 0)
+  // Release frame buffer if not decoding in frame parallel mode.
+  if (!pbi->frame_parallel_decode && cm->new_fb_idx >= 0 &&
+         cm->frame_bufs[cm->new_fb_idx].ref_count == 0)
     cm->release_fb_cb(cm->cb_priv,
                       &cm->frame_bufs[cm->new_fb_idx].raw_frame_buffer);
   cm->new_fb_idx = get_free_fb(cm);

vp9/vp9_dx_iface.c

diff --git a/vp9/vp9_dx_iface.c b/vp9/vp9_dx_iface.c
index 98faa7f..0738971 100644
--- a/vp9/vp9_dx_iface.c
+++ b/vp9/vp9_dx_iface.c
@@ -40,6 +40,7 @@
   vpx_image_t             img;
   int                     invert_tile_order;
   int                     frame_parallel_decode;  // frame-based threading.
+  int                     last_show_frame;  // Index of last output frame.
 
   // External frame buffer info to save for VP9 common.
   void *ext_priv;  // Private data associated with the external frame buffers.
@@ -238,6 +239,7 @@
   ctx->pbi->max_threads = ctx->cfg.threads;
   ctx->pbi->inv_tile_order = ctx->invert_tile_order;
   ctx->pbi->frame_parallel_decode = ctx->frame_parallel_decode;
+  ctx->last_show_frame = -1;
 
   // If postprocessing was enabled by the application and a
   // configuration has not been provided, default it.
@@ -430,6 +432,15 @@
       ctx->img.fb_priv = cm->frame_bufs[cm->new_fb_idx].raw_frame_buffer.priv;
       img = &ctx->img;
       *iter = img;
+      // Decrease reference count of last output frame in frame parallel mode.
+      if (ctx->frame_parallel_decode && ctx->last_show_frame >= 0) {
+        --cm->frame_bufs[ctx->last_show_frame].ref_count;
+        if (cm->frame_bufs[ctx->last_show_frame].ref_count == 0) {
+          cm->release_fb_cb(cm->cb_priv,
+              &cm->frame_bufs[ctx->last_show_frame].raw_frame_buffer);
+        }
+      }
+      ctx->last_show_frame = ctx->pbi->common.new_fb_idx;
     }
   }