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

diff --git a/vp9/decoder/vp9_decoder.c b/vp9/decoder/vp9_decoder.c
index 13d79ff44b4e5a7e1f41c818a8725f73885cf261..5859859fae68b07a7f6bcf55d60580624637f8c6 100644 (file)
--- a/vp9/decoder/vp9_decoder.c
+++ b/vp9/decoder/vp9_decoder.c
@@ -211,7 +211,10 @@ static void swap_frame_buffers(VP9Decoder *pbi) {
   }
 
   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 @@ int vp9_receive_compressed_data(VP9Decoder *pbi,
   }
 
   // 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);

diff --git a/vp9/vp9_dx_iface.c b/vp9/vp9_dx_iface.c
index 98faa7f65762a43c6b314bde185e447880273c7e..07389713a9af1219b6013f6cb56b90a4a3946242 100644 (file)
--- a/vp9/vp9_dx_iface.c
+++ b/vp9/vp9_dx_iface.c
@@ -40,6 +40,7 @@ struct vpx_codec_alg_priv {
   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 @@ static void init_decoder(vpx_codec_alg_priv_t *ctx) {
   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 @@ static vpx_image_t *decoder_get_frame(vpx_codec_alg_priv_t *ctx,
       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;
     }
   }