VTVDA: Optimize pic_order_cnt_type == 2.

media/gpu/vt_video_decode_accelerator_mac.cc

Index: media/gpu/vt_video_decode_accelerator_mac.cc
diff --git a/media/gpu/vt_video_decode_accelerator_mac.cc b/media/gpu/vt_video_decode_accelerator_mac.cc
index 59cb2ce28734e0afc6621ac8e7ce5c96fd4a4f45..53a312a04b12e9963dfb62d84b069a23591e1e62 100644
--- a/media/gpu/vt_video_decode_accelerator_mac.cc
+++ b/media/gpu/vt_video_decode_accelerator_mac.cc
@@ -209,6 +209,13 @@ bool InitializeVideoToolboxInternal() {
 
 // TODO(sandersd): Share this computation with the VAAPI decoder.
 int32_t ComputeReorderWindow(const H264SPS* sps) {
+  // When |pic_order_cnt_type| == 2, decode order always matches presentation
+  // order.
+  // TODO(sandersd): For |pic_order_cnt_type| == 1, analyze the delta cycle to
+  // find the minimum required reorder window.
+  if (sps->pic_order_cnt_type == 2)
+    return 0;
+
   // TODO(sandersd): Compute MaxDpbFrames.
   int32_t max_dpb_frames = 16;
 
@@ -592,6 +599,7 @@ void VTVideoDecodeAccelerator::DecodeTask(const BitstreamBuffer& bitstream,
 
           frame->has_slice = true;
           frame->is_idr = nalu.nal_unit_type == media::H264NALU::kIDRSlice;
+          frame->has_mmco5 = poc_.IsPendingMMCO5();
           frame->pic_order_cnt = pic_order_cnt;
           frame->reorder_window = ComputeReorderWindow(sps);
         }
@@ -604,9 +612,8 @@ void VTVideoDecodeAccelerator::DecodeTask(const BitstreamBuffer& bitstream,
     }
   }
 
-  if (frame->is_idr) {
+  if (frame->is_idr)
     waiting_for_idr_ = false;
-  }
 
   // If no IDR has been seen yet, skip decoding. Note that Flash sends
   // configuration changes as a bitstream with only SPS/PPS; we don't print
@@ -943,7 +950,8 @@ bool VTVideoDecodeAccelerator::ProcessTaskQueue() {
   switch (task.type) {
     case TASK_FRAME:
       if (reorder_queue_.size() < kMaxReorderQueueSize &&
-          (!task.frame->is_idr || reorder_queue_.empty())) {
+          (!task.frame->is_idr || !task.frame->has_mmco5 ||

[Pawel Osciak, 2017/02/17 04:53:26]

Should this be (!task.frame->is_idr && !task.frame->has_mmco5)?
Perhaps a comment here would be helpful.

[sandersd (OOO until July 31), 2017/02/18 00:46:34]

I expanded the code, hopefully it is clear now.

+           reorder_queue_.empty())) {
         DVLOG(2) << "Decode(" << task.frame->bitstream_id << ") complete";
         assigned_bitstream_ids_.erase(task.frame->bitstream_id);
         client_->NotifyEndOfBitstreamBuffer(task.frame->bitstream_id);
@@ -994,8 +1002,9 @@ bool VTVideoDecodeAccelerator::ProcessReorderQueue() {
   // the next frame is an IDR), then we don't need a full reorder buffer to send
   // the next frame.
   bool flushing =
-      !task_queue_.empty() && (task_queue_.front().type != TASK_FRAME ||
-                               task_queue_.front().frame->is_idr);
+      !task_queue_.empty() &&
+      (task_queue_.front().type != TASK_FRAME ||
+       task_queue_.front().frame->is_idr || task_queue_.front().has_mmco5);
 
   size_t reorder_window = std::max(0, reorder_queue_.top()->reorder_window);
   DVLOG(3) << __func__ << " size=" << reorder_queue_.size()