Switch from a DataPipe per DecoderBuffer to a single one.

media/mojo/services/mojo_demuxer_stream_impl.cc

Index: media/mojo/services/mojo_demuxer_stream_impl.cc
diff --git a/media/mojo/services/mojo_demuxer_stream_impl.cc b/media/mojo/services/mojo_demuxer_stream_impl.cc
index e89143649cb1ff1a3a735ff9675718b4842c955a..2461a09d1c4ae74493616e4374d1b15e49b23c49 100644
--- a/media/mojo/services/mojo_demuxer_stream_impl.cc
+++ b/media/mojo/services/mojo_demuxer_stream_impl.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/macros.h"
 #include "media/base/audio_decoder_config.h"
+#include "media/base/decoder_buffer.h"
 #include "media/base/video_decoder_config.h"
 #include "media/mojo/interfaces/demuxer_stream.mojom.h"
 #include "media/mojo/services/media_type_converters.h"
@@ -45,8 +46,16 @@ void MojoDemuxerStreamImpl::OnBufferReady(
     }
   }
 
-  // TODO(tim): Once using DataPipe, fill via the producer handle and then
-  // read more to keep the pipe full.
+  // Serialize the data section of the DecoderBuffer into our pipe.
+  uint32_t num_bytes = buffer->data_size();
+  CHECK_EQ(WriteDataRaw(stream_pipe_.get(), buffer->data(), &num_bytes,
+                        MOJO_READ_DATA_FLAG_ALL_OR_NONE),
+           MOJO_RESULT_OK);
+  CHECK_EQ(num_bytes, static_cast<uint32_t>(buffer->data_size()));
+
+  // TODO(dalecurtis): Once we can write framed data to the DataPipe, fill via
+  // the producer handle and then read more to keep the pipe full.  Waiting for
+  // space can be accomplished using an AsyncWaiter.
   callback.Run(static_cast<mojo::DemuxerStream::Status>(status),
                mojo::MediaDecoderBuffer::From(buffer));
 }
@@ -63,9 +72,25 @@ void MojoDemuxerStreamImpl::DidConnect() {
         mojo::VideoDecoderConfig::From(stream_->video_decoder_config()));
   }
 
-  // TODO(tim): Create a DataPipe, hold the producer handle, and pass the
-  // consumer handle here.
-  client()->OnStreamReady(mojo::ScopedDataPipeConsumerHandle());
+  MojoCreateDataPipeOptions options;
+  options.struct_size = sizeof(MojoCreateDataPipeOptions);
+  options.flags = MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE;
+  options.element_num_bytes = 1;
+
+  // Allocate DataPipe sizes based on content type to reduce overhead.  If this
+  // is still too burdensome we can adjust for sample rate or resolution.
+  if (stream_->type() == media::DemuxerStream::AUDIO) {
+    // Audio doesn't require a lot of room, so use a smaller pipe than video.
+    options.capacity_num_bytes = 512 * 1024;
+  } else {
+    // Video can get quite large; at 4K, VP9 delivers packets which are ~1MB in
+    // size; so allow for 50% headroom.
+    options.capacity_num_bytes = 1.5 * (1024 * 1024);

[xhwang, 2014/12/06 00:03:44]

nit: we have the config; we might be able to do better in estimating sizes...

[DaleCurtis, 2014/12/06 00:42:59]

I can try and figure out some metric based on resolution, but then what about
config changes... this is only created once?

[xhwang, 2014/12/06 01:16:54]

Low priority for now. But we may need to have some heuristic way to do this in
the future.

+  }
+

[xhwang, 2014/12/06 00:03:44]

nit: How about Demuxer::TEXT?

[DaleCurtis, 2014/12/06 00:42:59]

Flipped so only video gets the large pipe.

+  mojo::DataPipe data_pipe(options);
+  stream_pipe_ = data_pipe.producer_handle.Pass();
+  client()->OnStreamReady(data_pipe.consumer_handle.Pass());
 }
 
 }  // namespace media