media: Add MojoDecoderBuffer{Reader|Writer}

media/mojo/common/mojo_decoder_buffer_converter.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/mojo/common/mojo_decoder_buffer_converter.h"
+
+#include <memory>
+
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "base/single_thread_task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "media/base/audio_buffer.h"
+#include "media/base/cdm_context.h"
+#include "media/base/decoder_buffer.h"
+#include "media/mojo/common/media_type_converters.h"
+
+namespace media {
+
+namespace {
+
+std::unique_ptr<mojo::DataPipe> CreateDataPipe(DemuxerStream::Type type) {
+  MojoCreateDataPipeOptions options;
+  options.struct_size = sizeof(MojoCreateDataPipeOptions);
+  options.flags = MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE;
+  options.element_num_bytes = 1;
+
+  if (type == DemuxerStream::AUDIO) {
+    // TODO(timav): Consider capacity calculation based on AudioDecoderConfig.
+    options.capacity_num_bytes = 512 * 1024;
+  } else if (type == DemuxerStream::VIDEO) {
+    // Video can get quite large; at 4K, VP9 delivers packets which are ~1MB in
+    // size; so allow for 50% head room.
+    options.capacity_num_bytes = 1.5 * (1024 * 1024);

[sandersd (OOO until July 31), 2016/06/27 20:24:55]

I have a preference for more headroom, since we can't (currently) recover from a
failure due to a too-small size.

(It's actually even worse than that: since we don't wait for space in Write, we
will try to push ~4 frames into this capacity and fail with a decode error if
that doesn't work.)

We need to increase this or solve the underlying issue (a resize mechanism).

[xhwang, 2016/06/28 01:11:48]

Updated to match what MojoVideoDecoder does today.

Agreed this could be improved. Maybe we could pass in a size in CreateDataPipe()
so that clients can customize this. The client knows about the
VideoDecoderConfig, and how many parallel decodes it supports, so it could have
a better estimate. Or as you suggested, it'd be nice to be able to adjust this
at run time (not sure how though). 

+  } else {
+    NOTREACHED() << "Unsupported type: " << type;
+    // Choose a random size.

[sandersd (OOO until July 31), 2016/06/27 20:24:55]

Nit: a hardcoded value is never random.

[xhwang, 2016/06/28 01:11:48]

Done.

+    options.capacity_num_bytes = 512 * 1024;
+  }
+
+  return base::WrapUnique(new mojo::DataPipe(options));
+}
+
+}  // namespace
+
+// MojoDecoderBufferReader
+
+// static
+std::unique_ptr<MojoDecoderBufferReader> MojoDecoderBufferReader::Create(
+    DemuxerStream::Type type,
+    mojo::ScopedDataPipeProducerHandle* producer_handle) {
+  DVLOG(1) << __FUNCTION__;
+  std::unique_ptr<mojo::DataPipe> data_pipe = CreateDataPipe(type);
+  *producer_handle = std::move(data_pipe->producer_handle);
+  return base::WrapUnique(
+      new MojoDecoderBufferReader(std::move(data_pipe->consumer_handle)));
+}
+
+MojoDecoderBufferReader::MojoDecoderBufferReader(
+    mojo::ScopedDataPipeConsumerHandle consumer_handle)
+    : consumer_handle_(std::move(consumer_handle)) {
+  DVLOG(1) << __FUNCTION__;
+}
+
+MojoDecoderBufferReader::~MojoDecoderBufferReader() {
+  DVLOG(1) << __FUNCTION__;
+}
+
+scoped_refptr<DecoderBuffer> MojoDecoderBufferReader::ReadDecoderBuffer(
+    const mojom::DecoderBufferPtr& buffer) {
+  DVLOG(3) << __FUNCTION__;
+  scoped_refptr<DecoderBuffer> media_buffer(
+      buffer.To<scoped_refptr<DecoderBuffer>>());
+  DCHECK(media_buffer);
+
+  if (media_buffer->end_of_stream())
+    return media_buffer;
+
+  // Wait for the data to become available in the DataPipe.
+  MojoHandleSignalsState state;
+  MojoResult result =
+      MojoWait(consumer_handle_.get().value(), MOJO_HANDLE_SIGNAL_READABLE,
+               MOJO_DEADLINE_INDEFINITE, &state);

[sandersd (OOO until July 31), 2016/06/27 20:24:54]

VideoDecoderService comment was about this line.

[xhwang, 2016/06/28 01:11:48]

Done.

+
+  if (result != MOJO_RESULT_OK) {
+    DVLOG(1) << __FUNCTION__ << ": Peer closed the data pipe";
+    return nullptr;
+  }
+
+  // Read the inner data for the DecoderBuffer from our DataPipe.
+  uint32_t data_size = static_cast<uint32_t>(media_buffer->data_size());
+  DCHECK_EQ(data_size, buffer->data_size);
+  DCHECK_GT(data_size, 0u);
+
+  uint32_t bytes_read = data_size;
+  result = ReadDataRaw(consumer_handle_.get(), media_buffer->writable_data(),
+                       &bytes_read, MOJO_READ_DATA_FLAG_ALL_OR_NONE);
+  if (result != MOJO_RESULT_OK || bytes_read != data_size) {
+    DVLOG(1) << __FUNCTION__ << ": reading from pipe failed";
+    return nullptr;
+  }
+
+  return media_buffer;
+}
+
+// MojoDecoderBufferWriter
+
+// static
+std::unique_ptr<MojoDecoderBufferWriter> MojoDecoderBufferWriter::Create(
+    DemuxerStream::Type type,
+    mojo::ScopedDataPipeConsumerHandle* consumer_handle) {
+  DVLOG(1) << __FUNCTION__;
+  std::unique_ptr<mojo::DataPipe> data_pipe = CreateDataPipe(type);
+  *consumer_handle = std::move(data_pipe->consumer_handle);
+  return base::WrapUnique(
+      new MojoDecoderBufferWriter(std::move(data_pipe->producer_handle)));
+}
+
+MojoDecoderBufferWriter::MojoDecoderBufferWriter(
+    mojo::ScopedDataPipeProducerHandle producer_handle)
+    : producer_handle_(std::move(producer_handle)) {
+  DVLOG(1) << __FUNCTION__;
+}
+
+MojoDecoderBufferWriter::~MojoDecoderBufferWriter() {
+  DVLOG(1) << __FUNCTION__;
+}
+
+mojom::DecoderBufferPtr MojoDecoderBufferWriter::WriteDecoderBuffer(
+    const scoped_refptr<DecoderBuffer>& media_buffer) {
+  DVLOG(3) << __FUNCTION__;
+  mojom::DecoderBufferPtr buffer = mojom::DecoderBuffer::From(media_buffer);
+
+  if (media_buffer->end_of_stream())
+    return buffer;
+
+  // Serialize the data section of the DecoderBuffer into our pipe.
+  uint32_t num_bytes = base::checked_cast<uint32_t>(media_buffer->data_size());
+  DCHECK_GT(num_bytes, 0u);
+  MojoResult result =
+      WriteDataRaw(producer_handle_.get(), media_buffer->data(), &num_bytes,
+                   MOJO_WRITE_DATA_FLAG_ALL_OR_NONE);
+  if (result != MOJO_RESULT_OK || num_bytes != media_buffer->data_size()) {
+    DVLOG(1) << __FUNCTION__ << ": writing to data pipe failed";
+    return nullptr;
+  }
+
+  return buffer;
+}
+
+}  // namespace media