Render inband text tracks in the media pipeline

media/filters/text_decoder_impl.cc

+// Copyright (c) 2013 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/filters/text_decoder_impl.h"
+
+#include "base/callback_helpers.h"
+#include "media/base/bind_to_loop.h"
+#include "media/base/decoder_buffer.h"
+#include "media/base/demuxer.h"
+#include "media/base/text_cue.h"
+
+namespace media {
+
+TextDecoderImpl::TextDecoderImpl(
+    const scoped_refptr<base::MessageLoopProxy>& message_loop)
+    : message_loop_(message_loop),
+      weak_factory_(this) {
+}
+
+TextDecoderImpl::~TextDecoderImpl() {
+}
+
+void TextDecoderImpl::Initialize() {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+  weak_this_ = weak_factory_.GetWeakPtr();
+}
+
+void TextDecoderImpl::Read(DemuxerStream* stream, const ReadCB& read_cb) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+  DCHECK(!read_cb.is_null());
+
+  ReadCB& cb = read_callbacks_[stream];
+  CHECK(cb.is_null()) << "Overlapping decodes are not supported.";
+
+  cb = BindToCurrentLoop(read_cb);
+
+  stream->Read(base::Bind(
+      &TextDecoderImpl::BufferReady, weak_this_, stream));
+}
+
+void TextDecoderImpl::BufferReady(

[acolwell GONE FROM CHROMIUM, 2013/10/08 15:45:24]

I don't think you need this class. This method seems to be the bulk of the logic
here and you should be able to fold this method into the TextRenderer. You
already are keeping track of pending reads there anyways so you could just
convert that to mean pending reads on the DemuxerStream instead of on the
TextDecoder.

[Matthew Heaney (Chromium), 2013/10/13 05:30:17]

Done.

+    DemuxerStream* stream,
+    DemuxerStream::Status status,
+    const scoped_refptr<DecoderBuffer>& input) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  ReadCB& read_cb = read_callbacks_[stream];
+  DCHECK(!read_cb.is_null());
+
+  if (status == DemuxerStream::kAborted) {
+    DCHECK(!input.get());
+    base::ResetAndReturn(&read_cb).Run(stream, NULL);
+    return;
+  }
+
+  if (input->end_of_stream()) {
+    base::ResetAndReturn(&read_cb).Run(stream, NULL);
+    return;
+  }
+
+  DCHECK_EQ(status, DemuxerStream::kOk);
+  DCHECK(input.get());
+  DCHECK_GE(input->side_data_size(), 2);
+
+  // The side data contains both the cue id and cue settings,
+  // each terminated with a NUL.
+  const char* id_ptr = reinterpret_cast<const char*>(input->side_data());
+  size_t id_len = strlen(id_ptr);
+  std::string id(id_ptr, id_len);
+
+  const char* settings_ptr = id_ptr + id_len + 1;
+  size_t settings_len = strlen(settings_ptr);
+  std::string settings(settings_ptr, settings_len);
+
+  // The cue payload is stored in the data-part of the input buffer.
+  std::string text(input->data(), input->data() + input->data_size());
+
+  scoped_refptr<TextCue> text_cue(
+      new TextCue(input->timestamp(),
+                  input->duration(),
+                  id,
+                  settings,
+                  text));
+
+  base::ResetAndReturn(&read_cb).Run(stream, text_cue);
+}
+
+}  // namespace media