Render inband text tracks in the media pipeline

media/filters/ffmpeg_text_decoder.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/ffmpeg_text_decoder.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_buffer.h"
+#include "media/filters/ffmpeg_glue.h"
+
+namespace media {
+
+FFmpegTextDecoder::FFmpegTextDecoder(
+    const scoped_refptr<base::MessageLoopProxy>& message_loop)
+    : message_loop_(message_loop),
+      weak_factory_(this) {
+}
+
+FFmpegTextDecoder::~FFmpegTextDecoder() {
+}
+
+void FFmpegTextDecoder::Initialize(Demuxer* demuxer) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+  DCHECK_NE(demuxer, static_cast<Demuxer*>(NULL));
+
+  FFmpegGlue::InitializeFFmpeg();
+
+  if (!demuxer_streams_.empty()) {
+    // TODO(scherkus): initialization currently happens more than once in
+    // PipelineIntegrationTest.BasicPlayback.

[acolwell GONE FROM CHROMIUM, 2013/09/12 00:15:15]

Do we really need this? I don't think we should be copying this code. It doesn't
look like we are even using FFmpeg code in here.

[Matthew Heaney (Chromium), 2013/09/13 19:51:54]

Done.

+    LOG(ERROR) << "Initialize has already been called.";
+    CHECK(false);
+  }
+
+  weak_this_ = weak_factory_.GetWeakPtr();
+
+  int stream_count = demuxer->GetStreamCount();
+  demuxer_streams_.reserve(stream_count);
+
+  for (int idx = 0; idx < stream_count; ++idx) {
+    DemuxerStream* stream = demuxer->GetStreamByIndex(idx);
+    if (stream == NULL || stream->type() != DemuxerStream::TEXT) {
+      demuxer_streams_.push_back(NULL);
+    } else {
+      demuxer_streams_.push_back(stream);
+    }
+  }
+
+  read_callbacks_.resize(stream_count);
+}
+
+void FFmpegTextDecoder::Read(int index, const ReadCB& read_cb) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+  DCHECK(!read_cb.is_null());
+
+  ReadCB& cb = read_callbacks_[index];
+  CHECK(cb.is_null()) << "Overlapping decodes are not supported.";
+
+  cb = BindToCurrentLoop(read_cb);
+
+  DemuxerStream* stream = demuxer_streams_[index];
+  CHECK(stream);
+
+  stream->Read(base::Bind(
+      &FFmpegTextDecoder::BufferReady, weak_this_, index));
+}
+
+void FFmpegTextDecoder::BufferReady(

[acolwell GONE FROM CHROMIUM, 2013/09/12 00:15:15]

nit:There doesn't appear to be anything FFmpeg specific in this code so it
should probably be renamed.

[Matthew Heaney (Chromium), 2013/09/13 19:51:54]

Done.

+    int index,
+    DemuxerStream::Status status,
+    const scoped_refptr<DecoderBuffer>& input) {
+  DCHECK(message_loop_->BelongsToCurrentThread());
+
+  ReadCB& read_cb = read_callbacks_[index];
+  DCHECK(!read_cb.is_null());
+
+  if (status == DemuxerStream::kAborted) {
+    DCHECK(!input.get());
+    base::ResetAndReturn(&read_cb).Run(index, NULL);
+    return;
+  }
+
+  if (input->end_of_stream()) {
+    base::ResetAndReturn(&read_cb).Run(index, NULL);
+    return;
+  }
+
+  DCHECK_EQ(status, DemuxerStream::kOk);
+  DCHECK(input.get());
+
+  scoped_refptr<TextBuffer> text_buffer(
+      new TextBuffer(input->timestamp(),
+                     input->duration()));
+
+  // The side data here contains both the cue id and cue settings,
+  // separated using a 0xFF marker.
+  const uint8* side_data = input->side_data();
+  DCHECK_NE(side_data, static_cast<const uint8*>(NULL));
+
+  int side_data_size = input->side_data_size();
+  DCHECK_GE(side_data_size, 1);
+
+  const uint8* side_data_end = side_data + side_data_size;
+
+  const uint8* id_end = std::find(side_data, side_data_end, 0xFF);
+  DCHECK_NE(id_end, side_data_end);
+  DCHECK_EQ(*id_end, 0xFF);
+
+  int id_size = id_end - side_data;
+  DCHECK_GE(id_size, 0);
+
+  text_buffer->set_id(side_data, id_size);
+
+  int settings_size = side_data_size - id_size - 1;
+  DCHECK_GE(settings_size, 0);
+
+  text_buffer->set_settings(id_end + 1, settings_size);
+  text_buffer->set_text(input->data(), input->data_size());
+
+  base::ResetAndReturn(&read_cb).Run(index, text_buffer);
+}
+
+}  // namespace media