Decode entire in-memory file for WebAudio

content/renderer/media/audio_decoder.cc

 // Copyright 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 "content/renderer/media/audio_decoder.h"
 
 #include <stdint.h>
 
 #include <vector>
 
@@ skipping 14 matching lines @@
 namespace content {
 
 // Decode in-memory audio file data.
 bool DecodeAudioFileData(
     blink::WebAudioBus* destination_bus,
     const char* data, size_t data_size) {
   DCHECK(destination_bus);
   if (!destination_bus)
     return false;
 
-#if !defined(MEDIA_DISABLE_FFMPEG)
+#if defined(MEDIA_DISABLE_FFMPEG)
+  return false
+#else
   // Uses the FFmpeg library for audio file reading.
   InMemoryUrlProtocol url_protocol(reinterpret_cast<const uint8_t*>(data),
                                    data_size, false);
   AudioFileReader reader(&url_protocol);
 
   if (!reader.Open())
     return false;
 
   size_t number_of_channels = reader.channels();
   double file_sample_rate = reader.sample_rate();
-  size_t number_of_frames = static_cast<size_t>(reader.GetNumberOfFrames());
 
   // Apply sanity checks to make sure crazy values aren't coming out of
   // FFmpeg.
   if (!number_of_channels ||
       number_of_channels > static_cast<size_t>(media::limits::kMaxChannels) ||
       file_sample_rate < media::limits::kMinSampleRate ||
       file_sample_rate > media::limits::kMaxSampleRate)
     return false;
 
+  if (!reader.HasKnownDuration()) {
+    // We don't have an estimated duration so read the entire stream.
+    std::unique_ptr<AudioBus> decodedAudio = reader.StreamingRead();
+
+    // Allocate and configure the output audio channel data.

[DaleCurtis, 2017/01/25 22:42:25]

This adds an extra copy, how about returning the std::vector<> of AudioBus
instead and doing the copy out of that? Or teaching AudioFileReader how to
initialize a blink audio bus.

+    size_t number_of_frames = decodedAudio->frames();
+    destination_bus->initialize(number_of_channels, number_of_frames,
+                                file_sample_rate);
+
+    for (size_t ch = 0; ch < number_of_channels; ++ch) {
+      DCHECK(destination_bus->channelData(ch));
+      memcpy(destination_bus->channelData(ch), decodedAudio->channel(ch),
+             number_of_frames * sizeof(float));
+    }
+    DVLOG(1) << "Decoded file data (unknown duration)-"
+             << " data: " << data << " data size: " << data_size
+             << " decoded duration: " << number_of_frames / file_sample_rate
+             << " number of frames: " << number_of_frames
+             << " sample rate: " << file_sample_rate
+             << " number of channels: " << number_of_channels;
+    return true;
+  }
+
+  // An estimated duration is available so we can use that to allocate
+  // memory for the decoded data.
+  size_t number_of_frames = static_cast<size_t>(reader.GetNumberOfFrames());
+
   // Allocate and configure the output audio channel data.
   destination_bus->initialize(number_of_channels,
                               number_of_frames,
                               file_sample_rate);
 
   // Wrap the channel pointers which will receive the decoded PCM audio.
   vector<float*> audio_data;
   audio_data.reserve(number_of_channels);
   for (size_t i = 0; i < number_of_channels; ++i) {
     audio_data.push_back(destination_bus->channelData(i));
@@ skipping 18 matching lines @@
 
   DVLOG(1) << "Decoded file data -"
            << " data: " << data
            << " data size: " << data_size
            << " duration: " << duration
            << " number of frames: " << actual_frames
            << " sample rate: " << file_sample_rate
            << " number of channels: " << number_of_channels;
 
   return actual_frames > 0;
-#else
-  return false;
-#endif  // !defined(MEDIA_DISABLE_FFMPEG)
+#endif  // defined(MEDIA_DISABLE_FFMPEG)
 }
 
 }  // namespace content