Support (E)AC3 passthrough

media/base/audio_buffer.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 "media/base/audio_buffer.h"
 
 #include <cmath>
 
 #include "base/logging.h"
 #include "media/base/audio_bus.h"
@@ skipping 227 matching lines @@
                              AudioBus* dest) {
   // Deinterleave each channel (if necessary) and convert to 32bit
   // floating-point with nominal range -1.0 -> +1.0 (if necessary).
 
   // |dest| must have the same number of channels, and the number of frames
   // specified must be in range.
   DCHECK(!end_of_stream());
   DCHECK_EQ(dest->channels(), channel_count_);
   DCHECK_LE(source_frame_offset + frames_to_copy, adjusted_frame_count_);
 
+  dest->set_is_bitstream_format(IsBitstreamFormat());

[DaleCurtis, 2017/06/15 21:46:32]

Move into l.251 as set_is_bitstream_format(true);

[AndyWu, 2017/08/02 01:43:40]

Not really sure it's a good idea to assume the state of the parameter |dest|. I
would rather to ensure the state consistency.

+
   if (IsBitstreamFormat()) {
-    // TODO(tsunghung): Implement it along with AudioBus changes.
-    NOTREACHED() << "Invalid sample format!";
+    DCHECK(!source_frame_offset);
+    uint8_t* dest_data =
+        reinterpret_cast<uint8_t*>(dest->channel(0)) + dest->data_size();
+
+    memcpy(dest_data, channel_data_[0], data_size());
+    dest->set_data_size(dest_frame_offset + data_size());
+    dest->set_frames(dest->frames() + frame_count());
+    return;
   }
 
   DCHECK_LE(dest_frame_offset + frames_to_copy, dest->frames());
 
   if (!data_) {
     // Special case for an empty buffer.
     dest->ZeroFramesPartial(dest_frame_offset, frames_to_copy);
     return;
   }
 
@@ skipping 126 matching lines @@
 
   // Trim the leftover data off the end of the buffer and update duration.
   TrimEnd(frames_to_trim);
 }
 
 bool AudioBuffer::IsBitstreamFormat() {
   return IsBitstream(sample_format_);
 }
 
 }  // namespace media