Enhance AudioSplicer to crossfade marked splice frames.

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"
 #include "media/base/buffers.h"
 #include "media/base/limits.h"
 
 namespace media {
 
 AudioBuffer::AudioBuffer(SampleFormat sample_format,
                          int channel_count,
                          int frame_count,
@@ skipping 196 matching lines @@
   const uint8* source_data = data_.get() + source_frame_offset * frame_size;
   dest->FromInterleavedPartial(
       source_data, dest_frame_offset, frames_to_copy, bytes_per_channel);
 }
 
 void AudioBuffer::TrimStart(int frames_to_trim) {
   CHECK_GE(frames_to_trim, 0);
   CHECK_LE(frames_to_trim, adjusted_frame_count_);
 
   // Adjust timestamp_ and duration_ to reflect the smaller number of frames.
-  double offset = static_cast<double>(duration_.InMicroseconds()) *
-                  frames_to_trim / adjusted_frame_count_;
-  base::TimeDelta offset_as_time =
-      base::TimeDelta::FromMicroseconds(static_cast<int64>(offset));
+  const base::TimeDelta offset_as_time = base::TimeDelta::FromMicroseconds(
+      floor(static_cast<double>(duration_.InMicroseconds()) * frames_to_trim /

[acolwell GONE FROM CHROMIUM, 2014/02/24 21:46:11]

nit: Why can't you use (duration_ * frames_to_trim) / adjusted_frame_count_
here? It looks like the necessary operators are defined.

[DaleCurtis, 2014/02/26 02:38:45]

Removed in favor of using the AudioTimestampHelper to perform these calculations
when available.

+            adjusted_frame_count_));
   timestamp_ += offset_as_time;
   duration_ -= offset_as_time;
 
   // Finally adjust the number of frames in this buffer and where the start
   // really is.
   adjusted_frame_count_ -= frames_to_trim;
   trim_start_ += frames_to_trim;
 }
 
 void AudioBuffer::TrimEnd(int frames_to_trim) {
   CHECK_GE(frames_to_trim, 0);
   CHECK_LE(frames_to_trim, adjusted_frame_count_);
 
   // Adjust duration_ only to reflect the smaller number of frames.
-  double offset = static_cast<double>(duration_.InMicroseconds()) *
-                  frames_to_trim / adjusted_frame_count_;
-  base::TimeDelta offset_as_time =
-      base::TimeDelta::FromMicroseconds(static_cast<int64>(offset));
-  duration_ -= offset_as_time;
+  duration_ -= base::TimeDelta::FromMicroseconds(

[acolwell GONE FROM CHROMIUM, 2014/02/24 21:46:11]

Why does this computation differ from the one above now? Doesn't this mean that
the duration could be different if you remove the same number of frames from the
start vs from the end?

[DaleCurtis, 2014/02/26 02:38:45]

Ditto.

+      ceil(static_cast<double>(duration_.InMicroseconds()) * frames_to_trim /
+           adjusted_frame_count_));
 
   // Finally adjust the number of frames in this buffer.
   adjusted_frame_count_ -= frames_to_trim;
 }
 
 }  // namespace media