Enhance AudioSplicer to crossfade marked splice frames.

media/base/audio_buffer.cc

Index: media/base/audio_buffer.cc
diff --git a/media/base/audio_buffer.cc b/media/base/audio_buffer.cc
index 0bf37209b2b66489ff568547e5a4b9f363415c76..f21772ad6729501f7a651894824b5d420e5f584c 100644
--- a/media/base/audio_buffer.cc
+++ b/media/base/audio_buffer.cc
@@ -4,6 +4,8 @@
 
 #include "media/base/audio_buffer.h"
 
+#include <cmath>
+
 #include "base/logging.h"
 #include "media/base/audio_bus.h"
 #include "media/base/buffers.h"
@@ -220,10 +222,9 @@ void AudioBuffer::TrimStart(int frames_to_trim) {
   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;
 
@@ -238,11 +239,9 @@ void AudioBuffer::TrimEnd(int frames_to_trim) {
   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;