Remove AudioBuffer::set_duration(), instead base on 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 "base/logging.h"
 #include "media/base/audio_bus.h"
 #include "media/base/buffers.h"
 #include "media/base/limits.h"
 
 namespace media {
 
+static base::TimeDelta CalculateDuration(int frames, double sample_rate) {
+  return base::TimeDelta::FromMicroseconds(
+      frames * base::Time::kMicrosecondsPerSecond / sample_rate);
+}
+
 AudioBuffer::AudioBuffer(SampleFormat sample_format,
                          ChannelLayout channel_layout,
                          int channel_count,
                          int sample_rate,
                          int frame_count,
                          bool create_buffer,
                          const uint8* const* data,
-                         const base::TimeDelta timestamp,
-                         const base::TimeDelta duration)
+                         const base::TimeDelta timestamp)
     : sample_format_(sample_format),
       channel_layout_(channel_layout),
       channel_count_(channel_count),
       sample_rate_(sample_rate),
       adjusted_frame_count_(frame_count),
       trim_start_(0),
       end_of_stream_(!create_buffer && data == NULL && frame_count == 0),
       timestamp_(timestamp),
-      duration_(duration) {
+      duration_(CalculateDuration(adjusted_frame_count_, sample_rate_)) {

[jrummell, 2014/05/01 20:26:26]

nit: Would it be better to compute the duration only when needed? Code Search
isn't working for me right now, so I can't tell if duration() is referred to a
lot. Tests don't appear to check the duration very much.

[DaleCurtis, 2014/05/01 20:33:18]

It's cheap to calculate and I don't want to have to rename all the
hacker_style() duration() calls to GetDuration() :)

   CHECK_GE(channel_count_, 0);
   CHECK_LE(channel_count_, limits::kMaxChannels);
   CHECK_GE(frame_count, 0);
   DCHECK(channel_layout == CHANNEL_LAYOUT_DISCRETE ||
          ChannelLayoutToChannelCount(channel_layout) == channel_count);
 
   int bytes_per_channel = SampleFormatToBytesPerChannel(sample_format);
   DCHECK_LE(bytes_per_channel, kChannelAlignment);
   int data_size = frame_count * bytes_per_channel;
 
@@ skipping 42 matching lines @@
 AudioBuffer::~AudioBuffer() {}
 
 // static
 scoped_refptr<AudioBuffer> AudioBuffer::CopyFrom(
     SampleFormat sample_format,
     ChannelLayout channel_layout,
     int channel_count,
     int sample_rate,
     int frame_count,
     const uint8* const* data,
-    const base::TimeDelta timestamp,
-    const base::TimeDelta duration) {
+    const base::TimeDelta timestamp) {
   // If you hit this CHECK you likely have a bug in a demuxer. Go fix it.
   CHECK_GT(frame_count, 0);  // Otherwise looks like an EOF buffer.
   CHECK(data[0]);
   return make_scoped_refptr(new AudioBuffer(sample_format,
                                             channel_layout,
                                             channel_count,
                                             sample_rate,
                                             frame_count,
                                             true,
                                             data,
-                                            timestamp,
-                                            duration));
+                                            timestamp));
 }
 
 // static
 scoped_refptr<AudioBuffer> AudioBuffer::CreateBuffer(
     SampleFormat sample_format,
     ChannelLayout channel_layout,
     int channel_count,
     int sample_rate,
     int frame_count) {
   CHECK_GT(frame_count, 0);  // Otherwise looks like an EOF buffer.
   return make_scoped_refptr(new AudioBuffer(sample_format,
                                             channel_layout,
                                             channel_count,
                                             sample_rate,
                                             frame_count,
                                             true,
                                             NULL,
-                                            kNoTimestamp(),
                                             kNoTimestamp()));
 }
 
 // static
 scoped_refptr<AudioBuffer> AudioBuffer::CreateEmptyBuffer(
     ChannelLayout channel_layout,
     int channel_count,
     int sample_rate,
     int frame_count,
-    const base::TimeDelta timestamp,
-    const base::TimeDelta duration) {
+    const base::TimeDelta timestamp) {
   CHECK_GT(frame_count, 0);  // Otherwise looks like an EOF buffer.
   // Since data == NULL, format doesn't matter.
   return make_scoped_refptr(new AudioBuffer(kSampleFormatF32,
                                             channel_layout,
                                             channel_count,
                                             sample_rate,
                                             frame_count,
                                             false,
                                             NULL,
-                                            timestamp,
-                                            duration));
+                                            timestamp));
 }
 
 // static
 scoped_refptr<AudioBuffer> AudioBuffer::CreateEOSBuffer() {
   return make_scoped_refptr(new AudioBuffer(kUnknownSampleFormat,
                                             CHANNEL_LAYOUT_NONE,
                                             0,
                                             0,
                                             0,
                                             false,
                                             NULL,
-                                            kNoTimestamp(),
                                             kNoTimestamp()));
 }
 
 // Convert int16 values in the range [kint16min, kint16max] to [-1.0, 1.0].
 static inline float ConvertS16ToFloat(int16 value) {
   return value * (value < 0 ? -1.0f / kint16min : 1.0f / kint16max);
 }
 
 void AudioBuffer::ReadFrames(int frames_to_copy,
                              int source_frame_offset,
@@ skipping 69 matching lines @@
   int frame_size = channel_count_ * bytes_per_channel;
   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));
-  timestamp_ += offset_as_time;
-  duration_ -= offset_as_time;
-
-  // Finally adjust the number of frames in this buffer and where the start
-  // really is.
+  // 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;
+
+  // Adjust timestamp_ and duration_ to reflect the smaller number of frames.
+  const base::TimeDelta old_duration = duration_;
+  duration_ = CalculateDuration(adjusted_frame_count_, sample_rate_);
+  timestamp_ += old_duration - duration_;
 }
 
 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;
-
-  // Finally adjust the number of frames in this buffer.
+  // Adjust the number of frames and duration for this buffer.
   adjusted_frame_count_ -= frames_to_trim;
+  duration_ = CalculateDuration(adjusted_frame_count_, sample_rate_);
 }
 
 }  // namespace media