Revert of Remove AudioBuffer::set_duration(), instead base on frames.

media/base/audio_buffer_queue_unittest.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 "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/strings/stringprintf.h"
 #include "base/time/time.h"
 #include "media/base/audio_buffer.h"
 #include "media/base/audio_buffer_queue.h"
 #include "media/base/audio_bus.h"
 #include "media/base/buffers.h"
 #include "media/base/test_helpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace media {
 
 const int kSampleRate = 44100;
 
-static void VerifyBus(AudioBus* bus,
-                      int offset,
-                      int frames,
-                      int buffer_size,
-                      float start,
-                      float increment) {
-  for (int ch = 0; ch < bus->channels(); ++ch) {
-    const float v = start + ch * buffer_size * increment;
-    for (int i = offset; i < frames; ++i) {
-      ASSERT_FLOAT_EQ(v + (i - offset) * increment, bus->channel(ch)[i])
-          << "i=" << i << ", ch=" << ch;
-    }
+static void VerifyResult(float* channel_data,
+                         int frames,
+                         float start,
+                         float increment) {
+  for (int i = 0; i < frames; ++i) {
+    SCOPED_TRACE(base::StringPrintf(
+        "i=%d/%d start=%f, increment=%f", i, frames, start, increment));
+    ASSERT_EQ(start, channel_data[i]);
+    start += increment;
   }
 }
 
 template <typename T>
 static scoped_refptr<AudioBuffer> MakeTestBuffer(SampleFormat format,
                                                  ChannelLayout channel_layout,
                                                  T start,
-                                                 T step,
+                                                 T end,
                                                  int frames) {
+  const base::TimeDelta kNoTime = kNoTimestamp();
   return MakeAudioBuffer<T>(format,
                             channel_layout,
                             ChannelLayoutToChannelCount(channel_layout),
                             kSampleRate,
                             start,
-                            step,
+                            end,
                             frames,
-                            kNoTimestamp());
+                            kNoTime,
+                            kNoTime);
 }
 
 TEST(AudioBufferQueueTest, AppendAndClear) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_MONO;
   AudioBufferQueue buffer;
   EXPECT_EQ(0, buffer.frames());
   buffer.Append(
       MakeTestBuffer<uint8>(kSampleFormatU8, channel_layout, 10, 1, 8));
   EXPECT_EQ(8, buffer.frames());
   buffer.Clear();
@@ skipping 30 matching lines @@
   scoped_ptr<AudioBus> bus = AudioBus::Create(channels, 100);
 
   // Append 40 frames in 5 buffers. Intersperse ReadFrames() to make the
   // iterator is pointing to the correct position.
   buffer.Append(MakeTestBuffer<float>(
       kSampleFormatF32, channel_layout, 10.0f, 1.0f, 8));
   EXPECT_EQ(8, buffer.frames());
 
   EXPECT_EQ(4, buffer.ReadFrames(4, 0, bus.get()));
   EXPECT_EQ(4, buffer.frames());
-  VerifyBus(bus.get(), 0, 4, bus->frames(), 10, 1);
+  VerifyResult(bus->channel(0), 4, 10.0f, 1.0f);
 
   buffer.Append(MakeTestBuffer<float>(
       kSampleFormatF32, channel_layout, 20.0f, 1.0f, 8));
   EXPECT_EQ(12, buffer.frames());
   buffer.Append(MakeTestBuffer<float>(
       kSampleFormatF32, channel_layout, 30.0f, 1.0f, 8));
   EXPECT_EQ(20, buffer.frames());
 
   buffer.SeekFrames(16);
   EXPECT_EQ(4, buffer.ReadFrames(4, 0, bus.get()));
   EXPECT_EQ(0, buffer.frames());
-  VerifyBus(bus.get(), 0, 4, bus->frames(), 34, 1);
+  VerifyResult(bus->channel(0), 4, 34.0f, 1.0f);
 
   buffer.Append(MakeTestBuffer<float>(
       kSampleFormatF32, channel_layout, 40.0f, 1.0f, 8));
   EXPECT_EQ(8, buffer.frames());
   buffer.Append(MakeTestBuffer<float>(
       kSampleFormatF32, channel_layout, 50.0f, 1.0f, 8));
   EXPECT_EQ(16, buffer.frames());
 
   EXPECT_EQ(4, buffer.ReadFrames(4, 0, bus.get()));
-  VerifyBus(bus.get(), 0, 4, bus->frames(), 40, 1);
+  VerifyResult(bus->channel(0), 4, 40.0f, 1.0f);
 
   // Read off the end of the buffer.
   EXPECT_EQ(12, buffer.frames());
   buffer.SeekFrames(8);
   EXPECT_EQ(4, buffer.ReadFrames(100, 0, bus.get()));
-  VerifyBus(bus.get(), 0, 4, bus->frames(), 54, 1);
+  VerifyResult(bus->channel(0), 4, 54.0f, 1.0f);
 }
 
 TEST(AudioBufferQueueTest, Seek) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   AudioBufferQueue buffer;
 
   // Add 6 frames of data.
   buffer.Append(MakeTestBuffer<float>(
       kSampleFormatF32, channel_layout, 1.0f, 1.0f, 6));
   EXPECT_EQ(6, buffer.frames());
@@ skipping 17 matching lines @@
 
   // Add 76 frames of data.
   buffer.Append(
       MakeTestBuffer<float>(kSampleFormatF32, channel_layout, 1.0f, 1.0f, 6));
   buffer.Append(
       MakeTestBuffer<float>(kSampleFormatF32, channel_layout, 13.0f, 1.0f, 10));
   buffer.Append(
       MakeTestBuffer<float>(kSampleFormatF32, channel_layout, 33.0f, 1.0f, 60));
   EXPECT_EQ(76, buffer.frames());
 
-  // Read 3 frames from the buffer.
+  // Read 3 frames from the buffer. F32 is interleaved, so ch[0] should be
+  // 1, 3, 5, and ch[1] should be 2, 4, 6.
   scoped_ptr<AudioBus> bus = AudioBus::Create(channels, 100);
   EXPECT_EQ(3, buffer.ReadFrames(3, 0, bus.get()));
   EXPECT_EQ(73, buffer.frames());
-  VerifyBus(bus.get(), 0, 3, 6, 1, 1);
+  VerifyResult(bus->channel(0), 3, 1.0f, 2.0f);
+  VerifyResult(bus->channel(1), 3, 2.0f, 2.0f);
 
   // Now read 5 frames, which will span buffers. Append the data into AudioBus.
   EXPECT_EQ(5, buffer.ReadFrames(5, 3, bus.get()));
   EXPECT_EQ(68, buffer.frames());
-  VerifyBus(bus.get(), 0, 6, 6, 1, 1);
-  VerifyBus(bus.get(), 6, 2, 10, 13, 1);
+  VerifyResult(bus->channel(0), 8, 1.0f, 2.0f);
+  VerifyResult(bus->channel(1), 8, 2.0f, 2.0f);
 
   // Now skip into the third buffer.
   buffer.SeekFrames(20);
   EXPECT_EQ(48, buffer.frames());
 
   // Now read 2 frames, which are in the third buffer.
   EXPECT_EQ(2, buffer.ReadFrames(2, 0, bus.get()));
-  VerifyBus(bus.get(), 0, 2, 60, 45, 1);
+  VerifyResult(bus->channel(0), 2, 57.0f, 2.0f);
+  VerifyResult(bus->channel(1), 2, 58.0f, 2.0f);
 }
 
 TEST(AudioBufferQueueTest, ReadU8) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_4_0;
   const int channels = ChannelLayoutToChannelCount(channel_layout);
-  const int frames = 4;
   AudioBufferQueue buffer;
 
   // Add 4 frames of data.
   buffer.Append(
-      MakeTestBuffer<uint8>(kSampleFormatU8, channel_layout, 128, 1, frames));
+      MakeTestBuffer<uint8>(kSampleFormatU8, channel_layout, 128, 1, 4));
 
-  // Read all 4 frames from the buffer.
-  scoped_ptr<AudioBus> bus = AudioBus::Create(channels, frames);
-  EXPECT_EQ(frames, buffer.ReadFrames(frames, 0, bus.get()));
+  // Read all 4 frames from the buffer. Data is interleaved, so ch[0] should be
+  // 128, 132, 136, 140, other channels similar. However, values are converted
+  // from [0, 255] to [-1.0, 1.0] with a bias of 128. Thus the first buffer
+  // value should be 0.0, then 1/127, 2/127, etc.
+  scoped_ptr<AudioBus> bus = AudioBus::Create(channels, 100);
+  EXPECT_EQ(4, buffer.ReadFrames(4, 0, bus.get()));
   EXPECT_EQ(0, buffer.frames());
-  VerifyBus(bus.get(), 0, frames, bus->frames(), 0, 1.0f / 127.0f);
+  VerifyResult(bus->channel(0), 4, 0.0f, 4.0f / 127.0f);
+  VerifyResult(bus->channel(1), 4, 1.0f / 127.0f, 4.0f / 127.0f);
+  VerifyResult(bus->channel(2), 4, 2.0f / 127.0f, 4.0f / 127.0f);
+  VerifyResult(bus->channel(3), 4, 3.0f / 127.0f, 4.0f / 127.0f);
 }
 
 TEST(AudioBufferQueueTest, ReadS16) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   const int channels = ChannelLayoutToChannelCount(channel_layout);
   AudioBufferQueue buffer;
 
   // Add 24 frames of data.
   buffer.Append(
       MakeTestBuffer<int16>(kSampleFormatS16, channel_layout, 1, 1, 4));
   buffer.Append(
       MakeTestBuffer<int16>(kSampleFormatS16, channel_layout, 9, 1, 20));
   EXPECT_EQ(24, buffer.frames());
 
-  // Read 6 frames from the buffer.
-  const int frames = 6;
-  scoped_ptr<AudioBus> bus = AudioBus::Create(channels, buffer.frames());
-  EXPECT_EQ(frames, buffer.ReadFrames(frames, 0, bus.get()));
+  // Read 6 frames from the buffer. Data is interleaved, so ch[0] should be
+  // 1, 3, 5, 7, 9, 11, and ch[1] should be 2, 4, 6, 8, 10, 12.
+  // Data is converted to float from -1.0 to 1.0 based on int16 range.
+  scoped_ptr<AudioBus> bus = AudioBus::Create(channels, 100);
+  EXPECT_EQ(6, buffer.ReadFrames(6, 0, bus.get()));
   EXPECT_EQ(18, buffer.frames());
-  VerifyBus(bus.get(), 0, 4, 4, 1.0f / kint16max, 1.0f / kint16max);
-  VerifyBus(bus.get(), 4, 2, 20, 9.0f / kint16max, 1.0f / kint16max);
+  VerifyResult(bus->channel(0), 6, 1.0f / kint16max, 2.0f / kint16max);
+  VerifyResult(bus->channel(1), 6, 2.0f / kint16max, 2.0f / kint16max);
 }
 
 TEST(AudioBufferQueueTest, ReadS32) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   const int channels = ChannelLayoutToChannelCount(channel_layout);
   AudioBufferQueue buffer;
 
   // Add 24 frames of data.
   buffer.Append(
       MakeTestBuffer<int32>(kSampleFormatS32, channel_layout, 1, 1, 4));
   buffer.Append(
       MakeTestBuffer<int32>(kSampleFormatS32, channel_layout, 9, 1, 20));
   EXPECT_EQ(24, buffer.frames());
 
-  // Read 6 frames from the buffer.
+  // Read 6 frames from the buffer. Data is interleaved, so ch[0] should be
+  // 1, 3, 5, 7, 100, 106, and ch[1] should be 2, 4, 6, 8, 103, 109.
+  // Data is converted to float from -1.0 to 1.0 based on int32 range.
   scoped_ptr<AudioBus> bus = AudioBus::Create(channels, 100);
   EXPECT_EQ(6, buffer.ReadFrames(6, 0, bus.get()));
   EXPECT_EQ(18, buffer.frames());
-  VerifyBus(bus.get(), 0, 4, 4, 1.0f / kint32max, 1.0f / kint32max);
-  VerifyBus(bus.get(), 4, 2, 20, 9.0f / kint32max, 1.0f / kint32max);
+  VerifyResult(bus->channel(0), 6, 1.0f / kint32max, 2.0f / kint32max);
+  VerifyResult(bus->channel(1), 6, 2.0f / kint32max, 2.0f / kint32max);
 
   // Read the next 2 frames.
   EXPECT_EQ(2, buffer.ReadFrames(2, 0, bus.get()));
   EXPECT_EQ(16, buffer.frames());
-  VerifyBus(bus.get(), 0, 2, 20, 11.0f / kint32max, 1.0f / kint32max);
+  VerifyResult(bus->channel(0), 2, 13.0f / kint32max, 2.0f / kint32max);
+  VerifyResult(bus->channel(1), 2, 14.0f / kint32max, 2.0f / kint32max);
 }
 
 TEST(AudioBufferQueueTest, ReadF32Planar) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   const int channels = ChannelLayoutToChannelCount(channel_layout);
   AudioBufferQueue buffer;
 
   // Add 14 frames of data.
   buffer.Append(MakeTestBuffer<float>(
       kSampleFormatPlanarF32, channel_layout, 1.0f, 1.0f, 4));
   buffer.Append(MakeTestBuffer<float>(
       kSampleFormatPlanarF32, channel_layout, 50.0f, 1.0f, 10));
   EXPECT_EQ(14, buffer.frames());
 
-  // Read 6 frames from the buffer.
+  // Read 6 frames from the buffer. F32 is planar, so ch[0] should be
+  // 1, 2, 3, 4, 50, 51, and ch[1] should be 5, 6, 7, 8, 60, 61.
   scoped_ptr<AudioBus> bus = AudioBus::Create(channels, 100);
   EXPECT_EQ(6, buffer.ReadFrames(6, 0, bus.get()));
   EXPECT_EQ(8, buffer.frames());
-  VerifyBus(bus.get(), 0, 4, 4, 1, 1);
-  VerifyBus(bus.get(), 4, 2, 10, 50, 1);
+  VerifyResult(bus->channel(0), 4, 1.0f, 1.0f);
+  VerifyResult(bus->channel(0) + 4, 2, 50.0f, 1.0f);
+  VerifyResult(bus->channel(1), 4, 5.0f, 1.0f);
+  VerifyResult(bus->channel(1) + 4, 2, 60.0f, 1.0f);
 }
 
 TEST(AudioBufferQueueTest, ReadS16Planar) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   const int channels = ChannelLayoutToChannelCount(channel_layout);
   AudioBufferQueue buffer;
 
   // Add 24 frames of data.
   buffer.Append(
       MakeTestBuffer<int16>(kSampleFormatPlanarS16, channel_layout, 1, 1, 4));
   buffer.Append(MakeTestBuffer<int16>(
       kSampleFormatPlanarS16, channel_layout, 100, 5, 20));
   EXPECT_EQ(24, buffer.frames());
 
-  // Read 6 frames from the buffer.
+  // Read 6 frames from the buffer. Data is planar, so ch[0] should be
+  // 1, 2, 3, 4, 100, 105, and ch[1] should be 5, 6, 7, 8, 200, 205.
+  // Data is converted to float from -1.0 to 1.0 based on int16 range.
   scoped_ptr<AudioBus> bus = AudioBus::Create(channels, 100);
   EXPECT_EQ(6, buffer.ReadFrames(6, 0, bus.get()));
   EXPECT_EQ(18, buffer.frames());
-  VerifyBus(bus.get(), 0, 4, 4, 1.0f / kint16max, 1.0f / kint16max);
-  VerifyBus(bus.get(), 4, 2, 20, 5.0f / kint16max, 1.0f / kint16max);
+  VerifyResult(bus->channel(0), 4, 1.0f / kint16max, 1.0f / kint16max);
+  VerifyResult(bus->channel(0) + 4, 2, 100.0f / kint16max, 5.0f / kint16max);
+  VerifyResult(bus->channel(1), 4, 5.0f / kint16max, 1.0f / kint16max);
+  VerifyResult(bus->channel(1) + 4, 2, 200.0f / kint16max, 5.0f / kint16max);
 }
 
 TEST(AudioBufferQueueTest, ReadManyChannels) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_OCTAGONAL;
   const int channels = ChannelLayoutToChannelCount(channel_layout);
   AudioBufferQueue buffer;
 
   // Add 76 frames of data.
   buffer.Append(
       MakeTestBuffer<float>(kSampleFormatF32, channel_layout, 0.0f, 1.0f, 6));
   buffer.Append(MakeTestBuffer<float>(
       kSampleFormatF32, channel_layout, 6.0f * channels, 1.0f, 10));
   buffer.Append(MakeTestBuffer<float>(
       kSampleFormatF32, channel_layout, 16.0f * channels, 1.0f, 60));
   EXPECT_EQ(76, buffer.frames());
 
-  // Read 3 frames from the buffer.
+  // Read 3 frames from the buffer. F32 is interleaved, so ch[0] should be
+  // 1, 17, 33, and ch[1] should be 2, 18, 34. Just check a few channels.
   scoped_ptr<AudioBus> bus = AudioBus::Create(channels, 100);
   EXPECT_EQ(30, buffer.ReadFrames(30, 0, bus.get()));
   EXPECT_EQ(46, buffer.frames());
-  VerifyBus(bus.get(), 0, 6, 6, 0, 1);
-  VerifyBus(bus.get(), 6, 10, 10, 6 * channels, 1);
-  VerifyBus(bus.get(), 16, 14, 60, 16 * channels, 1);
+  for (int i = 0; i < channels; ++i) {
+    VerifyResult(bus->channel(i), 30, static_cast<float>(i), 8.0f);
+  }
 }
 
 TEST(AudioBufferQueueTest, Peek) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_4_0;
   const int channels = ChannelLayoutToChannelCount(channel_layout);
   AudioBufferQueue buffer;
 
   // Add 60 frames of data.
-  const int frames = 60;
-  buffer.Append(MakeTestBuffer<float>(
-      kSampleFormatF32, channel_layout, 0.0f, 1.0f, frames));
-  EXPECT_EQ(frames, buffer.frames());
+  buffer.Append(
+      MakeTestBuffer<float>(kSampleFormatF32, channel_layout, 0.0f, 1.0f, 60));
+  EXPECT_EQ(60, buffer.frames());
 
   // Peek at the first 30 frames.
-  scoped_ptr<AudioBus> bus1 = AudioBus::Create(channels, frames);
-  EXPECT_EQ(frames, buffer.frames());
-  EXPECT_EQ(frames, buffer.PeekFrames(60, 0, 0, bus1.get()));
+  scoped_ptr<AudioBus> bus1 = AudioBus::Create(channels, 100);
+  EXPECT_EQ(60, buffer.frames());
+  EXPECT_EQ(60, buffer.PeekFrames(100, 0, 0, bus1.get()));
   EXPECT_EQ(30, buffer.PeekFrames(30, 0, 0, bus1.get()));
-  EXPECT_EQ(frames, buffer.frames());
-  VerifyBus(bus1.get(), 0, 30, bus1->frames(), 0, 1);
+  EXPECT_EQ(60, buffer.frames());
 
   // Now read the next 30 frames (which should be the same as those peeked at).
-  scoped_ptr<AudioBus> bus2 = AudioBus::Create(channels, frames);
+  scoped_ptr<AudioBus> bus2 = AudioBus::Create(channels, 100);
   EXPECT_EQ(30, buffer.ReadFrames(30, 0, bus2.get()));
-  VerifyBus(bus2.get(), 0, 30, bus2->frames(), 0, 1);
+  for (int i = 0; i < channels; ++i) {
+    VerifyResult(bus1->channel(i),
+                 30,
+                 static_cast<float>(i),
+                 static_cast<float>(channels));
+    VerifyResult(bus2->channel(i),
+                 30,
+                 static_cast<float>(i),
+                 static_cast<float>(channels));
+  }
 
   // Peek 10 frames forward
-  bus1->Zero();
   EXPECT_EQ(5, buffer.PeekFrames(5, 10, 0, bus1.get()));
-  VerifyBus(bus1.get(), 0, 5, bus1->frames(), 40, 1);
+  for (int i = 0; i < channels; ++i) {
+    VerifyResult(bus1->channel(i),
+                 5,
+                 static_cast<float>(i + 40 * channels),
+                 static_cast<float>(channels));
+  }
 
   // Peek to the end of the buffer.
   EXPECT_EQ(30, buffer.frames());
-  EXPECT_EQ(30, buffer.PeekFrames(60, 0, 0, bus1.get()));
+  EXPECT_EQ(30, buffer.PeekFrames(100, 0, 0, bus1.get()));
   EXPECT_EQ(30, buffer.PeekFrames(30, 0, 0, bus1.get()));
 }
 
 TEST(AudioBufferQueueTest, Time) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   const int channels = ChannelLayoutToChannelCount(channel_layout);
   const base::TimeDelta start_time1;
   const base::TimeDelta start_time2 = base::TimeDelta::FromSeconds(30);
+  const base::TimeDelta duration = base::TimeDelta::FromSeconds(10);
   AudioBufferQueue buffer;
   scoped_ptr<AudioBus> bus = AudioBus::Create(channels, 100);
 
-  scoped_refptr<AudioBuffer> audio_buffer =
-      MakeAudioBuffer<int16>(kSampleFormatS16,
-                             channel_layout,
-                             channels,
-                             kSampleRate,
-                             1,
-                             1,
-                             10,
-                             start_time1);
-
   // Add two buffers (second one added later):
   //   first:  start=0s,  duration=10s
   //   second: start=30s, duration=10s
-  buffer.Append(audio_buffer);
+  buffer.Append(MakeAudioBuffer<int16>(kSampleFormatS16,
+                                       channel_layout,
+                                       channels,
+                                       kSampleRate,
+                                       1,
+                                       1,
+                                       10,
+                                       start_time1,
+                                       duration));
   EXPECT_EQ(10, buffer.frames());
 
   // Check starting time.
   EXPECT_EQ(start_time1, buffer.current_time());
 
   // Read 2 frames, should be 2s in (since duration is 1s per sample).
-  int frames_read = 2;
-  EXPECT_EQ(frames_read, buffer.ReadFrames(frames_read, 0, bus.get()));
-  EXPECT_EQ(
-      start_time1 +
-          frames_read * audio_buffer->duration() / audio_buffer->frame_count(),
-      buffer.current_time());
+  EXPECT_EQ(2, buffer.ReadFrames(2, 0, bus.get()));
+  EXPECT_EQ(start_time1 + base::TimeDelta::FromSeconds(2),
+            buffer.current_time());
 
   // Skip 2 frames.
   buffer.SeekFrames(2);
-  frames_read += 2;
-  EXPECT_EQ(
-      start_time1 +
-          frames_read * audio_buffer->duration() / audio_buffer->frame_count(),
-      buffer.current_time());
+  EXPECT_EQ(start_time1 + base::TimeDelta::FromSeconds(4),
+            buffer.current_time());
 
   // Add second buffer for more data.
   buffer.Append(MakeAudioBuffer<int16>(kSampleFormatS16,
                                        channel_layout,
                                        channels,
                                        kSampleRate,
                                        1,
                                        1,
                                        10,
-                                       start_time2));
+                                       start_time2,
+                                       duration));
   EXPECT_EQ(16, buffer.frames());
 
   // Read until almost the end of buffer1.
-  frames_read += 5;
   EXPECT_EQ(5, buffer.ReadFrames(5, 0, bus.get()));
-  EXPECT_EQ(
-      start_time1 +
-          frames_read * audio_buffer->duration() / audio_buffer->frame_count(),
-      buffer.current_time());
+  EXPECT_EQ(start_time1 + base::TimeDelta::FromSeconds(9),
+            buffer.current_time());
 
   // Read 1 value, so time moved to buffer2.
   EXPECT_EQ(1, buffer.ReadFrames(1, 0, bus.get()));
   EXPECT_EQ(start_time2, buffer.current_time());
 
   // Read all 10 frames in buffer2, timestamp should be last time from buffer2.
-  frames_read = 10;
   EXPECT_EQ(10, buffer.ReadFrames(10, 0, bus.get()));
-  const base::TimeDelta expected_current_time =
-      start_time2 +
-      frames_read * audio_buffer->duration() / audio_buffer->frame_count();
-  EXPECT_EQ(expected_current_time, buffer.current_time());
+  EXPECT_EQ(start_time2 + base::TimeDelta::FromSeconds(10),
+            buffer.current_time());
 
   // Try to read more frames (which don't exist), timestamp should remain.
   EXPECT_EQ(0, buffer.ReadFrames(5, 0, bus.get()));
-  EXPECT_EQ(expected_current_time, buffer.current_time());
+  EXPECT_EQ(start_time2 + base::TimeDelta::FromSeconds(10),
+            buffer.current_time());
 }
 
 TEST(AudioBufferQueueTest, NoTime) {
   const ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   const int channels = ChannelLayoutToChannelCount(channel_layout);
   const base::TimeDelta kNoTime = kNoTimestamp();
   AudioBufferQueue buffer;
   scoped_ptr<AudioBus> bus = AudioBus::Create(channels, 100);
 
   // Add two buffers with no timestamps. Time should always be unknown.
@@ skipping 25 matching lines @@
   // Read all 10 frames in buffer2.
   EXPECT_EQ(10, buffer.ReadFrames(10, 0, bus.get()));
   EXPECT_EQ(kNoTime, buffer.current_time());
 
   // Try to read more frames (which don't exist), timestamp should remain.
   EXPECT_EQ(0, buffer.ReadFrames(5, 0, bus.get()));
   EXPECT_EQ(kNoTime, buffer.current_time());
 }
 
 }  // namespace media