media/base/audio_discard_helper_unittest.cc - chromium/src - Git at Google

 // Copyright 2014 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_discard_helper.h"

 #include <stddef.h>

 #include <memory>

 #include "media/base/audio_buffer.h"
 #include "media/base/audio_bus.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/test_helpers.h"
 #include "media/base/timestamp_constants.h"
 #include "testing/gtest/include/gtest/gtest.h"

 namespace media {

 static const float kDataStep = 0.01f;
 static const size_t kSampleRate = 48000;

 static scoped_refptr<DecoderBuffer> CreateEncodedBuffer(
     base::TimeDelta timestamp,
     base::TimeDelta duration) {
   scoped_refptr<DecoderBuffer> result(new DecoderBuffer(1));
   result->set_timestamp(timestamp);
   result->set_duration(duration);
   return result;
 }

 static scoped_refptr<AudioBuffer> CreateDecodedBuffer(int frames) {
   return MakeAudioBuffer(kSampleFormatPlanarF32, CHANNEL_LAYOUT_MONO, 1,
                          kSampleRate, 0.0f, kDataStep, frames, kNoTimestamp);
 }

 static float ExtractDecodedData(const scoped_refptr<AudioBuffer>& buffer,
                                 int index) {
   // This is really inefficient, but we can't access the raw AudioBuffer if any
   // start trimming has been applied.
   std::unique_ptr<AudioBus> temp_bus =
       AudioBus::Create(buffer->channel_count(), 1);
   buffer->ReadFrames(1, index, 0, temp_bus.get());
   return temp_bus->channel(0)[0];
 }

 TEST(AudioDiscardHelperTest, TimeDeltaToFrames) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);

   EXPECT_EQ(0u, discard_helper.TimeDeltaToFrames(base::TimeDelta()));
   EXPECT_EQ(
       kSampleRate / 100,
       discard_helper.TimeDeltaToFrames(base::TimeDelta::FromMilliseconds(10)));

   // Ensure partial frames are rounded down correctly.  The equation below
   // calculates a frame count with a fractional part < 0.5.
   const int small_remainder =
       base::Time::kMicrosecondsPerSecond * (kSampleRate - 0.9) / kSampleRate;
   EXPECT_EQ(kSampleRate - 1,
             discard_helper.TimeDeltaToFrames(
                 base::TimeDelta::FromMicroseconds(small_remainder)));

   // Ditto, but rounded up using a fractional part > 0.5.
   const int large_remainder =
       base::Time::kMicrosecondsPerSecond * (kSampleRate - 0.4) / kSampleRate;
   EXPECT_EQ(kSampleRate,
             discard_helper.TimeDeltaToFrames(
                 base::TimeDelta::FromMicroseconds(large_remainder)));
 }

 TEST(AudioDiscardHelperTest, BasicProcessBuffers) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();

   // Use an estimated duration which doesn't match the number of decoded frames
   // to ensure the helper is correctly setting durations based on output frames.
   const base::TimeDelta kEstimatedDuration =
       base::TimeDelta::FromMilliseconds(9);
   const base::TimeDelta kActualDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kActualDuration);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kEstimatedDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Verify the basic case where nothing is discarded.
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kActualDuration, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames, decoded_buffer->frame_count());

   // Verify a Reset() takes us back to an uninitialized state.
   discard_helper.Reset(0);
   ASSERT_FALSE(discard_helper.initialized());

   // Verify a NULL output buffer returns false.
   ASSERT_FALSE(discard_helper.ProcessBuffers(*encoded_buffer, NULL));
 }

 TEST(AudioDiscardHelperTest, NegativeTimestampClampsToZero) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = -base::TimeDelta::FromSeconds(1);
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Verify the basic case where nothing is discarded.
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());
   EXPECT_EQ(base::TimeDelta(), decoded_buffer->timestamp());
   EXPECT_EQ(kDuration, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames, decoded_buffer->frame_count());
 }

 TEST(AudioDiscardHelperTest, ProcessBuffersWithInitialDiscard) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   // Tell the helper we want to discard half of the initial frames.
   const int kDiscardFrames = kTestFrames / 2;
   discard_helper.Reset(kDiscardFrames);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Verify half the frames end up discarded.
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration / 2, decoded_buffer->duration());
   EXPECT_EQ(kDiscardFrames, decoded_buffer->frame_count());
   ASSERT_FLOAT_EQ(kDiscardFrames * kDataStep,
                   ExtractDecodedData(decoded_buffer, 0));
 }

 TEST(AudioDiscardHelperTest, ProcessBuffersWithLargeInitialDiscard) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   // Tell the helper we want to discard 1.5 buffers worth of frames.
   discard_helper.Reset(kTestFrames * 1.5);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // The first call should fail since no output buffer remains.
   ASSERT_FALSE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());

   // Generate another set of buffers and expect half the output frames.
   encoded_buffer = CreateEncodedBuffer(kTimestamp + kDuration, kDuration);
   decoded_buffer = CreateDecodedBuffer(kTestFrames);
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));

   // The timestamp should match that of the initial buffer.
   const int kDiscardFrames = kTestFrames / 2;
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration / 2, decoded_buffer->duration());
   EXPECT_EQ(kDiscardFrames, decoded_buffer->frame_count());
   ASSERT_FLOAT_EQ(kDiscardFrames * kDataStep,
                   ExtractDecodedData(decoded_buffer, 0));
 }

 TEST(AudioDiscardHelperTest, AllowNonMonotonicTimestamps) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames, decoded_buffer->frame_count());

   // Process the same input buffer again to ensure input timestamps which go
   // backwards in time are not errors.
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   EXPECT_EQ(kTimestamp + kDuration, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames, decoded_buffer->frame_count());
 }

 TEST(AudioDiscardHelperTest, DiscardEndPadding) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Set a discard padding equivalent to half the buffer.
   encoded_buffer->set_discard_padding(
       std::make_pair(base::TimeDelta(), kDuration / 2));

   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration / 2, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames / 2, decoded_buffer->frame_count());
 }

 TEST(AudioDiscardHelperTest, BadDiscardEndPadding) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Set a discard padding equivalent to double the buffer size.
   encoded_buffer->set_discard_padding(
       std::make_pair(base::TimeDelta(), kDuration * 2));

   // Verify the end discard padding is rejected.
   ASSERT_FALSE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());
 }

 TEST(AudioDiscardHelperTest, InitialDiscardAndDiscardEndPadding) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Set a discard padding equivalent to a quarter of the buffer.
   encoded_buffer->set_discard_padding(
       std::make_pair(base::TimeDelta(), kDuration / 4));

   // Set an initial discard of a quarter of the buffer.
   const int kDiscardFrames = kTestFrames / 4;
   discard_helper.Reset(kDiscardFrames);

   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration / 2, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames / 2, decoded_buffer->frame_count());
   ASSERT_FLOAT_EQ(kDiscardFrames * kDataStep,
                   ExtractDecodedData(decoded_buffer, 0));
 }

 TEST(AudioDiscardHelperTest, InitialDiscardAndDiscardPadding) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Set all the discard values to be different to ensure each is properly used.
   const int kDiscardFrames = kTestFrames / 4;
   encoded_buffer->set_discard_padding(
       std::make_pair(kDuration / 8, kDuration / 16));
   discard_helper.Reset(kDiscardFrames);

   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration - kDuration / 4 - kDuration / 8 - kDuration / 16,
             decoded_buffer->duration());
   EXPECT_EQ(kTestFrames - kTestFrames / 4 - kTestFrames / 8 - kTestFrames / 16,
             decoded_buffer->frame_count());
 }

 TEST(AudioDiscardHelperTest, InitialDiscardAndDiscardPaddingAndDecoderDelay) {
   // Use a decoder delay of 5ms.
   const int kDecoderDelay = kSampleRate / 100 / 2;
   AudioDiscardHelper discard_helper(kSampleRate, kDecoderDelay, false);
   ASSERT_FALSE(discard_helper.initialized());
   discard_helper.Reset(kDecoderDelay);

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Set a discard padding equivalent to half of the buffer.
   encoded_buffer->set_discard_padding(
       std::make_pair(kDuration / 2, base::TimeDelta()));

   // All of the first buffer should be discarded, half from the inital delay and
   // another half from the front discard padding.
   //
   //    Encoded                   Discard Delay
   //   |--------|     |---------|     |----|
   //   |AAAAAAAA| --> |....|AAAA| --> |AAAA| -------> NULL
   //   |--------|     |---------|     |----|
   //                    Decoded               Discard Front Padding
   //
   ASSERT_FALSE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());

   // Processing another buffer that has front discard set to half the buffer's
   // duration should discard the back half of the buffer since kDecoderDelay is
   // half a buffer.  The end padding should not be discarded until another
   // buffer is processed.  kDuration / 4 is chosen for the end discard since it
   // will force the end discard to start after position zero within the next
   // decoded buffer.
   //
   //    Encoded                    Discard Front Padding (from B)
   //   |--------|     |---------|             |----|
   //   |BBBBBBBB| --> |AAAA|BBBB| ----------> |AAAA|
   //   |--------|     |---------|             |----|
   //                    Decoded
   //           (includes carryover from A)
   //
   encoded_buffer->set_timestamp(encoded_buffer->timestamp() + kDuration);
   encoded_buffer->set_discard_padding(
       std::make_pair(kDuration / 2, kDuration / 4));
   decoded_buffer = CreateDecodedBuffer(kTestFrames);
   ASSERT_FLOAT_EQ(0.0f, ExtractDecodedData(decoded_buffer, 0));
   ASSERT_NEAR(kDecoderDelay * kDataStep,
               ExtractDecodedData(decoded_buffer, kDecoderDelay),
               kDataStep / 1000);
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration / 2, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames / 2, decoded_buffer->frame_count());

   // Verify it was actually the latter half of the buffer that was removed.
   ASSERT_FLOAT_EQ(0.0f, ExtractDecodedData(decoded_buffer, 0));

   // Verify the end discard padding is carried over to the next buffer.  Use
   // kDuration / 2 for the end discard padding so that the next buffer has its
   // start entirely discarded.
   //
   //    Encoded                      Discard End Padding (from B)
   //   |--------|     |---------|             |-------|
   //   |CCCCCCCC| --> |BBBB|CCCC| ----------> |BB|CCCC|
   //   |--------|     |---------|             |-------|
   //                    Decoded
   //           (includes carryover from B)
   //
   encoded_buffer->set_timestamp(encoded_buffer->timestamp() + kDuration);
   encoded_buffer->set_discard_padding(
       std::make_pair(base::TimeDelta(), kDuration / 2));
   decoded_buffer = CreateDecodedBuffer(kTestFrames);
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   EXPECT_EQ(kTimestamp + kDuration / 2, decoded_buffer->timestamp());
   EXPECT_EQ(3 * kDuration / 4, decoded_buffer->duration());
   EXPECT_EQ(3 * kTestFrames / 4, decoded_buffer->frame_count());

   // Verify it was actually the second quarter of the buffer that was removed.
   const int kDiscardFrames = kTestFrames / 4;
   ASSERT_FLOAT_EQ(0.0f, ExtractDecodedData(decoded_buffer, 0));
   ASSERT_FLOAT_EQ(
       kDiscardFrames * 2 * kDataStep,
       ExtractDecodedData(decoded_buffer, kDecoderDelay - kDiscardFrames));

   // One last test to ensure carryover discard from the start works.
   //
   //    Encoded                      Discard End Padding (from C)
   //   |--------|     |---------|             |----|
   //   |DDDDDDDD| --> |CCCC|DDDD| ----------> |DDDD|
   //   |--------|     |---------|             |----|
   //                    Decoded
   //           (includes carryover from C)
   //
   encoded_buffer->set_timestamp(encoded_buffer->timestamp() + kDuration);
   encoded_buffer->set_discard_padding(DecoderBuffer::DiscardPadding());
   decoded_buffer = CreateDecodedBuffer(kTestFrames);
   ASSERT_FLOAT_EQ(0.0f, ExtractDecodedData(decoded_buffer, 0));
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   EXPECT_EQ(kTimestamp + kDuration / 2 + 3 * kDuration / 4,
             decoded_buffer->timestamp());
   EXPECT_EQ(kDuration / 2, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames / 2, decoded_buffer->frame_count());
   ASSERT_FLOAT_EQ(kTestFrames / 2 * kDataStep,
                   ExtractDecodedData(decoded_buffer, 0));
 }

 TEST(AudioDiscardHelperTest, DelayedDiscardInitialDiscardAndDiscardPadding) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, true);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);

   // Set all the discard values to be different to ensure each is properly used.
   const int kDiscardFrames = kTestFrames / 4;
   encoded_buffer->set_discard_padding(
       std::make_pair(kDuration / 8, kDuration / 16));
   discard_helper.Reset(kDiscardFrames);

   // Verify nothing is output for the first buffer, yet initialized is true.
   ASSERT_FALSE(discard_helper.ProcessBuffers(*encoded_buffer, NULL));
   ASSERT_TRUE(discard_helper.initialized());

   // Create an encoded buffer with no discard padding.
   encoded_buffer = CreateEncodedBuffer(kTimestamp + kDuration, kDuration);
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Verify that when the decoded buffer is consumed, the discards from the
   // previous encoded buffer are applied.
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration - kDuration / 4 - kDuration / 8 - kDuration / 16,
             decoded_buffer->duration());
   EXPECT_EQ(kTestFrames - kTestFrames / 4 - kTestFrames / 8 - kTestFrames / 16,
             decoded_buffer->frame_count());
 }

 TEST(AudioDiscardHelperTest, CompleteDiscard) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, false);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);
   discard_helper.Reset(0);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   encoded_buffer->set_discard_padding(
       std::make_pair(kInfiniteDuration, base::TimeDelta()));
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Verify all of the first buffer is discarded.
   ASSERT_FALSE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());
   encoded_buffer->set_timestamp(kTimestamp + kDuration);
   encoded_buffer->set_discard_padding(DecoderBuffer::DiscardPadding());

   // Verify a second buffer goes through untouched.
   decoded_buffer = CreateDecodedBuffer(kTestFrames / 2);
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration / 2, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames / 2, decoded_buffer->frame_count());
   ASSERT_FLOAT_EQ(0.0f, ExtractDecodedData(decoded_buffer, 0));
 }

 TEST(AudioDiscardHelperTest, CompleteDiscardWithDelayedDiscard) {
   AudioDiscardHelper discard_helper(kSampleRate, 0, true);
   ASSERT_FALSE(discard_helper.initialized());

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);
   discard_helper.Reset(0);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   encoded_buffer->set_discard_padding(
       std::make_pair(kInfiniteDuration, base::TimeDelta()));
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Setup a delayed discard.
   ASSERT_FALSE(discard_helper.ProcessBuffers(*encoded_buffer, NULL));
   ASSERT_TRUE(discard_helper.initialized());

   // Verify the first output buffer is dropped.
   encoded_buffer->set_timestamp(kTimestamp + kDuration);
   encoded_buffer->set_discard_padding(DecoderBuffer::DiscardPadding());
   ASSERT_FALSE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));

   // Verify the second buffer goes through untouched.
   encoded_buffer->set_timestamp(kTimestamp + 2 * kDuration);
   decoded_buffer = CreateDecodedBuffer(kTestFrames / 2);
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration / 2, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames / 2, decoded_buffer->frame_count());
   ASSERT_FLOAT_EQ(0.0f, ExtractDecodedData(decoded_buffer, 0));
 }

 TEST(AudioDiscardHelperTest, CompleteDiscardWithInitialDiscardDecoderDelay) {
   // Use a decoder delay of 5ms.
   const int kDecoderDelay = kSampleRate / 100 / 2;
   AudioDiscardHelper discard_helper(kSampleRate, kDecoderDelay, false);
   ASSERT_FALSE(discard_helper.initialized());
   discard_helper.Reset(kDecoderDelay);

   const base::TimeDelta kTimestamp = base::TimeDelta();
   const base::TimeDelta kDuration = base::TimeDelta::FromMilliseconds(10);
   const int kTestFrames = discard_helper.TimeDeltaToFrames(kDuration);

   scoped_refptr<DecoderBuffer> encoded_buffer =
       CreateEncodedBuffer(kTimestamp, kDuration);
   encoded_buffer->set_discard_padding(
       std::make_pair(kInfiniteDuration, base::TimeDelta()));
   scoped_refptr<AudioBuffer> decoded_buffer = CreateDecodedBuffer(kTestFrames);

   // Verify all of the first buffer is discarded.
   ASSERT_FALSE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   ASSERT_TRUE(discard_helper.initialized());
   encoded_buffer->set_timestamp(kTimestamp + kDuration);
   encoded_buffer->set_discard_padding(DecoderBuffer::DiscardPadding());

   // Verify 5ms off the front of the second buffer is discarded.
   decoded_buffer = CreateDecodedBuffer(kTestFrames * 2);
   ASSERT_TRUE(discard_helper.ProcessBuffers(*encoded_buffer, decoded_buffer));
   EXPECT_EQ(kTimestamp, decoded_buffer->timestamp());
   EXPECT_EQ(kDuration * 2 - kDuration / 2, decoded_buffer->duration());
   EXPECT_EQ(kTestFrames * 2 - kDecoderDelay, decoded_buffer->frame_count());
   ASSERT_FLOAT_EQ(kDecoderDelay * kDataStep,
                   ExtractDecodedData(decoded_buffer, 0));
 }

 }  // namespace media