Update media::AudioClock API to take time since writing into account.

media/filters/audio_clock_unittest.cc

 // 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_timestamp_helper.h"
 #include "media/base/buffers.h"
 #include "media/filters/audio_clock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace media {
@@ skipping 13 matching lines @@
     timestamp_helper_.AddFrames(static_cast<int>(frames * playback_rate));
     clock_.WroteAudio(
         frames, delay_frames, playback_rate, timestamp_helper_.GetTimestamp());
   }
 
   void WroteSilence(int frames, int delay_frames) {
     clock_.WroteSilence(frames, delay_frames);
   }
 
   int CurrentMediaTimestampInMilliseconds() {
-    return clock_.CurrentMediaTimestamp().InMilliseconds();
+    return CurrentMediaTimestampSinceLastWritingInMilliseconds(0);
+  }
+
+  int CurrentMediaTimestampSinceLastWritingInMilliseconds(int milliseconds) {
+    return clock_.CurrentMediaTimestamp(base::TimeDelta::FromMilliseconds(
+                                            milliseconds)).InMilliseconds();
   }
 
   int LastEndpointTimestampInMilliseconds() {
     return clock_.last_endpoint_timestamp().InMilliseconds();
   }
 
   const int sample_rate_;
   AudioTimestampHelper timestamp_helper_;
   AudioClock clock_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AudioClockTest);
 };
 
 TEST_F(AudioClockTest, TimestampsStartAtNoTimestamp) {
-  EXPECT_EQ(kNoTimestamp(), clock_.CurrentMediaTimestamp());
+  EXPECT_EQ(kNoTimestamp(), clock_.CurrentMediaTimestamp(base::TimeDelta()));
   EXPECT_EQ(kNoTimestamp(), clock_.last_endpoint_timestamp());
 }
 
 TEST_F(AudioClockTest, Playback) {
   // The first time we write data we should expect a negative time matching the
   // current delay.
   WroteAudio(10, 20, 1.0);
   EXPECT_EQ(-2000, CurrentMediaTimestampInMilliseconds());
   EXPECT_EQ(1000, LastEndpointTimestampInMilliseconds());
 
@@ skipping 106 matching lines @@
   // Ditto for silence.
   WroteSilence(10, 0);
   EXPECT_EQ(3000, CurrentMediaTimestampInMilliseconds());
   EXPECT_EQ(3000, LastEndpointTimestampInMilliseconds());
 
   WroteSilence(10, 0);
   EXPECT_EQ(3000, CurrentMediaTimestampInMilliseconds());
   EXPECT_EQ(3000, LastEndpointTimestampInMilliseconds());
 }
 
+TEST_F(AudioClockTest, CurrentMediaTimestampSinceLastWriting) {
+  // Construct an audio clock with the following representation:
+  //
+  // +-------------------+----------------+------------------+----------------+
+  // | 10 frames silence | 10 frames @ 1x | 10 frames @ 0.5x | 10 frames @ 2x |
+  // +-------------------+----------------+------------------+----------------+
+  // Media timestamp:    0              1000               1500             3500
+  // Wall clock time:  2000             3000               4000             5000
+  WroteAudio(10, 40, 1.0);
+  WroteAudio(10, 40, 0.5);
+  WroteAudio(10, 40, 2.0);
+  EXPECT_EQ(-2000, CurrentMediaTimestampInMilliseconds());
+  EXPECT_EQ(3500, LastEndpointTimestampInMilliseconds());
+
+  // Simulate passing 2000ms of initial delay in the audio hardware.
+  EXPECT_EQ(-2000, CurrentMediaTimestampSinceLastWritingInMilliseconds(0));
+  EXPECT_EQ(-1500, CurrentMediaTimestampSinceLastWritingInMilliseconds(500));
+  EXPECT_EQ(-1000, CurrentMediaTimestampSinceLastWritingInMilliseconds(1000));
+  EXPECT_EQ(-500, CurrentMediaTimestampSinceLastWritingInMilliseconds(1500));
+  EXPECT_EQ(0, CurrentMediaTimestampSinceLastWritingInMilliseconds(2000));
+
+  // New we should see the 1.0x buffer.
+  EXPECT_EQ(500, CurrentMediaTimestampSinceLastWritingInMilliseconds(2500));
+  EXPECT_EQ(1000, CurrentMediaTimestampSinceLastWritingInMilliseconds(3000));
+
+  // Now we should see the 0.5x buffer.
+  EXPECT_EQ(1250, CurrentMediaTimestampSinceLastWritingInMilliseconds(3500));
+  EXPECT_EQ(1500, CurrentMediaTimestampSinceLastWritingInMilliseconds(4000));
+
+  // Now we should see the 2.0x buffer.
+  EXPECT_EQ(2500, CurrentMediaTimestampSinceLastWritingInMilliseconds(4500));
+  EXPECT_EQ(3500, CurrentMediaTimestampSinceLastWritingInMilliseconds(5000));
+
+  // Times beyond the known length of the audio clock should return the last
+  // value we know of.
+  EXPECT_EQ(LastEndpointTimestampInMilliseconds(),
+            CurrentMediaTimestampSinceLastWritingInMilliseconds(5001));
+  EXPECT_EQ(LastEndpointTimestampInMilliseconds(),
+            CurrentMediaTimestampSinceLastWritingInMilliseconds(6000));
+}
+
 }  // namespace media