Make AudioTimestampHelper::TimeToFrames() more accurate

media/base/audio_timestamp_helper_unittest.cc

 // Copyright (c) 2012 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 <stddef.h>
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "media/base/audio_timestamp_helper.h"
 #include "media/base/timestamp_constants.h"
@@ skipping 62 matching lines @@
             AudioTimestampHelper::FramesToTime(48000000000, k48kHz));
 }
 
 TEST_F(AudioTimestampHelperTest, TimeToFrames) {
   // Negative value.
   EXPECT_EQ(-48000, AudioTimestampHelper::TimeToFrames(
                         base::TimeDelta::FromSeconds(-1), k48kHz));
   // Zero.
   EXPECT_EQ(0, AudioTimestampHelper::TimeToFrames(
                    base::TimeDelta::FromMicroseconds(0), k48kHz));
-  // Any duration less than 21 microseconds will return zero frames at 48 kHz
-  // because each frame is 20.833 microseconds.
+  // Duration of each frame is 20.833 microseconds. The result is rounded to
+  // integral.
   EXPECT_EQ(0, AudioTimestampHelper::TimeToFrames(
+                   base::TimeDelta::FromMicroseconds(10), k48kHz));
+  EXPECT_EQ(1, AudioTimestampHelper::TimeToFrames(
                    base::TimeDelta::FromMicroseconds(20), k48kHz));
   EXPECT_EQ(1, AudioTimestampHelper::TimeToFrames(
                    base::TimeDelta::FromMicroseconds(21), k48kHz));
   // Exact value with maximum precision of TimeDelta.
   EXPECT_EQ(750, AudioTimestampHelper::TimeToFrames(
                      base::TimeDelta::FromMicroseconds(15625), k48kHz));
   // One second.
   EXPECT_EQ(48000, AudioTimestampHelper::TimeToFrames(
                        base::TimeDelta::FromSeconds(1), k48kHz));
   // Argument and return value exceeding 32 bits.
@@ skipping 73 matching lines @@
   // tested above to verify that the code is rounding properly.
   TestGetFramesToTargetRange(0, 103, 124);
   TestGetFramesToTargetRange(-1, 80, 102);
   TestGetFramesToTargetRange(-2, 57, 79);
   TestGetFramesToTargetRange(-3, 35, 56);
   TestGetFramesToTargetRange(-4, 12, 34);
   TestGetFramesToTargetRange(-5, 0, 11);
 }
 
 }  // namespace media