Adds media::AudioPullFifo class to Chrome.

media/base/audio_pull_fifo_unittest.cc

Index: media/base/audio_pull_fifo_unittest.cc
diff --git a/media/base/audio_pull_fifo_unittest.cc b/media/base/audio_pull_fifo_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..168e6f3532711adafcedbaf5ed79fb51c23c27bb
--- /dev/null
+++ b/media/base/audio_pull_fifo_unittest.cc
@@ -0,0 +1,89 @@
+// 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 "base/bind.h"
+#include "base/bind_helpers.h"
+#include "media/base/audio_pull_fifo.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace media {
+
+// Block diagram of a possible real-world usage:
+//
+//       | Producer | ----> | AudioPullFifo | ----> | Consumer |
+//                    push                    pull
+//          2048      ---->       (2048)      ---->     ~512
+
+// Number of channels in each audio bus.
+static int kChannels = 2;
+
+// Max number of audio framed the FIFO can contain.
+static const int kMaxFramesInFifo = 2048;
+
+// List of |frames_to_consume| which will be used as input parameter to
+// AudioPullFifo::Consume() when the consumer asks for data.
+static const int kConsumeFrames[] =

[DaleCurtis, 2012/09/10 08:28:26]

How long does this take to run? We can probably cut this list in half or more
and still have excellent coverage. The problem with tests which move a lot of
data around like this is that valgrind/asan/tsan take an order of magnitude more
to run. So we want to make sure we're adding value with that additional time
overhead.

[henrika (OOO until Aug 14), 2012/09/10 09:35:31]

It takes ~10ms on my machine. Will keep as is.

+    {544, 512, 512, 512, 512, 2048, 544, 441, 442, 467, 540, 440, 433, 500};
+
+class AudioPullFifoTest : public testing::Test {
+ public:
+  AudioPullFifoTest()
+      : audio_bus_(AudioBus::Create(kChannels, kMaxFramesInFifo)),
+        fill_value_(0) {}
+  virtual ~AudioPullFifoTest() {}
+
+  void VerifyValue(const float data[], int size, float start_value) {
+    float value = start_value;
+    for (int i = 0; i < size; ++i) {
+      ASSERT_FLOAT_EQ(value++, data[i]) << "i=" << i;
+    }
+  }
+
+  // AudioPullFifo::ReadCB implementation where we increase a value for each
+  // audio frame that we provide. Note that all channels are given the same
+  // value to simplify the verification.
+  virtual void ProvideInput(AudioBus* audio_bus) {
+    EXPECT_EQ(audio_bus->channels(), audio_bus_->channels());
+    EXPECT_EQ(audio_bus->frames(), kMaxFramesInFifo);
+    for (int i = 0; i < audio_bus->frames(); ++i) {
+      for (int j = 0; j < audio_bus->channels(); ++j) {
+        // Store same value in all channels.
+        audio_bus->channel(j)[i] = fill_value_;
+      }
+      fill_value_++;
+    }
+  }
+
+ protected:
+  scoped_ptr<AudioBus> audio_bus_;
+  int fill_value_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioPullFifoTest);
+};
+
+// Emulate a scenario where the consumer ask for data using the sizes in
+// kConsumeFrames at each call. The producer is asked to provide input when
+// the FIFO can't fulfill the request and kReadFramesFromProvider will be
+// provided in each callback. The producer updates and stores a data value for
+// each audio frame it provides which makes it possible to verify that the
+// consumer reads out correct values.
+TEST_F(AudioPullFifoTest, Consume) {

[DaleCurtis, 2012/09/10 08:28:26]

Instead of using an array of test values like this you can templatize using
TEST_P and extending  AudioPullFifoTest from testing::TestWithParam<int> and
then use INSTANTIATE_TEST_CASE_P().

See sinc_resampler_unittest for an example. 

[henrika (OOO until Aug 14), 2012/09/10 09:35:31]

Nice tip; did not know about it. Will modify.

+  AudioPullFifo pull_fifo(kChannels, kMaxFramesInFifo, base::Bind(
+      &AudioPullFifoTest::ProvideInput, base::Unretained(this)));
+
+  // Consume data using different sizes, acquire audio frames from the FIFO
+  // and verify that the retrieved values matches the values written by the
+  // producer.
+  int start_value = 0;
+  for (size_t i = 0; i < arraysize(kConsumeFrames); ++i) {
+    int frames_to_consume = kConsumeFrames[i];

[DaleCurtis, 2012/09/10 08:28:26]

SCOPED_TRACE() with the kConsumeFrames information?

[henrika (OOO until Aug 14), 2012/09/10 09:35:31]

Thanks.

+    pull_fifo.Consume(audio_bus_.get(), frames_to_consume);
+    for (int j = 0; j < kChannels; ++j) {
+      VerifyValue(audio_bus_->channel(j), frames_to_consume, start_value);
+    }
+    start_value += frames_to_consume;
+  }
+}
+
+}  // namespace media