OLA Algorithm and test shell.

media/filters/audio_renderer_algorithm_ola.h

Index: media/filters/audio_renderer_algorithm_ola.h
===================================================================
--- media/filters/audio_renderer_algorithm_ola.h	(revision 0)
+++ media/filters/audio_renderer_algorithm_ola.h	(revision 0)
@@ -0,0 +1,75 @@
+// Copyright (c) 2009 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.
+
+// AudioRendererAlgorithmOLA [ARAO] is the pitch-preservation implementation of
+// AudioRendererAlgorithmBase [ARAB]. For speeds greater than 1.0f, FillBuffer()
+// consumes more input data than output data requested and crossfades
+// samples to fill |buffer_out|. For speeds less than 1.0f, FillBuffer()
+// consumers less input data than output data requested and draws overlapping
+// samples from the input data to fill |buffer_out|. As ARAB is thread-unsafe,
+// so is ARAO.
+
+#ifndef MEDIA_FILTERS_AUDIO_RENDERER_ALGORITHM_OLA_H_
+#define MEDIA_FILTERS_AUDIO_RENDERER_ALGORITHM_OLA_H_
+
+#include "media/filters/audio_renderer_algorithm_base.h"
+
+namespace media {
+
+class DataBuffer;
+
+class AudioRendererAlgorithmOLA : public AudioRendererAlgorithmBase {
+ public:
+  AudioRendererAlgorithmOLA();
+  virtual ~AudioRendererAlgorithmOLA();
+
+  // AudioRendererAlgorithmBase implementation
+  virtual size_t FillBuffer(DataBuffer* buffer_out);
+
+  virtual void FlushBuffers();
+
+  virtual void set_playback_rate(float new_rate);
+
+ private:
+  // Advances our input position by |bytes| bytes.
+  void AdvanceInput(size_t bytes);
+
+  // Aligns |value| to a channel and sample boundary.
+  void AlignToSampleBoundary(size_t* value);
+
+  // Copies |length| bytes from our buffers to |dest|. Returns how many bytes
+  // of data were copied.
+  size_t CopyInput(uint8* dest, size_t length);
+
+  // Crossfades |samples| samples of |dest| with the data in |src|. Assumes
+  // there is room in |dest| and enough data in |src|. Type is the datatype
+  // of a data point in the waveform (i.e. uint8, int16, int32, etc). Also,
+  // sizeof(one sample) == sizeof(Type) * channels.
+  template <class Type>
+  void Crossfade(int samples, const Type* src, Type* dest);
+
+  // Returns true if |saved_buf_| is NULL and the queue is empty.
+  bool IsInputFinished();
+
+  // Stores the front element of the queue so we can peek at the second one.
+  scoped_refptr<Buffer> saved_buf_;
+
+  // Remembers the amount of remaining audio data for our |saved_buf_|.
+  size_t data_offset_;
+
+  // Members for ease of calculation in FillBuffer(). These members are
+  // based on |playback_rate_|, but are stored seperately so they don't
+  // have to be recalculated on every call to FillBuffer().
+  size_t input_step_;
+  size_t output_step_;
+
+  // Length for crossfade in bytes.
+  size_t crossfade_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioRendererAlgorithmOLA);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_AUDIO_RENDERER_ALGORITHM_OLA_H_
Property changes on: media\filters\audio_renderer_algorithm_ola.h
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Added: svn:eol-style
   + LF