BufferQueue class to hide audio data micromanagement from scaling algorithms.

media/base/buffer_queue.h

+// 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.
+
+// BufferQueue is a simple Buffer manager that handles requests for data
+// while hiding Buffer boundaries, treating its internal queue of Buffers
+// as a contiguous region.
+//
+// This class is not threadsafe and requires external locking.
+
+#ifndef MEDIA_BASE_BUFFER_QUEUE_H_
+#define MEDIA_BASE_BUFFER_QUEUE_H_
+
+#include <deque>
+
+#include "base/ref_counted.h"
+
+namespace media {
+
+class Buffer;
+
+class BufferQueue {
+ public:
+  BufferQueue();
+  ~BufferQueue();
+
+  // Clears |queue_|.
+  void Clear();
+
+  // Advances front pointer |bytes_to_be_consumed| bytes and discards
+  // "consumed" buffers.
+  void Consume(size_t bytes_to_be_consumed);
+
+  // Tries to copy |bytes| bytes from our data to |dest|. Returns the number
+  // of bytes successfully copied.
+  size_t Copy(uint8* dest, size_t bytes);
+
+  // Enqueues |buffer_in| and adds a reference.
+  void Enqueue(Buffer* buffer_in);
+
+  // Returns true if the |queue_| is empty.
+  bool IsEmpty();
+
+  // Returns the number of bytes in the |queue_|.
+  size_t SizeInBytes();
+
+ private:
+  // Queued audio data.
+  std::deque< scoped_refptr<Buffer> > queue_;
+
+  // Remembers the amount of remaining audio data in the front buffer.
+  size_t data_offset_;
+
+  // Keeps track of the |queue_| size in bytes.
+  size_t size_in_bytes_;
+
+  DISALLOW_COPY_AND_ASSIGN(BufferQueue);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_BUFFER_QUEUE_H_