Support MPEG1 audio in the MPEG2-TS stream parser.

media/formats/mpeg/mpeg1_audio_stream_parser.h

+// 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.
+
+#ifndef MEDIA_FORMATS_MPEG_MPEG1_AUDIO_STREAM_PARSER_H_
+#define MEDIA_FORMATS_MPEG_MPEG1_AUDIO_STREAM_PARSER_H_
+
+#include "base/basictypes.h"
+#include "media/base/media_export.h"
+#include "media/formats/mpeg/mpeg_audio_stream_parser_base.h"
+
+namespace media {
+
+// MPEG1AudioStreamParser handles MPEG-1 audio streams (ISO/IEC 11172-3)
+// as well as the following extensions:
+// - MPEG-2 audio (ISO/IEC 13818-3),
+// - and MPEG2.5 (not an ISO standard).
+class MEDIA_EXPORT MPEG1AudioStreamParser : public MPEGAudioStreamParserBase {
+ public:
+  // Size of an MPEG-1 frame header in bytes.
+  enum {
+    kHeaderSize = 4,
+  };
+
+  // Versions and layers as defined in ISO/IEC 11172-3.
+  enum Version {
+    kVersion1 = 3,
+    kVersion2 = 2,
+    kVersionReserved = 1,
+    kVersion2_5 = 0,
+  };
+
+  enum Layer {
+    kLayer1 = 3,
+    kLayer2 = 2,
+    kLayer3 = 1,
+    kLayerReserved = 0,
+  };
+
+  struct Header {
+    Version version;
+
+    // Layer as defined in ISO/IEC 11172-3 bitstream specification.
+    Layer layer;
+
+    // Frame size in bytes.
+    int frame_size;
+
+    // Sample frequency.
+    int sample_rate;
+
+    // Channel mode as defined in ISO/IEC 11172-3 bitstream specification.
+    int channel_mode;
+
+    // Channel layout.
+    ChannelLayout channel_layout;
+
+    // Number of samples per frame.
+    int sample_count;
+  };
+
+  // Parses the header starting at |data|.
+  // Assumption: size of array |data| should be at least |kHeaderSize|.
+  // Returns false if the header is not valid.
+  static bool ParseHeader(
+      const LogCB& log_cb,
+      const uint8* data,
+      Header* header);
+
+  MPEG1AudioStreamParser();
+  virtual ~MPEG1AudioStreamParser();
+
+ private:
+  // MPEGAudioStreamParserBase overrides.
+  virtual int ParseFrameHeader(const uint8* data,
+                               int size,
+                               int* frame_size,
+                               int* sample_rate,
+                               ChannelLayout* channel_layout,
+                               int* sample_count,
+                               bool* metadata_frame) const OVERRIDE;
+
+  DISALLOW_COPY_AND_ASSIGN(MPEG1AudioStreamParser);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FORMATS_MPEG_MPEG1_AUDIO_STREAM_PARSER_H_