Media Galleries API Metadata: Add audio video metadata extractor.

media/base/audio_video_metadata_extractor.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_BASE_AUDIO_VIDEO_METADATA_EXTRACTOR_H_
+#define MEDIA_BASE_AUDIO_VIDEO_METADATA_EXTRACTOR_H_
+
+#include <map>

[Lei Zhang, 2014/01/07 21:44:25]

nit: remove

[tommycli, 2014/01/07 23:12:36]

Done.

+#include <string>
+
+#include "base/basictypes.h"
+#include "media/base/media_export.h"
+
+struct AVDictionary;

[Lei Zhang, 2014/01/07 21:44:25]

Are you going to use AVDictionary outside of this class? If not, then make it
private?

[tommycli, 2014/01/07 23:12:36]

Declared by FFmpeg.

+
+namespace media {
+
+class DataSource;
+
+// This class extracts a string dictionary of metadata tags for audio and video
+// files. It also provides the format name.
+class MEDIA_EXPORT AudioVideoMetadataExtractor {
+ public:
+  AudioVideoMetadataExtractor();
+  ~AudioVideoMetadataExtractor();
+
+  // Returns whether or not the fields were successfully extracted. Should only
+  // be called once.
+  bool Extract(media::DataSource* source);

[Lei Zhang, 2014/01/07 21:44:25]

nit:: you can omit media:: inside namespace media.

[tommycli, 2014/01/07 23:12:36]

Done.

+
+  double duration() const;

[Lei Zhang, 2014/01/07 21:44:25]

Mention this is in seconds.

[tommycli, 2014/01/07 23:12:36]

Done.

+
+  // Returns -1 for containers without video.
+  int width() const;
+  int height() const;
+
+  // Returns -1 or an empty string if the value is undefined.
+  const std::string& album() const;
+  const std::string& artist() const;
+  const std::string& comment() const;
+  const std::string& copyright() const;
+  const std::string& date() const;
+  int disc() const;
+  const std::string& encoder() const;
+  const std::string& encoded_by() const;
+  const std::string& genre() const;
+  const std::string& language() const;
+  const std::string& title() const;
+  int track() const;
+
+ private:
+  void ExtractDictionary(AVDictionary* metadata);
+
+  bool extracted_;
+
+  int duration_;
+  int width_;
+  int height_;
+
+  std::string album_;
+  std::string artist_;
+  std::string comment_;
+  std::string copyright_;
+  std::string date_;
+  int disc_;
+  std::string encoder_;
+  std::string encoded_by_;
+  std::string genre_;
+  std::string language_;
+  std::string title_;
+  int track_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioVideoMetadataExtractor);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_AUDIO_VIDEO_METADATA_EXTRACTOR_H_