media/filters/audio_file_reader.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_FILTERS_AUDIO_FILE_READER_H_
   6 #define MEDIA_FILTERS_AUDIO_FILE_READER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "media/base/media_export.h"
  11 #include "media/filters/ffmpeg_glue.h"
  12
  13 struct AVCodecContext;
  14 struct AVPacket;
  15 struct AVStream;
  16
  17 namespace base { class TimeDelta; }
  18
  19 namespace media {
  20
  21 class AudioBus;
  22 class FFmpegURLProtocol;
  23
  24 class MEDIA_EXPORT AudioFileReader {
  25  public:
  26   // Audio file data will be read using the given protocol.
  27   // The AudioFileReader does not take ownership of |protocol| and
  28   // simply maintains a weak reference to it.
  29   explicit AudioFileReader(FFmpegURLProtocol* protocol);
  30   virtual ~AudioFileReader();
  31
  32   // Open() reads the audio data format so that the sample_rate(),
  33   // channels(), GetDuration(), and GetNumberOfFrames() methods can be called.
  34   // It returns |true| on success.
  35   bool Open();
  36   void Close();
  37
  38   // After a call to Open(), attempts to fully fill |audio_bus| with decoded
  39   // audio data.  Any unfilled frames will be zeroed out.
  40   // |audio_data| must be of the same size as channels().
  41   // The audio data will be decoded as floating-point linear PCM with
  42   // a nominal range of -1.0 -> +1.0.
  43   // Returns the number of sample-frames actually read which will always be
  44   // <= audio_bus->frames()
  45   int Read(AudioBus* audio_bus);
  46
  47   // These methods can be called once Open() has been called.
  48   int channels() const { return channels_; }
  49   int sample_rate() const { return sample_rate_; }
  50
  51   // Please note that GetDuration() and GetNumberOfFrames() attempt to be
  52   // accurate, but are only estimates.  For some encoded formats, the actual
  53   // duration of the file can only be determined once all the file data has been
  54   // read. The Read() method returns the actual number of sample-frames it has
  55   // read.
  56   base::TimeDelta GetDuration() const;
  57   int GetNumberOfFrames() const;
  58
  59   // The methods below are helper methods which allow AudioFileReader to double
  60   // as a test utility for demuxing audio files.
  61   // --------------------------------------------------------------------------
  62
  63   // Similar to Open() but does not initialize the decoder.
  64   bool OpenDemuxerForTesting();
  65
  66   // Returns true if a packet could be demuxed from the first audio stream in
  67   // the file, |output_packet| will contain the demuxed packet then.
  68   bool ReadPacketForTesting(AVPacket* output_packet);
  69
  70   // Seeks to the given point and returns true if successful.  |seek_time| will
  71   // be converted to the stream's time base automatically.
  72   bool SeekForTesting(base::TimeDelta seek_time);
  73
  74   const AVStream* GetAVStreamForTesting() const;
  75   const AVCodecContext* codec_context_for_testing() const {
  76     return codec_context_;
  77   }
  78
  79  private:
  80   bool OpenDemuxer();
  81   bool OpenDecoder();
  82   bool ReadPacket(AVPacket* output_packet);
  83
  84   scoped_ptr<FFmpegGlue> glue_;
  85   AVCodecContext* codec_context_;
  86   int stream_index_;
  87   FFmpegURLProtocol* protocol_;
  88   int channels_;
  89   int sample_rate_;
  90
  91   // AVSampleFormat initially requested; not Chrome's SampleFormat.
  92   int av_sample_format_;
  93
  94   DISALLOW_COPY_AND_ASSIGN(AudioFileReader);
  95 };
  96
  97 }  // namespace media
  98
  99 #endif  // MEDIA_FILTERS_AUDIO_FILE_READER_H_