media/base/audio_decoder_config.h

   1 // Copyright (c) 2012 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_BASE_AUDIO_DECODER_CONFIG_H_
   6 #define MEDIA_BASE_AUDIO_DECODER_CONFIG_H_
   7
   8 #include <vector>
   9
  10 #include "base/basictypes.h"
  11 #include "base/time/time.h"
  12 #include "media/base/channel_layout.h"
  13 #include "media/base/media_export.h"
  14 #include "media/base/sample_format.h"
  15
  16 namespace media {
  17
  18 enum AudioCodec {
  19   // These values are histogrammed over time; do not change their ordinal
  20   // values.  When deleting a codec replace it with a dummy value; when adding a
  21   // codec, do so at the bottom before kAudioCodecMax.
  22   kUnknownAudioCodec = 0,
  23   kCodecAAC,
  24   kCodecMP3,
  25   kCodecPCM,
  26   kCodecVorbis,
  27   kCodecFLAC,
  28   kCodecAMR_NB,
  29   kCodecAMR_WB,
  30   kCodecPCM_MULAW,
  31   kCodecGSM_MS,
  32   kCodecPCM_S16BE,
  33   kCodecPCM_S24BE,
  34   kCodecOpus,
  35   kCodecEAC3,
  36   // DO NOT ADD RANDOM AUDIO CODECS!
  37   //
  38   // The only acceptable time to add a new codec is if there is production code
  39   // that uses said codec in the same CL.
  40
  41   // Must always be last!
  42   kAudioCodecMax
  43 };
  44
  45 // TODO(dalecurtis): FFmpeg API uses |bytes_per_channel| instead of
  46 // |bits_per_channel|, we should switch over since bits are generally confusing
  47 // to work with.
  48 class MEDIA_EXPORT AudioDecoderConfig {
  49  public:
  50   // Constructs an uninitialized object. Clients should call Initialize() with
  51   // appropriate values before using.
  52   AudioDecoderConfig();
  53
  54   // Constructs an initialized object. It is acceptable to pass in NULL for
  55   // |extra_data|, otherwise the memory is copied.
  56   AudioDecoderConfig(AudioCodec codec, SampleFormat sample_format,
  57                      ChannelLayout channel_layout, int samples_per_second,
  58                      const uint8* extra_data, size_t extra_data_size,
  59                      bool is_encrypted);
  60
  61   ~AudioDecoderConfig();
  62
  63   // Resets the internal state of this object.
  64   void Initialize(AudioCodec codec, SampleFormat sample_format,
  65                   ChannelLayout channel_layout, int samples_per_second,
  66                   const uint8* extra_data, size_t extra_data_size,
  67                   bool is_encrypted, bool record_stats,
  68                   base::TimeDelta seek_preroll,
  69                   base::TimeDelta codec_delay);
  70
  71   // Returns true if this object has appropriate configuration values, false
  72   // otherwise.
  73   bool IsValidConfig() const;
  74
  75   // Returns true if all fields in |config| match this config.
  76   // Note: The contents of |extra_data_| are compared not the raw pointers.
  77   bool Matches(const AudioDecoderConfig& config) const;
  78
  79   AudioCodec codec() const { return codec_; }
  80   int bits_per_channel() const { return bytes_per_channel_ * 8; }
  81   int bytes_per_channel() const { return bytes_per_channel_; }
  82   ChannelLayout channel_layout() const { return channel_layout_; }
  83   int samples_per_second() const { return samples_per_second_; }
  84   SampleFormat sample_format() const { return sample_format_; }
  85   int bytes_per_frame() const { return bytes_per_frame_; }
  86   base::TimeDelta seek_preroll() const { return seek_preroll_; }
  87   base::TimeDelta codec_delay() const { return codec_delay_; }
  88
  89   // Optional byte data required to initialize audio decoders such as Vorbis
  90   // codebooks.
  91   const uint8* extra_data() const {
  92     return extra_data_.empty() ? NULL : &extra_data_[0];
  93   }
  94   size_t extra_data_size() const { return extra_data_.size(); }
  95
  96   // Whether the audio stream is potentially encrypted.
  97   // Note that in a potentially encrypted audio stream, individual buffers
  98   // can be encrypted or not encrypted.
  99   bool is_encrypted() const { return is_encrypted_; }
 100
 101  private:
 102   AudioCodec codec_;
 103   SampleFormat sample_format_;
 104   int bytes_per_channel_;
 105   ChannelLayout channel_layout_;
 106   int samples_per_second_;
 107   int bytes_per_frame_;
 108   std::vector<uint8> extra_data_;
 109   bool is_encrypted_;
 110
 111   // |seek_preroll_| is the duration of the data that the decoder must decode
 112   // before the decoded data is valid.
 113   base::TimeDelta seek_preroll_;
 114
 115   // |codec_delay_| is the overall delay overhead added by the codec while
 116   // encoding. This value should be subtracted from each block's timestamp to
 117   // get the actual timestamp.
 118   base::TimeDelta codec_delay_;
 119
 120   // Not using DISALLOW_COPY_AND_ASSIGN here intentionally to allow the compiler
 121   // generated copy constructor and assignment operator. Since the extra data is
 122   // typically small, the performance impact is minimal.
 123 };
 124
 125 }  // namespace media
 126
 127 #endif  // MEDIA_BASE_AUDIO_DECODER_CONFIG_H_