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 = 1,
  24   kCodecMP3 = 2,
  25   kCodecPCM = 3,
  26   kCodecVorbis = 4,
  27   kCodecFLAC = 5,
  28   kCodecAMR_NB = 6,
  29   kCodecAMR_WB = 7,
  30   kCodecPCM_MULAW = 8,
  31   kCodecGSM_MS = 9,
  32   kCodecPCM_S16BE = 10,
  33   kCodecPCM_S24BE = 11,
  34   kCodecOpus = 12,
  35   // kCodecEAC3 = 13,
  36   kCodecPCM_ALAW = 14,
  37   // DO NOT ADD RANDOM AUDIO CODECS!
  38   //
  39   // The only acceptable time to add a new codec is if there is production code
  40   // that uses said codec in the same CL.
  41
  42   // Must always be last!
  43   kAudioCodecMax
  44 };
  45
  46 // TODO(dalecurtis): FFmpeg API uses |bytes_per_channel| instead of
  47 // |bits_per_channel|, we should switch over since bits are generally confusing
  48 // to work with.
  49 class MEDIA_EXPORT AudioDecoderConfig {
  50  public:
  51   // Constructs an uninitialized object. Clients should call Initialize() with
  52   // appropriate values before using.
  53   AudioDecoderConfig();
  54
  55   // Constructs an initialized object. It is acceptable to pass in NULL for
  56   // |extra_data|, otherwise the memory is copied.
  57   AudioDecoderConfig(AudioCodec codec, SampleFormat sample_format,
  58                      ChannelLayout channel_layout, int samples_per_second,
  59                      const uint8* extra_data, size_t extra_data_size,
  60                      bool is_encrypted);
  61
  62   ~AudioDecoderConfig();
  63
  64   // Resets the internal state of this object.
  65   void Initialize(AudioCodec codec, SampleFormat sample_format,
  66                   ChannelLayout channel_layout, int samples_per_second,
  67                   const uint8* extra_data, size_t extra_data_size,
  68                   bool is_encrypted, bool record_stats,
  69                   base::TimeDelta seek_preroll,
  70                   base::TimeDelta codec_delay);
  71
  72   // Returns true if this object has appropriate configuration values, false
  73   // otherwise.
  74   bool IsValidConfig() const;
  75
  76   // Returns true if all fields in |config| match this config.
  77   // Note: The contents of |extra_data_| are compared not the raw pointers.
  78   bool Matches(const AudioDecoderConfig& config) const;
  79
  80   AudioCodec codec() const { return codec_; }
  81   int bits_per_channel() const { return bytes_per_channel_ * 8; }
  82   int bytes_per_channel() const { return bytes_per_channel_; }
  83   ChannelLayout channel_layout() const { return channel_layout_; }
  84   int samples_per_second() const { return samples_per_second_; }
  85   SampleFormat sample_format() const { return sample_format_; }
  86   int bytes_per_frame() const { return bytes_per_frame_; }
  87   base::TimeDelta seek_preroll() const { return seek_preroll_; }
  88   base::TimeDelta codec_delay() const { return codec_delay_; }
  89
  90   // Optional byte data required to initialize audio decoders such as Vorbis
  91   // codebooks.
  92   const uint8* extra_data() const {
  93     return extra_data_.empty() ? NULL : &extra_data_[0];
  94   }
  95   size_t extra_data_size() const { return extra_data_.size(); }
  96
  97   // Whether the audio stream is potentially encrypted.
  98   // Note that in a potentially encrypted audio stream, individual buffers
  99   // can be encrypted or not encrypted.
 100   bool is_encrypted() const { return is_encrypted_; }
 101
 102  private:
 103   AudioCodec codec_;
 104   SampleFormat sample_format_;
 105   int bytes_per_channel_;
 106   ChannelLayout channel_layout_;
 107   int samples_per_second_;
 108   int bytes_per_frame_;
 109   std::vector<uint8> extra_data_;
 110   bool is_encrypted_;
 111
 112   // |seek_preroll_| is the duration of the data that the decoder must decode
 113   // before the decoded data is valid.
 114   base::TimeDelta seek_preroll_;
 115
 116   // |codec_delay_| is the overall delay overhead added by the codec while
 117   // encoding. This value should be subtracted from each block's timestamp to
 118   // get the actual timestamp.
 119   base::TimeDelta codec_delay_;
 120
 121   // Not using DISALLOW_COPY_AND_ASSIGN here intentionally to allow the compiler
 122   // generated copy constructor and assignment operator. Since the extra data is
 123   // typically small, the performance impact is minimal.
 124 };
 125
 126 }  // namespace media
 127
 128 #endif  // MEDIA_BASE_AUDIO_DECODER_CONFIG_H_