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 <string>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/time/time.h"
  13 #include "media/base/channel_layout.h"
  14 #include "media/base/media_export.h"
  15 #include "media/base/sample_format.h"
  16
  17 namespace media {
  18
  19 enum AudioCodec {
  20   // These values are histogrammed over time; do not change their ordinal
  21   // values.  When deleting a codec replace it with a dummy value; when adding a
  22   // codec, do so at the bottom before kAudioCodecMax, and update the value of
  23   // kAudioCodecMax to equal the new codec.
  24   kUnknownAudioCodec = 0,
  25   kCodecAAC = 1,
  26   kCodecMP3 = 2,
  27   kCodecPCM = 3,
  28   kCodecVorbis = 4,
  29   kCodecFLAC = 5,
  30   kCodecAMR_NB = 6,
  31   kCodecAMR_WB = 7,
  32   kCodecPCM_MULAW = 8,
  33   kCodecGSM_MS = 9,
  34   kCodecPCM_S16BE = 10,
  35   kCodecPCM_S24BE = 11,
  36   kCodecOpus = 12,
  37   // kCodecEAC3 = 13,
  38   kCodecPCM_ALAW = 14,
  39   kCodecALAC = 15,
  40   // DO NOT ADD RANDOM AUDIO CODECS!
  41   //
  42   // The only acceptable time to add a new codec is if there is production code
  43   // that uses said codec in the same CL.
  44
  45   // Must always be equal to the largest entry ever logged.
  46   kAudioCodecMax = kCodecALAC,
  47 };
  48
  49 // TODO(dalecurtis): FFmpeg API uses |bytes_per_channel| instead of
  50 // |bits_per_channel|, we should switch over since bits are generally confusing
  51 // to work with.
  52 class MEDIA_EXPORT AudioDecoderConfig {
  53  public:
  54   // Constructs an uninitialized object. Clients should call Initialize() with
  55   // appropriate values before using.
  56   AudioDecoderConfig();
  57
  58   // Constructs an initialized object. It is acceptable to pass in NULL for
  59   // |extra_data|, otherwise the memory is copied.
  60   AudioDecoderConfig(AudioCodec codec, SampleFormat sample_format,
  61                      ChannelLayout channel_layout, int samples_per_second,
  62                      const uint8* extra_data, size_t extra_data_size,
  63                      bool is_encrypted);
  64
  65   ~AudioDecoderConfig();
  66
  67   // Resets the internal state of this object.  |codec_delay| is in frames.
  68   void Initialize(AudioCodec codec,
  69                   SampleFormat sample_format,
  70                   ChannelLayout channel_layout,
  71                   int samples_per_second,
  72                   const uint8* extra_data,
  73                   size_t extra_data_size,
  74                   bool is_encrypted,
  75                   base::TimeDelta seek_preroll,
  76                   int codec_delay);
  77
  78   // Returns true if this object has appropriate configuration values, false
  79   // otherwise.
  80   bool IsValidConfig() const;
  81
  82   // Returns true if all fields in |config| match this config.
  83   // Note: The contents of |extra_data_| are compared not the raw pointers.
  84   bool Matches(const AudioDecoderConfig& config) const;
  85
  86   // Returns a human-readable string describing |*this|.  For debugging & test
  87   // output only.
  88   std::string AsHumanReadableString() const;
  89
  90   std::string GetHumanReadableCodecName() const;
  91
  92   AudioCodec codec() const { return codec_; }
  93   int bits_per_channel() const { return bytes_per_channel_ * 8; }
  94   int bytes_per_channel() const { return bytes_per_channel_; }
  95   ChannelLayout channel_layout() const { return channel_layout_; }
  96   int samples_per_second() const { return samples_per_second_; }
  97   SampleFormat sample_format() const { return sample_format_; }
  98   int bytes_per_frame() const { return bytes_per_frame_; }
  99   base::TimeDelta seek_preroll() const { return seek_preroll_; }
 100   int codec_delay() const { return codec_delay_; }
 101
 102   // Optional byte data required to initialize audio decoders such as Vorbis
 103   // codebooks.
 104   const uint8* extra_data() const {
 105     return extra_data_.empty() ? NULL : &extra_data_[0];
 106   }
 107   size_t extra_data_size() const { return extra_data_.size(); }
 108
 109   // Whether the audio stream is potentially encrypted.
 110   // Note that in a potentially encrypted audio stream, individual buffers
 111   // can be encrypted or not encrypted.
 112   bool is_encrypted() const { return is_encrypted_; }
 113
 114  private:
 115   AudioCodec codec_;
 116   SampleFormat sample_format_;
 117   int bytes_per_channel_;
 118   ChannelLayout channel_layout_;
 119   int samples_per_second_;
 120   int bytes_per_frame_;
 121   std::vector<uint8> extra_data_;
 122   bool is_encrypted_;
 123
 124   // |seek_preroll_| is the duration of the data that the decoder must decode
 125   // before the decoded data is valid.
 126   base::TimeDelta seek_preroll_;
 127
 128   // |codec_delay_| is the number of frames the decoder should discard before
 129   // returning decoded data.  This value can include both decoder delay as well
 130   // as padding added during encoding.
 131   int codec_delay_;
 132
 133   // Not using DISALLOW_COPY_AND_ASSIGN here intentionally to allow the compiler
 134   // generated copy constructor and assignment operator. Since the extra data is
 135   // typically small, the performance impact is minimal.
 136 };
 137
 138 }  // namespace media
 139
 140 #endif  // MEDIA_BASE_AUDIO_DECODER_CONFIG_H_