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      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   // DO NOT ADD RANDOM AUDIO CODECS!
     40   //
     41   // The only acceptable time to add a new codec is if there is production code
     42   // that uses said codec in the same CL.
     43 
     44   // Must always be equal to the largest entry ever logged.
     45   kAudioCodecMax = kCodecPCM_ALAW,
     46 };
     47 
     48 // TODO(dalecurtis): FFmpeg API uses |bytes_per_channel| instead of
     49 // |bits_per_channel|, we should switch over since bits are generally confusing
     50 // to work with.
     51 class MEDIA_EXPORT AudioDecoderConfig {
     52  public:
     53   // Constructs an uninitialized object. Clients should call Initialize() with
     54   // appropriate values before using.
     55   AudioDecoderConfig();
     56 
     57   // Constructs an initialized object. It is acceptable to pass in NULL for
     58   // |extra_data|, otherwise the memory is copied.
     59   AudioDecoderConfig(AudioCodec codec, SampleFormat sample_format,
     60                      ChannelLayout channel_layout, int samples_per_second,
     61                      const uint8* extra_data, size_t extra_data_size,
     62                      bool is_encrypted);
     63 
     64   ~AudioDecoderConfig();
     65 
     66   // Resets the internal state of this object.  |codec_delay| is in frames.
     67   void Initialize(AudioCodec codec, SampleFormat sample_format,
     68                   ChannelLayout channel_layout, int samples_per_second,
     69                   const uint8* extra_data, size_t extra_data_size,
     70                   bool is_encrypted, bool record_stats,
     71                   base::TimeDelta seek_preroll,
     72                   int codec_delay);
     73 
     74   // Returns true if this object has appropriate configuration values, false
     75   // otherwise.
     76   bool IsValidConfig() const;
     77 
     78   // Returns true if all fields in |config| match this config.
     79   // Note: The contents of |extra_data_| are compared not the raw pointers.
     80   bool Matches(const AudioDecoderConfig& config) const;
     81 
     82   // Returns a human-readable string describing |*this|.  For debugging & test
     83   // output only.
     84   std::string AsHumanReadableString() const;
     85 
     86   AudioCodec codec() const { return codec_; }
     87   int bits_per_channel() const { return bytes_per_channel_ * 8; }
     88   int bytes_per_channel() const { return bytes_per_channel_; }
     89   ChannelLayout channel_layout() const { return channel_layout_; }
     90   int samples_per_second() const { return samples_per_second_; }
     91   SampleFormat sample_format() const { return sample_format_; }
     92   int bytes_per_frame() const { return bytes_per_frame_; }
     93   base::TimeDelta seek_preroll() const { return seek_preroll_; }
     94   int codec_delay() const { return codec_delay_; }
     95 
     96   // Optional byte data required to initialize audio decoders such as Vorbis
     97   // codebooks.
     98   const uint8* extra_data() const {
     99     return extra_data_.empty() ? NULL : &extra_data_[0];
    100   }
    101   size_t extra_data_size() const { return extra_data_.size(); }
    102 
    103   // Whether the audio stream is potentially encrypted.
    104   // Note that in a potentially encrypted audio stream, individual buffers
    105   // can be encrypted or not encrypted.
    106   bool is_encrypted() const { return is_encrypted_; }
    107 
    108  private:
    109   AudioCodec codec_;
    110   SampleFormat sample_format_;
    111   int bytes_per_channel_;
    112   ChannelLayout channel_layout_;
    113   int samples_per_second_;
    114   int bytes_per_frame_;
    115   std::vector<uint8> extra_data_;
    116   bool is_encrypted_;
    117 
    118   // |seek_preroll_| is the duration of the data that the decoder must decode
    119   // before the decoded data is valid.
    120   base::TimeDelta seek_preroll_;
    121 
    122   // |codec_delay_| is the number of frames the decoder should discard before
    123   // returning decoded data.  This value can include both decoder delay as well
    124   // as padding added during encoding.
    125   int codec_delay_;
    126 
    127   // Not using DISALLOW_COPY_AND_ASSIGN here intentionally to allow the compiler
    128   // generated copy constructor and assignment operator. Since the extra data is
    129   // typically small, the performance impact is minimal.
    130 };
    131 
    132 }  // namespace media
    133 
    134 #endif  // MEDIA_BASE_AUDIO_DECODER_CONFIG_H_
    135