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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 <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   kCodecPCM_ALAW,
     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_
    129