content/media/video/public/nsAudioStream.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   3 /* ***** BEGIN LICENSE BLOCK *****
   4  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   5  *
   6  * The contents of this file are subject to the Mozilla Public License Version
   7  * 1.1 (the "License"); you may not use this file except in compliance with
   8  * the License. You may obtain a copy of the License at
   9  * http://www.mozilla.org/MPL/
  10  *
  11  * Software distributed under the License is distributed on an "AS IS" basis,
  12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  13  * for the specific language governing rights and limitations under the
  14  * License.
  15  *
  16  * The Original Code is Mozilla code.
  17  *
  18  * The Initial Developer of the Original Code is the Mozilla Corporation.
  19  * Portions created by the Initial Developer are Copyright (C) 2007
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *  Chris Double <chris.double@double.co.nz>
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * either the GNU General Public License Version 2 or later (the "GPL"), or
  27  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  28  * in which case the provisions of the GPL or the LGPL are applicable instead
  29  * of those above. If you wish to allow use of your version of this file only
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  34  * the provisions above, a recipient may use your version of this file under
  35  * the terms of any one of the MPL, the GPL or the LGPL.
  36  *
  37  * ***** END LICENSE BLOCK ***** */
  38 #if !defined(nsAudioStream_h_)
  39 #define nsAudioStream_h_
  40
  41 #include "nscore.h"
  42 #include "prlog.h"
  43 #include "nsTArray.h"
  44
  45 extern PRLogModuleInfo* gAudioStreamLog;
  46
  47 class nsAudioStream
  48 {
  49  public:
  50   enum SampleFormat
  51   {
  52     FORMAT_U8,
  53     FORMAT_S16_LE,
  54     FORMAT_FLOAT32_LE
  55   };
  56
  57   // Initialize Audio Library. Some Audio backends require initializing the
  58   // library before using it.
  59   static void InitLibrary();
  60
  61   // Shutdown Audio Library. Some Audio backends require shutting down the
  62   // library after using it.
  63   static void ShutdownLibrary();
  64
  65   nsAudioStream();
  66
  67   // Initialize the audio stream. aNumChannels is the number of audio channels
  68   // (1 for mono, 2 for stereo, etc) and aRate is the frequency of the sound
  69   // samples (22050, 44100, etc).
  70   void Init(PRInt32 aNumChannels, PRInt32 aRate, SampleFormat aFormat);
  71
  72   // Closes the stream. All future use of the stream is an error.
  73   void Shutdown();
  74
  75   // Write sound data to the audio hardware.  aBuf is an array of samples in
  76   // the format specified by mFormat of length aCount.  aCount should be
  77   // evenly divisible by the number of channels in this audio stream.
  78   void Write(const void* aBuf, PRUint32 aCount);
  79
  80   // Return the number of sound samples that can be written to the audio device
  81   // without blocking.
  82   PRInt32 Available();
  83
  84   // Store in aVolume the value of the volume setting. This is a value from
  85   // 0 (meaning muted) to 1 (meaning full volume).
  86   float GetVolume();
  87
  88   // Set the current volume of the audio playback. This is a value from
  89   // 0 (meaning muted) to 1 (meaning full volume).
  90   void SetVolume(float aVolume);
  91
  92   // Block until buffered audio data has been consumed.
  93   void Drain();
  94
  95   // Pause sound playback.
  96   void Pause();
  97
  98   // Resume sound playback.
  99   void Resume();
 100
 101   // Return the position (in seconds) of the audio sample currently being
 102   // played by the audio hardware.
 103   double GetTime();
 104
 105  private:
 106   double mVolume;
 107   void* mAudioHandle;
 108   int mRate;
 109   int mChannels;
 110
 111   // The byte position in the audio buffer where playback was last paused.
 112   PRInt64 mSavedPauseBytes;
 113   PRInt64 mPauseBytes;
 114
 115   float mStartTime;
 116   float mPauseTime;
 117   PRInt64 mSamplesBuffered;
 118
 119   SampleFormat mFormat;
 120
 121   // When a Write() request is made, and the number of samples
 122   // requested to be written exceeds the buffer size of the audio
 123   // backend, the remaining samples are stored in this variable. They
 124   // will be written on the next Write() request.
 125   nsTArray<short> mBufferOverflow;
 126
 127   PRPackedBool mPaused;
 128 };
 129 #endif