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
  30  * under the terms of either the GPL or the LGPL, and not to allow others to
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  32  * decision by deleting the provisions above and replace them with the notice
  33  * and other provisions required by the GPL or the LGPL. If you do not delete
  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
  44 extern PRLogModuleInfo* gAudioStreamLog;
  45
  46 class nsAudioStream
  47 {
  48  public:
  49   enum SampleFormat
  50   {
  51     FORMAT_U8,
  52     FORMAT_S16_LE,
  53     FORMAT_FLOAT32_LE
  54   };
  55
  56   // Initialize Audio Library. Some Audio backends require initializing the
  57   // library before using it.
  58   static void InitLibrary();
  59
  60   // Shutdown Audio Library. Some Audio backends require shutting down the
  61   // library after using it.
  62   static void ShutdownLibrary();
  63
  64   nsAudioStream();
  65
  66   // Initialize the audio stream. aNumChannels is the number of audio channels
  67   // (1 for mono, 2 for stereo, etc) and aRate is the frequency of the sound
  68   // samples (22050, 44100, etc).
  69   void Init(PRInt32 aNumChannels, PRInt32 aRate, SampleFormat aFormat);
  70
  71   // Closes the stream. All future use of the stream is an error.
  72   void Shutdown();
  73
  74   // Write sound data to the audio hardware.  aBuf is an array of samples in
  75   // the format specified by mFormat of length aCount.  aCount should be
  76   // evenly divisible by the number of channels in this audio stream.
  77   void Write(const void* aBuf, PRUint32 aCount);
  78
  79   // Return the number of sound samples that can be written to the audio device
  80   // without blocking.
  81   PRInt32 Available();
  82
  83   // Store in aVolume the value of the volume setting. This is a value from
  84   // 0 (meaning muted) to 1 (meaning full volume).
  85   float GetVolume();
  86
  87   // Set the current volume of the audio playback. This is a value from
  88   // 0 (meaning muted) to 1 (meaning full volume).
  89   void SetVolume(float aVolume);
  90
  91   // Block until buffered audio data has been consumed.
  92   void Drain();
  93
  94   // Pause sound playback.
  95   void Pause();
  96
  97   // Resume sound playback.
  98   void Resume();
  99
 100   // Return the position (in seconds) of the audio sample currently being
 101   // played by the audio hardware.
 102   double GetTime();
 103
 104  private:
 105   double mVolume;
 106   void* mAudioHandle;
 107   int mRate;
 108   int mChannels;
 109
 110   // The byte position in the audio buffer where playback was last paused.
 111   PRInt64 mSavedPauseBytes;
 112   PRInt64 mPauseBytes;
 113
 114   float mStartTime;
 115   float mPauseTime;
 116   PRInt64 mSamplesBuffered;
 117
 118   SampleFormat mFormat;
 119
 120   PRPackedBool mPaused;
 121 };
 122 #endif