content/media/video/public/nsAudioStream.h

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   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
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  34  * the provisions above, a recipient may use your version of this file under
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  36  *
  37  * ***** END LICENSE BLOCK ***** */
  38 #include "nscore.h"
  39 #include "prlog.h"
  40
  41 extern PRLogModuleInfo* gAudioStreamLog;
  42
  43 class nsAudioStream
  44 {
  45  public:
  46   // Initialize Audio Library. Some Audio backends (eg. PortAudio) require initializing
  47   // library before using it.
  48   static nsresult InitLibrary();
  49
  50   // Shutdown Audio Library. Some Audio backends (eg. PortAudio) require shutting down
  51   // the library after using it.
  52   static void ShutdownLibrary();
  53
  54   nsAudioStream();
  55
  56   // Initialize the audio stream. aNumChannels is the number of audio channels
  57   // (1 for mono, 2 for stereo, etc) and aRate is the frequency of the sound
  58   // samples (22050, 44100, etc).
  59   nsresult Init(PRInt32 aNumChannels, PRInt32 aRate);
  60
  61   // Closes the stream. All future use of the stream is an error.
  62   nsresult Shutdown();
  63
  64   // Pause sound playback.
  65   nsresult Pause();
  66
  67   // Resume playback of sound.
  68   nsresult Resume();
  69
  70   // Write sound data to the audio hardware. aBuf is an array of floats of
  71   // length aCount. aCount should be evenly divisible by the number of
  72   // channels in this audio stream.
  73   nsresult Write(float* aBuf, PRUint32 count);
  74
  75   // Store in aTime the position (in seconds) of the audio sample currently
  76   // being played by the audio hardware.
  77   nsresult GetTime(double* aTime);
  78
  79   // Store in aVolume the value of the volume setting. This is a value from
  80   // 0 (meaning muted) to 1 (meaning full volume).
  81   nsresult GetVolume(float* aVolume);
  82
  83   // Set the current volume of the audio playback. This is a value from
  84   // 0 (meaning muted) to 1 (meaning full volume).
  85   nsresult SetVolume(float aVolume);
  86
  87  private:
  88   double mVolume;
  89 #if defined(SYDNEY_AUDIO_NO_POSITION)
  90   // The time, in seconds, that playback was last paused.
  91   double mPauseTime;
  92 #else
  93   // The byte position in the audio buffer where playback
  94   // was last paused.
  95   PRInt64 mPauseBytes;
  96 #endif
  97   void* mAudioHandle;
  98   int mRate;
  99   int mChannels;
 100   PRBool mPaused;
 101 };