gecko-dev/content/media/nsAudioStream.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla code.
*
* The Initial Developer of the Original Code is the Mozilla Corporation.
* Portions created by the Initial Developer are Copyright (C) 2007
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Chris Double <chris.double@double.co.nz>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#if !defined(nsAudioStream_h_)
#define nsAudioStream_h_
#include "nscore.h"
#include "prlog.h"
#include "nsTArray.h"
extern PRLogModuleInfo* gAudioStreamLog;
class nsAudioStream
{
public:
enum SampleFormat
{
FORMAT_U8,
FORMAT_S16_LE,
FORMAT_FLOAT32
};
// Initialize Audio Library. Some Audio backends require initializing the
// library before using it.
static void InitLibrary();
// Shutdown Audio Library. Some Audio backends require shutting down the
// library after using it.
static void ShutdownLibrary();
nsAudioStream();
~nsAudioStream();
// Initialize the audio stream. aNumChannels is the number of audio channels
// (1 for mono, 2 for stereo, etc) and aRate is the frequency of the sound
// samples (22050, 44100, etc).
void Init(PRInt32 aNumChannels, PRInt32 aRate, SampleFormat aFormat);
// Closes the stream. All future use of the stream is an error.
void Shutdown();
// Write sound data to the audio hardware. aBuf is an array of samples in
// the format specified by mFormat of length aCount. aCount should be
// evenly divisible by the number of channels in this audio stream.
void Write(const void* aBuf, PRUint32 aCount);
// Return the number of sound samples that can be written to the audio device
// without blocking.
PRInt32 Available();
// Set the current volume of the audio playback. This is a value from
// 0 (meaning muted) to 1 (meaning full volume).
void SetVolume(float aVolume);
// Block until buffered audio data has been consumed.
void Drain();
// Pause audio playback
void Pause();
// Resume audio playback
void Resume();
// Return the position in seconds of the sample being played by the
// audio hardware.
float GetPosition();
private:
double mVolume;
void* mAudioHandle;
int mRate;
int mChannels;
SampleFormat mFormat;
// When a Write() request is made, and the number of samples
// requested to be written exceeds the buffer size of the audio
// backend, the remaining samples are stored in this variable. They
// will be written on the next Write() request.
nsTArray<short> mBufferOverflow;
};
#endif