content/media/nsAudioStream.h
author Matheus Kerschbaum <matjk7@gmail.com>
Sat, 02 Apr 2011 19:14:00 -0700
changeset 67579 70cedf3a3327ce6cbb671a061dad6d94b2723b4e
parent 64570 c1553501c4966df32d22dcd117532d62bdfe9731
child 68335 f548e43998be6a1bfb24245b8dc03c559150c0d3
permissions -rw-r--r--
Bug 639754 - Remove MOZ_IPC checks since IPC is always built now; r=bsmedberg

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
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 * 1.1 (the "License"); you may not use this file except in compliance with
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 * Contributor(s):
 *  Chris Double <chris.double@double.co.nz>
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#if !defined(nsAudioStream_h_)
#define nsAudioStream_h_

#include "nscore.h"
#include "nsISupportsImpl.h"
#include "nsIThread.h"
#include "nsAutoPtr.h"

class nsAudioStream : public nsISupports
{
public:

  enum SampleFormat
  {
    FORMAT_U8,
    FORMAT_S16_LE,
    FORMAT_FLOAT32
  };

  virtual ~nsAudioStream();

  // 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();

  // Thread that is shared between audio streams.
  // This may return null in the child process
  nsIThread *GetThread();

  // AllocateStream will return either a local stream or a remoted stream
  // depending on where you call it from.  If you call this from a child process,
  // you may receive an implementation which forwards to a compositing process.
  static nsAudioStream* AllocateStream();

  // 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).
  virtual nsresult Init(PRInt32 aNumChannels, PRInt32 aRate, SampleFormat aFormat) = 0;

  // Closes the stream. All future use of the stream is an error.
  virtual void Shutdown() = 0;

  // 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.
  // When aBlocking is PR_TRUE, we'll block until the write has completed,
  // otherwise we'll buffer any data we can't write immediately, and write
  // it in a later call.
  virtual nsresult Write(const void* aBuf, PRUint32 aCount, PRBool aBlocking) = 0;

  // Return the number of sound samples that can be written to the audio device
  // without blocking.
  virtual PRUint32 Available() = 0;

  // Set the current volume of the audio playback. This is a value from
  // 0 (meaning muted) to 1 (meaning full volume).
  virtual void SetVolume(double aVolume) = 0;

  // Block until buffered audio data has been consumed.
  virtual void Drain() = 0;

  // Pause audio playback
  virtual void Pause() = 0;

  // Resume audio playback
  virtual void Resume() = 0;

  // Return the position in milliseconds of the sample being played by the
  // audio hardware.
  virtual PRInt64 GetPosition() = 0;

  // Return the position, measured in samples played since the start, by
  // the audio hardware.
  virtual PRInt64 GetSampleOffset() = 0;

  // Returns PR_TRUE when the audio stream is paused.
  virtual PRBool IsPaused() = 0;

  // Returns the minimum number of samples which must be written before
  // you can be sure that something will be played.
  virtual PRInt32 GetMinWriteSamples() = 0;

protected:
  nsCOMPtr<nsIThread> mAudioPlaybackThread;
};

#endif