BStreamingGameSound

Derived from: BGameSound
Declared in:  be/game/StreamingGameSound.h
Library: libgame.so
Allocation: Constructor only
Summary:  more...

The BStreamingGameSound class provides the ability to stream audio data. A hook function is called whenever a buffer needs to be filled with audio data. This hook function is set by calling SetStreamHook().

Using this class requires special magic powers; unless you're directly in contact with Be about it, don't use it. You'll regret it later.

Constructor and Destructor

BStreamingGameSound()

BStreamingGameSound(size_t inBufferFrameCount,       const gs_audio_format *format,       size_t inBufferCount = 2,       BGameSoundDevice *device = NULL)

protected:

BStreamingGameSound(BGameSoundDevice device)

Prepares the object to play streamed audio. inBufferFrameCount specifies the number of frames each audio buffer should be able to hold. format indicates the audio format that will be streamed. inBufferCount specifies the number of buffers to use, and, as always, device is the sound device to use for playback.

Currently, device must always be NULL to indicate that the default playback device should be used.

By default, two audio buffers are used.

~BStreamingGameSound

virtual ~BStreamingGameSound()

Stops playing the sound.

Member Functions

FillBuffer()

virtual void FillBuffer(void *inBuffer, size_t byteCount)

Fills the buffer specified by inBuffer with byteCount bytes of audio data.

In the BStreamingGameSound implemenation, this function calls the stream hook, if one exists.

See also: SetStreamHook()

InitCheck()

status_t InitCheck(void) const

Returns a status_t indicating whether or not the object was successfully instantiated.

RETURN CODES

• B_OK. The sound was successfully initialized.

• B_ERROR. Unable to create a sound player.

• Other errors. The sound player may return errors.

See also: the BStreamingGameSound constructor

Lock() , Unlock()

bool Lock(void) void Unlock(void)

Lock() locks the BStreamingGameSound to prevent unpleasant collisions in the land of multithreadedness; it returns true if it was able to lock the object, otherwise false is returned. Unlock() releases the lock.

SetAttributes()

virtual status_t SetAttributes(gs_attribute *inAttributes, size_t inAttributeCount)

SetAttributes() is implemented to disallow the B_GS_LOOPING attribute, since streamed sounds can't loop.

See also: BGameSound::SetAttributes()

SetParameters()

protected:

virtual status_t SetParameters(size_t inBufferFrameCount,       const gs_audio_format *format,       size_t inBufferCount)

Changes the BStreamingGameSound object's parameters. This lets you change the buffer size, audio format, and number of buffers after the object has been instantiated.

RETURN CODES

• B_OK. No error.

• B_ERROR. Couldn't change the parameters.

SetStreamHook()

virtual status_t SetStreamHook(void (*hook)(void *cookie, void *inBuffer,       size_t byteCount, BStreamingGameSound *object),       void *cookie)

Specfies the hook function to be called to fill buffers with audio data. cookie indicates the cookie pointer that will be passed to the hook function.

The inputs to the hook function are:

• cookie
  A user-defined value.

• inBuffer
  A pointer to the buffer to be filled with audio data.

• byteCount
  The size of the buffer in bytes.

• object
  A pointer to the BStreamingGameSound object.

RETURN CODES

• B_OK. The hook function was set without error.

Unlock() see Lock()