BPushGameSound

Constructor and Destructor

BPushGameSound()

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

Prepares the object to play audio pushed by your application. 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.

Note

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

By default, two audio buffers are used.

Be sure to call InitCheck() before using the BPushGameSound object.

~BPushGameSound()

virtual BPushGameSound::~BPushGameSound()

Deletes the semaphore used to lock the object.

Member Functions

InitCheck()

status_t BPushGameSound::InitCheck() const

Returns a status_t indicating whether or not the object was successfully initialized. A return value of B_OK means everything’s fine; any other value means an error occurred in the constructor.

LockForCyclic(), UnlockCyclic(), CurrentPosition()

virtual lock_status BPushGameSound::LockForCyclic(void **outBasePtr, size_t *outSize)

virtual status_t BPushGameSound::UnlockCyclic()

virtual size_t BPushGameSound::CurrentPosition()

LockForCyclic() gives you access to the entire sound buffer; audio playback continues while you have access. Use CurrentPosition() to determine where the playback is currently located in the buffer area, and be sure to stay well ahead of it. See the overview for a more in-depth discussion. If lock_failed is returned, you can’t access the audio area, but if lock_ok is returned, you can start pushing audio.

On return, outBasePtr points to the first byte of the audio buffer area, and outSize indicates the total size of the audio buffer area.

UnlockCyclic() releases the audio area.

Return Code	Description
B_OK.	UnlockCyclic() succeeded.

LockNextPage(), UnlockPage()

virtual lock_status BPushGameSound::LockNextPage(void **outPagePtr, size_t *outPageSize)

virtual status_t BPushGameSound::UnlockPage(void *inPagePtr)

LockNextPage() requests access to the next page of the sound buffer. The lock_status return value is lock_ok or lock_ok_frames_dropped if a valid page has been returned. If either of these values is returned, you can then write up to outPageSize bytes of audio data into the audio page returned in outPagePtr.

If lock_failed is returned, you can’t access an audio page.

UnlockPage() releases the audio page pointed to by inPagePtr and returns B_OK if it succeeds in unlocking the page.

Constants

lock_status

Constant	Description
lock_failed	Couldn’t get the lock; it’s not time to update yet.
lock_ok	Locked; you can update.
lock_ok_frames_dropped	Locked; you can update, but you may have missed some buffers.

These values are returned by the locking functions in the BPushGameSound class ( LockNextPage() and LockForCyclic()). If either function returns lock_failed, there isn’t a buffer to be filled; your code is pushing buffers too fast.

If lock_ok is returned, the next buffer is ready. The lock_ok_frames_dropped result is received if a buffer is available but some buffers have been lost; this can happen if you’re not pushing fast enough.