This function sets the playback rate of a waveform output device.
At a Glance
| Header file: | Mmsystem.h |
| Windows CE versions: | 2.0 and later |
Syntax
MMRESULT waveOutSetPlaybackRate(HWAVEOUT hwo,
DWORD dwRate);
Parameters
hwo
Handle to the waveform-audio output device.
dwRate
Specifies a new playback rate setting. This setting is a multiplier indicating the current change in playback rate from the original authored setting. The playback rate multiplier must be a positive value.
The rate is specified as a fixed-point value. The high-order word contains the signed integer part of the number, and the low-order word contains the fractional part. A value of 0x8000 in the low-order word represents one-half, and 0x4000 represents one-quarter. For example, the value 0x00010000 specifies a multiplier of 1.0 (no playback rate change), and a value of 0x000F8000 specifies a multiplier of 15.5.
Return Values
One of the values described in the following table is returned.
| Value | Description |
| MMSYSERR_NOERROR | Success. |
| MMSYSERR_INVALHANDLE | Specified device handle is invalid. |
| MMSYSERR_NODRIVER | No device driver is present. |
| MMSYSERR_NOMEM | Unable to allocate or lock memory. |
| MMSYSERR_NOTSUPPORTED | Function is not supported. |
Remarks
Changing the playback rate does not change the sample rate but does change the playback time. Not all devices support playback rate changes. To determine whether a device supports playback rate changes, use the WAVECAPS_PLAYBACKRATE flag to test the dwSupport member of the WAVEOUTCAPS structure (filled by the waveOutGetDevCaps function).