waveOutSetPlaybackRate

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).