[wdmaudiodev] Delay between record and play (10 ms) in Vista

From: Chinmay Mahata <chinmay.mahata@xxxxxxxxx>
To: wdmaudiodev <wdmaudiodev@xxxxxxxxxxxxx>
Date: Mon, 9 Feb 2009 15:11:33 +0530

Dear All,

During simultaneous play and record in windows Vista with our driver and
application we found that record device starts before the play device. And
the difference is 10 millisecond, which is significant for our
application. (In XP, this driver and application pair works fine with a
delay of only 1ms.)

Our driver is a WDM wavePci driver for Vista.

In application we did the follwoing steps.

OPEN AUDIO
OpenAuido(): WaveInOpen - Port1
OpenAuido(): WaveOutOpen - Port0

STOP AUDIO
StopPlay(): waveOutReset - Port 0
StopRecord(): waveInReset - Port 1
RESET AUDIO

StopPlay(): waveOutReset - Port 0

EnablePlay(): Prepared Header - Port 0
EnablePlay(): waveOutPause - Port 0
EnablePlay() waveOutWrite - Port 0
EnablePlay(): waveOutPause - Port 0

EnableRecord(): waveInStop() - Port 1
EnableRecord(): Prepared Header - Port 1
EnableRecord(): waveInAddBuffer - Port 1

START AUDIO
RestartPlay(): waveOutRestart - Port 0
StartRecord(): waveInStart - Port 1

*DeviceControl DSP_StartAll    // Our driver does not start DSP at RUN
state.
                              // So we start the DSP using this IOCTL to
ensure
                              // all open device start play and record at
the same time.
*
OnPlayComplete(): waveOutUnprepareHeader - Port 0
OnPlayComplete(): waveOutReset - Port 0
OnRecordComplete(): waveInUnprepareHeader - Port 1

OnRecordComplete(): waveInReset - Port 1
OnRecordComplete(): waveInStop - Port 1

StopPlay(): waveOutReset - Port 0


We are completely in dark why the delay or who is causing the delay.
Can anyone please let us know how we can remove or minimize the delay of
10ms?

Thanks in advance.

Best regards,
--Chinmay

[wdmaudiodev] Delay between record and play (10 ms) in Vista

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