Hello Phil,
Thanks for your input. I will let you know if I can not find your earlier
posting.
I have wrote a sample application to open the "/dev/dsp" in a non blocking
operation and wrote the data and read the data sample of about 128 bytes
alternatively in a loop to test this scenario. So there was no 'ticking' but
read and write in an alternate fashion.
With best regards,
Venkat.
--
From: [EMAIL PROTECTED] [EMAIL PROTECTED] On Behalf Of Phil Quiney [EMAIL
PROTECTED]
Sent: Tuesday, December 02, 2008 9:25 PM
To: Venkatachala Upadhya
Cc: davinci-linux-open-source@linux.davincidsp.com
Subject: Re: Using /dev/dsp to record and playback simultaneously
Hi,
The audio driver on the DM6446 is capable of full duplex operation. The
only issue really is that it is stereo only regardless of the ioctl that
sets the number of channels.
If you search the Davinci mail list you should find some simple test
programs that I posted a while back that can be used to demonstrate the
audio capability. If you can't find them then let me know and I will see
if I can dig them out again.
The 'garbled' voice could be a symptom of under/overrunning, that is
your application has not written enough data in one go to keep the
output buffer full of enough data till the next write. Similarly on the
read, if you do not empty the input buffer it will fill up and then drop
input.
You did not describe how your application 'ticks' to perform the
non-blocking operation...you can use SIGALRM to interrupt a select for
example (or 'nanosleep' in a loop). You can use the ioctl to check for
samples before the read and similarly the output space ioctl before the
write. This will prevent the read or write blocking as you simply skip
the read or write if no data or space for data is present.
Regards
Phil Q
Venkatachala Upadhya wrote:
>Hello all,
>
>I am using DM6446 EVM board. Using DVSDK 1.20.00.10 version. Running gstreamer
>on the board. I am trying to use the device "/dev/dsp" for both recoding and
>playback simultaneously. I am un-able to do so after setting the device to
>full-duplex mode using the ioctl call "ioctl(soundFd, SNDCTL_DSP_SETDUPLEX );"
>
>If I use the device in non-blocking mode for recording and playback I am
>getting the voicce as garbled. Is "recording and playback simultaneously"
>possible?
>Can any one share the experience?
>
>With best regards,
>Venkat.
>--
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