Unable to achieve 30fps using 'read()' in C

Hi all, I am new in v4l programming. What I did in my code is I used 'read( )' in C programming to read images from my Logitech Quickcam Express. My problem is I can't get 30frames per second, what I got is just 5fps when I loop and read for 200times. Do anyone know why is it under performance? Thanks

Rgds,
nik2031

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Is your webcam is connected to a usb2 port(if it requires)?

Do lsusb

And dmesg | grep usb

dmesg | grep Logitech

which driver r u using for v4l2

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of wei kin
Sent: 28 novembre 2008 03:03
To: [email protected]
Subject: Unable to achieve 30fps using 'read()' in C

Hi all, I am new in v4l programming. What I did in my code is I used 'read( )' in C programming to read images from my Logitech Quickcam Express. My problem is I can't get 30frames per second, what I got is just 5fps when I loop and read for 200times. Do anyone know why is it under performance? Thanks

Rgds,
nik2031

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Wei,

You will only get half rate or worse using read() because there is no buffer queue for the frames. Please use streaming IO to get all of the frames that your device produces as in the API example:

http://www.linuxtv.org/downloads/video4linux/API/V4L2_API/spec/a16706.htm

Regards,
Jackson Yee
The Possum Company
540-818-4079
[email protected]

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