v4l2 on Meego tablet

v4l2 on Meego tablet

hi!all: I've create a video capture program with v4l2 in QtCreator(in Windows) But I got a strange problem with Meego tablet version. When I test my program with Meego netbook , it works well. But when I test it on another Meego tablet, the video shows few seconds then whole screen become black. But the program is still working in background. I did some printout to make sure that. It works in background ,just the display is gone. I try to use setActiveWindows in my code, didn't help. It seems related to video capturing. If I remove the video capturing part, the strange problem won't happen since the program is almost a empty program after the removement. Does anyone has the same experience ? Any comments is welcome. Thanks!
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Hi Stone:

Can you tell me the resolution of your video and also what codec are you using (video & audio)?

Do you know how to pull data out of /var/log/messages? If so, can you exit out of your program after the blank screen and see if you can pull out the last 300 lines of /var/log/messages to see if there are anything interesting (on the tablet)?



Dear Vincent:

Sorry for late reply.
I set the video format to 640x480 , V4L2_PIX_FMT_YUYV

And /var/log/messages is empty. 0 KB. It's under my drive, C:\MeeGoSDK_1.2\MADDE\sysroots\meego-tablet-ia32-madde-sysroot-\var\log
May I know what I can do to get this log?

Hi Stone:

My apology. I may not have been very clear.
When I asked about /var/log/message in my previous message (to pull data out of /var/log/messages?), I meant to ask you to look at /var/log/messages on your tablet (not under Windows) during when the screen is blank. I am hoping there may be some lines in that file that may give us a clue why the screen is blank during the draw.

Will you be able to look into that file after you run your program on a tablet?


Hi! Vincent:

Thanks for your comments.
I am so stupid, of course I should get the log from the device.
I solved my problem today with changing some logic in my program.
I found it was cause by I raise a while loop to process video data(from camera).
After changing to use a timer instead of while loop, it seems work normally.
Still don't know why the old way is works in meego 1.1 but fail in meego 1.2.(maybe 1.2 has different windows management policy?)

Thanks a lot for your kindly help.
Please let me know if you still want to study the log to find out the different between 1.1 and 1.2.
I can also post the log if you like.
Thanks !

Glad to know things are working.


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