The issue about image rate

Nov 12, 2007 at 7:30 AM
Edited Nov 12, 2007 at 7:34 AM
I use pro 5000 webcam. I found if I used the image rate not 30hz, the pImageDecoder->GetImageInfo would always fail . If I set the image rate as 30hz, it happend too, but not always. Another question is the image is not right. The upper part is correct, but the lower part is not.

Does anybody has these problems?

Nov 12, 2007 at 7:13 PM
About the problem with the incorrect lower part of the image:
See also threads "Videostream 90% broken" and "Frame Error while streaming MJPEG".
I'd also like to know the reason / the solution to this.

Nov 18, 2007 at 12:18 AM
I believe much of this is due to USB 2 issues on CE 5. However, some (most) hardware running CE simply can't handle the conversion speeds necessary for streaming frame rates of 15 fps or higer with large image sizes. If you're using a CEPC with a 2+ Ghz CPU, this isn't a problem. But with Via or Geode CPUs, there are problems.

Let me know your hardware config and the version of your driver. Perhaps its something else.

Nov 21, 2007 at 6:16 AM
Edited Nov 21, 2007 at 6:16 AM
This problem has been resolved. I modified the USB driver and the structure of webcam driver. It can work well with 32024020fps.
But I still have problem with the 32024025fps. Sometimes the image size I received is not correct, so I think the webcam driver must miss some packet. But the data I received is same with the usb protocol analyzer. So I think the calling IssueIsochTransfer function frequency is not fast enough to receive the data. Some frame of usb isochronous transaction are lost. My cpu is 600HZ and the USB version is 2.0.
Does anybody has the same problem?
Dec 2, 2007 at 7:28 PM
What do you modified in the sourcecode USB driver and structure ?