Re: [Imtoolkit-users] im_capture doubt

[cykt <cy...@aj...>]

Hi, Scuri

 

Now, it works. My webcam takes  two loops to capture the image.

For color mode parameter, I have changed to “IM_BYTE|IM_RGB|IM_PACKED”.

 

Thanks a lot, for your prompt answer and valuable information.

I’d like to congratulate for your initiative to publish this great job.

 

Best regards

 

Luiz

 

From: Antonio Scuri [mailto:sc...@te...] 
Sent: quarta-feira, 28 de julho de 2010 20:18
To: 'IM discussion list.'
Subject: Re: [Imtoolkit-users] im_capture doubt

 

  Hi,

 

  The problem could be related to a hardware delay. Maybe you have to wait
some time before trying to capture a frame right after you connect, in other
words between imVideoCaptureConnect and imVideoCaptureOneFrame you should
delay some time.

 

  Another option is to try to capture a few times before giving up. I mean,
call imVideoCaptureOneFrame inside a small loop until it returns a non zero
value, then break the loop. If all attempts failed then print the error.

 

   By the way, don’t use “1” as a parameter, use the definitions in “im.h”
that describes a color mode.

 

Best,

scuri

 

From: cykt [mailto:cy...@aj...] 
Sent: quarta-feira, 28 de julho de 2010 18:23
To: imt...@li...
Subject: [Imtoolkit-users] im_capture doubt

 

Hi,

 

I’m trying to use im_capture library in order to capture one frame from USB
2.0 webcam (640x480 resolution).

I have followed capture guide basic program exactly the same way is written
in the document. I  mean:

 

      void capturaCamera(unsigned char *pImage)

      {

            imVideoCapture* vc = imVideoCaptureCreate();

            if (vc == NULL)

                  printf ("\nCreation error");

 

            if (!imVideoCaptureConnect(vc, 0)){

                  printf ("\nConnection Error");

 

            }

            int width=0, height=0;

            imVideoCaptureGetImageSize(vc, &width, &height);

 

printf ("\n width = %d, height = %d", width, height );

 

            if (!imVideoCaptureOneFrame(vc, pImage, 1))

                  printf ("\nCapture Error");

 

            imVideoCaptureDisconnect(vc);

            imVideoCaptureDestroy(vc);

                }

 

It works until imVideoCaptureOneFrame() procedure. But here, it returns a
NULL value.

I’m using Windows Vista Home, Eclipse CDT, MingW 3.4.5. The program  is
written in C language.

 

I have already tested imVideoCaptureLive() and imVideoCaptureFrame()
functions, but the results was the same.

Also, I have tested imVideoCaptureReloadDevices(), aiming to clear device,
but no result.

 

I have tested webcam using the following  applications: AMcap and ÑAUSA
(which uses im library). And it works well.

 

What is wrong ?

 

 

Thanks in advance

 

Luiz

Nenhum vírus encontrado nessa mensagem recebida.
Verificado por AVG - www.avgbrasil.com.br
Versão: 9.0.851 / Banco de dados de vírus: 271.1.1/3035 - Data de
Lançamento: 07/28/10 14:38:00