# opencv with pwcbsd usb camera



## kasse (Jun 12, 2009)

I wonder if the opencv port with ffmpeg enabled is supposed to work with pwc driven usb-cameras. 
When I try to create a camera capture and query a frame I get

```
HIGHGUI ERROR: V4L: Could not SYNC to video stream. Operation not supported
```
Also I compiled the demo programs atPhilips SPC 900 NC - OpenCV Webcam demonstration,
but I got the same error when I tried to run those demos.


Edit: Later I tried to recompile opencv with ffmpeg enabled (I was not sure ffmpeg was enabled initially). I got these errors compiling opencv:

```
cvcap_ffmpeg.cpp: In function 'int icvOpenAVI_FFMPEG(CvCaptureAVI_FFMPEG*, const char*)':
cvcap_ffmpeg.cpp:128: warning: comparison between signed and unsigned integer expressions
cvcap_ffmpeg.cpp: In function 'void cvReleaseVideoWriter(CvVideoWriter**)':
cvcap_ffmpeg.cpp:797: warning: comparison between signed and unsigned integer expressions
cvcap_ffmpeg.cpp:804: error: cannot convert 'ByteIOContext**' to 'ByteIOContext*' for argument '1' to 'int url_fclose(ByteIOContext*)'
gmake[3]: *** [cvcap_ffmpeg.lo] Error 1
gmake[3]: Leaving directory `/usr/ports/graphics/opencv/work/opencv-1.0.0/otherlibs/highgui'
gmake[2]: *** [all-recursive] Error 1
```

I know that there have been previous errors that were similar http://www.freebsd.org/cgi/query-pr.cgi?pr=117173

Is the latest opencv supposed to compile with ffmpeg enabled?


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