When using camera with opencv api, the default camera resolution is ALWAYS 160x120
From source code modules/highgui/src/cap_libv4l.cpp the default resolution should be 640x480
/* Defaults - If your board can do better, set it here. Set for the most common type inputs. */
#define DEFAULT_V4L_WIDTH 640
#define DEFAULT_V4L_HEIGHT 480
I have study a little bit of modules/highgui/src/cap_libv4l.cpp then I found the problem.
CvCaptureCAM_V4L * capture = (CvCaptureCAM_V4L*)cvAlloc(sizeof(CvCaptureCAM_V4L));
if (!capture) {
fprintf( stderr, "HIGHGUI ERROR: V4L: Could not allocate memory for capture process.\n");
return NULL;
}
/* set the default size */
capture->width = DEFAULT_V4L_WIDTH;
capture->height = DEFAULT_V4L_HEIGHT;
...
...
/* w/o memset some parts arent initialized - AKA: Fill it with zeros so it is clean */
memset(capture,0,sizeof(CvCaptureCAM_V4L));
/* Present the routines needed for V4L funtionality. They are inserted as part of
the standard set of cv calls promoting transparency. "Vector Table" insertion. */
capture->FirstCapture = 1;
if (_capture_V4L2 (capture, deviceName) == -1) {
The memset instruction is called after setting width & height. @@
So, just move up memset behind alloc memory.
--- modules/highgui/src/cap_libv4l.cpp.org 2012-08-06 19:28:58.746347834 +0800
+++ modules/highgui/src/cap_libv4l.cpp 2012-08-06 19:29:42.510348966 +0800
@@ -1007,6 +1007,9 @@
return NULL;
}
+ /* w/o memset some parts arent initialized - AKA: Fill it with zeros so it is clean */
+ memset(capture,0,sizeof(CvCaptureCAM_V4L));
+
/* set the default size */
capture->width = DEFAULT_V4L_WIDTH;
capture->height = DEFAULT_V4L_HEIGHT;
@@ -1028,8 +1031,6 @@
/* Print the CameraNumber at the end of the string with a width of one character */
sprintf(deviceName, "/dev/video%1d", index);
- /* w/o memset some parts arent initialized - AKA: Fill it with zeros so it is clean */
- memset(capture,0,sizeof(CvCaptureCAM_V4L));
/* Present the routines needed for V4L funtionality. They are inserted as part of
the standard set of cv calls promoting transparency. "Vector Table" insertion. */
capture->FirstCapture = 1;
