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Merge pull request #5489 from paroj:v4l2noconvert

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This commit is contained in:
Alexander Alekhin 2015-10-23 16:35:36 +00:00
commit 9a0beda037
2 changed files with 135 additions and 23 deletions
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94
modules/videoio/src/cap_v4l.cpp
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@ -294,6 +294,9 @@ typedef struct CvCaptureCAM_V4L
int index;
int width, height;
__u32 fps;
bool convert_rgb;
bool frame_allocated;
/* V4L2 variables */
buffer buffers[MAX_V4L_BUFFERS + 1];
struct v4l2_capability cap;
@ -674,6 +677,43 @@ static int v4l2_set_fps(CvCaptureCAM_V4L* capture) {
return ioctl (capture->deviceHandle, VIDIOC_S_PARM, &setfps);
}
static int v4l2_num_channels(__u32 palette) {
switch(palette) {
case V4L2_PIX_FMT_MJPEG:
case V4L2_PIX_FMT_JPEG:
return 1;
case V4L2_PIX_FMT_YUYV:
case V4L2_PIX_FMT_UYVY:
return 2;
default:
return 0;
}
}
static void v4l2_create_frame(CvCaptureCAM_V4L *capture) {
CvSize size(capture->form.fmt.pix.width, capture->form.fmt.pix.height);
int channels = 3;
if (!capture->convert_rgb) {
if (capture->palette == V4L2_PIX_FMT_MJPEG || capture->palette == V4L2_PIX_FMT_JPEG) {
size = CvSize(capture->buffers[capture->bufferIndex].length, 1);
}
channels = v4l2_num_channels(capture->palette);
}
/* Set up Image data */
cvInitImageHeader(&capture->frame, size, IPL_DEPTH_8U, channels);
/* Allocate space for pixelformat we convert to.
* If we do not convert frame is just points to the buffer
*/
if(capture->convert_rgb) {
capture->frame.imageData = (char*)cvAlloc(capture->frame.imageSize);
}
capture->frame_allocated = capture->convert_rgb;
}
static int _capture_V4L2 (CvCaptureCAM_V4L *capture)
{
char deviceName[MAX_DEVICE_DRIVER_NAME];
@ -829,13 +869,7 @@ static int _capture_V4L2 (CvCaptureCAM_V4L *capture)
}
}
/* Set up Image data */
cvInitImageHeader( &capture->frame,
cvSize( capture->form.fmt.pix.width,
capture->form.fmt.pix.height ),
IPL_DEPTH_8U, 3, IPL_ORIGIN_TL, 4 );
/* Allocate space for RGBA data */
capture->frame.imageData = (char *)cvAlloc(capture->frame.imageSize);
v4l2_create_frame(capture);
// reinitialize buffers
capture->FirstCapture = 1;
@ -1022,6 +1056,7 @@ static CvCaptureCAM_V4L * icvCaptureFromCAM_V4L (int index)
capture->width = DEFAULT_V4L_WIDTH;
capture->height = DEFAULT_V4L_HEIGHT;
capture->fps = DEFAULT_V4L_FPS;
capture->convert_rgb = true;
if (_capture_V4L2 (capture) == -1) {
icvCloseCAM_V4L(capture);
@ -1939,18 +1974,16 @@ static int sonix_decompress(int width, int height, unsigned char *inp, unsigned
static IplImage* icvRetrieveFrameCAM_V4L( CvCaptureCAM_V4L* capture, int) {
#ifdef HAVE_CAMV4L2
if (V4L2_SUPPORT == 0)
#endif /* HAVE_CAMV4L2 */
#ifdef HAVE_CAMV4L
if (V4L2_SUPPORT == 0)
{
/* [FD] this really belongs here */
if (ioctl(capture->deviceHandle, VIDIOCSYNC, &capture->mmaps[capture->bufferIndex].frame) == -1) {
fprintf( stderr, "VIDEOIO ERROR: V4L: Could not SYNC to video stream. %s\n", strerror(errno));
}
}
#endif /* HAVE_CAMV4L */
#endif /* HAVE_CAMV4L2 */
/* Now get what has already been captured as a IplImage return */
@ -1960,15 +1993,19 @@ static IplImage* icvRetrieveFrameCAM_V4L( CvCaptureCAM_V4L* capture, int) {
if (V4L2_SUPPORT == 1)
{
// we need memory iff convert_rgb is true
bool recreate_frame = capture->frame_allocated != capture->convert_rgb;
if(((unsigned long)capture->frame.width != capture->form.fmt.pix.width)
|| ((unsigned long)capture->frame.height != capture->form.fmt.pix.height)) {
cvFree(&capture->frame.imageData);
cvInitImageHeader( &capture->frame,
cvSize( capture->form.fmt.pix.width,
capture->form.fmt.pix.height ),
IPL_DEPTH_8U, 3, IPL_ORIGIN_TL, 4 );
capture->frame.imageData = (char *)cvAlloc(capture->frame.imageSize);
if (!capture->convert_rgb) {
// for mjpeg streams the size might change in between, so we have to change the header
recreate_frame += capture->frame.imageSize != (int)capture->buffers[capture->bufferIndex].length;
}
if(recreate_frame) {
// printf("realloc %d %zu\n", capture->frame.imageSize, capture->buffers[capture->bufferIndex].length);
if(capture->frame_allocated)
cvFree(&capture->frame.imageData);
v4l2_create_frame(capture);
}
}
@ -1996,6 +2033,11 @@ static IplImage* icvRetrieveFrameCAM_V4L( CvCaptureCAM_V4L* capture, int) {
if (V4L2_SUPPORT == 1)
{
if(!capture->convert_rgb) {
capture->frame.imageData = (char*)capture->buffers[capture->bufferIndex].start;
return &capture->frame;
}
switch (capture->palette)
{
case V4L2_PIX_FMT_BGR24:
@ -2174,6 +2216,8 @@ static double icvGetPropertyCAM_V4L (CvCaptureCAM_V4L* capture,
return capture->palette;
case CV_CAP_PROP_FORMAT:
return CV_8UC3;
case CV_CAP_PROP_CONVERT_RGB:
return capture->convert_rgb;
}
if(property_id == CV_CAP_PROP_FPS) {
@ -2416,10 +2460,8 @@ static int icvSetControl (CvCaptureCAM_V4L* capture,
static int icvSetPropertyCAM_V4L( CvCaptureCAM_V4L* capture,
int property_id, double value ){
static int width = 0, height = 0;
int retval;
/* initialization */
retval = 0;
int retval = 0;
bool possible;
/* two subsequent calls setting WIDTH and HEIGHT will change
the video size */
@ -2447,6 +2489,12 @@ static int icvSetPropertyCAM_V4L( CvCaptureCAM_V4L* capture,
capture->fps = value;
retval = v4l2_reset( capture);
break;
case CV_CAP_PROP_CONVERT_RGB:
// returns "0" for formats we do not know how to map to IplImage
possible = v4l2_num_channels(capture->palette);
capture->convert_rgb = bool(value) && possible;
retval = !possible && bool(value) ? -1 : 0;
break;
default:
retval = icvSetControl(capture, property_id, value);
break;

64
samples/python2/video_v4l2.py Normal file
View File

@ -0,0 +1,64 @@
#!/usr/bin/env python
'''
VideoCapture sample showcasing some features of the Video4Linux2 backend
Sample shows how VideoCapture class can be used to control parameters
of a webcam such as focus or framerate.
Also the sample provides an example how to access raw images delivered
by the hardware to get a grayscale image in a very efficient fashion.
Keys:
ESC - exit
g - toggle optimized grayscale conversion
'''
import cv2
def decode_fourcc(v):
v = int(v)
return "".join([chr((v >> 8 * i) & 0xFF) for i in range(4)])
font = cv2.FONT_HERSHEY_SIMPLEX
color = (0, 255, 0)
cap = cv2.VideoCapture(0)
cap.set(cv2.CAP_PROP_AUTOFOCUS, False)
cv2.namedWindow("Video")
convert_rgb = True
fps = int(cap.get(cv2.CAP_PROP_FPS))
focus = int(cap.get(cv2.CAP_PROP_FOCUS)) * 100
cv2.createTrackbar("FPS", "Video", fps, 30, lambda v: cap.set(cv2.CAP_PROP_FPS, v))
cv2.createTrackbar("Focus", "Video", focus, 100, lambda v: cap.set(cv2.CAP_PROP_FOCUS, v / 100))
while True:
status, img = cap.read()
fourcc = decode_fourcc(cap.get(cv2.CAP_PROP_FOURCC))
fps = cap.get(cv2.CAP_PROP_FPS)
if not bool(cap.get(cv2.CAP_PROP_CONVERT_RGB)):
if fourcc == "MJPG":
img = cv2.imdecode(img, cv2.IMREAD_GRAYSCALE)
elif fourcc == "YUYV":
img = cv2.cvtColor(img, cv2.COLOR_YUV2GRAY_YUYV)
else:
print("unsupported format")
break
cv2.putText(img, "Mode: {}".format(fourcc), (15, 40), font, 1.0, color)
cv2.putText(img, "FPS: {}".format(fps), (15, 80), font, 1.0, color)
cv2.imshow("Video", img)
k = cv2.waitKey(1)
if k == 27:
break
elif k == ord("g"):
convert_rgb = not convert_rgb
cap.set(cv2.CAP_PROP_CONVERT_RGB, convert_rgb)