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Merge pull request #15973 from VadimLevin:dev/vlevin/video_capture_inf_loop

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* Fix infinite loop when trying to change state of the busy camera

  - Add finite number of attempts in tryIoctl functions
    10 by default.

* Introduced new flag for ioctl call to handle EBUSY
This commit is contained in:
Vadim Levin 2019-11-23 01:10:16 +03:00 committed by Alexander Alekhin
parent 50ac880335
commit 373160ce00
1 changed files with 23 additions and 7 deletions
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30
modules/videoio/src/cap_v4l.cpp
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@ -353,7 +353,7 @@ struct CvCaptureCAM_V4L CV_FINAL : public CvCapture
bool initCapture();
bool streaming(bool startStream);
bool setFps(int value);
bool tryIoctl(unsigned long ioctlCode, void *parameter) const;
bool tryIoctl(unsigned long ioctlCode, void *parameter, bool failIfBusy = true, int attempts = 10) const;
bool controlInfo(int property_id, __u32 &v4l2id, cv::Range &range) const;
bool icvControl(__u32 v4l2id, int &value, bool isSet) const;
@ -406,10 +406,10 @@ bool CvCaptureCAM_V4L::try_palette_v4l2()
form.fmt.pix.field = V4L2_FIELD_ANY;
form.fmt.pix.width = width;
form.fmt.pix.height = height;
if (!tryIoctl(VIDIOC_S_FMT, &form))
{
return false;
}
return palette == form.fmt.pix.pixelformat;
}
@ -481,6 +481,8 @@ bool CvCaptureCAM_V4L::autosetup_capture_mode_v4l2()
//in case palette is already set and works, no need to setup.
if (palette != 0 && try_palette_v4l2()) {
return true;
} else if (errno == EBUSY) {
return false;
}
__u32 try_order[] = {
V4L2_PIX_FMT_BGR24,
@ -637,7 +639,9 @@ bool CvCaptureCAM_V4L::initCapture()
}
if (!autosetup_capture_mode_v4l2()) {
fprintf(stderr, "VIDEOIO ERROR: V4L2: Pixel format of incoming image is unsupported by OpenCV\n");
if (errno != EBUSY) {
fprintf(stderr, "VIDEOIO ERROR: V4L2: Pixel format of incoming image is unsupported by OpenCV\n");
}
return false;
}
@ -857,10 +861,21 @@ bool CvCaptureCAM_V4L::read_frame_v4l2()
return true;
}
bool CvCaptureCAM_V4L::tryIoctl(unsigned long ioctlCode, void *parameter) const
bool CvCaptureCAM_V4L::tryIoctl(unsigned long ioctlCode, void *parameter, bool failIfBusy, int attempts) const
{
if (attempts == 0) {
return false;
}
while (-1 == ioctl(deviceHandle, ioctlCode, parameter)) {
if (!(errno == EBUSY || errno == EAGAIN))
const bool isBusy = (errno == EBUSY);
if (isBusy & failIfBusy) {
return false;
}
if ((attempts > 0) && (--attempts == 0)) {
return false;
}
if (!(isBusy || errno == EAGAIN))
return false;
fd_set fds;
@ -1969,8 +1984,9 @@ CvCapture* cvCreateCameraCapture_V4L( int index )
{
cv::CvCaptureCAM_V4L* capture = new cv::CvCaptureCAM_V4L();
if(capture->open(index))
if(capture->open(index)) {
return capture;
}
delete capture;
return NULL;