Fix infinite loop when trying to change state of the busy camera#15973
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alalek merged 2 commits intoopencv:3.4from Nov 22, 2019
Merged
Fix infinite loop when trying to change state of the busy camera#15973alalek merged 2 commits intoopencv:3.4from
alalek merged 2 commits intoopencv:3.4from
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- Add finite number of attempts in tryIoctl functions
10 by default.
alalek
reviewed
Nov 22, 2019
modules/videoio/src/cap_v4l.cpp
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| form.fmt.pix.height = height; | ||
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| if (!tryIoctl(VIDIOC_S_FMT, &form)) | ||
| if (!tryIoctl(VIDIOC_S_FMT, &form, 2)) |
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What is about adding parameter to handle "EBUSY" case?
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Ok, I will add it as additional argument, before attempts count.
I would like to keep limited attempts to ensure that loop is finite.
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According to the paragraph about multiple opens of the video device, filehandle becomes the owner of the device only after buffers allocations. Simple call to
opendoes not affect theirs state, so it falls down to capture initialization, which will stuck on palette setup.resolves #15782
This pullrequest changes
Add finite number of attempts in
tryIoctlfunctions (10 by default).First function that tries to change state of the camera is
VIDIOC_S_FMTand it fails witherrno EBUSY.