Grabber::openDev Method |
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Opens a video capture device for grabbing. | |||||||||||||||||||||||
Syntax: | bool openDev( const VideoCaptureDeviceItem& dev ); bool openDev( const char* dev ); bool openDev( const std::string& devstring ); bool openDev( const std::wstring& devstring ); bool openDev( const int64_t& serial ); |
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Return value: | true, if the device was opened successfully, false, otherwise. |
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Remarks: | An already opened device will be closed before opening a new one. openDev is usually one of the first actions on the Grabber. Querying for device capabilities such as the available video formats (Grabber::getAvailableVideoFormats ) is only possible, if a device is open. You can get a VideoCaptureDeviceItem by iterating the list generated by Grabber::getAvailableVideoCaptureDevices. After opening the device, a video format has to be set to a valid one, using Grabber::setVideoFormat. Please note that even if you have a device opened with Grabber::openDev, it may become invalid at any time (e.g. if the device is unplugged). A device which has become invalid will not automatically be reopened, if it gets plugged in again. You should rather check whether the device is still valid using Grabber::isDevValid by time and react accordingly. |
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See also: | Grabber, Grabber::closeDev, Grabber::getAvailableVideoCaptureDevices, Grabber::isDevOpen |