capture_one_image_from_stream

capture one image from stream using ffmpeg.

Video protocols

HTTP: ffmpeg -i {HTTP://XXX.XXXX.XX/XXX} {loacl/path/img.jpg}

RTSP(TCP、UDP): ffmpeg -rtsp_transport {tcp or udp} -i {RTSP://XXX.XXX.XX/XXX} {loacl/path/img.jpg}