利用v4l2标准采集原始的yuv420视频图像-Using standard v4l2 collecting original yuv420 video images

called when fresh samples are available. Currently, samples are in YUV420 format, and can be up to width x 24 in size (depending on the in-loop filtering level, e.g.). -called when fresh samples are available. Currently, samples are in YUV420 form