并且自动选择使用uyvy422来替代yuv420p
Selected pixel format (yuv420p) is not supported by the input device. Supported pixel formats: uyvy422 yuyv422 nv12 0rgb bgr0 Overriding selected pixel format to use uyvy422 instead.与此同时，也成功开始采集摄像头的视频数据了。
像素格式：uyvy422
分辨率：1280x720
帧率：30
Input #0, avfoundation, from '0': Stream #0:0: Video: rawvideo, uyvy422, 1280x720 Output #0, rawvideo, to 'out.yuv': Stream #0:0: Video: rawvideo, uyvy422, 1280x720, 30 fps播放录制好的YUV。
ffplay -video_size 1280x720 -pixel_format uyvy422 -framerate 30 out.yuv