What pixel formats does your USB camera support ?
# v4l2-ctl -d /dev/video1 --list-formats-ext
ioctl: VIDIOC_ENUM_FMT
Index : 0
Type : Video Capture
Pixel Format: 'YUYV'
Name : YUYV 4:2:2
Size: Discrete 320x240
Interval: Discrete 0.005s (187.000 fps)
Interval: Discrete 0.007s (150.000 fps)
Interval: Discrete 0.007s (137.000 fps)
Interval: Discrete 0.008s (125.000 fps)
Interval: Discrete 0.010s (100.000 fps)
Interval: Discrete 0.013s (75.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.020s (50.000 fps)
Interval: Discrete 0.027s (37.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 640x480
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.020s (50.000 fps)
Interval: Discrete 0.025s (40.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)