[FFmpeg-user] /dev/video1 :ioctl(VIDIOC_DQBUF): Operation not permitted when run ffmpeg

[Soho Soho123]

hi all,

When I try to use ffmpeg with the command line:
ffmpeg  -loglevel debug -f video4linux2 -r 12 -s 640x480 -input_format
yuyv422 -i /dev/video0 -vcodec copy http://localhost:8090/feed1.ffm >
/dev/null 2>&1 &
It is work normally.

but when I try to use another usb interface(same USB device) that
support h264 format.
the ffmpeg command is :
fmpeg  -loglevel debug -f video4linux2 -r 10 -s 640x480 -input_format
h264 -i /dev/video1 -vcodec copy http://localhost:8090/feed1.ffm

I have checked the right of /dev/video0 and /dev/video1.
they have the same right,
but
why /dev/video1 can not DQBUF?

Does anyone have ideas?