关于v4l2抓图的问题

[复制链接] · 发表于 2023-5-31 09:18:58

我用V4L2-ctl命令抓video0的输出，显示了抓图进程没问题，但是保存的数据大小却是0kb，请问这是什么问题呢？

# v4l2-ctl -d /dev/video0 --stream-mmap=3 --stream-count=1 --stream-poll --stream-skip=3 --set-fmt-video=width=1024,height=768,pixelformat=GREY --verbose --stream-to mp.out
VIDIOC_QUERYCAP: ok
VIDIOC_G_FMT: ok
VIDIOC_S_FMT: ok
Format Video Capture Multiplanar:
      Width/Height    : 1024/768
      Pixel Format    : 'GREY' (8-bit Greyscale)
      Field          : None
      Number of planes  : 1
      Flags          :
      Colorspace       : Default
      Transfer Function : Default
      YCbCr/HSV Encoding: Default
      Quantization    : Default
      Plane 0          :
         Bytes per Line : 1024
         Size Image    : 786432
            VIDIOC_REQBUFS returned 0 (Success)
            VIDIOC_QUERYBUF returned 0 (Success)
            VIDIOC_QUERYBUF returned 0 (Success)
            VIDIOC_QUERYBUF returned 0 (Success)
            VIDIOC_QBUF returned 0 (Success)
            VIDIOC_QBUF returned 0 (Success)
            VIDIOC_QBUF returned 0 (Success)
            VIDIOC_STREAMON returned 0 (Success)
cap dqbuf: 0 seq:    0 bytesused: 786432 ts: 3231.759931 (ts-monotonic, ts-src-eof)
cap dqbuf: 1 seq:    1 bytesused: 786432 ts: 3231.779974 delta: 20.043 ms (ts-monotonic, ts-src-eof)
cap dqbuf: 2 seq:    2 bytesused: 786432 ts: 3231.800305 delta: 20.331 ms (ts-monotonic, ts-src-eof)
cap dqbuf: 0 seq:    3 bytesused: 786432 ts: 3231.820026 delta: 19.721 ms (ts-monotonic, ts-src-eof)