V4L2 APIに従ってV4L2 カメラのパラメーターを設定しようとしています。
ただし、API は OS によって設定された正しいパラメーターを表示しないようです。
この問題をデバッグして、カメラが正しいパラメータを表示できないことが問題であるかどうかを判断する方法を提案できますか?
- 私のコードで、
- カメラで、
- それともAPIで？
問題のデモンストレーション:
$ v4l2-ctl -d2 --set-fmt-video=width=424,height=240,pixelformat=1
$ v4l2-ctl -d2 --get-fmt-video | egrep 'Pixel Format|Width/Height'
Width/Height : 424/240
Pixel Format : 'UYVY'
$ python incorrect_pix_format.SO.py
>> device capabilities
Driver: uvcvideo
Camera: Intel(R) RealSense(TM) 410
video capture device? True
Supports read() call? False
Supports streaming? True
>> format parameters
pix_format.width: 0
pix_format.height: 0
pix_format.pixelformat: 0
>> Stop streaming
$ v4l2-ctl --list-formats-ext -d 2
ioctl: VIDIOC_ENUM_FMT
Index : 0
Type : Video Capture
Pixel Format: ''
Name : 00000032-0000-0010-8000-00aa003
Size: Discrete 424x240
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 480x270
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 640x360
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 640x480
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 848x480
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 1280x720
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Index : 1
Type : Video Capture
Pixel Format: 'UYVY'
Name : UYVY 4:2:2
Size: Discrete 424x240
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 480x270
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 640x360
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 640x480
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 848x480
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 1280x720
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Index : 2
Type : Video Capture
Pixel Format: 'Y8I '
Name : Greyscale 8 L/R (Y8I)
Size: Discrete 424x240
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 480x270
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 640x360
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 640x480
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 848x480
Interval: Discrete 0.011s (90.000 fps)
Interval: Discrete 0.017s (60.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 1280x720
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Interval: Discrete 0.167s (6.000 fps)
Size: Discrete 1920x1080
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Index : 3
Type : Video Capture
Pixel Format: 'Y12I'
Name : Greyscale 12 L/R (Y12I)
Size: Discrete 960x540
Interval: Discrete 0.040s (25.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Size: Discrete 1920x1080
Interval: Discrete 0.040s (25.000 fps)
Interval: Discrete 0.067s (15.000 fps)
Python コード (mcve):
$ cat incorrect_pix_format.SO.py
#!/usr/bin/env python3
from __future__ import print_function
import fcntl
import v4l2
def get_capability(vd):
cp = v4l2.v4l2_capability()
fcntl.ioctl(vd, v4l2.VIDIOC_QUERYCAP, cp)
return cp
def show_capability(cp):
print("Driver:", cp.driver)
print("Camera:", cp.card)
print("video capture device?\t", bool(cp.capabilities & v4l2.V4L2_CAP_VIDEO_CAPTURE))
print("Supports read() call?\t", bool(cp.capabilities & v4l2.V4L2_CAP_READWRITE))
print("Supports streaming?\t", bool(cp.capabilities & v4l2.V4L2_CAP_STREAMING))
def show_format(vd):
fmt = v4l2.v4l2_format()
pix_format = v4l2.v4l2_pix_format()
print("pix_format.width:", pix_format.width)
print("pix_format.height:", pix_format.height)
print("pix_format.pixelformat:", pix_format.pixelformat)
if __name__ == "__main__":
vd = open('/dev/video2', 'rb+', buffering=0)
print(">> device capabilities")
cp = get_capability(vd)
show_capability(cp)
print(">> format parameters")
show_format(vd)
print(">> Stop streaming")
vd.close()
環境：
OS: Ubuntu 16.04
V4L2 calls based on https://www.linuxtv.org/downloads/legacy/video4linux/API/V4L2_API/spec-single/v4l2.html