K230_linux_Opencv调用UVC指南#
概述#
本文将讲解如何在k230开发板Linux侧驱动USB摄像头，并通过opencv调用uvc。sdk默认镜像已经包含向量加速的opencv。本文档以01studio板子为例。
检查uvc设备状态及信息#
lsusb #查看usb设备信息
v4l2-ctl --list-devices #命令查看所有支持v4l2的摄像头信息
v4l2-ctl -d /dev/video1 --all #查看摄像头所有信息
v4l2-ctl --list-formats-ext --device /dev/video1 #查询可输出的图像格式
使用 lsusb 命令查看usb设备信息#
[ 2.350021] usb 1-1: New USB device found, idVendor=0bda, idProduct=8152, bcdDevice=20.00
[ 2.358228] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 2.365370] usb 1-1: Product: USB 10/100 LAN
[ 2.369647] usb 1-1: Manufacturer: Realtek
[ 2.373748] usb 1-1: SerialNumber: 00E04C421C8E
[ 2.410027] usb 2-1: config 1 interface 0 altsetting 0 endpoint 0x83 has an invalid bInterval 32, changing to 9
[ 2.420336] usb 2-1: New USB device found, idVendor=1b3f, idProduct=2247, bcdDevice= 1.00
[ 2.428541] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 2.435690] usb 2-1: Product: GENERAL WEBCAM
[ 2.439973] usb 2-1: Manufacturer: GENERAL
[ 2.444796] usb 2-1: Found UVC 1.00 device GENERAL WEBCAM (1b3f:2247)
[ 2.453534] usb 2-1: UVC non compliance - GET_DEF(PROBE) not supported. Enabling workaround.
[root@canaan ~ ]#lsusb
Bus 002 Device 002: ID 1b3f:2247
Bus 001 Device 001: ID 1d6b:0002
Bus 001 Device 002: ID 0bda:8152
Bus 002 Device 001: ID 1d6b:0002
[root@canaan ~ ]#
使用v4l2-ctl --list-devices命令查看所有支持v4l2的摄像头信息#
[root@canaan ~ ]#v4l2-ctl --list-devices
Linlon Video device (platform:mvx):
/dev/video0
vvcam-isp-subdev.0 (platform:vvcam-isp-subdev.0):
/dev/v4l-subdev0
verisilicon_media (platform:vvcam-video.0):
/dev/media1
vvcam-video.0.0 (platform:vvcam-video.0.0):
/dev/video3
vvcam-video.0.1 (platform:vvcam-video.0.1):
/dev/video4
vvcam-video.0.2 (platform:vvcam-video.0.2):
/dev/video5
vvcam-video.0.3 (platform:vvcam-video.0.3):
/dev/video6
GENERAL WEBCAM: GENERAL WEBCAM (usb-91540000.usb-1):
/dev/video1
/dev/video2
/dev/media0
[root@canaan ~ ]#
使用v4l2-ctl -d /dev/video1 --all查看摄像头的所有信息#
[root@canaan ~ ]#v4l2-ctl -d /dev/video1 --all
Driver Info:
Driver name : uvcvideo
Card type : GENERAL WEBCAM: GENERAL WEBCAM
Bus info : usb-91540000.usb-1
Driver version : 6.6.36
Capabilities : 0x84a00001
Video Capture
Metadata Capture
Streaming
Extended Pix Format
Device Capabilities
Device Caps : 0x04200001
Video Capture
Streaming
Extended Pix Format
Media Driver Info:
Driver name : uvcvideo
Model : GENERAL WEBCAM: GENERAL WEBCAM
Serial :
Bus info : usb-91540000.usb-1
Media version : 6.6.36
Hardware revision: 0x00000100 (256)
Driver version : 6.6.36
Interface Info:
ID : 0x03000002
Type : V4L Video
Entity Info:
ID : 0x00000001 (1)
Name : GENERAL WEBCAM: GENERAL WEBCAM
Function : V4L2 I/O
Flags : default
Pad 0x01000007 : 0: Sink
Link 0x02000013: from remote pad 0x100000a of entity 'Extension 7' (Video Pixel Formatter): Data, Enabled, Immutable
Priority: 2
Video input : 0 (Camera 1: ok)
Format Video Capture:
Width/Height : 1920/1080
Pixel Format : 'MJPG' (Motion-JPEG)
Field : None
Bytes per Line : 0
Size Image : 1843200
Colorspace : sRGB
Transfer Function : Rec. 709
YCbCr/HSV Encoding: ITU-R 601
Quantization : Default (maps to Full Range)
Flags :
Crop Capability Video Capture:
Bounds : Left 0, Top 0, Width 1920, Height 1080
Default : Left 0, Top 0, Width 1920, Height 1080
Pixel Aspect: 1/1
Selection Video Capture: crop_default, Left 0, Top 0, Width 1920, Height 1080, Flags:
Selection Video Capture: crop_bounds, Left 0, Top 0, Width 1920, Height 1080, Flags:
Streaming Parameters Video Capture:
Capabilities : timeperframe
Frames per second: 30.000 (30/1)
Read buffers : 0
User Controls
brightness 0x00980900 (int) : min=1 max=255 step=1 default=-8193 value=16
contrast 0x00980901 (int) : min=1 max=255 step=1 default=57343 value=16
hue 0x00980903 (int) : min=-128 max=127 step=1 default=-8193 value=16
power_line_frequency 0x00980918 (menu) : min=0 max=2 default=2 value=2 (60 Hz)
0: Disabled
1: 50 Hz
2: 60 Hz
Camera Controls
[root@canaan ~ ]#
使用 v4l2-ctl --list-formats-ext --device /dev/video1 查询可输出的图像格式#
[root@canaan ~ ]#v4l2-ctl --list-formats-ext --device /dev/video1
ioctl: VIDIOC_ENUM_FMT
Type: Video Capture
[0]: 'MJPG' (Motion-JPEG, compressed)
Size: Discrete 1920x1080
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 1440x1080
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 1280x720
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 800x600
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 800x480
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 720x480
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 640x480
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 640x360
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 480x270
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 320x240
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 176x144
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 1920x1080
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.033s (30.000 fps)
[1]: 'YUYV' (YUYV 4:2:2)
Size: Discrete 800x480
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 720x480
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 640x480
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 640x360
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 480x270
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 320x240
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 176x144
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 800x480
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.033s (30.000 fps)
Interval: Discrete 0.033s (30.000 fps)
[root@canaan ~ ]#
使用v4l获取图像#
使用v4l2-ctl --device /dev/video1 --stream-mmap --stream-to=video0-output.jpg --stream-count=1命令采集一张jpg图片
[root@canaan ~ ]#v4l2-ctl --device /dev/video0 --stream-mmap --stream-to=video0-
output.jpg --stream-count=1
<
[root@canaan ~ ]#ls -lh
total 222K
-rw-r--r-- 1 root root 221.7K Jan 1 00:11 video0-output.jpg
opencv获取图像#
c语言版本#
拷贝video_cap测试应用到文件系统中并执行，会生成一个test.jpg文件
[root@canaan ~ ]#./video_cap
[root@canaan ~ ]#ls
nfs test.jpg video_cap
video_cap可通过命令/opt/toolchain/Xuantie-900-gcc-linux-6.6.0-glibc-x86_64-V2.10.1/bin/riscv64-unknown-linux-gnu-g++ --sysroot=output/k230_canmv_01studio_defconfig/host/riscv64-buildroot-linux-gnu/sysroot video_cap.cpp -lopencv_videoio -lopencv_core -lopencv_imgcodecs -o video_cap来编译生成，video_cap.cpp源码如下：
#include "opencv2/opencv.hpp"
using namespace cv;
int main()
{
VideoCapture capture(1);
Mat frame;
capture>>frame;
imwrite("test.jpg", frame);
return 0;
}
python版本#
使用如下python脚本可以获取一张图像
import cv2
# 初始化摄像头
cap = cv2.VideoCapture(1)
if not cap.isOpened():
print("Error: Could not open video device.")
exit()
# 抓取一帧图像
ret, frame = cap.read()
if not ret:
print("Error: Could not read frame from video device.")
cap.release()
exit()
# 保存图像
image_filename = 'captured_image.jpg'
cv2.imwrite(image_filename, frame)
print(f"Image saved as {image_filename}")
# 释放摄像头资源
cap.release()
用户应用#
通过v4l接口去采集图像，具体请参考
v4l用户编程API或v4l-utils源码通过opencv接口去采集图像，具体请参考
opencv编程