rv1126 v4l2-utils两大常用工具及命令实例
1. v4l2-utils工具包
v4l-utils工具是由Linux维护的V4L2开发工具包。
它提供了一套用于配置V4L2子设备属性的V4L2和媒体框架相关工具,测试V4L2设备,并提供开发库,如libv4l2等等。
v4l-utils工具包主要包含两个常用工具,分别是media-ctl、v4l2-ctl。
2. media-ctl
media-ctl是v4l2-utils包中的一个工具,主要用来查看、配置Media Framework的各Entity的信息,如格式、裁剪、链接使能等。
2.1显示拓扑结构
命令:
media-ctl -p -d /dev/media0
结果:
[root@RV1126_RV1109:/]# media-ctl -p -d /dev/media0
Media controller API version 4.19.111
Media device information
------------------------
driver rkcif
model rkcif_mipi_lvds
serial
bus info
hw revision 0x0
driver version 4.19.111
Device topology
- entity 1: stream_cif_mipi_id0 (1 pad, 4 links)
type Node subtype V4L flags 0
device node name /dev/video0
pad0: Sink
<- "rockchip-mipi-csi2":1 [ENABLED]
<- "rockchip-mipi-csi2":2 []
<- "rockchip-mipi-csi2":3 []
<- "rockchip-mipi-csi2":4 []
- entity 5: stream_cif_mipi_id1 (1 pad, 4 links)
type Node subtype V4L flags 0
device node name /dev/video1
pad0: Sink
<- "rockchip-mipi-csi2":1 []
<- "rockchip-mipi-csi2":2 [ENABLED]
<- "rockchip-mipi-csi2":3 []
<- "rockchip-mipi-csi2":4 []
- entity 9: stream_cif_mipi_id2 (1 pad, 4 links)
type Node subtype V4L flags 0
device node name /dev/video2
pad0: Sink
<- "rockchip-mipi-csi2":1 []
<- "rockchip-mipi-csi2":2 []
<- "rockchip-mipi-csi2":3 [ENABLED]
<- "rockchip-mipi-csi2":4 []
- entity 13: stream_cif_mipi_id3 (1 pad, 4 links)
type Node subtype V4L flags 0
device node name /dev/video3
pad0: Sink
<- "rockchip-mipi-csi2":1 []
<- "rockchip-mipi-csi2":2 []
<- "rockchip-mipi-csi2":3 []
<- "rockchip-mipi-csi2":4 [ENABLED]
- entity 17: rockchip-mipi-csi2 (5 pads, 17 links)
type V4L2 subdev subtype Unknown flags 0
device node name /dev/v4l-subdev1
pad0: Sink
[fmt:SBGGR10_1X10/2112x1568 field:none
crop.bounds:(0,0)/2112x1568
crop:(0,0)/2112x1568]
<- "rockchip-mipi-dphy-rx":1 [ENABLED]
pad1: Source
[fmt:SBGGR10_1X10/2112x1568 field:none
crop.bounds:(0,0)/2112x1568
crop:(0,0)/2112x1568]
-> "stream_cif_mipi_id0":0 [ENABLED]
-> "stream_cif_mipi_id1":0 []
-> "stream_cif_mipi_id2":0 []
-> "stream_cif_mipi_id3":0 []
pad2: Source
[fmt:SBGGR10_1X10/2112x1568 field:none
crop.bounds:(0,0)/2112x1568
crop:(0,0)/2112x1568]
-> "stream_cif_mipi_id0":0 []
-> "stream_cif_mipi_id1":0 [ENABLED]
-> "stream_cif_mipi_id2":0 []
-> "stream_cif_mipi_id3":0 []
pad3: Source
[fmt:SBGGR10_1X10/2112x1568 field:none
crop.bounds:(0,0)/2112x1568
crop:(0,0)/2112x1568]
-> "stream_cif_mipi_id0":0 []
-> "stream_cif_mipi_id1":0 []
-> "stream_cif_mipi_id2":0 [ENABLED]
-> "stream_cif_mipi_id3":0 []
pad4: Source
[fmt:SBGGR10_1X10/2112x1568 field:none
crop.bounds:(0,0)/2112x1568
crop:(0,0)/2112x1568]
-> "stream_cif_mipi_id0":0 []
-> "stream_cif_mipi_id1":0 []
-> "stream_cif_mipi_id2":0 []
-> "stream_cif_mipi_id3":0 [ENABLED]
- entity 23: rockchip-mipi-dphy-rx (2 pads, 2 links)
type V4L2 subdev subtype Unknown flags 0
device node name /dev/v4l-subdev2
pad0: Sink
[fmt:SBGGR10_1X10/2112x1568@10000/300000 field:none]
<- "m01_b_ov13850 1-0010":0 [ENABLED]
pad1: Source
[fmt:SBGGR10_1X10/2112x1568@10000/300000 field:none]
-> "rockchip-mipi-csi2":0 [ENABLED]
- entity 28: rkcif-mipi-luma (0 pad, 0 link)
type Node subtype V4L flags 0
device node name /dev/video4
- entity 31: m01_b_ov13850 1-0010 (1 pad, 1 link)
type V4L2 subdev subtype Sensor flags 0
device node name /dev/v4l-subdev3
pad0: Source
[fmt:SBGGR10_1X10/2112x1568@10000/300000 field:none]
-> "rockchip-mipi-dphy-rx":0 [ENABLED]
- entity 35: m00_b_vm149c 1-000c (0 pad, 0 link)
type V4L2 subdev subtype Lens flags 0
device node name /dev/v4l-subdev4
[root@RV1126_RV1109:/]#
从 entity31 信息中可以看到:
- 该Entity完整的名称是:m01_b_ov13850 1-0010
- 它是一个V4L2 subdev(Sub-Device) Sensor
- 它对应的节点是/dev/v4l-subdev3,应用程序(如v4l2-ctl)可以打开它,并进行配置
- 它仅有一个输出(Source)节点,记为pad0
- 它的输出格式是[fmt:SBGGR10_1X10/2112x1568],其中SBGGR10是一种mbus-code的简称
- 它的pad0:Source 链接到”rockchip-mipi-dphy-rx”的pad0,并且当前的状态是 ENABLED。
拓扑图如下:
2.2找到设备的video节点
拓扑结构中有多个的Entity,一些是sub device,一些是video device。前者对应的设备节点是/dev/v4l-subdev,后者对应的是/dev/video。多个的video device中,最常关注的是哪个设备可以输出图像。
命令:
media-ctl -d /dev/media0 -e "stream_cif_mipi_id0"
结果:
[root@RV1126_RV1109:/]# media-ctl -d /dev/media0 -e "stream_cif_mipi_id0"
/dev/video0
[root@RV1126_RV1109:/]#
3. v4l2-ctl
V4l2-ctl 工具则是针对/dev/video0,/dev/video1 等 video设备,它在 video 设备上进行 set_fmt,reqbuf(申请buf),qbuf(送buf回队列),dqbuf(从队列取出buf),stream_on,stream_off 等一系列操作。
v4l2-ctl的帮助信息查看:
[root@RV1126_RV1109:/]# v4l2-ctl -h
General/Common options:
--all display all information available
-C, --get-ctrl <ctrl>[,<ctrl>...]
get the value of the controls [VIDIOC_G_EXT_CTRLS]
-c, --set-ctrl <ctrl>=<val>[,<ctrl>=<val>...]
set the value of the controls [VIDIOC_S_EXT_CTRLS]
-D, --info show driver info [VIDIOC_QUERYCAP]
-d, --device <dev> use device <dev> instead of /dev/video0
if <dev> starts with a digit, then /dev/video<dev> is used
-e, --out-device <dev> use device <dev> for output streams instead of the
default device as set with --device
if <dev> starts with a digit, then /dev/video<dev> is used
-h, --help display this help message
--help-all all options
--help-io input/output options
--help-meta metadata format options
--help-misc miscellaneous options
--help-overlay overlay format options
--help-sdr SDR format options
--help-selection crop/selection options
--help-stds standards and other video timings options
--help-streaming streaming options
--help-subdev sub-device options
--help-tuner tuner/modulator options
--help-vbi VBI format options
--help-vidcap video capture format options
--help-vidout vidout output format options
--help-edid edid handling options
-k, --concise be more concise if possible.
-l, --list-ctrls display all controls and their values [VIDIOC_QUERYCTRL]
-L, --list-ctrls-menus
display all controls and their menus [VIDIOC_QUERYMENU]
-r, --subset <ctrl>[,<offset>,<size>]+
the subset of the N-dimensional array to get/set for control <ctrl>,
for every dimension an (<offset>, <size>) tuple is given.
-w, --wrapper use the libv4l2 wrapper library.
--list-devices list all v4l devices
--log-status log the board status in the kernel log [VIDIOC_LOG_STATUS]
--get-priority query the current access priority [VIDIOC_G_PRIORITY]
--set-priority <prio>
set the new access priority [VIDIOC_S_PRIORITY]
<prio> is 1 (background), 2 (interactive) or 3 (record)
--silent only set the result code, do not print any messages
--sleep <secs> sleep <secs>, call QUERYCAP and close the file handle
--verbose turn on verbose ioctl status reporting
[root@RV1126_RV1109:/]#
3.1列出所有设备
命令:
v4l2-ctl --list-devices
结果:
[root@RV1126_RV1109:/]# v4l2-ctl --list-devices
rkisp-statistics (platform: rkisp):
/dev/video14
/dev/video15
/dev/video16
rkispp_input_params (platform: rkispp):
/dev/video23
/dev/video24
rkcif (platform:rkcif_mipi_lvds):
/dev/video0
/dev/video1
/dev/video2
/dev/video3
/dev/video4
rkisp_mainpath (platform:rkisp-vir0):
/dev/video5
/dev/video6
/dev/video7
/dev/video8
/dev/video9
/dev/video10
/dev/video11
/dev/video12
/dev/video13
rkispp_input_image (platform:rkispp-vir0):
/dev/video17
/dev/video18
/dev/video19
/dev/video20
/dev/video21
/dev/video22
[root@RV1126_RV1109:/]#
3.2获取指定设备的所有信息
命令:
v4l2-ctl --all --device /dev/video0
或者
v4l2-ctl --all -d /dev/video0
结果:
[root@RV1126_RV1109:/]# v4l2-ctl --all --device /dev/video0
Driver Info:
Driver name : rkcif
Card type : rkcif
Bus info : platform:rkcif_mipi_lvds
Driver version : 4.19.111
Capabilities : 0x84201000
Video Capture Multiplanar
Streaming
Extended Pix Format
Device Capabilities
Device Caps : 0x04201000
Video Capture Multiplanar
Streaming
Extended Pix Format
Media Driver Info:
Driver name : rkcif
Model : rkcif_mipi_lvds
Serial :
Bus info :
Media version : 4.19.111
Hardware revision: 0x00000000 (0)
Driver version : 4.19.111
Interface Info:
ID : 0x03000002
Type : V4L Video
Entity Info:
ID : 0x00000001 (1)
Name : stream_cif_mipi_id0
Function : V4L2 I/O
Pad 0x01000004 : 0: Sink
Link 0x02000024: from remote pad 0x1000013 of entity 'rockchip-mipi-csi2': Data, Enabled
Link 0x0200002c: from remote pad 0x1000014 of entity 'rockchip-mipi-csi2': Data
Link 0x02000034: from remote pad 0x1000015 of entity 'rockchip-mipi-csi2': Data
Link 0x0200003c: from remote pad 0x1000016 of entity 'rockchip-mipi-csi2': Data
Priority: 2
Format Video Capture Multiplanar:
Width/Height : 640/480
Pixel Format : 'NV12' (Y/CbCr 4:2:0)
Field : None
Number of planes : 1
Flags :
Colorspace : Default
Transfer Function : Default
YCbCr/HSV Encoding: Default
Quantization : Default
Plane 0 :
Bytes per Line : 640
Size Image : 460800
Crop Capability Video Capture:
Bounds : Left 0, Top 0, Width 2112, Height 1568
Default : Left 0, Top 0, Width 2112, Height 1568
Pixel Aspect: 1/1
Crop Capability Video Output:
Bounds : Left 0, Top 0, Width 0, Height 0
Default : Left 0, Top 0, Width 0, Height 0
Pixel Aspect: 1/1
Crop: Left 0, Top 0, Width 640, Height 480
Selection: crop, Left 0, Top 0, Width 640, Height 480, Flags:
Selection: crop_default, Left 0, Top 0, Width 640, Height 480, Flags:
Selection: crop_bounds, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: compose, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: compose_default, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: compose_bounds, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: compose_padded, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: native_size, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: crop, Left 0, Top 0, Width 640, Height 480, Flags:
Selection: crop_default, Left 0, Top 0, Width 640, Height 480, Flags:
Selection: crop_bounds, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: compose, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: compose_default, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: compose_bounds, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: compose_padded, Left 0, Top 0, Width 2112, Height 1568, Flags:
Selection: native_size, Left 0, Top 0, Width 2112, Height 1568, Flags:
User Controls
exposure 0x00980911 (int) : min=4 max=1660 step=1 default=1536 value=1536
Camera Controls
focus_absolute 0x009a090a (int) : min=0 max=64 step=1 default=64 value=64
Image Source Controls
vertical_blanking 0x009e0901 (int) : min=96 max=31199 step=1 default=96 value=96
horizontal_blanking 0x009e0902 (int) : min=2688 max=2688 step=1 default=2688 value=2688 flags=read-only
analogue_gain 0x009e0903 (int) : min=16 max=248 step=1 default=16 value=16
Image Processing Controls
link_frequency 0x009f0901 (intmenu): min=0 max=0 default=0 value=0 flags=read-only
pixel_rate 0x009f0902 (int64) : min=0 max=120000000 step=1 default=120000000 value=120000000 flags=read-only
test_pattern 0x009f0903 (menu) : min=0 max=4 default=0 value=0
[root@RV1126_RV1109:/]#
3.3获取指定设备的预览支持格式
命令:
v4l2-ctl --list-formats-ext --device /dev/video0
或者
v4l2-ctl --list-formats-ext -d /dev/video0
结果:
[root@RV1126_RV1109:/]# v4l2-ctl --list-formats-ext -d /dev/video0
ioctl: VIDIOC_ENUM_FMT
Type: Video Capture Multiplanar
[0]: 'NV16' (Y/CbCr 4:2:2)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[1]: 'NV61' (Y/CrCb 4:2:2)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[2]: 'NV12' (Y/CbCr 4:2:0)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[3]: 'NV21' (Y/CrCb 4:2:0)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[4]: 'YUYV' (YUYV 4:2:2)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[5]: 'YVYU' (YVYU 4:2:2)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[6]: 'UYVY' (UYVY 4:2:2)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[7]: 'VYUY' (VYUY 4:2:2)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[8]: 'RGB3' (24-bit RGB 8-8-8)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[9]: 'RGBP' (16-bit RGB 5-6-5)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[10]: 'BGRH' (18-bit BGRX 6-6-6-14)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[11]: 'RGGB' (8-bit Bayer RGRG/GBGB)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[12]: 'GRBG' (8-bit Bayer GRGR/BGBG)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[13]: 'GBRG' (8-bit Bayer GBGB/RGRG)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[14]: 'BA81' (8-bit Bayer BGBG/GRGR)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[15]: 'RG10' (10-bit Bayer RGRG/GBGB)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[16]: 'BA10' (10-bit Bayer GRGR/BGBG)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[17]: 'GB10' (10-bit Bayer GBGB/RGRG)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[18]: 'BG10' (10-bit Bayer BGBG/GRGR)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[19]: 'RG12' (12-bit Bayer RGRG/GBGB)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[20]: 'BA12' (12-bit Bayer GRGR/BGBG)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[21]: 'GB12' (12-bit Bayer GBGB/RGRG)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[22]: 'BG12' (12-bit Bayer BGBG/GRGR)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[23]: 'BYR2' (16-bit Bayer BGBG/GRGR)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[24]: 'Y16 ' (16-bit Greyscale)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[25]: 'GREY' (8-bit Greyscale)
Size: Stepwise 64x64 - 2112x1568 with step 8/8
[root@RV1126_RV1109:/]#
3.4获取摄像头参数
命令:
v4l2-ctl --list-ctrls --device /dev/video0
或者
v4l2-ctl -d /dev/video0 -l
结果:
[root@RV1126_RV1109:/]# v4l2-ctl -d /dev/video0 -l
User Controls
exposure 0x00980911 (int) : min=4 max=1660 step=1 default=1536 value=1536
Camera Controls
focus_absolute 0x009a090a (int) : min=0 max=64 step=1 default=64 value=64
Image Source Controls
vertical_blanking 0x009e0901 (int) : min=96 max=31199 step=1 default=96 value=96
horizontal_blanking 0x009e0902 (int) : min=2688 max=2688 step=1 default=2688 value=2688 flags=read-only
analogue_gain 0x009e0903 (int) : min=16 max=248 step=1 default=16 value=16
Image Processing Controls
link_frequency 0x009f0901 (intmenu): min=0 max=0 default=0 value=0 flags=read-only
pixel_rate 0x009f0902 (int64) : min=0 max=120000000 step=1 default=120000000 value=120000000 flags=read-only
test_pattern 0x009f0903 (menu) : min=0 max=4 default=0 value=0
[root@RV1126_RV1109:/]#
3.5增加曝光exposure
exposure值的区间从摄像头参数里面的MIN和MAX看,如上面显示信息,区间为: 4-1660
命令:
v4l2-ctl -d /dev/video0 --set-ctrl exposure=1660
结果:
[root@RV1126_RV1109:/]# v4l2-ctl -d /dev/video0 --set-ctrl exposure=3324
[root@RV1126_RV1109:/]# v4l2-ctl -d /dev/video0 -l
User Controls
exposure 0x00980911 (int) : min=4 max=1660 step=1 default=1536 value=1660
Camera Controls
focus_absolute 0x009a090a (int) : min=0 max=64 step=1 default=64 value=64
Image Source Controls
vertical_blanking 0x009e0901 (int) : min=96 max=31199 step=1 default=96 value=96
horizontal_blanking 0x009e0902 (int) : min=2688 max=2688 step=1 default=2688 value=2688 flags=read-only
analogue_gain 0x009e0903 (int) : min=16 max=248 step=1 default=16 value=16
Image Processing Controls
link_frequency 0x009f0901 (intmenu): min=0 max=0 default=0 value=0 flags=read-only
pixel_rate 0x009f0902 (int64) : min=0 max=120000000 step=1 default=120000000 value=120000000 flags=read-only
test_pattern 0x009f0903 (menu) : min=0 max=4 default=0 value=0
[root@RV1126_RV1109:/]#
exposure后面的value值改变了。
3.6增加图片亮度analogue_gain
analogue_gain用于设置显示的图像的亮度,值的范围也是从摄像头参数里面看,从摄像头参数看区间为:16-248
命令:
v4l2-ctl -d /dev/video1 --set-ctrl analogue_gain=240
结果:
[root@RV1126_RV1109:/]# v4l2-ctl -d /dev/video0 --set-ctrl analogue_gain=240
[root@RV1126_RV1109:/]# v4l2-ctl -d /dev/video0 -l
User Controls
exposure 0x00980911 (int) : min=4 max=1660 step=1 default=1536 value=1660
Camera Controls
focus_absolute 0x009a090a (int) : min=0 max=64 step=1 default=64 value=64
Image Source Controls
vertical_blanking 0x009e0901 (int) : min=96 max=31199 step=1 default=96 value=96
horizontal_blanking 0x009e0902 (int) : min=2688 max=2688 step=1 default=2688 value=2688 flags=read-only
analogue_gain 0x009e0903 (int) : min=16 max=248 step=1 default=16 value=240
Image Processing Controls
link_frequency 0x009f0901 (intmenu): min=0 max=0 default=0 value=0 flags=read-only
pixel_rate 0x009f0902 (int64) : min=0 max=120000000 step=1 default=120000000 value=120000000 flags=read-only
test_pattern 0x009f0903 (menu) : min=0 max=4 default=0 value=0
[root@RV1126_RV1109:/]#
analogue_gain=16 现象 :
analogue_gain=240 现象 :
3.7查看滤光器状态及控制滤光器开关
3.7.1查看滤光器状态
命令:
v4l2-ctl -d /dev/v4l-subdev4 --get-ctrl band_stop_filter
结果:
[root@RV1126_RV1109:/userdata]# v4l2-ctl -d /dev/v4l-subdev4 --get-ctrl band_stop_filter
band_stop_filter: 1
3.7.2控制滤光器开关
打开命令:
v4l2-ctl -d /dev/v4l-subdev4 --set-ctrl 'band_stop_filter=1'
关闭命令:
v4l2-ctl -d /dev/v4l-subdev4 --set-ctrl 'band_stop_filter=0'
3.8抓取yuv帧
命令:
v4l2-ctl -d /dev/video0 --set-fmt-video=width=1920,height=1080,pixelformat=NV12 --stream-mmap=3 --stream-to=./test-rv1126-4.yuv --stream-count=10 --stream-poll
结果:
[root@RV1126_RV1109:/userdata/share/rv1126-test/rkmedia-test]# v4l2-ctl -d /dev/video0 --set-fmt-video=width=1920,height=1080,pixelformat=NV12 --stream-mm
ap=3 --stream-to=./test-rv1126-4.yuv --stream-count=10 --stream-poll
<<<<<<<<<<
[root@RV1126_RV1109:/userdata/share/rv1126-test/rkmedia-test]#
参数说明:
-d: 摄像头对应设备文件
--set-fmt-video:指定了宽高及pxielformat(用FourCC表示)。NV12即用FourCC表示的pixelformat
--stream-mmap:指定buffer的类型为mmap,即由kernel分配的物理连续的或经过iommu映射的buffer
--stream-to:指定帧数据保存的文件路径
--stream-skip:指定丢弃(不保存到文件)前3帧
--stream-count:指定抓取的帧数,不包括--stream-skip丢弃的数量
其他参数
--set-selection,指定对输入图像进行裁剪。特别是当RKISP1的前级大小发生变化时要保证selection不大于前级输出大小。RKCIF的裁剪则是通过--set-crop参数设置的
--stream-poll,该选项指示v4l2-ctl采用异步IO,即在dqbuf前先用select等等帧数据完成,从而保证dqbuf不阻塞。否则dqbuf将会阻塞直到有数据帧到来
用ffmpeg播放抓取的yuv文件或者直接用pc的工具打开yuv文件,ffplay的命令:
ffplay out.yuv -f rawvideo -pixel_format nv12 -video_size 800x600
3.9测试显示信息test_pattern
参数test_pattern,可以用于切换摄像头的测试用的显示图像
- 0:摄像头
- 1-3 测试图片 命令实例:
命令:
v4l2-ctl -d /dev/video0 --set-ctrl test_pattern=0
不同值对应的测试图像:
test_pattern = 1 :
test_pattern = 2 :
test_pattern = 3 :
3.9获取摄像头捕获视频格式
命令:
v4l2-ctl -d /dev/video0 -V
结果:
[root@RV1126_RV1109:/userdata/share/rv1126-test/rkmedia-test]# v4l2-ctl -d /dev/video0 -V
Format Video Capture Multiplanar:
Width/Height : 1920/1080
Pixel Format : 'NV12' (Y/CbCr 4:2:0)
Field : None
Number of planes : 1
Flags :
Colorspace : Default
Transfer Function : Default
YCbCr/HSV Encoding: Default
Quantization : Default
Plane 0 :
Bytes per Line : 1920
Size Image : 3110400
[root@RV1126_RV1109:/userdata/share/rv1126-test/rkmedia-test]#
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