Yavta

简介

Yavta代表“另一个V4L2测试应用程序”。这是一个基于V4L2 Linux®内核接口的测试应用程序，它可以测试，调试和控制相机子系统。

如何使用Yavta

/usr/sbin # yavta --help
Usage: yavta [options] device
Supported options:
-c, --capture[=nframes]         Capture frames
-C, --check-overrun             Verify dequeued frames for buffer overrun
-d, --delay                     Delay (in ms) before requeuing buffers
-D, --display                   Display frames
-f, --format format             Set the video format
-F, --file[=name]               Read/write frames from/to disk
        For video capture devices, the first '#' character in the file name is
        expanded to the frame sequence number. The default file name is
        'frame-#.bin'.
-h, --help                      Show this help screen
-i, --input input               Select the video input
-I, --fill-frames               Fill frames with check pattern before queuing them
-l, --list-controls             List available controls
-n, --nbufs n                   Set the number of video buffers
-p, --pause                     Pause before starting the video stream
-q, --quality n                 MJPEG quality (0-100)
-r, --get-control ctrl          Get control 'ctrl'
-R, --realtime=[priority]       Enable realtime RR scheduling
-s, --size WxH                  Set the frame size
-t, --time-per-frame num/denom  Set the time per frame (eg. 1/25 = 25 fps)
-u, --userptr                   Use the user pointers streaming method
-w, --set-control 'ctrl value'  Set control 'ctrl' to 'value'
    --enum-formats              Enumerate formats
    --enum-inputs               Enumerate inputs
    --no-query                  Don't query capabilities on open
    --offset                    User pointer buffer offset from page start
    --requeue-last              Requeue the last buffers before streamoff
    --skip n                    Skip the first n frames
    --sleep-forever             Sleep forever after configuring the device
    --stride value              Line stride in bytes

使用示例

• 获取相机支持的 控制/格式/分辨率：

yavta -l --enum-formats --enum-inputs /dev/video0

Device /dev/video0 opened.
Device `STM32 Camera Memory Interface' on `platform:dcmi' is a video capture device.
--- Image Processing Controls (class 0x009f0001) ---
control 0x009f0903 `Test Pattern' min 0 max 1 step 1 default 0 current 1.
1 control found.
- Available formats:
        Format 0: RGB565 (50424752)
        Type: Video capture (1)
        Name: 16-bit RGB 5-6-5
        Frame size: 640x480 ()
        Frame size: 320x240 ()
        Frame size: 160x120 ()

- Available inputs:
        Input 0: Camera.

Video format: RGB565 (50424752) 160x120 (stride 320) buffer size 38400

• 捕获10帧数据到磁盘上（默认格式/分辨率）:

yavta -F /dev/video0 --capture=10

/usr/sbin # yavta -F /dev/video0 --capture=10
Device /dev/video0 opened.
Device `STM32 Camera Memory Interface' on `platform:dcmi' is a video capture device.
Video format: RGB565 (50424752) 160x120 (stride 320) buffer size 38400
8 buffers requested.
length: 38400 offset: 0
Buffer 0 mapped at address 0xc0710000.
length: 38400 offset: 40960
Buffer 1 mapped at address 0xc0720000.
length: 38400 offset: 81920
Buffer 2 mapped at address 0xc0730000.
length: 38400 offset: 122880
Buffer 3 mapped at address 0xc0740000.
length: 38400 offset: 163840
Buffer 4 mapped at address 0xc0750000.
length: 38400 offset: 204800
Buffer 5 mapped at address 0xc0760000.
length: 38400 offset: 245760
Buffer 6 mapped at address 0xc0770000.
length: 38400 offset: 286720
Buffer 7 mapped at address 0xc0780000.
0 (0) [-] 0 38400 bytes 1378.374325 1378.374535 17.819 fps
1 (1) [-] 1 38400 bytes 1378.407623 1378.407822 30.032 fps
2 (2) [-] 2 38400 bytes 1378.440939 1378.441111 30.016 fps
3 (3) [-] 3 38400 bytes 1378.474288 1378.474450 29.986 fps
4 (4) [-] 4 38400 bytes 1378.507624 1378.507827 29.998 fps
5 (5) [-] 5 38400 bytes 1378.540989 1378.541196 29.972 fps
6 (6) [-] 6 38400 bytes 1378.574288 1378.574489 30.031 fps
7 (7) [-] 7 38400 bytes 1378.607624 1378.607827 29.998 fps
8 (0) [-] 8 38400 bytes 1378.640959 1378.641162 29.999 fps
9 (1) [-] 9 38400 bytes 1378.674288 1378.674488 30.004 fps
Captured 10 frames in 0.356282 seconds (28.067590 fps, 1077795.461669 B/s).