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Semantic MediaWiki
There are 1 incomplete or pending task to finish installation of Semantic MediaWiki. An administrator or user with sufficient rights can complete it. This should be done before adding new data to avoid inconsistencies.1. Overview[edit source]
Yavta stands for "Yet Another V4L2 Test Application". This is a test application based on V4L2 Linux® kernel interface that allows testing, debugging and controlling camera subsystem.
2. How to use Yavta[edit source]
/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
3. Examples[edit source]
- Getting supported controls/formats/resolutions:
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
- Capturing 10 frames on the disk (default format/resolution):
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).