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camv(1), nusb(4): add more details on camera operation

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qwx 2022-10-02 03:30:43 +00:00
parent 00d06ac617
commit 8237f8c583
2 changed files with 83 additions and 11 deletions
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51
sys/man/1/camv
View file

@ -1,16 +1,55 @@
.TH CAMV 1
.SH NAME
camv, camera display
camv \- USB camera display
.SH SYNOPSIS
.B camv cam-device
.B camv
.I cam-device
.SH DESCRIPTION
.I Camv
uses the underlying
uses the
.I cam-device
file system to start a graphical camera display stream.
file tree provided by
.IR nusb (4)
to use and control a USB camera.
It opens the tree's
.I video
file to play the video stream directly in the window.
.PP
The file system is initialized using nusb/cam (see nusb(4)).
The middle mouse button menu shows and allows editing the current picture settings.
While it lists resolution, format and framerate per second,
those must be set manually before starting
.IR camv (1).
One can quit the program from the right mouse button menu.
.SH EXAMPLES
Initialize and configure a camera before starting
.I camv
in its own window.
.IP
.EX
% nusb/cam 5
% window -dx 320 -dy 240 \\
'label cam
cat <<EOF >/dev/cam5.1/ctl
format 320x240
fps 30
backlight-compensation 1
brightness 20
contrast 95
saturation 40
sharpness 7
gamma 200
EOF
camv /dev/cam5.1
\'
.EE
.SH SOURCE
.B /sys/src/cmd/camv.c
.SH SEE ALSO
.SH "SEE ALSO"
.IR nusb (4)
.SH HISTORY
.I Camv
first appeared in 9front (March, 2018).
.SH BUGS
Not all available picture settings can be set while
.IR camv (1)
is running, some possibly not at all.

43
sys/man/4/nusb
View file

@ -271,11 +271,34 @@ compatible with
.IR audio (3).
.SS Camera devices
.I Cam
configures and manages a USB camera device.
It implements a file system (normally seen under
.BR /dev ),
compatible with
.IR camv (1).
configures and exposes a USB camera device's capabilities,
implementing a file system compatible with
.IR camv (1),
under a directory named
.BI cam N [. M ].
It provides the following files:
.BR desc ,
showing all of the device's internal descriptors and their values;
.BR format ,
listing admissible image resolutions and framerates;
.BR ctl ,
the picture settings control file;
.BR frame ,
which captures and outputs a single video frame as an
.IR image (6)
file;
and
.IR video ,
streaming video in a preset format, resolution and framerate.
In particular, reading from the
.B ctl
file yields a space-separated list of parameter settings,
where the second and third columns correspond to key-value pairs,
and an optional fourth column corresponds to the range of possible numerical values
(formatted as
.IR minimum / increment / maximum ).
The same pairs can be written to the file to configure the camera.
Currently, only the YUY2 video format is supported.
.SH SOURCE
.B /sys/src/cmd/nusb
.SH "SEE ALSO"
@ -288,11 +311,15 @@ compatible with
.IR uart (3),
.IR usb (3),
.IR shr (3),
.IR image (6),
.IR nusbrc (8),
.IR kbdfs (8)
.SH HISTORY
.I Joy
first appeared in 9front (March, 2014).
.br
.I Cam
first appeared in 9front (March, 2018).
.SH BUGS
The various device drivers are generic USB drivers and
may work only for certain devices of each class.
@ -307,3 +334,9 @@ and
signals and some of the extra features are not implemented.
For Ftdi, only the Sheevaplug and Guruplug have been tried.
There is support for the EHCI debug port, but it loses bytes.
.PP
USB video format settings cannot be changed while
.IR camv (1)
is running, and must be set manually by writing them to
.IR cam (4)'s ctl
file before starting the viewer.