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Man Pages


Manual Reference Pages  -  PWCVIEW (1)

NAME

pwcview - view video, create jpeg snapshots and alter settings of a webcam controlled by the pwc(4) driver.

CONTENTS

Synopsis
Description
Command Line Options
Motion Detection
Keyboard Controls
Menu System
Videodisplay
Examples
See Also
Copyright

SYNOPSIS

pwcview [options]

DESCRIPTION

The pwcview utility is used to view the video, create jpeg snapshots, and alter the settings of a webcam controlled by the pwc(4) driver.

COMMAND LINE OPTIONS

General options:

-? Display help message
-h Run pwcview in headless mode (without the gui)
-p Enable webcam snapshot button (only works with the FreeBSD pwc driver and not with all cameras)
-k Add time date string to picture.

Device options:

-d device Selects the video device to open. The default is /dev/video0
-s size Sets the webcam’s video size. The default is sif. Can be one of ’sqcif’, ’qsif’, ’qcif’, ’sif’, ’cif’ or ’vga’, for an image size of resp. 128x96, 160x120, 176x144,320x240, 352x288 and 640x480 (of course, only for those cameras that support these resolutions).
-f fps Sets the webcam’s frame rate. The default is 5. Should be in the range of 5-30.

JPEG output options:

-c count Number of automatic jpeg snapshots to take. Set this to -1 for unlimited automatic jpeg snapshots. The default is 0
-i interval Automatic jpeg snapshot interval in milliseconds. The default is 3000
-q quality Quality of jpeg output images, range 0-100. The default is 75
-o outfile Filename of the jpeg output images. This is a string that is passed to the strftime(3) function and thus can contain the format specifiers as documented in the strftime(3) man page. The default is /tmp/%Y%m%d%H%M%S.jpg
-e command Command to execute after each jpeg snapshot. This command will be executed with the filename of the jpeg image as it’s only command line argument. If you want to execute a command that requires multiple arguments, you can create a wrapper shell script. The default is not to execute any command.

Motion detection options:

-r Enable motion detection recording. When this option is specified pwcview will write all raw YUV420P frames that have a number of blocks with motion in them that is higher than threshold to stdout. For this option to work you must redirect stdout to a file or pipe it to another command (e.g.
.Cd mencoder )
-m Show detected motion. When this option is specified the regions in the picture in which motion is detected are displayed in negative.
-j command Command to execute when motion is detected. The default is not to execute any command.
-g interval Minimum time in seconds between motion commands. The default is 60 seconds.
-u sensitivity Motion detection sensitivity. The lower you set this the more sensitive. The default is 1000.
-t threshold Motion detection threshold. The number of blocks (a block is 8x8 pixels) that must have motion in them before any of the actions motion record, motion fullscreen or motion beep is taken. The default is 1.
-l frames Recording margin. The number of extra frames that are written to stdout after the last frame that had motion in it. The default is 15.

Video display options:

-x Create window without frame
-y Use IYUV overlay instead of YV12 overlay
-z Create the video surface in system memory (SDL_SWSURFACE)
-a Always use video surface (SDL_ANYFORMAT)
-b bpp Bits per pixel to setup video surface with. The default is 0, which means to use the current display bits per pixel.

MOTION DETECTION

pwcview can also detect motion in the webcam’s image and write the frames with motion in them to stdout so you can for example encode them with
.Cd mencoder to MPEG4.

Sometimes it can be useful to exclude some areas in the picture from motion detection. With pwcview you can use the m key to enter motion mask editing mode. In motion mask editing mode you can add areas to exclude from motion detection with the mouse. In motion mask editing mode masked areas are displayed in negative.

To add an area to the motion mask: move the mouse pointer to the top left position of the area that you want to exclude and left click then move your mouse pointer to the bottom right position of the area that you want to exclude and left click again. You can repeat this as many times as you want.

To remove areas from the motion mask do the same but this time use the right mouse button. To clear the entire mask press the middle mouse button.

You can save the motion mask with the w key. Each time pwcview starts it will look for the mask file in the current directory and automatically load it.

To leave motion mask editing mode press the m key again.

KEYBOARD CONTROLS

Besides the keys used for the menu system the following keys can be used:

f Toggle fullscreen mode.
p Take a manual jpeg snapshot.
q Quit the application.
m Enter/leave motion mask editing mode.
w Saves motion mask to pwcview.msk in current directory.
space Freeze/unfreeze picture.

MENU SYSTEM

With pwcview you can alter various settings of your webcam. It provides a menu like structure where you specify what setting you want to alter with the up arrow and down arrow. The current menu item and thus the setting to alter will then be displayed in the title bar.

The following settings of the webcam can be altered:

framerate Use the left arrow and right arrow to change the webcam’s frame rate.
brightness Use the left arrow and right arrow to change the webcam’s brightness.
contrast Use the left arrow and right arrow to change the webcam’s contrast.
saturation Use the left arrow and right arrow to change the webcam’s saturation.
gamma Use the left arrow and right arrow to change the webcam’s gamma.
gain control Use the enter key to switch between auto and manual gain control. Use the left arrow and right arrow in manual mode to change the webcam’s gain control.
shutter speed Use the enter key to switch between auto and manual shutter speed. Use the left arrow and right arrow in manual mode to change the webcam’s shutter speed.
white balance Use the enter key to switch between auto, manual, indoor, outdoor and fluorescent white balance. Use the left arrow and right arrow in manual mode to change the webcam’s red gain and blue gain.
contour Use the enter key to switch between auto and manual contour. Use the left arrow and right arrow in manual mode to change the webcam’s contour.
dnr mode Use the enter key to switch between the webcam’s various modes of dynamic noise reduction.
backlight compensation
  Use the enter key to switch the webcam’s backlight compensation on/off.
anti flicker mode
  Use the enter key to switch the webcam’s anti flicker mode on/off.
color mode Use the enter key to switch the webcam to color or black and white mode (FreeBSD only)
compression Use the left arrow and right arrow to change the webcam’s compression level.
save user settings
  Use the enter key to save the current webcam settings to the webcam’s EEPROM.
restore user settings
  Use the enter key to load the current webcam settings from the webcam’s EEPROM.
restore factory settings
  Use the enter key to load the current webcam settings from the factory defaults.
led on Use the left arrow and right arrow to change the webcam’s led on time.
led off Use the left arrow and right arrow to change the webcam’s led off time.

The following settings of pwcview can be altered:

time date string
  Use the enter key to toggle the addition of a time date string to the picture. (command line equivalent -k)
scaling Use the enter key to switch between none, double and full scaling.
motion record Use the enter key to enable/disable motion recording (command line equivalent -r)
motion fullscreen
  Use the enter key to enable/disable going to full screen mode when motion is detected.
motion beep Use the enter key to enable/disable the speaker beep when motion is detected.
motion show Use the enter key to toggle the display of motion in negative (command line equivalent -m)
motion command interval
  Use the left arrow and right arrow to change the motion command interval (command line equivelant -g)
motion sensitivity
  Use the left arrow and right arrow to change the motion detection sensitivity (command line equivalent -u)
motion threshold
  Use the left arrow and right arrow to change the motion detection threshold (command line equivalent -t)
recording margin
  Use the left arrow and right arrow to change the recording margin (command line equivalent -l)

VIDEODISPLAY

pwcview uses the SDL library to display the video of your webcam. The default video mode used by pwcview is in general the most efficient, but this is very much dependent on the capabilities of your video card. If it doesn’t quite work the way you want it to, you can tune the video settings with any of the command line options listed in the "Video display options" section at the beginning of this man page. See the SDL_SetVideoMode(3) man page for exact details.

EXAMPLES

Set the webcam to vga mode at 15 fps and execute the firefox command whenever a jpeg snapshot is taken:


.Cd pwcview -s vga -f 15 -e firefox

Take one automatic jpeg snapshot image using the default sif resolution, save it as foo.jpg and then exit:


.Cd pwcview -h -c 1 -o foo.jpg

Run pwcview in headless mode with the webcam set to 320x240@15fps, add a time date string to the picture, write the frames in which motion is detected to stdout and encode them with mencoder to motion.avi:


.Cd pwcview -hkr -s sif -f 15 | mencoder -demuxer rawvideo -rawvideo fps=15:w=320:h=240:i420 - -ovc lavc -lavcopts vcodec=mpeg4 -o motion.avi

SEE ALSO

The Linux PWC Documentation Project:

pwc(4), SDL_SetVideoMode(3), strftime(3)

COPYRIGHT

This is free software licensed under the GPLv2; There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Copyright (C) 2006-2007 Raaf

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