pjWebCam Documentation
Version 1.2a

Overview

pjWebCam is a simple application to enable a windows video capture device to be accessed across an intranet or internet.

The latest version of pjWebCam can be found at http://www.homeusers.prestel.co.uk/cherryjam/utilities.html

Features

HTTP Server.

This turns the machine that the camera is attached to into an HTTP (web) server. This responds to blank http requests by sending the current image from the camera.

Optionally a refresh interval can be configured, which will cause some browsers to effect a "client pull" on the image at the selected interval.

FTP Client.

Each time an image is captured (at the end of each capture interval, or as a result of the user pressing the take button) the Image can be uploaded to an FTP server.

Local Save.

Each time an image is captured (at the end of each capture interval, or as a result of the user pressing the take button) the Image can be saved locally. Incremental filenames are not currently supported.

Captioned Images.

Captured images can be captioned. This caption uses a user defined, font, colors and message which can use escape sequences to include time strings (using standard C strftime escapes), using the host machines current locale settings.

Overlayed Images.

A Bitmap file can be superimposed on the captured image. This can be used to display a logo or other image on top of the capture.

Image Processing.

The captured image can be processed before being displayed. Processing options include, blur, sharpen, negative, edge detect.

Multiple Configurations.

Multiple configurations can be stored. This allows simultaneous use of multiple cameras, or simultaneous use of the same camera using different settings, for example ftp'ing captured images at different rates to different locations. The configuration can be specified by name as a command line parameter, so shortcuts can be setup to start pjWebCam with different configurations.

Multiple instances of pjWebCam running the same configuration aren't allowed. If a second instance of pjWebCam is started with the same configuration as an already running instance then you are prompted for different a configuration name.

Configuration

Named configurations are stored beneath that key, so a configuration foobar would be stored in the key HKEY_CURRENT_USER\Software\Pacaro\pjWebCam\foobar

Banners

If you use pjWebCam on your site you might want to link back to my website. I have provided a couple of banners that you can use. The following html will link back to the pjWebCam homepage.

<a href="http://www.homeusers.prestel.co.uk/cherryjam/utilities.html">
<img src=pjWebCam.banner.jpg 
     width=256 height=64 border=0
     alt="Powered by pjWebCam"></a>

This Banner is provided in three sizes...

Normal
Small
Tiny

Any suggestions for better banners will be gratefully recieved!

Legal Information

This program is copyright © Paul Roberts 1998 - 2000.

This program is based in part on the work of the Independent Jpeg Group

This program is licensed free of charge and can be freely distributed provided this file is distributed with it and that there are no charges beyond those necessary for administrative purposes.

BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

I Wrote This

I Welcome your input and constructive criticism but may not have time to respond.

Changes

Version 1.2a - 23 June 2000

Version 1.2 - 27 January 1999

Version 1.1b - 5 January 1999

Version 1.1a - 2 January 1999

Version 1.1 - 18 September 1998

Version 1.0d - 28 July 1998

Version 1.0c - 23 June 1998

Version 1.0b - 4 June 1998

Version 1.0a - 13 May 1998

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Capture Settings

Capture Interval

This is the number of interval units between captures.

Interval Units

This is the units to use for counting capture intervals, options are...

• Seconds
• Minutes
• Hours
• Days
• Weeks

Time Remaining

This displays the amount of time remaining until the next automatic capture.

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Video Settings

Capture Device

This is the video capture device that pjWebCam is currently using.

Preview Video

If this button is selected a video capture preview is displayed.

Source

Adjust settings for the video source.

Format

Adjust video format options.

Display

Adjust video display options.

Quality

This specifies the "quality" setting to be used when encoding the jpeg file. This is a value between 0 and 100 where 0 represents the lowest quality (best compression) and 100 the highest quality (least compression). The table shows the effects on file size of 5 different quality settings.

Quality	Size in k	Image
0	3
25	7
50	9
75	13
100	60

Details

This shows a summary of the current image capture options.

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HTTP Server

Enable HTTP

If this is checked then pjWebCam operates as a simple HTTP server. Using the port number etc. specified in the http settings dialog.

HTTP Settings

This opens the http settings dialog.

HTTP Settings Dialog

Port Number

This specifies the port number that the http server listens on. The default port for http is 80, a common alternative (to avoid clashing with another webserver on the same address, or to avoid using a privilidged port) is 8080.

Client Pull Refresh

If this is checked then the server will send and Http header asking the web client to perform a client pull after the time specified by the refresh interval.

Refresh Interval

This is the number of seconds the client should wait before performing a client pull.

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FTP Settings

Enable FTP

If this is checked then each time pjWebCam captures and image it is uploaded to the ftp server specified in the ftp settings dialog.

FTP Settings

This opens the ftp settings dialog.

FTP Settings Dialog

Username

This specifies the username to use when logging on to the ftp server.

Password

This specifies the password to use when logging on to the ftp server. The password is stored (like all other pjWebCam configuration information) in the registry. It is encrypted using a relatively simple encryption mechanism. There is a potential security risk. If someone has access to your registry they could break the encryption, given sufficient time and expertise, thus giving them access to your ftp account.

Account

This specifies an account name to connect to the ftp server with. This is not tested because i couldn't find an FTP server that uses this facility. The likelyhood is that you will not need to enter anything in this box.

Server

This is the internet address of your ftp server.

Directory

This is the subdirectory on that server that you wish to store the image file in.

Filename

This is the filename that you wish to store.

Passive Mode

If this is checked then the image file is ftp'd to the server in passive(PASV) mode. An ftp session consists of 2 TCP/IP connectections between the clent and the server. A control connection created from the client to the server, this is used to send control messages to the server, and a data connection (used to send and recieve data). Normally the server connects to the client to create the data connection, in passive mode this is reversed. This can be helpful for ftp'ing through some firewalls.

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Caption Settings

Caption Image

If this is checked then any captured image has a caption using the settings specified in the caption settings dialog.

Overlay and Caption Settings

This opens the overlay and caption settings dialog.

Overlay and Caption Settings Dialog

Caption

This specifies the string to be used as a caption. The following escapes are used to insert date and time information into the string.

Escape	Meaning
%a	Abbreviated weekday name
%A	Full weekday name
%b	Abbreviated month name
%B	Full month name
%c	Date and time representation, appropriate for locale
%d	Day of month as decimal number (01 - 31)
%H	Hour in 24-hour format (00 - 23)
%I	Hour in 12-hour format (01 - 12)
%j	Day of year as decimal number (001 - 366)
%m	Month as decimal number (01 - 12)
%M	Minute as decimal number (00 - 59)
%p	Current locale's A.M./P.M. indicator for 12-hour clock
%S	Second as decimal number (00 - 59)
%U	Week of year as decimal number, with Sunday as first day of week (00 - 51)
%w	Weekday as decimal number (0 - 6; Sunday is 0)
%W	Week of year as decimal number, with Monday as first day of week (00 - 51)
%x	Date representation for current locale
%X	Time representation for current locale
%y	Year without century, as decimal number (00 - 99)
%Y	Year with century, as decimal number
%z, %Z	Time-zone name or abbreviation; no characters if time zone is unknown
%%	Percent sign

A flag # can be inserted in any escape, changing the meanings as follows

Escape	Meaning
%#a, %#A, %#b, %#B, %#p, %#X, %#z, %#Z, %#%	# flag is ignored
%#c	Long date and time representation, appropriate for locale.
%#x	Long date representation for current locale
%#d, %#H, %#I, %#j, %#m, %#M, %#S, %#U, %#w, %#W, %#y, %#Y	removes leading zeros (if any)

Vertical Position

Specifies the vertical position of the caption.

Horizontal Position

Specifies the horizontal position of the caption.

Transparent

If this is checked then the Caption is drawn onto the image transparantly, other wise the text is drawn in a box.

Caption Font

Clicking this button allows you to select a caption font.

Foreground Colour

Clicking this button allows you to select the foreground colour of the caption.

Background Colour

Clicking this button allows you to select the background colour of the caption. This is the colour of the box that the text is drawn onto unless transparent is selected, in which case this is used as the outline colour for the text.

Swap Colours

Clicking this button exchanges the current foreground and baground colours.

Image Processing

This combo box allows the selection of image processing. Available options are

• Blur
• Sharpen
• Sharpen More
• Edge Detect
• Trace Contours
• Negative

Use Overlay

If this is selected then an overlay image will be used

Bitmap

This is the name of the bitmap file to be used as an overlay image

Bitmap browse

This allows you to browse for a bitmap file

Overlay Method

This is the method used to overlay the bitmap on the captured image. The available methods are

Average

This averages the pixels in the captured and overlay images.

Difference

This subtracts the pixels in the captured image from the overlay image and offsets the result by 128

Distance

This calculates the linear distance in color space of the pixels.

Interlace

This alternates lines from the two images.

Alternate

This alternates pixels from the two images

Add

This adds the pixels from the two images.

Subtract

This subtracts the source pixels from the overlay pixels.

Multiply

This multiplies the pixel values and divides by 256.

TL Transparent

Treats the colour of the top left pixel in the overlay image as a transparent colour.

Overlay Position

Caption Preview

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File Settings

Save File

If this is checked then the captured image is saved locally.

Filename

This is the filename of the image to save.

Browse

This button allows you to browse for a filename to save as.

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Other

Progress Indicator

This shows an indication of outstanding file transfers.

Take

This button causes a capture to happen immediately, resetting the timer.

About

Displays copyright information about pjWebCam.

Exit

Closes pjWebCam.

log - checkbox

The state of this checkbox determines whether or not actions are logged to the listbox.

log - listbox

This shows a log of actions in the current session, if loggin is enabled.