Table of Contents
Forevid is an open-source software for the forensic analysis of surveillance videos. Forevid offers you an extensive set of features required in your forensic case work, including e.g. various options for video playback, processing and result documentation. Forevid uses well-known Avisynth frameserver as its video processing backend.
You can use Forevid for different purposes. You can either use it as an intuitive and simple tool for previewing surveillance videos, or as an advanced tool for enhancing low quality videos, analyzing the events in videos and documenting your analysis results.
Forevid is developed at the Forensic laboratory of National Bureau of Investigation, Finland. The software is freely available under the terms of GNU General Public License.
The following list is a short overview of some of the features which Forevid offers you:
Project management. Each case is handled as a separate project, helping (and forcing) you to organize your work.
Extensive support for video formats and codecs. The software contains a built-in support for large amount of different video formats and codecs. Moreover, the support can be extended through the Microsoft DirectShow framework. If some videos are only playable with proprietary players, such videos can be imported using screen recording.
Video processing filters. With various filters for video processing, you can perform operations such as blocking artefact removal, deinterlacing, histogram enhancement, noise removal, resizing, sharpening, etc.
Many options for exporting. Still-images in various formats, as well re-encoded videos can be exported from the software. Moreover, with still-image editor, arrows, shapes, text etc. can be added to the images, or effects such as blurring, pixelation or spotlighting can be applied.
Documentation of analysis results. The most interesting frames of case videos can be bookmarked and annotated to better understanding of the events of interest.
Various other options, such as scripting interface, video editing, meta data viewing, hash calculation etc. are included.
First, download and run the Forevid installer. Thereafter, the installer will ask you to provide the location for installation, and copy necessary files to the given folder. If you don't have necessary rights to copy files to a given folder, the installation will fail. In addition, the installer will generate the Forevid project folder. Finally, a desktop icon is created for Forevid. Double-click the icon to start Forevid.
The software/hardware requirements for Forevid are:
Forevid manages investigated cases as projects. Every time an investigation of a new case is started, a new project needs to be created. This will help you to organize your case work. When the program is started, the project management window is displayed.
New project is created in the project management window. For each new project, a project name, description and author is given. Later on this information will be displayed for all you projects in the project management window. The projects create a folder structure, which root folder is displayed in Location. For this reason, the project name can only contain characters allowed in the Windows folder names. The location of your project root folder can be changed by pressing . After a new project is created, or and old project opened, the main window of Forevid is opened.
The project management window displays the list of all projects located under your project root folder. In addition, description of the project, amount of videos, last modification time and author for each project is displayed. Existing project can be opened by selecting the project name and pressing. Similarly, existing project can be deleted by pressing . When a project is removed, the project folder and all its contents are deleted permanently.
Figure 3.1. The main user interface for Forevid: (A) imported videos, (B) menus and toolbar, (C) bookmarks (D) video controls.
Forevid provides playback for videos stored with a variety of different containers and codecs. When importing a new video (→ or toolbar button) user can select one of the following methods for importing:
FFmpeg- Video is imported using the built-in FFmpeg library. The FFmpeg library supports an extensive amount of different container formats and codecs.
DirectShow- Video is imported using the Microsoft DirectShow framework . In order to successfully import the video, operating system needs to have the necessary DirectShow splitters and codecs installed.
Video for Windows- Video stored in AVI format is imported using Microsoft's legacy Video for Windows framework. In order to successfully import the video, the file needs to be in AVI format, and operating system needs to have necessary VfW codec installed.
Avisynth script- AviSynth script file is imported as a video.
Moreover, videos can be imported by dragging the video files directly from the Windows Explorer to the list of imported videos. In such case, the video is imported using the FFmpeg method. All imported videos are shown as icons at the Videos part. By default, the names of the imported videos are defined by the corresponding file names, but they can be modified by selecting→ . Renaming does not change the actual file name. If the actual video file needs to be accessed later on, → opens the folder where the file is located using Windows Explorer.
If for some reason, Forevid is not able to import the given video, an error dialog is displayed. By selecting FourCC code of the required codec can be identified.from the dialog, detailed information of the video file can be explored, and e.g. the
Sometimes surveillance videos are (unfortunately) stored in proprietary formats which can only played using proprietary players provided by the manufacturers. In such case, the video can be imported to Forevid using screen recording functionality which copies the frames that are displayed in the screen while playing the video with the proprietary player. Thereafter, new uncompressed video file is generated and imported to Forevid.
Screen recording is started by selecting→ . User can then define two recording parameters:
After the parameters are set and thebutton is pressed, a dashed rectangle is shown, which is used to define the area of recording. The recording is controlled with the following buttons:
Starts screen recording after three seconds. While recording it acts as a pause button.
Stops screen recording and returns to the previous dialog. After the dialog is closed, the new video is imported to the current project.
Selects the recording area based on the window below.
There are different options for video playback. The normal playback of the current video is started with the 2] A keyboard shortcut for the Play/Pause operation is spacebar. Playback rate can be modified by clicking with the right mouse button over the button, and selecting a new rate. When → is selected, the next video is automatically started when the current video is finished. With operations and , user can move forwards and backwards frame by frame.  Corresponding keyboard shortcuts are arrows to left and right.button, and video is displayed with the normal playback rate, from the current frame to the last frame of the video. [
If the video contains an event which somehow modifies the recorded scene (e.g. fire, explosion etc.), binary search based seeking can be used to locate this event. In case of a long video, this method can be significantly faster than the traditional seeking. The binary search based seeking proceeds by displaying the frame in the middle of the remaining video, if the event has already occured, then the seeking is repeated on the video between the previous displayed frame and the middle frame or, if the event has not occured, on the remaining video the right. The seeking is iteratively continued by each time decreasing the remaining video to the half. The seeking is started with Shift + right arrow and is iteratively continued by keeping Shift pressed and selecting the seeking direction with left and right arrows.
The displayed video can be zoomed temporarily with Z and X. In addition, the original size of the video can be restored with C.and buttons available in the toolbar. The corresponding keyboard shortcuts are
Figure 4.1. Information about the video file. For example, Codec ID reveals which decoder is required to play file.
 However, the performance of screen recording is dependent on the performance of your computer. Always verify that all relevant information was captured.
 However, depending on the performance level of the computer, resolution of the video, and applied video processing operations, the video may playback at a slower rate. p>
 If the used video codec does not provide frame accurate indexing, moving backwards may not be possible.
Various video processing operations can be applied to the imported videos. All processing is performed in the computer memory, leaving the original video untouched. Applied video processing operations generate a processing chain, which can be modified afterwards.
Video processing is controlled in the video processing window. By selecting→ (or corresponding toolbar button), a window is opened where the left paragraph displays available processing filters, and the right paragraph filters that have already been applied to the video (the processing chain). When a filter is added, a window is opened, where the parameters of the filter can be modified. When selecting , a preview of the video, processed with the given filter, is displayed. When the parameters are modified, button updates the preview of the video. When is pressed, the filter with given parameters is added to the processing chain. The last filter of the chain can be deleted with or its parameters modified with . In the main window. the effect of video processing can be visualized by displaying the original and modified video side-by-side. This is done by selecting → .
The filters are divided into four categories, according to their function: resize, enhance, deinterlace, and other. Following filters are currently available in Forevid 
PointResize- The simplest resizer possible. Resizing is done using the Nearest Neighbour algorithm, which usually results in a very blocky image.
BilinearResize- Resizes the input video frames to an arbitrary new resolution using bilinear filtering.
BicubicResize- Similar to BilinearResize, except that instead of a linear filtering function the Mitchell-Netravali two-part cubic function is used. The parameters b and c can be used to adjust the properties of the cubic (sometimes referred to as "blurring" and "ringing" respectively).
Lanczos4Resize- Alternative to BicubicResize which produces quite strong sharpening. It usually offers better quality (fewer artifacts) and a sharp image.
Spline36Resize- Spline based resizer using 6 sample points.
Sharpen- Sharpens the video frames. The parameter controls the amount of sharpening applied.
Blur- Blur the video frames. The parameter controls the amount of blurring applied.
Deblock- Deblock the video frames. Parameter quant controls the strenth of deblocking. Parameter aOffset controls the blocking detector threshold. Higher the value, more edges are deblocked. bOffset is another parameter for controlling block detecting and for deblocking strength.
SpatialSoften- Remove noise from video frames by selectively blending pixels. Filter replaces each sample in a frame with the average of all nearby samples with differ from the central sample by no more than a certain threshold value. The size of filtering area is defined by the parameter radius, and thresholds separately for luma luma_threshold and chroma chroma_threshold.
TemporalSoften- Works similarly as SpatialSoften, except the pixels are searched in nearby frames, instead of nearby pixels in the same frame.
Levels- Adjust brightness, contrast, and gamma of the video. Parameters low and high determine what input pixel values are treated as pure black and pure white. To help selecting correct values, image histogram is displayed next to parameters. Parameter gamma adjusts the relative proportions of bright and dark areas in the video frames.
Invert- Invert the colors of the video.
SeparateFields- Takes a frame-based clip and splits each frame into its component fields, producing a new clip with twice the frame rate and twice the frame count.
ComplementParity- If the input clip is field-based, ComplementParity changes top fields to bottom fields and vice-versa.
Bob- Takes a clip and bob-deinterlaces it. This means that it enlarges each field into its own frame by interpolating between the lines. The top fields are nudged up a little bit compared with the bottom fields, so the picture will not actually appear to bob up and down.
TurnLeft- Rotates the video 90 degrees counter-clockwise,
TurnRight- Rotates the video 90 degrees clockwise.
Turn180- Rotates the video 180 degrees.
Reverse- Makes the video play in reverse.
FlipVertical- Flips the video upside-down.
FlipHorizontal- Flips the video from left to right.
ShowRed- Displays the red channel of the video.
ShowGreen- Displays the green channel of the video.
ShowBlue- Displays the blue channel of the video.
AssumeFPS- Changes video playback speed by assuming a given frame rate.
Loop- Loops the video given amount of times.
 Filter descriptions are adopted from www.avisynth.org.
Documentation of analysis results is an essential part of every case. In Forevid, you can document your results by exporting still-images and re-encoded videos, or by generating bookmarks and PDF-reports. Each project has its own export folder, where all material is stored by default. The export folder can be accessed by selecting→ (or with corresponding toolbar button).
The location of most interesting frames can be stored with bookmarks. A bookmark is created by selecting 5] Bookmarks and their descriptions can be stored as a PDF report by selecting → → . Before generation of the PDF file, the details of the report, and the location of the file can be modified. Since there is a possibility for inaccurate bookmarks, it is recommended to test the accuracy of bookmarks before creating the PDF file.→ (or with toolbar button). This will create a bookmark pointing to the location of the current frame. In addition, a written description for the frame can be added. All bookmarks are shown on the bookmark list. When clicking a bookmark, the bookmarked frame is displayed. [
Still-images can be generated in different ways. First, the most straightforward way to store an interesting frame is to press the record button (video controls part of the main window). It is a shortcut operation which automatically saves a still-image to the export folder in a predefined format. The naming convention and image format for this option can be modified by selecting→ . Second, the current frame can be exported to clipboard by selecting → → . All bookmarks can be stored as still-images by selecting → → . Finally, a set of consecutive frames can be saved by selecting a part of video timeline and selecting → → .
Before saving the selected frame as an image, it can be edited. This is done by selecting Figure 6.2. The resulting image can be either saved as an image or copied to the clipboard.→ → . Thereafter, the current frame is opened in the image editor as shown in
Below the main functionality of the image editor is described:
Zooms the image for visualization purposes. Does not change the size of the resulting image.
Scales the image with a given amount. Scaling can be done freely in both horizontal and vertical directions, or by preserving a certain aspect ratio.
Changes the size and color of the underlying image canvas. This operation can be used to add borders around the original image.
Crops the image to a given size. The area of cropping is selected by changing the size of highlighted area over the image.
Adds rectangular, square, elliptical or circular objects to the image. In addition to the shape, color and opacity of the objects can be controlled.
Similar as the previous operation, except the objects contain only borders. In addition, the border width and style can be selected.
Adds lines with or without arrow head to the image. Color, width and style of the lines can be selected.
Adds text with given font, font size, font color and opacity to the image.
Blurs rectangular, square, elliptical or circular part of the image. The amount of blurring can be controlled.
Similar as the previous operation, except instead of the blurring, the resolution under selected area is decreased.
Similar as blurring or pixelation operations, except the brightness or contrast of the selected area is modified.
Adds given watermark to the image. Watermark is given as an image file and the opacity of the image is modified.
Modified videos videos can be exported as re-encoded videos by x264 encoder which is a state-of-the-art encoder for H.264/MPEG-4 AVC compression. The encoding parameters are defined by selecting one of the pre-defined setting profiles from the list. Available containers for the encoded videos are Matroska (mkv), MPEG-4 Part 14 (mp4) and Flash (flv). In addition, the encoded video can be exported wrapped inside a self extracting video player (SFX Player), which automatically plays the included video.→ → . The encoding is done using
Figure 6.3. When exporting videos wrapped inside the self extracting video player, the sharing of exported videos becomes more straightforward.
 Bookmark might not point to the correct frame, if the used codec does not support indexing
This section describes some miscellaneous features of Forevid.
Although Forevid is not intended for video editing, it offers some simple editing operations. For example, you can remove part of the video, by selecting the area to be removed and pressingbutton. After the part is removed, the cut operation will part of the processing pipeline ( → ), from where the operation can be canceled.
Videos can be merged together by selecting Source list to the timeline. Currently, only videos which share the same resolution and frame rate can be added together.→ . The merging is done by adding the videos from the
Simple title clips can be created by selecting. A title clip is a clip, for which you can define the title (text, color, size), type (blank, colorbars) and duration. In addition, a template clip needs to be defined for each title clip. Title clip's resolution and frame rate will be based on the template.
Hash value can be used to verify that a video file has not changed (since the previous calculation of the hash). You can calculate the hash for a given video file by selecting Given value field, select hash algorithm and press . The Result field will tell if the values match.→ . Thereafter, paste the previous hash value to the
 Avisynth. http://avisynth.org .
 Binary search. http://en.wikipedia.org/wiki/Binary_search_algorithm .
 DirectShow. http://en.wikipedia.org/wiki/DirectShow .
 FFmpeg. http://www.ffmpeg.org .
 FourCC. http://en.wikipedia.org/wiki/FourCC .
 Video for Windows. http://en.wikipedia.org/wiki/Video_for_Windows .
 x264 - a free h264/avc encoder. http://www.videolan.org/developers/x264.html .
Version 2, June 1991
Copyright © 1989, 1991 Free Software Foundation, Inc.
Version 2, June 1991
GNU General Public License
The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software - to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too.
When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.
We protect your rights with two steps:
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offer you this license which gives you legal permission to copy, distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations.
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The precise terms and conditions for copying, distribution and modification follow.
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The “Program”, below, refers to any such program or work, and a “work based on the Program” means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term “modification”.) Each licensee is addressed as “you”.
Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does.
1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program.
You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee.
2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:
You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change.
You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.
If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: If the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.)
These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.
Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program.
In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License.
3. You may copy and distribute the Program (or a work based on it, under Section 2 in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following:
Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,
Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,
Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.)
The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable.
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4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.
5. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it.
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This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License.
8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License.
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Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and “any later version”, you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation.
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END OF TERMS AND CONDITIONS
How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
<one line to give the program's name and a brief idea of what it does.> Copyright (C) <year> <name of author>
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
Also add information on how to contact you by electronic and paper mail.
If the program is interactive, make it output a short notice like this when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) year name of author Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type “show w”. This is free software, and you are welcome to redistribute it under certain conditions; type “show c” for details.
The hypothetical commands “show w” and “show c” should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than “show w” and “show c”; they could even be mouse-clicks or menu items--whatever suits your program.
You should also get your employer (if you work as a programmer) or your school, if any, to sign a “copyright disclaimer” for the program, if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the program “Gnomovision” (which makes passes at compilers) written by James Hacker.
<signature of Ty Coon>, 1 April 1989 Ty Coon, President of Vice
This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Library General Public License instead of this License.