I want to use portions of code from the FFMPEG library to provide screen capture function for a commercial application I'm writing. I do understand I need to make a shared library out of the function or it'll make the entirety of our application LGPL, fair enough. The library part will be LGPL with the usual LGPL 2.1 notices and source code availability.
After I'm done chopping the function(s) to suit my use case, it will not really function in a meaningful way in the context of the FFmpeg anymore. I want a series of discrete bitmaps for processing display contents, not a constant video stream that will be encoded or displayed. So it probably does not make sense to provide it as a contribution to the FFmpeg project.
What should I exactly write in the copyright notice? The original says
/* * XCB input grabber * Copyright (C) 2014 Luca Barbato <firstname.lastname@example.org> * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version.
In my derived source code I should keep Luca's copyright line as-is and add mine under it? I change the "FFmpeg" to say "MyExcellentScreenCaptureLibrary" and add a note somewhere saying this is based on the FFmpeg XCB input grabber code?