Alexander Bokovikov wrote:
> Hi,
>
> On December 24, 2009 at 1:09 PM Luca Abeni wrote:
>
>> - If you configure ffmpeg as LGPL, you have to distribute the sources
>> of the ffmpeg libraries and some binaries of your program which allow
>> to build the final application (plus makefiles and/or build scripts, if
> ^^^^^^^^^^^^^^^^^^
>> needed).
>
> I'm sorry for invasion into your discussion but I'd like to ask if I'm
> understanding LGPL correctly or not. AFAIU, "final application" in the
> quoted phrase means not a third-party application ("Application that
> uses the Library", according to LGPL 2.1), but just the LGPL'ed Library
> itself. For example, I'm writing a closed-source EXE which uses a DLL,
> built using the LGPL-ed code. In this case I must:
> - Provide the source code for LGPL-ed stuff, which DLL uses;
> - Provide the source code of the DLL itself, as it is also falls under
> LGPL;
> - Declare in my application the fact, that it uses LGPL-ed stuff
> - Provide a link to download the source code for DLL and the used stuff.
>
> These four steps make it possible to rebuild the LGPL'ed DLL
> independently from the closed-sourced application. The application
> itself may be provided in the binary form only, because (and as long as)
> it does not include any portion of the LGPL-ed code.
>
> GPL differs from LGPL, because it discuss not a "Library", but an
> "Application". Therefore GPL can't be applied to a DLL.
>
> Just would like to ensure myself that I'm understanding LGPL correctly.
> Am not I?
>
Nearly there, but not quite. You also need to provide enough of the
application for me to rebuild it to use the LGPL DLL I built, not the
LGPL DLL you built.
Lots of ways to do this, depending on platform:
*) Have a decent dynamic linker, so all I need do is replace your LGPL
DLL with my LGPL DLL, and your binary application picks up my code.
*) Provide your application as a partially linked object file, stripped
of everything bar the bits it needs to link to the LGPL DLL. I can then
link your bits together with my LGPL DLL build, and get a working
application.
*) Provide your application as source code, under a licence of your choice.
Other people may come up with more methods.
--
Simon Farnsworth
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