[Libav-user] reduce dll size

Alex Cohn alexcohn at netvision.net.il
Tue Mar 25 08:51:55 CET 2014

On Tue, Mar 25, 2014 at 4:40 AM, YIRAN LI <mrfun.china at gmail.com> wrote:
> > I'm trying to build all components into one dll, because my manager
> > insisted that building into a single dll may save space by avoiding
> > build duplicated code into separate dlls.
> How is this supposed to work?
> Or, to rephrase: What are the duplicated code parts that you found
> in different FFmpeg dlls and how much (in %) did they take of the
> overall space?
> >> Hi Carl,
> I found that every dll links to libm, if it's a static lib (I can only find .a on my system), does that mean
> some code will be built into every dll?

Yes, there definitely is some amount of duplication with multiple
DLLs. You can easily find the amount of overhead, in a supported way.
Build your project with static version of ffmpeg libraries, and
compare the size of your binary with the size of binary you have now
(which is built with libavcodec.dll, libavformat.dll, etc.). For the
latter, sum up all the DLLs that you need to deploy.

If you find that the difference is significant for your project, only
then it's worthwhile to work on reducing the size of DLLs or the
amount of code duplication.

As CameraMan mentioned above, the monolithic binary may require
special considerations re ffmpeg license, but again, it would be wise
to delay these discussions until you have an evidence that the simple
way (with multiple DLLs) can be shrinked down significantly.

Alex Cohn

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