[GRASS-dev] GRASS FFMPEG support

[Glynn Clements]

marco.pasetti at alice.it wrote:

> I'm building ffmpeg on windows through MinGW; standard build went
> succesfully, but I have some doubts: what does GRASS need to enable
> ffmpeg support in it?

You need to run configure with the --with-ffmpeg switch, and possibly
the --with-ffmpeg-includes= and/or --with-ffmpeg-libs= switches.

I would expect that you need --with-ffmpeg-includes=, as the headers
normally get installed into a subdirectory, but the headers don't
specify the subdirectory when they include each other.

> I built ffmpeg enabling shared and disabling static libraries, but
> enabling shared produces only libavutil, libavcodec and libavformat as
> DLLs, and not a ffmpeg DLL, as I roughly expected (I checked on the
> official ffmpeg web site, that's normal, there is any ffmpeg.dll
> mentioned)

That's correct (on Linux, I also have libpostproc, but that isn't
required by any of the other libraries).

Configure checks for the headers avcodec.h, avformat.h and swscale.h,
for the function avcodec_init with -lavcodec (and optionally
-lavutil), and for the function av_set_parameters with -lavformat (and
optionally -lavutil).

If using --with-ffmpeg results in configure errors, and you used any
necessary --with-ffmpeg-includes= and/or --with-ffmpeg-libs= switches,
then look in config.log for any error messages.

-- 
Glynn Clements <glynn at gclements.plus.com>