R: [GRASS-dev] GRASS FFMPEG support

[Hamish]

Benjamin:
> > Berkeley MPEG Encoder: This is a little utility (aka
> > ppmtompeg) used by r.out.mpeg to generate animated sequences of
> > raster maps.

I think the ppmtompeg version from NetPBM contains fixes and is better maintained than the Berkley mpeg_encode version, so NetPBM is preferred.

MPEG-1 is many years/generations old, out of date, and does a crappy job. MPEG-4 etc. do a much better job, in much less time, and into smaller files.

The only thing MPEG-1 has going for it is that it is in the public domain and there are no patent claims against it so it may be used with FOSS without worry. (even if there were I guess they would have expired by now)
I am no expert about this stuff, but even FOSS MPEG-4 codecs like Xvid, while "free" code themselves, could violate algorithm patents in places that recognize those. maybe the --gpl flag you used with ffmpeg tends to those issues?


Marco:
> I succesfully built ffmpeg with the current configuration:
...
> My current configure cuurently supports the following
> *mpeg* encoders:
> mpeg1video
> mpeg2video
> mpeg4
> msmpeg4v1
> msmpeg4v2
> msmpeg4v3
>
> are they enough for r.out.mpeg or does it mandatory need
> the Berkeley MPEG Encoder?

r.out.mpeg does not use FFMPEG. It relies on the ppmtompeg program which comes with NetPBM tools to do the encoding.


FFMPEG is only used in NVIZ to support automatic creation of movies from the keyframe animator, instead of just dumping the individual frames to a series of files which you would then feed into a movie encoder yourself.
It tries to do tricks like decide which encoder to use based on the file extension you use for the output file name. I would mention that this part of the NVIZ code is rather young and lightly tested.

If GRASS does not include FFMPEG it just means you need your own encoder to create the movies from the series of frame images instead of it happening automatically.


Hamish