[MEncoder-users] PNGs from POV-Ray and stdin

[Rich Felker]

On Thu, Jan 10, 2008 at 07:17:05PM +0100, Nicolas George wrote:
> Le decadi 20 nivôse, an CCXVI, Rich Felker a écrit :
> > Yes, concatenating a sequence of png files is not valid or reasonable
> > though. Try using ppm and ffmpeg's pnmpipe input. (There's absolutely
> > no need for mencoder here; just use ffmpeg.)
> 
> I concur, PPM is the best format in this case. There is no need to waste
> time compressing and then decompressing PNG.
> 
> In the case of POV-Ray, there is another difficulty: POV-Ray is not able to
> output to a pipe. More precisely, it can write a single frame to stdout, but
> for an animation, it closes stdout after the first frame, and then fails to
> write the next ones.
> 
> I managed to work around this with a pre-frame and post-frame script which
> creates and removes FIFO as needed. That is ugly.

It's not this difficult. Just use a single FIFO and keep it open for
writing by a second process that will never write anything, e.g.
cat>fifo in another terminal. This will prevent the reading end from
getting EOF each time povray closes and reopens the fifo.

Rich