ismindex: Allow adding a path prefix to the generated .ism file

This allows storing the .ismv/.isma/.ismc files separately from
the .ism file on a server, without having to manually edit the
.ism file after generating it with the ismindex tool.

Signed-off-by: Martin Storsjö <martin@martin.st>
ismindex: Add an option for outputting files elsewhere than in the current directory

Signed-off-by: Martin Storsjö <martin@martin.st>
daud: split muxer and demuxer

Signed-off-by: Diego Biurrun <diego@biurrun.de>
Merge commit '6bc4934b75dde9354ee16a6e700ebe6775abf69e'

* commit '6bc4934b75dde9354ee16a6e700ebe6775abf69e':
  ismindex: Allow adding a path prefix to the generated .ism file

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'f920d089535bf7cf10aeda900cc43201c5e18cd0'

* commit 'f920d089535bf7cf10aeda900cc43201c5e18cd0':
  ismindex: Add an option for outputting files elsewhere than in the current directory

Conflicts:
	tools/ismindex.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '0955e57ad07640574fc20ce0bea3c0b83982ada1'

* commit '0955e57ad07640574fc20ce0bea3c0b83982ada1':
  daud: split muxer and demuxer

Conflicts:
	libavformat/Makefile

Merged-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/dvdsubdec: Fix off-by-one error

Fix an off-by-one error that causes the height of decoded
subtitles to be too small, thus cutting off the lowest row
of pixels.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/dvdsubdec: fix alpha in debuging code

improve the debugging function for saving subtitles
to PPM files: Actually use the alpha channel.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>