Used to play separate intro+loop files, mask channels, play subsongs in
single files without having to demux, etc.
Also a channel mask parsing during main render_vgmstream.
It's not the easiest thing to follow so here is what's going on with
STREAMFILEs:
- external player opens base-streamfile, with a base FILE
- meta scd parses stuff, then per DSP channel/layer:
- open temp-streamfile, which does custom IO with base-streamfile
(doesn't open any FILE)
- pass temp-streamfile to init_vgmstream_ngc_dsp_std
- init parses ok, and re-opens temp-streamfile (with custom IO) as its
own dsp-vgmstream-streamfile; internally it does fopen/fdopen the
original FILE from base-streamfile
- scd_int_layout stores the newly created VGMSTREAM (internally has
the dsp-vgmstream-streamfile too)
- close temp-streamfile, that doesn't close base-streamfile as it's
wrapped to avoid doing so, nor affects dsp-vgmstream-streamfile in any
way.
- meta parsing is done, so external player closes base-streamfile (but
the re-fopen'ed dsp-vgmstream-streamfile FILE remains)
- vgmstream renders pcm buffers, etc
- finally player calls close_vgmstream
- scd_int_layout calls close_vgmstream for each stored VGMSTREAM
- the VGMSTREAM internally closes the dsp-vgmstream-streamfile, which
in turn closes its own FILE
So ultimately all FILEs, STREAMFILEs and their clones should be properly
handled and closed.
Remove layout_interleave_shortblock for clarity as the value is enough
to signal its use. Also fix .snd last block calculation, and clean some
metas since I was testing changes anyway.
Layout was not actually needed, remove to simplify. Rename
vgm_vorbis_info_t to ogg_vorbis_meta_info_t to clarify it's only for
meta, also don't pass filename to init ogg (not useful even as an
optimization since getting the name is a minuscule part in parsing a
meta)
