Re: new feature implementation : goto midi marker

On Tue, Nov 13, 2012 at 12:06:19AM +0100, gorest wrote:
> hello,
> 
> after a first pass reading the code, i dropped some notes and
> questions about what to do and where. As there is no developer
> docs, i need to understand the global behavior of the program and
> its specificities.
> 
> So the following statements are considered for a first step :
> parsing the meta events of the SMF file into the meta track of
> the song structure.
> 
> ev.h
> 	> add a "#DEFINE EV_MARKER 0xValue" > errr? if it must be
> 	  only 1 byte (char), then there is only 0x01 left, is it
> 	  usable ?

yes; if more event types are needed, meta events could be moved at
offset 0x10, if so, afaics only EV_xxx and EVSPEC_ macros need to
be updated.

If you don't mind, I'd prefer a shorter word or abreviation for
marker, (eg. tag or mark)

> 	> add a #"define marker_val" to struct ev {...} > what
> 	  value ? v0 or v1 ?

v0 would be more consistent with what we do for other events

> ev.c
> 	> ev_dbg(?) : add EV_MARKER case

yes

> smf.c
> 	> smf_getvar(?) read a variable length value usefull to get
> 	  the marker info
> 	> smf_puttrack : store a track in the smf > add marker
> 	  events to the meta track ?
> 	> song_exportsmf : open the smf and store the whole song >  add marker events to the meta track ?
> 	> smf_gettrack : parse a track 'varlen event ... ' 
> 		> THE PLACE TO PARSE THE MARKER EVENTS
> 		> add statement : else if (type == 0x06) {?} /*marker event*/

I don't know how markers are stored in .mid files

> song.h
> 	> add an entry to "struct song" for a marker meta track, or
> 	  use the meta track ? (the meta track is reffered as
> 	  "tempo track" in comments)

afaics using the tempo/meta track seems simpler for markers; for
instance if silence is inserted, markers won't need special
handling to move naturally.

> song.c
> 	> add a function like : does_song_have_markers(?) ?
> 	> if any, add marker track initialisation
> 	> add EV_MARKER case to song_metaput(?) if some action is to be done when a marker is reached
> xxxx?

yes

> 	> add a new proc "lmarkers" to show the list of markers
> 	  listed in the song's meta track

I've no clear opinion here, may be the "minfo" function could be
used for this as well.

-- Alexandre