Re: [Linuxsampler-devel] Initial findings on .gig files

[Mark K. <mar...@at...>]

Josh,
   Exciting news here, or at least for me.

   PLEASE - use me and my Gig library as a resource. If I can be of help
somehow, please let me know and I'll try.

On Wed, 2003-03-19 at 15:45, Josh Green wrote:
> The DLS parser in libInstPatch is now functioning to the point of
> loading a DLS file (I'm sure there are some bugs still). I threw a
> couple of .gig files at it and they seem to load fine too. To help debug
> things I wrote a test program to output the RIFF chunks and I found many
> custom chunks that aren't part of the DLS standard. I think it will take
> a little bit of reverse engineering to figure out what they contain. It
> would probably help if I'd used GigaStudio before. Can anyone comment on
> what the synthesis model is? Is it fixed like DLS2/SF2 is (2 LFOs, 2
> Envelopes, low pass filter, etc) or is it modular?

I'm not sure I understand this question exactly, but I think it's a
fixed model, or at least relatively fixed. I could post some screen
shots or something like that if it would be helpful.

I think there are two things in GSt to keep in mind. They sort of
interact, but we'll have to decide what to focus on:

1) The gig files themselves - what's in them, etc. This is the basic
sound. In GSt these have some ADSRs, LFO (I think) and most important,
layering of samples across a number of parameters like MIDI velocity..

2) Performance files. These set up how a user wants to use the gig files
in GSt. This sets up the mixer, the effects, and other things. I don't
actually do to much with performance files other than make sure I get
the right instruments loaded on the right MIDI channel, but they do much
more.


> 
> Since I haven't seen any DLS articulation (effect parameter) data in
> .gig files I'm assuming most of these chunks (especially in regions) is
> custom .gig effect parameters. The content of many of the chunks seem to
> be the same across different files, so perhaps some of them can be
> ignored.

I don't understand 'DLS'. Sorry. However, I 'think' much of what you are
thinking about might be in the Performance file and not in the Gig file.
> 
> The weirdest thing I saw was a "nam0" chunk in one .gig file that had a
> size of 3. This apparently breaks the RIFF spec I believe, because chunk
> sizes are supposed to be even. Also it appears to be actually 4 bytes in
> length, since the next chunk starts 4 bytes later (maybe its just a
> broken .gig file?).
> 
> I think its also quite lame that there doesn't seem to be a way to
> identify a .gig file from a DLS file besides its file extension (and
> running across those custom chunks). I think this is kind of stupid and
> makes things difficult when determining the file type from its data
> rather than file extension. Although the DLS standard is designed to
> allow custom chunks. I'm curious if these chunks are registered with the
> MIDI Manufacturers Association (ones who designed DLS)?

Please understand that I know absolutely nothing about the internals,
but I hope to be helpful, without being a hinderance I hope.
> 
> Cheers.
> 	Josh
> 
> P.S. here are some details on the custom chunks that I found.
> Indentation indicates embedded chunks, the toplevel chunk listed for
> each of these blocks is the last standard DLS chunk in the ancestry.
> 
> 'DLS '<LIST> (Standard DLS RIFF chunk)
>   '3gri'<LIST> (size = 88)
>     '3gnl'<LIST> (size = 76)
>       '3gnm' (size = 64) (values seen: "Default Sample Group")
>   'einf' (size = 98)
> 
> 'rgn '<LIST> (Standard DLS region, effect parameters, key splits, etc)
>   '3lnk' (size = 172)
>   '3prg'<LIST> (varies)
>     '3ewl'<LIST> (size = 196)
>       'wsmp' (size = 36) (seems identical to Standard DLS wsmp chunk)
>       '3ewa' (size = 140)
>   '3dnl'<LIST> (varies)
>     'nam0' (size = 3!!!)
>   '3ddp' (size = 10)
> 
> 'lart'<LIST> (DLS articulation data [effect parameters] list)
>   '3ewg' (size = 12)
> 
> 'wave'<LIST> (DLS sample chunk)
>   '3gix' (size = 4)
> 
> 
> 
> 
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