Re: [fluid-dev] Short note durations on percussion channel

[josh]

Quoting "S. Christian Collins" <address@hidden>:
> Josh,
>
> I think your resolution is reasonable, and it seems it will only really
> affect GM/GS MIDI files, and not other usage, so that's good.
>
> The reason I brought up the GS sound effects bank (patch 56 on the
> percussion channel, if memory serves me correctly) is that many of the
> sounds are looped, and would respond badly to having no note-off event,
> essentially leaving them looping indefinitely throughout the song.
> Also, there are a few other exceptions in the GS percussive presets
> that could cause problems, such as the different order of percussion
> sounds in some of the patches.  Examples include the Orchestral bank
> (patch 48), which includes a sustained applause sound effect as one of
> its notes, and the brushed kit, which has brush swirls that should
> respond to length.
>
> This is why I proposed simply setting a minimum note length value for
> the percussion channel in GM/GS mode.  If you set the minimum note
> length to 10ms, for example, that would cause all percussion
> instruments to sound properly--short sounds will play their duration
> because of the long release values SoundFont creators use on such
> sounds, and long sounds won't hold out indefinitely due to a lack of
> note-off.  I can't think of any downsides to this solution.
>
> -~Chris


Hello Chris,

Your concerns bring up the question as to what the standard is in  
regards to percussion for GS, which I admit I was overlooking.  GS is  
an extension to GM, but the statement about ignoring percussion  
note-offs was in a GM standard document.  This means that there are  
likely additional rules for the extended sounds/patches in the GS  
instrument map.  I'm not sure if there is a specific definition, in  
regards to GS and percussion instrument note-offs, but if someone  
knows of a document describing this, that would be helpful.  I found  
mention on the net that there are SYSEX messages for turning on/off  
the handling of note-off messages, though I haven't found a direct  
reference to the particular SYSEX message yet, except perhaps one that  
designates which channels are Percussion channels, documented in the  
manual for the SC-8850 here:
http://www.synthman.com/roland/support/SC-8850_OM.html

I suppose I don't really like the idea of extending the note length by  
a specific amount, simply because there isn't anything that says we  
should do it that way.  Checking to see if it works properly would  
require testing many MIDI files, etc.  The amount of the note  
extension would affect the result as well.  Perhaps we should limit  
the note-off ignore logic to just the Standard drum kit and other kits  
which are based on it.  An additional thing we could add, is to always  
handle note-offs for looped instruments.

I'd like to try and resolve the missing percussion notes issue and at  
the same time not introduce any other problems.  We can start  
perfecting the GM/GS handling in future versions.

Josh