Re: [Linuxsampler-devel] Occasional clicks at the beginning of the played sample (fwd)

[Holger M. <ho...@ma...>]

On Fri, 27 Jun 2014, Christian Schoenebeck wrote:

> seq_* opcodes seems to define "round robin" selection for regions in the SFZ 
> format. I just had a short look at current SFZ code, and as far as I could see 
> it right now, round robin selection in the SFZ engine could indeed be buggy.
> 
> bool Region::OnKey(const Query& q) [src/engines/sfz/sfz.cpp]
> 
> is called by the SFZ engine on each region, when a new note was triggered, to 
> check which region shall be used and played. However that method ATM assumes 
> to be called only once and due to this increments the round robin counter at 
> the end of its call. The SFZ engine however calls this in a while loop:
> 
> 	while (::sfz::Region* region = q.next()) {
> 							[src/engines/sfz/Engine.cpp, line 110]
> 
> which seems to cause the misbehavior you encountered. That is, that it falsely 
> also triggers the 2nd region you have there at the same time.

I made a soundfont with 2 different (in frequency) samples, so I could
hear if both samples are played together instead alternating. It didn't
happen. They were never played together. So this bug candidate doesn't
seem to be one.

I investigated the sound font some more. The clicking sample was
different compared to the others: it lacked loop information in the
wav-header. Since there wasn't any loop_start/loop_end in the sfz-file
linuxsampler probably used the defaults 0/0. Could be a reason for the
occasional klicks.

Another "bug" in the soundfont could be the release sound:
  ampeg_decay=37
  loop_mode=one_shot
  trigger=release
One_shot mode together with a very long decay could possibly lead to
voice-stealing, another possible source of occasional klicks.


TL;DR
-----
After fixing the soundfont I have now much better results.