[Linuxsampler-devel] problem with SFZ release samples

[David G. <dlg...@am...>]

I have been trying to implement release sample  (trigger=release) in 
linuxsampler using the sfz engine. For these cases the sample triggered 
by note on is looped with loop_continuous, and on note off the release 
sample which contains instrument turn off and room acoustic information 
should be triggered so that the note on sample release time and the 
release sample attack time providing a cross fade so that there is no 
audible transient during the transition.   This approach has worked well 
in the past using GIG files

there are two problems:  In recent linuxsampler implementations 
(2.0.0svn68) the release sample sounds silently (that is no sound is 
heard, but qsampler indicates a sample playing after note off) if the 
region defining it has not lovel/hivel qualifiers.  If these qualifiers 
are present the release sample is never activated.  This leads me to 
believe that the engine is not preserving the note on velocity for use 
with the release sample, and that it is also ignoring a group 
amp_veltrack=0 command.

In earlier linuxsampler implementations, the release sounds audibly for 
both of the cases above. However, the release time for the playing 
sample and the attack time for the release sample are not happening 
properly.  In most cases I see the release time of the playing sample to 
be much faster than specified, and the attack time of the release sample 
to be the specified time.  Also, the release of the playing sample 
occurs some time before the beginning of the attack of the release 
sample.  In order for cross fade to work these both need to begin at the 
same instant in time.  In other cases I have seen behavior where the 
attack and release profiles have large steps in them.

I have copied below an SFZ file to demonstrate these behaviors. The 
sample=sine.wav refers to a 262 Hz sine wave of fixed amplitude duration 
5 seconds that I created with audacity.  The octave below middle C has 
the lovel/hivel qualifiers, the octave above has no such qualifier.  The 
sfz file sounds the release pitched an octave higher than the note on 
pitch so recordings with audacity can easily show the transitions 
between samples.

<group>
amp_veltrack=0
ampeg_attack=0.05
ampeg_release=0.05
sample=sine.wav

<region>
lokey=60
hikey=71
pitch_keycenter=60
loop_mode=loop_continuous


<region>
lokey=60
hikey=71
trigger=release
pitch_keycenter=48
ampeg_hold=0.2
ampeg_decay=2
ampeg_sustain=0
loop_mode=no_loop

<region>
lokey=48
hikey=59
lovel=30
hivel=100
pitch_keycenter=60
loop_mode=loop_continuous


<region>
lokey=48
hikey=59
trigger=release
lovel=30
hivel=100
pitch_keycenter=48
ampeg_hold=0.2
ampeg_decay=2
ampeg_sustain=0
loop_mode=no_loop


Thanks for your attention
Dave Gritter