Antares Infinity user manual

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LOOP POINTS IN OTHER FILE FORMATS
Two loop points exist in the AIFF and the Sound Designer I formats, the
sustain loop and the release loop. Currently, Infinity only deals with the
sustain loop.
In Sound Designer II, the sustain loop is called Loop 1 and the release loop
is called Loop 2. Infinity will read only Loop 1 from a Sound Designer file as
the sustain loop. When Infinity writes to a Sound Designer II file, all other
loops are lost.
THE CROSSFADE LOOPER
The standard crossfade loop is created by blending part of the attack
segment into the end of the loop segment of the soundfile to create a
smooth transition back to the loop start. Infinity’s Crossfade Looper allows
for precise control of the process and contains many enhancements includ-
ing a scalable looping display, a non-destructive audition feature, fully
adjustable crossfade parameters, and an intelligent loop point scanning
technology called Smart Auto-Scan. This section explains these features and
their controls.
LOOPING DISPLAY 
AUTO-SCAN ARROWS 
AUTO-SCAN 
MATCHING VALUE   
The soundfile can be auditioned while the Crossfade Looper is the active
window. Playback works by pressing the space bar or clicking on the
Speaker icon. If the cursor is in a text box, playback can be started only
with the Speaker Icon. Terminate playback by clicking on the Speaker icon
or pressing the space bar. During playback, unusable controls are grayed. 
						

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ABOUT SMART AUTO-SCAN
This algorithm searches the soundfile for places where the sound at one
loop point matches the sound at the other loop point. The closeness of the
match and the number of places in the soundfile that are searched are
controllable using the Auto-Scan Settings dialog shown below.
Conventional “auto” functions move the loop points to the nearest zero
crossing or the nearest zero crossing with the same slope. Smart Auto-Scan
compares the amplitude and the phase of the major harmonics at the loop
points and searches until a good match is found. The result is a loop point
which always creates good crossfade loops, i.e. without unwanted phase
cancellations of the major harmonics. The illustration below shows the
result of a Smart Auto-Scan; the alignment of the waveforms is exact. The
slopes at the loop interface will blend after the crossfade is complete.
UNDERSTANDING THE DIALOG CONTROLS
Soundfile Menu: The Soundfile Menu shows the name of the last active
soundfile. All open soundfiles are listed in the menu. The Crossfade Looper
operates on the soundfile which is displayed in the menu.
Looping Display: The Looping Display shows the interface between the
loop end and the loop start. The vertical line in the middle of the display
shows the interface point. The left half shows the Loop End region, the
right shows the Loop Start region. Certain combinations of display resolu-
tion and loop point positions will show the loop point in the opposite
display. In this case, the loop point marker is shown as a vertical line.
The display resolution can be changed using the Display Scale Arrows on
the Palette. The position of the cursor is also shown in the Palette cursor
tracking display.
Auto-Scan Arrows: Clicking on a double arrow will cause Infinity to begin
searching for a matching loop point in the direction of the arrow. When
one is found, the loop point marker is moved to the new location. 
						

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Infinity will continue to search until it finds a matching value which is
greater than or equal to the value of the Matching Threshold set in the
Auto-Scan Settings dialog. If none is found, an audio signal will sound,
indicating the end of the search. The loop points will remain in their
original locations. Pressing  or  will terminate the
search.
Clicking on a single arrow will move the loop point one pixel in the direc-
tion of the arrow. Pressing on a single arrow will cause the loop point to
move and slowly accelerate. The longer the arrow is pressed, the faster the
loop point will move.
Auto-Scan Matching Value: This displays the matching values found during
Auto-Scan searches. Watching this value during the search gives you an
idea of how closely the sound at the loop points is matching. Use this
information to change the Matching Threshold in the Auto-Scan Settings
dialog, if necessary.
Auto-Scan Settings: Clicking on the Auto-Scan Settings command button
will bring up the dialog shown below.
Matching Threshold: The Matching Threshold determines how closely the
loop end must match the loop start. The range of the control is from zero
to 100. Higher numbers require a closer match. A value of 100 equals a
perfect match. Non-periodic sounds typically have lower matching values
than periodic sounds.
Match Trial Points: This control changes the number of locations in the
soundfile which are searched during an Auto-Scan. The soundfile is first
divided by the number of Match Trial Points, then the search begins in the
direction of the arrow which was clicked. The range is from 10 to 1000.
Crossfade Length (%): This control adjusts the amount of attack data which
is crossfaded with the loop end to create a smooth transition back to the
loop start. The range is from 0% to 100% of the attack segment. If the loop
segment is shorter than the attack segment, then the crossfade length
percentage refers to the amount of the loop data which is effected by the
crossfade. 
						

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Crossfade Taper: This control adjusts the taper shape of the crossfade that
is used to blend the attack and loop segments. It is adjustable from 0
(linear taper) to 100 (equal power taper). It should be adjusted to provide
the smoothest transition between the attack and loop segments of the
sample. Use equal power taper for string sounds, choruses, and other non-
periodic sounds. Linear taper is best used with periodic waveforms like solo
instruments.
100 
EQUAL POWER TAPER
0 
LINEAR TAPER
Linear taper should be used for editing simple periodic waveforms like solo
instruments. Equal power taper should be used when editing complex non-
periodic waveforms like string sections or noise.
Audition Crossfade: When the Audition Crossfade checkbox is checked,
clicking on the Speaker icon (or pressing the space bar) will compute the
crossfade loop and play it until the Speaker icon is clicked again. This feature
allows you to hear the crossfade without permanently changing the
soundfile.
Do Crossfade: Clicking on the Do Crossfade command button executes the
crossfade loop process. Pressing  or  terminates the
process.
THE FREEZE LOOPER
The Freeze Looper is an automatic looping algorithm that creates a perfectly
seamless loop with no sonic variations. It is excellent for making short loops
in relatively periodic sounds like solo instruments, and for “freezing” the
timbre of decaying instruments that have clearly defined harmonics like
harp, piano, guitar notes, etc.
If the sound to be looped has nearly uniform waveshapes, the Freeze Looper
will change the aural qualities of the sound very little and result in a con-
tinuous uniform loop. If the Freeze Looper is used on a more complex sound,
the resulting loop will sound very different from the original.
The crossfade used in the Freeze Looper is different from a normal crossfade
loop in that a portion of the loop segment is blended into the attack rather
than a portion of the attack being blended into the loop. This modification
of the attack segment occurs every time a Freeze Loop is created. 
						

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HOW IT WORKS
The Freeze Looper quantizes all the sound energy in the loop to a precise
harmonic series, giving a waveform that is perfectly repeated in every cycle.
The Freeze Looper outputs a constant pitch equal to the average pitch of
the original loop segment.
The Freeze Looper uses the MIDI Note Number to set internal processing
parameters. Because these settings effect the results, the MIDI Note
Number should be set to the approximate pitch of the sound being looped.
The size of the loop segment is reduced by processing with the Freeze
Looper. The loop end point is moved to shorten the loop. The loop start is
left where it was before processing. This shortening is necessary because
the Freeze Looper uses an FFT algorithm that requires the number of
samples in the loop be equal to a power of two. The finished loop is also
shortened slightly so that it contains an integral number of waveform
periods. So, the output loop end point will be earlier than that which was
input.
If the computations cause the loop data to exceed 90% of maximum, the
entire file will be scaled so that the loop data are 90% of maximum and
thereby do not clip. Thus, data are scaled so no overflow occurs. When
scaling occurs, the user is notified with an alert which indicates how much
the data was scaled. The scaling information will allow you to maintain
volume control of your samples. If you are getting clipping in the fade from
the attack segment, check out that the crossfade taper may be set more
towards linear taper. 
						

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UNDERSTANDING THE DIALOG CONTROLS
Soundfile Menu: The Soundfile Menu shows the name of the last active
soundfile. All open soundfiles are listed in the menu. The Freeze Looper
operates on the soundfile which is displayed in the menu.
Pitch Control Radio: Previously, Freeze Looper had Pitch Detection built-in.
This means the harmonic series energy distribution and output tuning was
determined by an algorithm that detected the exact pitch of the original
loop. The MIDI note was used as an initial guide such that if the MIDI note
was way off, an incorrect result would occur. This algorithm is used when
you select the Pitch Detection radio.
Unfortunately, if you process a short loop (less than 20 cycles), the Pitch
Detection algorithm will not be precise and the result may be slightly out
of tune. Also, it may be the original sample was out of tune and you wish
to tune it up. In these cases, you should select the MIDI Note radio. This will
force the harmonic series energy distribution and output tuning to be
determined using the MIDI Note number of the sample and the standard
that A3 is 440Hz.
Pre-condition Data (%): The purpose of the Pre-condition Data feature is to
taper the data at the loop start and loop end so that all the energy compo-
nents in the loop begin and end on zero. The control has a range from 0%
to 100%. Any setting larger than a few percent leaves little or no energy at
the loop points to cause a click which might inject unwanted noise into the
process.
Increasing the Pre-conditioning percentage favors the timbre of the sound
near the middle of the loop. Using different values gives different aural
qualities to the resulting sound. The diagram below shows the effect of
changing the amount of the loop tapered by the Pre-conditioning process.
(The taper does not show up in the finished loop.)
LOOP DATA AMPLITUDE AS A FUNCTION
OF PRE-CONDITION DATA PERCENTAGE
0%
25%
50%
100% 
						

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Crossfade Length: This control sets the amount of the loop that is blended
with the attack segment. It is variable from 0% to 100% of the attack
duration. A large crossfade length will cause the attack to slowly blend into
the loop sound. A smaller crossfade length will create a quick but blended
transition between the two segments of the sample. A setting of zero
creates no crossfade.
AT TACK
SEGMENTLOOP
SEGMENT
50%
Crossfade Taper: This control adjusts the taper shape of the crossfade that
is used in the attack/loop merge. It is adjustable from 0 (linear taper) to 100
(equal power taper). It should be adjusted to provide the smoothest
transition between the attack and loop segments of the sample.
100 
EQUAL POWER TAPER
0 
LINEAR TAPER
Linear taper should be used for editing simple periodic waveforms like solo
instruments. Equal power taper should be used when editing complex non-
periodic waveforms like string sections or noise.
Do It: Clicking on the Do It command button executes the Freeze looping
process. Pressing  or  terminates the process. 
						

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THE ROTATED SUMS LOOPER
The Rotated Sums Looper creates seamless loops by randomly distributing
sonic irregularities throughout the loop. It is very effective with sounds that
have non-periodic waveforms like chorus, string orchestra, complex synth
patches, sounds that include noise, and so on.
NOTE: Sounds must be pre-looped before using the Rotated Sums
Looper. Any clicks, pops or other irregularities will be distributed
throughout the loop and show up as noise. Use the Crossfade Looper
to smooth out the loop data before processing with the Rotated Sums
Looper.
Use the Smart Auto-Scan feature of the Crossfade Looper to place the loop
points before processing with the Rotated Sums Looper. This will insure
that the resulting loop will more closely match the tone color of the
original data.
If the computations cause the loop data to exceed 90% of maximum, the
entire file will be scaled so that the loop data are 90% of maximum and
thereby do not clip. Thus, data are scaled so no overflow occurs. When
scaling occurs, the user is notified with an alert which indicates how much
the data was scaled. The scaling information will allow you to maintain
volume control of your samples. If you are getting clipping in the fade from
the attack segment, check out that the crossfade taper may be set more
towards linear taper. 
						

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HOW IT WORKS
In a crossfade loop, all of the different frequencies in the sound make a
transition from one phase to another during the crossfade. This causes
different combinations of constructive and destructive interference at the
location of the crossfade. Because this happens for all frequencies at the
same point in the loop, a noticeable “bump” is produced by the crossfade
looping process.
The Rotated Sums Looper creates a seamless loop by adding together many
random rotations of the input loop, thereby distributing the irregularity of
the crossfade bump throughout the loop. This is a time domain solution to
the crossfade bump problem in complex sounds. The more rotations that
are chosen, the better the results, up to a limit that exists because of the
natural variations in the sound. The Rotated Sums Looper does not change
the length of the loop.
Because the Rotated Sums Looper chooses random amounts by which to
perform loop rotations, different trials using the same input sound will
yield different results.
UNDERSTANDING THE DIALOG CONTROLS
The Rotated Sums Looper divides the looping process into two distinct
phases; processing the loop data, and merging the attack and loop seg-
ments. These can be controlled separately and executed at different times.
With both phases of the process enabled, the loop data and the attack data
are altered every time the Rotated Sums process is run. It is sometimes
desirable to disable the attack/loop merge phase of the process, and do
several takes of processing the loop data without merging the loop with
the attack. This saves time and allows for selecting the best sounding loop
before the attack segment is altered by merging. After the best sounding
loop is found, the merge can be done separately by disabling the loop
processing phase.
Soundfile Menu: This menu has the same function as in the other loopers.
Process The Loop Segment: Check this item if you wish to apply the Ro-
tated Sums process to the data inside loop. When this item is not checked,
the slider labeled Rotation Count is inactive and no change will be made to
the loop data.
Rotation Count: The Rotation Count is the number of times that the loop
data will be rotated and added in the accumulator during the loop process-
ing phase. The range of the control is from 1 to 100. More rotations give
better results, up to a point, but take more time.
Merge The Attack And Loop Segments: Checking this item enables the
second phase of the looping process; merging the loop segment with the
attack segment of the sample. Enable this part of the process only when
you want to crossfade the loop data with the attack segment of the sound.
When this item is not checked, the sliders labeled Loop Start Test Points,
Crossfade Length, and Crossfade Taper are inactive. 
						

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When Merge the Attack and Loop Segments is checked in the dialog,
Infinity will automatically search a number of points in the loop segment to
find the point which most closely correlates to the end of the attack
segment. The number of test points that are tried during the search can be
controlled using the Loop Start Test Points control. Processing time in-
creases as more points are tried.
When the best merge point is found, Infinity rotates the data in the loop
until the merge point is located at the loop start. The loop is then merged
with the attack segment. The type of crossfade that is used only modifies
the attack segment. The length and taper of the crossfade that is used to
merge the two segments can be controlled.
Loop Start Test Points: This controls the number of points that are tested
during the search phase of the merging process. It is variable from 0 to 100
points. A large number of test points results in a better attack/loop merge
but will also increase the processing time.
Crossfade Length: This control sets the amount of the loop that is blended
with the attack segment. It is variable from 0% to 100% of the attack
duration. A large crossfade length will cause the attack to slowly blend into
the loop sound. A smaller crossfade length will create a quick but blended
transition between the two segments of the sample. A setting of zero
creates no crossfade.
AT TACK
SEGMENTLOOP
SEGMENT
50%