[RWP] Audio Quantization in Reaper

[indigo]

http://wiki.cockos.com/wiki/index.php/Audio_Quantization_in_Reaper
Audio quantization is aligning the beats in an audio-item to a grid or 
to a predefined
groove.
In Reaper this is actually item-quantization, as you can apply it to 
midi or audio-items.
Note however, regarding midi you'd normally use
midi notes quantization
.
In other DAWs audio quantization are named e.g. Elastic Audio, Audio 
Quantize, Beat
Detective and Time Warp.
Native solution
Natively Reaper has rather poorly implemented audio quantization 
functionality. However
when used in conjunction with the recommended tools below, you'll get a 
fully functional
way of doing this.
Dynamic Split
View > Dynamic split items
Dynamic split.png
How to use? See 2. below.
Dynamic split
Quantize
You can quantize items with the
action
:
"
Item: Quantize item positions to grid.
Action_List_Reference
Action:
Item: Quantize item positions to grid...
Aligns audio- or midi-items to grid.

"
Recommended tools
Fingers Groove Tool
See:
Fingers Groove Tool
AW - Fill gaps between selected items
See:
AW - Fill gaps
Recommended workflow
1.  Select the audio-clip you wan't to apply changes to
2.  Use
Dynamic split
  to split the clip at the beats.
3.  Quantize, either..
1.  Use
Quantize items to grid
, or
2.  Use
Fingers Groove Tool
4.  Use
AW - Fill gaps
  to stretch and smooth out crossovers

2.  "Dynamic split" splits audio-items according to transients/beats or 
gate-setting.
How to get there
View > Dynamic split items
Right-click item > Item processing > Dynamic split items…
Remove Silent Passages
One way of using REAPER's Dynamic Splitting is to clean up a track and 
remove those
passages that should be silent. This can be handy, for example, with a 
vocal track,
to automatically clean up the passages between verses which might 
contain unwanted
background noises such as breathing or shuffling sounds.
Dynamic split2.png
Parameters
When used in this way, dynamic splitting basically employs a noise gate 
to tell REAPER
how often and where to split your media items and which areas are to be 
removed.
At transients: Deselect this option when using dynamic splitting for 
this purpose.
When gate opens/ closes: Both of these options need to be turned on, so 
that REAPER
can work out the beginning and end of each passage that is to be removed.
Reduce splits: In most cases, when using dynamic splitting for this 
purpose this
item should be deselected.
Min slice length: This sets the shortest length for any slice. You will 
probably
need to experiment to get it right. Usually, this should be set to a low 
value. Happily,
REAPER's dynamic splitting interface gives you immediate visual 
feedback. You can
see by looking at the screen when your settings are right. The 
illustration below
shows the effect of setting this value too high. Notice that it can 
result in some
recorded passages also being removed
Min silence length: This is another parameter that will require fine 
tuning. Set
too high it will fail to catch all the periods of silence,
Constrain slice length: In most cases for this particular application 
this setting
should not matter. If in doubt, try both and be guided by the visual 
feedback.
Gate threshold: This setting is important, but usually has a reasonable 
range of
acceptable values. If you make this too low you might allow unwanted 
sounds thru
the noise gate. If you set it too high you risk deleting quieter 
passages of the
recorded material. Start around -50dB and make any necessary adjustments 
from there.
Hysteresis: This setting can be used to adjust the level at which the 
gate closes
relative to that at which it opens. Raising the hysteresis figure closer 
to or even
above 0dB will have the effect of creating more splits.
Remove silence This option should be enabled.
Fade Pad Enabling fade pad can help ensure a smoother transition.
Each split point is indicated by a colored vertical line, and those 
areas marked
for removal are shown as darker.
Split at transients
If you want to
quantize audio-items
, this is the the first tool you need to use.
Dynamic split.png
For splitting at transients:
At transients: Have this checked
When gate opens/closes: Unchecked
Reduce splits: Optional, tweak to remove some unwanted splits
Min slice length: Set a little bit shorter then the shortest split you 
want to make
Constrain slice length: ..
Preserve beat location, even if tempo changes: Checked
Split grouped items at times of selected item splits: Usually checked
Set transients sensitivity
Transient detection settings.png
Sensitivity: Where on transients splits should be set
Threshold: Lowest level for transients to be detected
Display threshold in media items while this window is open: Displays a 
visual preview
of threshold on selected items.
Create chromatic MIDI item from slices.

3. AW - Fill gaps[
]
  1 About
  2 How to get there
  3 Settings
  3.1 Trigger Pad
  3.2 Crossfade Length
  3.3 Maximum Gap
  3.4 Maximum Stretch
  3.5 Preserve Transient
  3.6 Transient Crossfade Length
  3.7 Fade Shape
  3.8 Mark possible artifacts?
  4 See also
About
"AW - Fill gaps between selected items" is created by Adam Wathan and is 
part of
the
SWS extension
. Usually used as last step in
quantizing audio
.
How to get there
Install the
SWS extension
Extensions > Fill gaps..
Settings
Trigger Pad
This is a leading pad added to the beginning of each chunk and 
subtracted from the
end of the previous chunk. The snap offset is adjusted to compensate so 
that your
media will still snap to the transient. It is a sort of safety buffer. 
Imagine you
have a section where the snare and ride hits at the same time, but the 
ride is a
tiny bit early. Dynamic split cut at the snare transient though for one 
of a variety
of reasons. This buffer would ensure that the ride transient is 
preserved directly
before the snare and that it is cut out of the previous item. It 
basically just lets
you be lazier when checking the quality of your splits
Crossfade Length
This is the length of the crossfade created between the tail of any item 
and the
beginning of the next item. It is always placed to the left and is in 
addition to
any trigger pad (ie. a trigger pad of 5ms and a crossfade length of 5ms 
will result
in a minimum of 10ms between the start of the crossfade and the 
transient in the
next item.)
Maximum Gap
This is the maximum allowable gap before the code attempts to time 
stretch the previous
item. If you set a max gap of 20ms and the code detects a gap of 50ms, 
it will timestretch
the previous item until either a) the gap has been reduced to 20ms, or 
b) the Maximum
Stretch value has been reached. If the detected gap is less than the 
Maximum Gap,
the following item is simply trimmed back to fill it with no stretching 
applied whatsoever.
Maximum Stretch
This is the maximum amount that an item will stretch. The value 
corresponds with
the "Rate" value displayed in a media item when timestretching it, so 
0.85 means
the item will stretch to a maximum rate of 0.85 In my experience, it 
usually sounds
better to allow more stretching than it does to allow a larger Maximum 
Gap, so don't
be afraid to set this value low. A value of 0 will let the item stretch 
as much as
it needs to while a value of 1 will disable stretching entirely.
Preserve Transient
This is the amount of the item you want to prevent from stretching no 
matter what.
Stretching the initial attack of a media item usually sounds poor, so 
this will prevent
that initial attack from stretching and only stretch the tail of the 
item. If this
is set to 35ms for example, a split is placed 35ms after the transient 
and only the
item to the right of the split will be stretched, leaving the initial 
attack untouched.
A value of 0 disables this function completely. The default value of 
35ms is usually
pretty good.
Transient Crossfade Length
This is simply the length of the crossfade used when splitting at the 
"Preserve Transient"
point.
Fade Shape
This determines the shape of the fades used when performing any 
crossfades. It is
an integer from 0 to 5, the following chart explains which is which.
Mark possible artifacts?
This is a value of 0 (no) or 1 (yes). If 1 is entered, the action will 
insert a marker
everywhere that the gap exceeded the maximum allowable gap AND the 
maximum stretch
value was reached, which means it had to trim the start of the following 
item more
than expected. This allows you to easily identify areas where there 
might be an audible
glitch so you can listen to them with special attention and either time 
stretch more
to fix it, or copy and paste a better hit from a different part of the song.


4. The SWS extension adds additional workflow and productivity features 
to Reaper.
See www.standingwaterstudios.com
[1]
  for
Download
Manual
, by Geoffrey Francis
Further info
Features
The SWS extension is a collection of windows and actions that seamlessly 
integrate
into your REAPER environment.
These features are mostly for workflow enhancement, as apposed to audio 
processing.
With the SWS extension you will be able to work faster and be more 
productive.
For more information about the specific features available in the SWS 
extension,
check out the manual.
Wiki documentation
Fingers Groove Tool
AW - Fill gaps
Cycle Action editor
Live Config
  page