Pro Tools Reference Guide
Elastic Audio Analysis
When recording, pasting, moving, or importing
un-analyzed audio to an Elastic Audio-enabled
track, or when enabling Elastic Audio on an ex-
isting audio track, Pro Tools automatically ana-
lyzes the audio for transient events. In Wave-
form view, the waveform initially appears
grayed out because regions go offline during
Elastic Audio analysis. Once the analysis is com-
plete, the audio comes back online. Elastic Au-
dio analysis is file-based, which means that even
if you are only working with a small region of a
large file, the entire audio file is analyzed.
Elastic Audio analysis detects transient events in
the audio file. These transient events are indi-
cated by Event markers. Event markers are dis-
played in both the Warp and Analysis track
views. Elastic Audio analysis also calculates the
native tempo of the analyzed audio file and its
duration in bars and beats.
Elastic Audio analysis data (detected events,
tempo, and duration in Bars|Beats) is stored with
the file. In DigiBase browsers, analyzed audio
files are indicated by a check mark to the left of
the file name, and these files display their dura-
tion in Bars|Beats, their timebase as ticks, and
their native tempo in BPM.
Elastic Audio analysis does its best to detect a
regular tempo for all analyzed audio. Any audio
containing regular periodic rhythm can be suc-
cessfully analyzed for tempo and duration in
bars and beats. Analyzed files in which a tempo
was detected are treated as tick-based files. Tick-
based files can be conformed to the session
tempo for preview and import.
Analyzed files in which no tempo was detected
are treated as sample-based files. If there is only
a single transient in the file (such as with a sin-
gle snare hit), no tempo will be detected. Also,
longer files that contain tempo changes or ru-
bato, or that do not contain regular periodic
rhythmic patterns will probably not have a de-
tected tempo and will be treated as sample-
Transient events are detected with a certain de-
gree of confidence. The level of confidence is
based on the relative clarity of transients.
For example, a drum loop is likely to have clear,
sharp transients. These will be detected with a
high degree of confidence. However, a legato vi-
olin melody may not have clear, sharp tran-
sients, so transients will be detected with a lower
degree of confidence.
Note that peak amplitude is not the most
important measure for event confidence.
The clarity of transients is measured in part
by the spectral transition from one moment
to the next. This tends to favor higher fre-
quency content in terms of event confidence.
For example, changing the Event Sensitivity
in the Elastic Properties window for a se-
lected drum loop results in the clearer tran-
sients of the higher frequency hi-hat hits
having more event confidence than the less
well defined transients of the lower fre-
quency kick drum hits even though kick
drum hits have a higher peak amplitude.
Chapter 41: Elastic Audio 865
Pro Tools is very aggressive with its transient de-
tection in order to detect every possible audio
event. Consequently, it is possible to have erro-
neously detected events. These events will be
analyzed with a low degree of confidence and
can be filtered out by lowering the Event Sensi-
tivity in the Elastic Properties window (see
“Event Sensitivity Property” on page 881). Fil-
tering out any false transients can result in
higher quality Elastic Audio processing.
Conversely, for material with few clear tran-
sients, Elastic Audio analysis may not accurately
detect audio events, and those detected may be
detected with a low level of confidence. You can
relocate or add Event markers where necessary
in Analysis view (see “Editing in Analysis View”
on page 877).
For example, a slow synth pad may not have
clear transients and detected Event markers may
be incorrectly located or may have not been de-
tected at all. In Analysis view, you can relocate,
remove, and add Event markers as necessary
(such as where the chord changes). Accurately
locating Event markers yields better results
when applying Elastic Audio processing.
Real-Time and Rendered
Elastic Audio Processing
Real-Time Elastic Audio processing means that
any changes to Elastic Audio processing—
whether it be a tempo change or a manual TCE
warp, or pitch shifting—take effect immedi-
ately. However, Real-Time Elastic Audio process-
ing can be very demanding on your system’s re-
sources. Consequently, you may want to use
Rendered Elastic Audio processing in some
cases. With Rendered Elastic Audio processing,
when you make a change to Elastic Audio pro-
cessing, any affected audio regions temporarily
go offline, a new “rendered” audio file is gener-
ated, and any affected audio regions come back
To set an Elastic Audio track to Real-Time or
Click the track’s Elastic Audio Plug-In selector.
From the pop-up menu, select an Elastic Au-
From the pop-up menu, select one of the
• Real-Time Processing
– or –
• Rendered Processing
When processing non-rhythmic audio (such
as legato strings) with the Polyphonic plug-
in, reducing the number of Event markers
often yields better sounding results. You can
either manually remove Event markers in
Analysis view (see “Editing in Analysis
View” on page 877) or lower the Event Sen-
sitivity setting in the Elastic Properties win-
dow for the region you want to process (see
“Elastic Properties Window” on page 880).
In rendered mode, any change you make is
rendered using the original source audio to
avoid generational loss from multiple subse-
Select Real-Time processing for tick-based
Elastic Audio processing (such as tempo
changes). Rendered audio processing can be
useful for sample-based Elastic Audio
processing or if you need to save system
Pro Tools Reference Guide
About Rendered Files
Pro Tools creates temporary files for Rendered
Elastic Audio processing. These files are kept in
an auto-created Rendered Files folder in the ses-
sion folder. Once you commit Rendered Elastic
Audio processing to a track, a new file is written
to disk in the Audio Files folder, and the tempo-
rary rendered file from which it was created is
deleted from the Rendered Files folder.
Region Clip Indicator
(Rendered Processing Only)
Since Rendered Elastic Audio processing is not
real-time, it does not report clipping due to Elas-
tic Audio processing in the Elastic Audio plug-in
window. Instead, when clipping occurs due to
Rendered Elastic Audio processing, the region
displays an Elastic Audio Processing Clip indica-
tor just to the left of the Warp indicator.
To avoid clipping on playback, lower the Input
Gain for the region in the Elastic Properties win-
dow (see “Elastic Properties Window” on
Elastic Audio Plug-Ins
Pro Tools provides several algorithms for real-
time and rendered track-based Elastic Audio pro-
cessing. The selected Elastic Audio plug-in deter-
mines how the audio is processed. Each plug-in
uses different algorithms for Elastic Audio pro-
cessing. Different algorithms are better suited to
different types of audio. Select the plug-in
whose algorithm is appropriate to the material
on the track you want to process.
Elastic Audio plug-ins have their own selector
that is only available in the Edit window. You
cannot insert Elastic Audio plug-ins on track in-
Elastic Audio plug-ins provide few to no adjust-
able parameters. The adjustable controls, if any,
are available in the Elastic Audio Plug-In win-
dow. Elastic Audio plug-in parameters cannot be
To open an Elastic Audio Plug-In window:
Click the Elastic Audio Plug-In button.
Elastic Audio Plug-In selector and pop-up menu
To toggle between Real-Time and Rendered
Elastic Audio processing, Control-Start-click
(Windows) or Command-Control-click
(Mac) the Elastic Audio Plug-In button.
Elastic Audio Region Clip indicator
Elastic Audio plug-in button
Elastic Audio Region
Chapter 41: Elastic Audio 867
Elastic Audio Plug-In Window
The Elastic Audio Plug-In window provides a set
of controls in the window header that are com-
mon to all Elastic Audio plug-ins.
Track Selector Lets you access any other audio
track in the session.
Plug-In Selector Lets you select any Elastic Audio
plug-in or disable Elastic Audio.
Plug-In Settings Menu Lets you copy, paste, save,
and import plug-in presets.
Plug-In Librarian Menu Recalls Elastic Audio
plug-in settings files (presets) saved in the plug-
in’s root settings folder or in the current ses-
sion’s Settings folder.
Next (+) and Previous (–) Setting Buttons Lets
you select the next or previous preset from the
Plug-In Librarian menu.
Plug-Ins Settings Select Button Accesses the
Plug-In Settings dialog, which lists the presets
for the current plug-in. From this list, you can
select a new preset, or audition a series of pre-
Compare Toggles between the original saved
plug-in settings and any changes you have made
to it so you can compare them.
Clip LED Lights red to indicate clipping in the
Elastic Audio processing. Clipping can occur
when time compressing audio. If clipping oc-
curs, you can lower the Input Gain in the Elastic
Properties window (“Input Gain Property” on
page 882), or attenuate the Default Input Gain
in the Processing Preferences page (see “Elastic
Audio Options” on page 325).
You can undo any Elastic Audio processing and
apply an appropriate amount of AudioSuite
Gain reduction, and then try the Elastic Audio
processing again. The Clip LED only functions
for Real-Time Elastic Audio processing; it does
not function for Rendered Elastic Audio process-
ing. For Real-Time Elastic Audio plug-ins, the
Elastic Audio plug-in button on the audio track
also turns red to indicate clipping.
Elastic Audio plug-in controls
Next Setting button
Plug-In Settings Select button
Previous Setting button
You will lose the current plug-in settings if
they are not saved before you use the Next
and Previous Setting buttons. Always save
your plug-in settings as presets using the
Plug-In Settings menu.
For Rendered Elastic Audio processing, clip-
ping is indicated by the appearance of the
Elastic Audio Processing Clip indicator on
the region (see “Region Clip Indicator” on
Pro Tools Reference Guide
Target Button When multiple Elastic Audio
Plug-In windows are open, clicking this button
selects that plug-in as the target for any com-
puter keyboard commands. Deselecting the Tar-
get button lets you open another targeted Elastic
Audio Plug-In window.
The Polyphonic plug-in is a general, all-purpose
algorithm that is effective with a wide range of
material. For complex loops and multi-instru-
ment mixes, use the Polyphonic plug-in. The
Polyphonic plug-in supports region-based pitch
Selecting the Follow option enables an envelope
follower that simulates the original acoustics of
the audio being stretched. Click the Follow but-
ton to enable or disable envelope following.
The Polyphonic plug-in provides a single con-
trol for adjusting the analysis window size for
TCE processing. Experiment with adjusting the
Window size for different types of material until
you achieve the best results. The following table
provides some recommended Window sizes for
different types of material.
The Rhythmic plug-in is best suited to material
with clear attack transients, such as drums. The
Rhythmic plug-in supports region-based pitch
The Polyphonic plug-in is the default plug-
in for previewing and importing from Di-
giBase browsers or the Region List.
Elastic Audio plug-in: Polyphonic
If you frequently work with distinct types of
material, you may want to find the best
Window settings for each type of material
and save them as plug-in settings for quick
and easy recall.
Type of Material
20 ms or lower
Pads and other legato
60 ms or higher
Elastic Audio plug-in: Rhythmic
Documents you may be interested
Documents you may be interested