Antares MDT user manual

							MDT UserÕs Manual21
CHAPTER 3MDT Tutorial
ÒI donÕt want to know how it works Ð 
I want to know how to work it!Ó
Ð Keith Emerson
This chapter is a step-by-step explanation of how to use MDT. MDT is a
breakthrough in technology and is therefore unique. If you follow these les-
sons one step at a time, you will master MDT and fully beneÞt from its
capabilities.
The whole tutorial takes about 90 minutes to complete.
Lesson 1: MDT Basics
This lesson presents the elements of MDTÕs user interface.
In/Out Grid
I/O Curve
Peak Level Indicator
Input Offset Arrows
Input Offset DisplayInput/Output Display 
						

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About DSP Plug-ins
DSP Plug-ins are software programs that run inside ProTools, and other
programs to add functionality and provide a variety of DSP tools. All TDM
compatible plug-ins have a few basic features in common. This section
describes those features.
1. Start ProTools and open the session named ÒMDT TutorialÓ.
2. Select ÒShow Inserts ViewÓ from the Display Menu.
3. Click on the MDT insert in the track labeled ÒAux 1Ó.
4. Choose Reset Settings from MDTÕs Setting menu.
5. In the Transport Window, click on the locator point labeled ÒShort VoiceÓ.
The Peak Level Indicator
1. Start playback with looping.
A Peak Level Indicator appears at the bottom of the In/Out Grid of 
MDT. It displays the current input level that MDT uses to make gain 
adjustments.
As the soundÞle plays, notice the dynamic range that the Peak Level 
Indicator covers. 
MDT uses look-ahead peak averaging to determine the loudness of a
sound. Look-ahead peak averaging means MDT scans the data about to be
processed for upcoming peaks while calculating the average peak level of
the data itÕs currently working on. It uses both numbers to derive the Þnal
input level. MDT can scan up to 1024 samples ahead, depending on the DSP
card being used.
2. Use the mouse to press on the right arrow of the Release slider. Increase the 
release time to 4,999 mS (milliseconds).
Notice that, as the release time increases, the Peak Level Indicator Õs 
movement slows down and the displayed signal level gets higher on the 
IN scale. This is because, as the release time increases, it takes longer for 
hot peaks to be averaged out of the level calculation. The actual signal  
						

							MDT UserÕs Manual23 Lesson 1: MDT Basics
may be ßuctuating wildly, but the displayed level will always be the 
average value of the peaks inside the time window determined by the 
Attack and Release settings.
3. Drag the Release slider to the far left position. Notice the change in the Peak Level 
Indicator.
With a release time of 0 milliseconds, the Peak Level Indicator more 
closely reßects the actual instantaneous sound level.
4. Stop playback.
5. Reset MDT by choosing Reset Settings from the Setting menu.
The I/O Curve
MDT uses a unique graphic interface to describe the relationship between
Input and Output levels. This relationship is called the transfer characteristic
or, in MDT parlance, the I/O Curve. This section demonstrates the manipu-
lation of the I/O Curve.
NOTE: Points on the I/O Curve or the In/Out Grid will always be written
as a pair of negative numbers, e. g. -60:-60. The Þrst number is the location
Press here to increase 
the Release time
In/Out Display
I/O Curve
In/Out Grid
Threshold
Lower Terminator Upper Terminator 
						

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of the point on the In coordinate of the In/Out Grid. The second is equal to
its Out value on the Grid.
1. Move your mouse cursor into the In/Out Grid.
The cursor changes into the cross cursor shape.
2. Click and drag the mouse inside the Grid. 
A threshold appears in the I/O Curve. As you move the threshold 
around the Grid, the I/O Curve Òrubber bandsÓ to follow the move-
ments of the cursor. Notice that the threshold location is displayed in the 
In/Out Display. Also notice that the In/Out Display shows the angle of 
the two moving line segments expressed as the ratio of the Input to the 
Output. 
3. Release the mouse. 
The threshold remains at the release point. It is now highlighted as 
shown in the illustration above.
4. Move the threshold to In/Out coordinates -60:-60 by placing the cursor over the 
threshold and dragging it to the new location. 
5. Place the cursor over the lower terminator (the small square object in the lower 
left corner of the In/Out Grid) and drag it to the right to -60.5:-96.
Notice that the lower terminator is ÒgluedÓ to the In axis. It will always 
have an Out value of -96 dB. The In/Out Display shows the ratio of the 
moving curve segment. As you drag the lower terminator to the right, 
notice that it cannot go past the threshold at -60:-60. This is to prevent 
the I/O Curve from having more than one output value for any given 
input value.
6. Drag the upper terminator (in the upper right corner of the In/Out Grid) to 0:-48.
The upper terminator is glued to the Out axis. It will always have an In 
value of 0dB. During the drag, the In/Out Display shows the ratio of the 
moving curve segment.
7. Add a second threshold by clicking the cursor at -24:-24.
While positioning this threshold, notice that the In/Out Display is dis-
playing the positive going curve on the left as an N to 1 ratio, and the 
negative going curve on the right as a -N to 1 ratio. It is possible to use 
MDT to create inverse gain functions. 
						

							MDT UserÕs Manual25 Lesson 1: MDT Basics
At this point in the exercise, MDT should look like this:
8. Delete the thresholds by pressing  and clicking on the thresholds.
The thresholds disappear and the curve snaps to its new position auto-
matically.
9. Reset MDT by choosing Reset Settings from the Setting: menu.
The In/Out Grid
MDT works by detecting the level of the input signal, looking for the point
on the I/O Curve with that input value, and then adjusting the gain so that
the output level equals that of the I/O Curve at that point.
All the possible points where the I/O Curve can exist are represented by the
In/Out Grid. It is divided by a diagonal line that represents the points on
the Grid that have input levels equal to output levels (e.g. -48:-48). Placing
the I/O Curve on this diagonal will cause MDT to output the signal at the
same level as it was input. 
The points on the Grid which have output levels lower than their input lev-
els (e.g. -48:-72) are located below the diagonal. Placing the I/O Curve
below the diagonal will cause MDT to output the signal at a lower level
than it was input (gain reduction).
Lower terminator at -60.5:-96Threshold at -60:-60 Threshold at -24:-24
Upper terminator at 0:-48 
						

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Points on the Grid which have output levels higher than their input levels
(e.g. -72:-48) are located above the diagonal. Placing the I/O Curve above
the diagonal will cause MDT to output the signal at a higher level than it
was input (gain ampliÞcation).
The following section demonstrates the relationship between I/O Curve
position and gain.
1. Choose 1:1, -12 dB gain from the Settings menu.
2. Start playback with looping.
The voice is heard 12 dB lower in volume because the I/O Curve shifts 
every point on the In axis -12dB on the Out axis.
3. Adjust the Gain slider to read 12 dB. 
4. Click the Bypass button on and off to verify the level match.
The processed level is now precisely the same as the original level 
because of the additional gain supplied by the Gain slider. The gain fac-
tor set into the Gain slider is applied after the signal is processed by the 
I/O Curve and is the last stage of control in MDT.
5. Choose 1:1, -24 dB gain from the Settings menu.
The voice is heard 12 dB lower in volume because the I/O Curve has 
shifted everything an additional -12 dB lower on the Out axis.
6. Adjust the Gain slider to read -12 dB. 
-48:-72-48:-48 -72:-48 
						

							MDT UserÕs Manual27 Lesson 1: MDT Basics
7. Choose 1:1, +12 dB gain from the Settings menu.
The voice is now heard at the original volume level. The I/O Curve is 
amplifying it by 12 dB and the Gain slider is reducing the gain by -12 dB. 
Use the Bypass button to verify this.
8. Stop playback.
9. Choose Reset Settings from the Settings menu.
The Input Offset Arrows
Input Offset is another unique feature of MDT. The Input Offset Arrows
(see illustration) allow you to change the relationship of the input signal to
the I/O Curve without actually changing the signal level of the input data. 
In a single band conÞguration, the placement of the thresholds can be
tweaked using the Input Offset without disturbing the I/O Curve. In multi-
band conÞgurations, spectral bands can be independently adjusted. By
adjusting the different bands to the same level, coloration is reduced.
Adjusting the different bands to completely separate sections of the I/O
Curve allows independent compression ratios and levels for each band.
These multiband cases will be demonstrated later. 
1. Choose Input Offset Test from the Settings menu.
Input Offset ArrowsInput Offset Display 
						

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2. Start playback with looping.
3. Press and hold down the downward Input Offset Arrow.
As the Peak Level Indicator moves to the left, notice that the loudness of 
the playback remains the same. This is because the input data is not 
being changed. Only its relationship to the I/O Curve is being changed.
When the Peak Level Indicator moves through the region between -36 
dB and -60 dB on the Input scale, notice that the loudness of the sound 
decreases by 36 dB. This is because the I/O Curve is set for a -36 dB gain 
reduction in that region. As the Peak Level Indicator moves below -60 
dB, the output goes back to normal because the I/O Curve is back at 
unity gain (0 dB gain).
The Input Offset Arrows always increment in 1 dB steps. Press  
then press on the arrows slows the rate of change.
4. Press on the upward Input Offset Arrow until the reading returns to 0.
The value displayed in the Input Offset Display (see illustration) is the 
difference in dB between the actual input level and the displayed level.
5. Stop playback.
6. Choose Reset Settings from the Settings menu.
The Setting Menu
MDT has a Setting menu which allows you to store your most used MDT
set-ups and instantly recall them. The Setting menu allows an unlimited
number of ÒsnapshotsÓ of MDTÕs settings to be saved. This data is saved in
the ÒMDT PreferencesÓ Þle in the SystemÕs ÒPreferencesÓ folder. In this sec-
tion you will learn how to save, recall, and delete settings from the Setting
menu.
1. Put four thresholds on the I/O Grid at In:Out = -12:-48, -24:-12, -36:-48, and -48:-12.
2. Choose 5 band AP from the Filter Mode menu.
3. Increase the Attack time to 50 mS. 
4. Increase the Release time to 4,999 mS. 
5. Decrease Gain to -24 dB.  
						

							MDT UserÕs Manual29 Lesson 1: MDT Basics
6. Decrease the Low Band Input Offset to -15.
At this point MDT should look like this:
To save these settings, 
1. Choose Save Settings AsÉ from the Setting menu.
A dialog box appears requesting a setting name.
2. Type Test in the text box and click on Save.
The settings are now saved under the name ÒTestÓ. These settings 
appear at the bottom of the Setting menu.
3. Choose Reset Settings from the Setting menu to revert to the default values.
To recall the setting;
1. Choose Test from the Setting menu.
The settings are recalled as you saved them.
To delete the setting;
1. Choose Delete SettingsÉ from the Setting menu.
A dialog appears with the list of the settings in the menu.
2. Scroll down to Test and select it by clicking on it.
3. Click on the Delete button. 
						

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The setting is deleted from the menu. You may select multiple settings 
for deletion by shift-clicking or click dragging over the items to be 
deleted. To make a non-contiguous selection, press  and 
click on the items to select them. Note that the settings themselves 
remain on MDT until you move them yourself or choose another setting.
Lesson 2: Single Band Applications
The following section demonstrates how to conÞgure MDT as a single band
compressor, limiter, gate, expander, Òsoft kneeÓ compressor/gate, and
ÒtubeÓ compander.
Compressor
1. Select the ÒFetes 1Ó soundÞle for playback.
2. Click on the MDT insert in the track labeled ÒAux 1Ó.
3. Choose Reset Settings from the Setting menu.
4. Start playback with looping.
The selection is an excerpt from Fetes (rhymes with ÒpetÓ), the second of 
DebussyÕs Nocturnes for orchestra. Notice the relative loudness of the 
brass notes compared to the quiet strings that follow. The Peak Level 
Indicator shows an approximate dynamic range of -24 dB.
5. Choose 3:1, -48 dB threshold from the Settings menu.
Notice the shape of the I/O Curve. Sounds that have input levels lower 
than -48 dB are in a 1 to 1 relationship with the output. Above -48 dB, the 
signal will get a different gain reduction depending on its input level. 
For example, a sound input at -12 dB will get a -24 dB gain reduction and 
be output at -36 dB. A sound at -24 dB input will only get a -16 dB gain 
reduction and be output at -40 dB, and so on. A piece of music with a 
dynamic range from -12 dB to -36 dB (a 24 dB dynamic range) would be 
output from -36 dB to -44 dB (an 8 dB dynamic range). Shrinking 24 dB 
down to 8 dB is a 3 to 1 compression ratio.