Beat Detective

Beat Detective is function of Pro Tools that can be used to extract, manipulate or correct the timing information found in either Audio or MIDI clips.

When working with audio, Beat Detective can be used to slice the audio in smaller clips and reposition them in relation to the grid without applying any ‘time-stretching’ processing. This can produce more natural results than using Elastic Audio in many cases. Beat Detective works best on content that has sharp and defined transients such as drums or percussion. Beat Detective makes educated guesses when analysing the material, but it invariably needs addition user tweaking to get the best results. In the following tutorial we will take an in-depth look at how to get the most out of this exciting feature of Pro Tools.

Beat Detective can be accessed from the Pro Tools Event Menu or by using the Control 8 (PC) or Command 8 (Mac Numerical Pad) keyboard shortcuts.

The Beat Detective Window

Beat Detective Modes

Beat Detective can be used to perform the following functions listed in the ‘Operations’ area on the left-hand side of the Beat Detective window.

 
The ‘Operations’ area of the Beat Detective window.

Bar/Beat Marker Generation - When working with content that was freely recorded (without a click track), Beat Detective can be used to create a Tempo Map by analysing the materials transients, this allows Pro Tools to align its grid to the selected clip and follow its tempo variations.

Groove Templates Extraction - Beat Detective can analyse the selected clip and extract its timing information creating a ‘groove template’ that can then be applied to other clips to match the original clips timing and feel.

Clip Separation - After analysing content and detecting its transient information, Beat Detective can be used to separate the information between adjacent transients into individual clips.

Clip Conform (Audio) - After analysing the selected clip, creating ‘beat triggers’, and separating the clip at its transient points, Beat detective can be used to conform the newly created clips to the existing session’s tempo map, allowing you to repair timing imperfections.

Edit Smoothing (Audio) - Beat Detective can be used to smooth edits in audio content that has been chopped into smaller individual clips and repositioned, automatically filling any resulting gaps by trimming and crossfading.

The Selection Area

Correctly defining the selected clips properties in relation to its start/end positions, time signature and divisions is a crucial step to getting the expected results from Beat Detective, if the selection area’s information is incorrect then you will never achieve the desired results. For this reason it is essential to focus on this area first before attempting any Beat Detective analysis.

Capture Selection

If the material you wish to capture was recorded to or matches the session tempo then you can use the ‘Capture Selection’ button to copy the selection’s start, end and length information into the selection area of the Beat Detective window.

Note: the selection area’s information does not update automatically for any new selections you make, so you will need to use ‘Capture Selection’ again when working with a different selection.

When working with live drums you may need to modify your selection slightly using Slip Mode in order to avoid cutting into the selected areas first downbeat or following downbeat. This occurs frequently when working with drummers who ‘pull’ or ‘push’ the beat in relation to the grid.

Working with Non-Synchronised Content

When working with clips that do not match the session tempo, the ‘Capture Selection’ method will not work. In those specific cases you will need to count the bars and beats of the content relative to itself and manually enter the information (relative to the content) into the ‘Selection’ fields.

Time Signature, Contains & Triplets

It is important to enter the correct information in the ‘Time Signature’, ‘Contains’ & ‘Triplet’ fields. The ‘Contains’ area should include the smallest division present in the content. In the case of a drummer who plays a pattern predominantly consisting of 1/8 notes with the occasional 1/16 note fill on the high-hat, this field would be set to 1/16 notes. If there are Triplets present the box
labelled ‘3’ should also be ticked.

Analysing Transients

The Detection area of Beat Detective is used to analyse the clips transients (The detection area is only available in ‘Bar/Beat Marker Generation’, ‘Groove Templates Extraction’ and ‘Clip Separation’ operation modes).

Analysis Modes

Beat Detective offers three ‘analysis’ modes that each offer benefits when working with certain types of material.

High Emphasis: Prioritises non-harmonic high frequency content such as high hats and cymbals.

Low Emphasis: Prioritises non-harmonic low frequency content such as bass and kick drums, but also works well with harmonic content such as piano or guitar.

Enhanced: Works well with a varied range of material including full mixes and drum loops.

Analysing and Sensitivity

Once you have chosen the relevant ‘Analysis’ mode and pressed ‘Analyze’, the ‘Sensitivity’ slider becomes active, The sensitivity slider allows you to lower or raise the sensitivity of Beat Detective’s transient detection. Higher sensitivity settings result in more (purple) ‘Beat Trigger’ markers but can also result in ‘false transients’ - the incorrect detection of events that do not represent actual transient points.

Resolution

The ‘Resolution’ buttons in the Detection area allow you to filter out certain Beat Trigger markers from the results, for example - using the ‘Bars’ setting will only allow Beat Triggers that are located on the start of each bar to be revealed, the ‘Beats’ setting reveals only triggers that appear on each beat and so on.

Show Trigger Time

When this function is activated Pro Tools overlays timing information next to each transient marker, this displays the relative position of the transient according to Beat Detective’s analysis.

Double-clicking on a trigger with the Grabber tool opens the ‘Identify Trigger’ window, this allows you to manually re-identify a marker with its actual bar and beat position if the Beat Detective analysis is incorrect.

Manually Placing and Promoting Triggers

Promoting a trigger locks it permanently in place when lowering the sensitivity, a promoted trigger will then remain visible at any sensitivity value (except zero). Trigger markers can be inserted, moved, deleted and promoted using the Grabber tool in the following ways if necessary:

Separating and Padding Clips

Once you have identified the correct trigger points Beat Detective’s Clip Separation mode can be used to slice the audio into segments, these individual clips can later be repositioned using Beat Detective’s Conform Mode to modify or correct a clips timing.

It is advisable to use the Detection area’s ‘Trigger Pad’ option to insert a small gap between the transient trigger and the actual slice point, this safeguards against cutting into any waveform information that slightly proceeds the transient, small values of 5 - 10 ms generally work best. The ‘Separate’ button is used to perform the ‘clip separation’.

Note: Although the padded start point of the clip now starts slightly before the transient Beat Detective still uses the Beat Trigger (purple) location point as the reference when it performs any timing corrections, as shown in the image below.

Conforming Clips

Once the audio has been separated between each ‘Beat Trigger’ marker into individual clips the audio can be manipulated in various ways.

Tick Based Manipulation

Setting a tracks timebase to ‘Ticks’ locks clips to specific locations relative to the Bars & Beats timescale, this means that the individual clips would then follow any session tempo changes. This method works well when increasing the tempo slightly (decreasing the tempo would result in small gaps between the clips as they become further apart). The benefit of this method over using Elastic Audio is that no time-based processing has been applied to the audio which can sometimes introduce artefacts.

Image: Setting the track’s timebase to ‘Ticks’ by pressing the Timebase selector (indicated by the red arrow).

Conforming

The ‘Conform Clip’ Mode can be used to quantise the individual clips to the Pro Tools sessions’ grid.

Note: It is important that the current selection still matches the original area that you analysed whilst performing the ‘Detection’ part of the process, if it doesn’t, reselect the desired area manually or use the ‘Capture Selection’ function to correct this.

Pro Tools can either conform the clips to the standard grid increments or to groove quantise presets (shown below), these two options are located in the upper menu of the conform section (visible only after selecting ‘Conform Clip’ operation mode).

Conform Options

When using the ‘Standard’ conform setting which quantises to the regular bars and beats grid in Pro Tools there are a number of further parameters that can be adjusted (shown below).

Strength - This sets the strength of the quantise, a value of 100% moves the clips exactly to the grid divisions, a value of 50% would move the clip half way to the division from its original position, this feature can be used to retain some of the drummer’s original feel whilst tightening up the performance.

Exclude Within - This function is used to ignore certain clips if they already fall within the specified percentage of the grid.

Swing - This function imparts a swing time feel on the timing of the clips, where certain clips are pushed later to create a more groovy feel, the 1/8th and 16th note buttons below the swing slider are used in conjunction to dictate a 1/8th or 1/16 note swing.

Pressing the ‘Conform’ button at the bottom of the window applies the processing, the settings can be modified and reapplied at anytime by changing the settings and pressing the ‘Conform’ button again.

Edit Smoothing Mode

One of the main issues after conforming the audio is that gaps can start to appear between clips that have been repositioned further apart (shown in the image below), the ‘Edit Smoothing’ function in Beat Detective can be used to address this by filling in the gaps and adding crossfades.

The ‘Edit Smoothing’ mode works by automatically trimming back any selected audio until it meets the clip to the left, it can also add crossfades at the join point by selecting the ‘Fill and Crossfade’ option at the length specified in the Crossfade Length area (shown below).

Bar / Beat Marker Generation

The Bar / Beat Marker Generation Mode can be used to match the Pro Tools Grid to the timing of audio that was recorded without the use of a click track by adding tempo changes throughout the session that follow the chosen clip. This is particularly useful if you need to make edits to a live recording or add additional MIDI parts later on.

For this to work correctly it is essential that your Beat Detective ‘Selection’ values accurately represents the relative bar and beat information relevant to the selected clip. Remember the Pro Tools grid and clip are not synchronised at this point so you will need to play the audio and count the bars and beats contained in the selected portion of the clip and then enter the correct amount into beat detective. You will find it easier to work in small sections of perhaps four to eight bars if the material timing is fairly stable.

Tip: When making selections, holding shift allows you to modify your selection by dragging the selection edge, holding shift and using the Tab key allows you to move your selection to the next transient point (with Tab To Transient enabled, shown below).

Tab to Transient

The image below shows a two bar selection relative to the clips’s content which ends relatively at bar 3, notice the session’s bar 3 indicated by the red arrow which is unrelated.

The information relating to the internal timing of the audio then needs to be entered into the ‘Selection’ area of Beat Detective. In the case of the two bar loop (shown above) it would start on Bar1/Beat1 and ends on Bar3/Beat1 (even though the actual session grid shows different values). This loop only contains 1/8 notes so that option has been selected in the ‘Contains’ drop down menu.

The Beat Trigger markers are used to create the session’s tempo map, which involves the parameters found in the Detection area (shown below), a process described earlier in this tutorial. The main difference in the case of generating bar and beat markers is that a ‘Beats’ resolution is probably sufficient rather than ‘Sub-Beats’.

When you are ready to commit to your settings press the ‘Generate’ button. If ‘Tick’ based tracks (which will respond to tempo changes) are present in the session you will see the following window. The choice you make will depend on your individual session’s requirements.

Once Pro Tools has processed the content you will see the relevant tempo changes inserted in the sessions tempo ruler, the session now varies its tempo and bar/beat position to match the audio (shown below).

Groove Template Extraction

Beat Detective’s ‘Groove Template Extraction’ mode is designed to analyse the timing information of a selected clip in order that its timing or ‘groove’ can be applied to another clip in the session. This is useful when you wish to preserve the human feel across different tracks but have them tightly synchronised.

It is important that the Selection area in Beat Detective accurately represents the information present in the selected portion of the clip (use ‘Capture Selection’ if necessary). The detection area is again used to correctly identify where beat triggers should be located via the sensitivity slider and other methods described earlier, in the case of groove templates a detection resolution of ‘subbeats’
would be most appropriate as we wish to capture all the finer elements that make up the groove.

The ‘Extract’ button is used to analyse the clip and generates the ‘groove’ template, once pressed the ‘Extract Groove Template’ window (shown below) opens.

The window gives the following options for where you wish to save the template:

‘Save To Groove Clipboard’ This option places the template in the computers temporary ‘clipboard’ memory for immediate use.

‘Save To Disk’ This option saves the template permanently to disk in the Pro Tools ‘Grooves’ folder, in order that it can be used in future sessions.

Accessing Grooves

Grooves can either be accessed from the ‘Groove’ dropdown menu of the Conform area of Beat Detective, when in Clip Conform mode as mentioned previously.

Grooves can also be accessed from the ‘Quantize Grid’ drop down menu found in the Pro Tools Quantize window (Event Menu > Event Operations > Quantize). These Quantize grooves can then be applied to MIDI or Elastic Audio enabled audio tracks.