REAPER: How To Change Tempo Without Stretching The Pitch

Let’s check out how REAPER handles audio items, tempo changes, stretch behavior, and playback rate shifts. This article will also cover a common question: how to change the tempo/BPM in REAPER without stretching the audio or altering the pitch?

There’s a big difference between how traditional producers and many modern producers utilize sampled audio like drum one-shots. Traditional musicians like me would use a sampler like ReaSamplOmatic5000 to load the sample files and use MIDI input to trigger the samples. Conversely, many contemporary producers prefer to add samples directly onto the arrangement page. This workflow would require drums and percussion samples to remain unstretched when a tempo change occurs, whereas melodic samples like vocals should be stretched to match the tempo.

How To Change The BPM In REAPER Without Stretching The Audio/Pitch?

You can change the tempo/BPM in REAPER without stretching the audio or pitch by changing the project timebase to “Beats (position only).” Go to the Files menu, find the project settings, and change the timebase for items in the Project Settings tab. Note that doing so will affect every item in your project.

REAPER allows you to change each audio item’s stretch and pitch behavior in your project using the media properties window. You can use the feature to alter the tempo change and stretch behavior per item depending on your need. Otherwise, you can assign the default behavior for any media clip you add, as I mentioned above, if you prefer the modern workflow.

Before we get into the steps to change the settings, let’s understand what different ways REAPER offers for stretching audio and MIDI items. Understanding the various timebases in REAPER is crucial to make the DAW behave as you want.

Timebase

The timebase in REAPER refers to the way a media item reacts to tempo changes. You can assign a timebase to the entire project, also called the default timebase. Similarly, you can assign a timebase to each track and media item. REAPER prioritizes the timebase of these elements in the following order: media item, track, and project default. So, setting a media item timebase bypasses both the track and project timebases.

Here are the timebases available in REAPER:

• Time
  The Time mode uses the real-world clock to position the media items. So, if you place an audio item at exactly 3 seconds from the start of the project, the media item’s position will stay at 3 seconds regardless of your tempo. This feature is excellent for sound designers working with fixed media like films and advertisements. You can compose the music synced to the beat while keeping all the sound effects attached to the real-world clock to sync with the video.
• Beats (position, length, rate)
  As the name suggests, this timebase uses your project’s tempo as the internal clock instead of real-world time to position the media items. It also stretches the media items to match your new tempo. Note that it doesn’t stretch the media items to match tempo automation.
• Beats (position only)
  The “Beats (position only)” timebase allows you to position the media items according to the tempo and beats, but it doesn’t stretch the audio. You want to use this timebase for any one-shot percussion and drum samples. Similarly, I use it on audio recordings that were live performed. Then, I can change and automate the tempo to match the live performance and get a humanized piece of music. While the Time timebase could do the same, the Beats (position only) timebase makes it a breeze to keep the start of a recording fixed at the start of a measure/bar.
  Try using the snap offset as shown below for further convenience. You can create a snap offset by dragging your mouse from the lower-left corner of a media item, where the mouse cursor turns into a two-way arrow with something like an “L” shape.
  
• Beats (auto-stretch at tempo changes)
  This timebase uses REAPER’s stretch marker feature on the media item to match any tempo automation (including gradual changes) in your project. It also stretches and positions the media item according to the tempo. However, the feature works best when you add the media item before creating gradually changing tempo automation.
  When you add a media item in a section where a gradual tempo automation already exists, REAPER will use the faster tempo as the base rate, where the audio will play at its original speed. You can change this behavior by manually assigning a tempo to the audio item, which I will describe further in a later section.

Changing The Timebase

REAPER allows you to change the timebase at three levels, each with a different priority for the DAW. We’ll go through the steps to change the timebase at each level from the lowest to the highest priority.

Changing The Project Timebase

Changing the project timebase is the easiest way to switch to a certain type of workflow, like using sample files on the arrangement page. Similarly, I use it for a specific job like sound designing for a video or audiobook, where I use the Time timebase. Let’s check out the steps to change the project timebase:

1. Open the Files menu and click on Project Settings. You can also press Alt + Enter or Option + Return to open this page.
   
2. Go to the Project Settings tab on the window that opens. It’s the first tab.
3. Assign the timebase you want in the drop-down menu next to “Timebase for items/envelopes/markers.” You can also change the timebase for the tempo/time signature envelope. However, if you don’t know what you’re doing, I recommend using Beats for it, which is the default.
   

Changing The Track Timebase

Changing the track timebase is handy when adding media items that go against your workflow’s requirements. For example, if you’ve set the project timebase to keep REAPER from stretching audio when changing the tempo, it’s not good for, say, vocal recordings. Changing the track timebase allows you to stretch the vocal track’s audio items to match the tempo.

Furthermore, the track timebase can save you time by only setting the percussion and drum tracks to avoid stretching with tempo changes. You can even save such tracks as a track template to save time further! Let’s check out how to change the track timebase:

1. Select the track on which you want to change the timebase. You can hold the Control/Command key to manually select multiple tracks or the Shift key to select a series of tracks.
   
2. Right-click on one of the selected tracks and find “Track timebase.”
3. Under the drop-down menu, you’ll find “Project timebase,” the default that uses the project settings. Furthermore, the menu includes other timebases I’ve described above. Select the one you need.
   

Changing The Media Item Timebase

If you mix multiple workflows while producing music, I recommend using the media item timebase the most as it gives you the most flexibility. I often find myself using either the media item timebase or the track timebase while leaving the project timebase at its default. Furthermore, the timebase called “Beats (auto-stretch at tempo changes) is only available for media item timebase because it requires individual calculation for each media item.

Hence, it’s a good idea to familiarize yourself with this feature. Here are the steps to change the media item timebase using the item properties page:

1. Select the items on which you want to change the timebase. You can hold the Shift key for multiple selections or use marquee select.
   
2. Right-click on one of the selected items and click “Item properties.” To open item properties, you can also press F2 on Windows and Shift + F2 on macOS.
   
3. Find “Item timebase” and select the one you want from the drop-down menu.

Alternatively, you can also change the item timebase using the following method:

1. Select the items for which you want to change the timebase.
2. Right-click one of the selected items and find “Item settings,” which should be the first menu item.
   
3. Find the “Set item timebase to…” menus and select the one you want.

The Timebase In Audio vs. MIDI Items

REAPER doesn’t treat both audio and MIDI items in the same manner. Since MIDI items use your project’s tempo as the playback rate reference by default, it will continue to stretch its MIDI contents regardless of what timebase you’ve selected. Contrastingly, an audio item’s content has nothing to do with your project’s tempo, making them behave as expected when assigning a timebase.

You can expect regular behavior with the “Beats (position, length, rate)” timebase in MIDI items. However, when you’re using the “Beats (position only)” or “Time” timebase, MIDI items will continue to stretch their content, unlike audio items. REAPER allows you to assign a source tempo to the MIDI item to make it behave like an audio item.

This feature is essential if you record a MIDI item straight into your REAPER project without figuring out its tempo first. Many of my projects start with me playing the keyboard without thinking about the exact tempo. So, being able to change the project tempo without altering the playback speed of the recorded MIDI item is vital to my workflow.

Let’s check out how to assign a source tempo to a MIDI item:

1. Select the MIDI item you wish to modify. You can select multiple items, but you’ll have to assign a source tempo to each item individually. However, it can still be quicker than working with each item manually.
2. Right-click on one of the selected items and click “Source properties.” Alternatively, press Ctrl + F2 or Command + F2 to open the source properties window.
   
3. Enable the “Ignore project tempo” menu item and assign the source tempo in the box next to the menu. Type in your current project tempo if you haven’t changed the project tempo after recording your MIDI item. However, if you’ve already changed the project tempo, type in the BPM you had before you changed the project tempo. Note that you can also assign a source time signature.

Sometimes, you might need to use the source tempo and time signature grid for editing your MIDI. A good example is when you’re composing a polyrhythmic piece. So, let’s learn how to change the media item’s piano roll to display the source beats or grid:

1. Double-click the media item to open its MIDI Editor in the piano roll mode.
2. Open the View menu, find “Piano roll timebase,” and click “Source beats.”
   

Once you’re done, you can switch back to the default timebase anytime. Note that the piano roll timebase is only for display and does not affect the playback. Furthermore, it only works for the piano roll and the named-notes editor; it doesn’t work for the musical notation editor.

Good Practices & Bonus Tips

Most of the things I will talk about here are logical and optional to read. However, there are some tips I’d like to share that can help you have an easier time working with timebases. Using REAPER’s features and quirks to your advantage can help you save time and effort when producing music.

• Keep certain types of samples in an individual track. For example, if you have kick samples on your arrangement page, keep all of them on the same track. Doing so allows you to easily switch the timebase of the track to change all the kick sample items’ behavior easily. Of course, if you need to process the kicks in a certain song section differently, you should use another track.
• Right-click a track and use “Free items positioning” to add multiple audio items in one track simultaneously. It’s a great feature for mixing two samples, which you can group to make them behave like a single item. Furthermore, use each item’s volume handle to fine-tune your sound and create variations.
  
• The media explorer in REAPER allows you to change the sample file in your project’s selected items. For example, suppose you don’t like the sound of your current snare sample. First, select all of the snare samples in your project by double-clicking the snare track (hopefully, you already follow my first tip!). Then, find a sample you’d like to use in the media explorer, right-click the file, find “Insert in selected media items,” and click “Replace media source.”
  
  
• Use project and track templates to help you save time. As a film music composer, I’m happy with the default audio-stretching timebase for my project. However, when making electronic music, I might add a lot of samples to the arrangement page. I have a project template with a few common tracks like kick, snare, hi-hat, toms, and cymbals. Each track uses the “Beats (position only)” timebase to keep the samples from stretching.
• Disable “Preserve pitch when changing rate” in the media item properties (F2 for Windows/Shift + F2 for macOS) to make REAPER change the pitch when stretching the audio item. You can combine it with stretch markers (right-click media items) to create tape-stop effects.
  
  

Conclusion

I hope this article helped you understand how timebases work in REAPER and how to select the correct timebase for your intention. You can generally change the project timebase to “Beats (position only)” to change the tempo without stretching the audio items. However, as I’ve explained above, mixing multiple types of workflows requires you to choose where to change the timebase.

To recap, you can change the timebase in three places in the lowest to highest priority order: project, track, and media item. Change the project timebase to the one you use most often, depending on your workflow. Then, you can use the track and media item timebases for the rarer elements of your project.

With that, we reach the end of this article. I hope I’ve helped you learn a thing or two in REAPER. And, as always, happy music-making!

K. M. Joshi

K. M. Joshi is a multi-award-winning composer and sound designer, specializing in film, game, and TV audio. He enjoys making cinematic music, rock, blues, and electronica. Read more..