Tempo and Follow Project Tempo

Miaou has one visible project BPM in the top bar. Audio regions can individually follow that BPM when Follow project tempo is enabled.

For the full audio-region editing workflow around trim, fades, clip gain, transients, slicing, and restore, see Audio Regions.

The top-bar BPM is the visible project tempo. It drives the grid, metronome, MIDI timing, synced effects, and tempo-following audio regions.

Import audio onto the intended lane first, then decide whether that region should keep original timing or follow the project tempo.

The Mental Model

Concept	What it means
Project BPM	The visible top-bar tempo at beat 0. It drives the grid, chord blocks, MIDI editing, metronome, synced effects, and tempo-following audio.
MIDI tempo map	Tempo and time-signature events imported from MIDI files. They can update or preserve imported MIDI timing depending on import policy. Miaou does not include a manual tempo-map editor.
Source BPM	The original tempo of one audio region's source file. Miaou needs this to know how much to stretch when the project BPM changes.
Follow project tempo	A per-audio-region switch that makes the selected region keep beat length instead of fixed source-file seconds.
Stretch mode	The processing strategy used when a region follows project tempo.

Tempo is not per track. Audio tempo following is per region. MIDI clips follow the project/grid timing unless imported with a policy that preserves the original file timing.

Choose the Right Tempo Action

Use this table before changing BPM or importing a file:

You want...	Do this
A whole project sketch at a new tempo	Change top-bar BPM before writing MIDI, chords, or recording.
An imported loop to match the current project	Import the file, set Source BPM, enable Follow project tempo, then choose a stretch mode.
The project tempo to match an imported loop	Use Set project tempo from sample during import, or select the region and use Use BPM.
A song file to stay exactly like the original recording	Keep Follow project tempo off.
A loose live loop to tighten without slicing	Enable Follow project tempo, then use tempo markers or Quantize transient anchors.
MIDI from another project to define Miaou's tempo	Import MIDI with Use file tempo.
MIDI to fit Miaou's existing grid	Import MIDI with Keep project tempo.

Before changing BPM

If audio is already on the timeline, first decide which regions should follow the new tempo. BPM changes affect MIDI and chords immediately, but audio only stretches when Follow project tempo is enabled on that region.

Change BPM After Audio Exists

Use this checklist when a project already contains imported or recorded audio and you want to change the song tempo without guessing why some regions move and others do not.

Step	Do this	Listen for
1	Save a version before the tempo change.	You have a recovery point if several regions need correction.
2	Select each audio region that should follow the new tempo.	The Selection inspector shows that region's Source BPM and Follow project tempo.
3	Correct Source BPM first, using Detected, Half, or Double when useful.	The region plays at the expected bar length before you push the project BPM far away.
4	Enable Follow project tempo only on regions that should stretch with the song.	Reference tracks or full songs can stay fixed if they are only there for listening.
5	Choose Beats for drums, Tones for sustained material, Tape for pitch-changing speed.	Attacks stay clearer, sustained notes stay smoother, or tape-style pitch movement is clear.
6	Change the top-bar BPM.	MIDI, chords, grid, synced effects, and enabled audio regions move together.
7	Play the busiest section and adjust stretch mode or markers only where timing sounds wrong.	Avoid adding dense tempo markers to regions that already follow correctly.

If one audio region should keep original timing, leave Follow project tempo off for that region. If one loop follows tempo but lands late, fix Trim Start, Set downbeat, or tempo markers on that region instead of changing the global BPM again.

Project BPM

Use the top-bar BPM field to set the project tempo. It affects:

• Timeline bar/beat grid.
• Chord block positions and durations.
• MIDI editor grid and quantize timing.
• Metronome and count-in.
• Tempo-synced effects such as Delay, Tremolo, Auto-pan, Auto-filter, Chorus, Flanger, and Phaser.
• Audio regions with Follow project tempo enabled.

Changing BPM does not automatically time-stretch every audio file. Only regions with Follow project tempo enabled react to the change.

The top-bar BPM field keeps normal text-editing behavior while focused. Type partial values freely; Miaou commits the parsed tempo when you press Enter or leave the field. Use ArrowUp / ArrowDown in the field for intentional step changes.

MIDI Import Policies

When importing a Standard MIDI File, choose the tempo policy before import:

Policy	Use it when	Result
Keep project tempo	You want the MIDI to fit the current project grid.	Imported notes are placed against the current project BPM.
Use file tempo	The MIDI file's tempo map should define the project timing.	The file tempo and time-signature map update the project before placing clips.
Original timing	The MIDI was performed at another tempo and should sound close to the file's original timing.	Clip timing is converted so playback stays close under the current project tempo.

Imported MIDI tempo, time-signature, key-signature, controller, program, pitch-bend, pressure, and text events are preserved for MIDI export where applicable.

Audio Source BPM

Source BPM is the tempo of the source audio before Miaou stretches it. Detection can fill this automatically for regular loops, but you should correct it when:

• The loop has pickup notes or silence before the first downbeat.
• The source has swing or loose timing.
• The detected value is double-time or half-time.
• The imported material is not a regular loop.

Example: a loop recorded at 100 BPM with project BPM set to 125 should have Source BPM set to 100 and Follow project tempo enabled.

When Miaou detects a tempo, the Selection inspector also shows quick Source BPM choices:

Choice	Use it when
Detected BPM	The loop plays at the expected bar length.
Half	The loop sounds twice as fast as expected, or an 8-bar phrase is read as 4.
Double	The loop sounds half as fast as expected, or a 4-bar phrase is read as 8.

The Source BPM value field also keeps partial typing while focused and commits on Enter or blur. Press Escape before committing to discard the typed draft.

Follow Project Tempo

Select an audio region and use the Selection inspector:

1. Set Source BPM to the source tempo.
2. Enable Follow project tempo.
3. Choose a Stretch mode.
4. Press Play and verify timing by ear.

The setting is stored on the audio region. Two regions using the same source file can have different Follow project tempo settings, stretch modes, offsets, fades, clip gain, and loop lengths.

Tempo Markers

Tempo markers are per-region timing anchors for audio that does not line up perfectly from only one Source BPM. They are non-destructive: Miaou stores the marker positions on the region and keeps the original source audio unchanged.

In the Selection inspector:

Control	What it does
Add playhead	Adds a marker at the current playhead position inside the selected tempo-following region.
Detect	Replaces the marker list with markers from detected transients in the selected source slice.
Quantize	Replaces the marker list with detected transients snapped toward the current Grid, Amount, and Swing settings.
Extract groove	Stores the detected transient timing as a reusable groove for MIDI notes.
Clear	Removes custom markers so the region follows a straight Source BPM again.
Remove	Removes one listed marker.

Use Detect when you want Miaou to preserve the measured transient timing as anchors. Use Quantize when you want those detected hits to move toward the editor grid without cutting or replacing the source file. Quantize uses the same grid family as MIDI editing, plus Amount and Swing, and enables Follow project tempo with Beats mode when the region was not already following tempo.

Each listed marker has editable Beat and Source s fields. Beat is the output beat inside the region. Source s is the source-file time that should play at that beat. Edit these when a detected hit is slightly late, the downbeat is wrong, or one anchor needs manual correction.

Audio regions with custom tempo markers show small timing ticks on the timeline, so you can see which clips have active anchors before opening the inspector. Select the region and drag a tick to move that marker's output beat while keeping its source time anchored.

Selected audio regions also show subtle detected-transient ticks when waveform analysis is available. These are passive visual guides for Detect, Quantize, Extract groove, and manual marker correction; they do not edit the source audio by themselves.

Use Extract groove when you want MIDI notes to borrow the feel of an audio loop. Select the audio region, extract the groove, then select a MIDI region or notes and use Apply audio groove from MIDI actions. The audio source stays unchanged; the MIDI note starts move toward the extracted timing using the current Amount control.

Use tempo markers when a loop has a loose drummer, a live pickup, a late downbeat, or a few hits that need to stay pinned to the grid. If every marker makes the audio sound worse, clear the list and correct Source BPM first.

If the audio file has silence before the real first hit, drag the left-edge Trim Start handle until the hit lines up with the intended beat. If you want to decide the downbeat manually, move the playhead to the hit that should become the region start, then click Set downbeat in the selected audio region actions. Miaou hides the earlier source audio non-destructively, keeps the original file, and shifts or rebuilds tempo markers so their source anchors stay coherent with the new region start.

For new imports, set the audio import Start policy to Trim to first hit when you want the detected first hit to land exactly at the playhead or drop position.

Stretch Modes

Mode	Best for	Tradeoff
Default	Mixed loops, full songs, first-pass imports.	Balanced behavior, but not always best for drums or exposed vocals.
Beats	Drums, percussion, rhythmic loops, transient-heavy material.	Keeps attacks clearer, but sustained tones can sound choppy at extremes.
Tones	Vocals, bass notes, pads, strings, sustained tonal material.	Smoother sustain, but hard transients can smear.
Tape	Resampled speed changes where pitch should move with tempo.	Musical for turntable/tape effects, but pitch changes by design.

Extreme tempo changes can create artifacts in any real-time browser stretch engine. Smaller changes usually sound more natural than large changes.

Realtime and Export

Realtime playback and export use the same project timing choices:

• Tempo-following regions stretch from the original referenced source audio.
• Synced effects use the project tempo.
• The full exported mix includes Track Effects, routing, Master Effects, and Master track-head mute/volume/balance.
• Per-track stems stay source-track based and do not include final Master output controls.

If export sounds different from playback, first check that the project is saved, unlocked, and that all source audio files have restored in the project.

Non-Destructive Source Handling

Follow Project Tempo does not overwrite imported or recorded files. Miaou stores:

• The original source audio.
• Region start, duration, loop, fade, clip gain, and source offset.
• Source BPM.
• Follow project tempo state.
• Stretch mode.
• Tempo markers.

Turning Follow project tempo off returns the region to normal source-file timing.

Common Mistakes

Symptom	Likely cause	Fix
BPM change does not affect an audio region.	Follow project tempo is off for that region.	Select the region and enable it.
Region follows tempo but is too fast or too slow.	Source BPM is wrong, often half-time or double-time.	Try the Half or Double Source BPM choice.
A few hits drift while the overall tempo is right.	The source has loose timing or a pickup.	Add tempo markers at important playhead positions, or use Detect.
Drums smear or lose punch.	Stretch mode is not suited to transients.	Try Beats.
Vocal or pad has clicks or chopped sustain.	Beat-focused stretching is cutting sustained material.	Try Tones or a smaller tempo change.
Pitch changes when BPM changes.	Tape mode is selected.	Use Default, Beats, or Tones if pitch should stay stable.
Imported MIDI feels off-grid.	MIDI import policy did not match the file.	Reimport with Use file tempo or Original timing, depending on intent.

Related Pages

• Import and Export covers audio import policies, MIDI import tempo policies, and ZIP export behavior.
• Audio Regions explains audio-region editing around Source BPM, trim, fades, transients, slicing, custom samples, and restore.
• Timeline Editing covers selected-region tempo controls on the timeline.
• Practical Limits explains tempo-map and stretch-quality boundaries.