Transport Controls

Learn how to control playback in RMT Compose.

Overview

The transport controls are located in the top bar on the left side:

Control	Icon	Function
Play/Pause	▶ / ⏸	Start or pause playback
Stop	■	Stop and reset to beginning
Volume	Slider	Adjust playback volume

Play/Pause

Starting Playback

Click the Play button (▶) to start playback:

• Notes play in order by start time
• The playhead moves across the workspace
• Audio outputs through your speakers/headphones

Pausing

Click the Pause button (⏸) while playing:

• Playback pauses at the current position
• The playhead stops moving
• Audio fades out gracefully

Resuming

Click Play again after pausing:

• Playback continues from the paused position
• Audio fades back in

Stop

Click the Stop button (■):

• Playback stops immediately
• The playhead resets to the beginning (time = 0)
• All playing notes are silenced

Volume Control

The volume slider adjusts the output level:

Position	Level
Left	0% (muted)
Middle	50%
Right	100% (full)

Default: 20% (0.2)

TIP

Start with a lower volume when exploring unfamiliar modules - some can be surprisingly loud!

Real-Time Adjustment

Volume changes take effect immediately:

• Adjust during playback to find the right level
• No need to stop and restart

Playhead

The playhead is a vertical line showing the current playback position:

• Moves left-to-right during playback
• Shows which notes are currently playing
• Resets to the beginning when you click Stop

Playhead Tracking

Enable tracking mode to keep the playhead centered:

• The workspace scrolls automatically
• Useful for long compositions
• See Playhead Tracking for details

Audio Processing

RMT Compose uses the Web Audio API for playback:

Audio Graph

Oscillators → Note Gains → Master Gain → Compressor → Output

• Oscillators: Generate the sound for each note
• Note Gains: Individual note volume (for envelopes)
• Master Gain: Overall volume control
• Compressor: Prevents clipping on loud passages

Streaming Scheduler

Notes are scheduled in batches:

• Lookahead: 2 seconds ahead
• Batch interval: 100ms
• This prevents audio glitches on large compositions

Keyboard Shortcuts

Currently, there are no keyboard shortcuts for transport controls.

Planned for future versions:

• Space: Play/Pause
• Escape: Stop

Troubleshooting

No Sound

1. Check browser audio permissions
2. Verify volume slider is not at minimum
3. Check system volume
4. Ensure notes have valid frequency expressions
5. Try a different browser

Choppy Playback

1. Close other browser tabs
2. Check CPU usage
3. Reduce the number of simultaneous notes
4. Try a different browser

Audio Delayed

1. Web Audio has inherent latency (~20-100ms)
2. This is normal for browser-based audio
3. Not suitable for real-time performance

Tips

1. Use the volume slider - Find a comfortable level before exploring
2. Watch the playhead - See which notes are playing
3. Enable tracking - For compositions longer than one screen
4. Stop before editing - Avoid confusion during playback