(help-timing)=
# Measurement Timing

Timing gives the Helix and the audio system time to settle before MatchPatch
records and measures a snapshot.

This matters because preset changes, snapshot changes, audio latency, delay
tails, and reverb trails can all affect the next measurement.

## Timing Fields

### Pre-Roll

Silence recorded before the reference DI starts. This gives the recording a
little space before the performance.

### Post-Roll

Silence recorded after the reference DI ends. This gives the recording room for
latency and short tails.

### Round-Trip Latency

The time it takes for audio to leave the computer, pass through the Helix, and
return to the computer.

### Preset Wait

How long MatchPatch waits after switching to a preset.

### Snapshot Wait

How long MatchPatch waits after switching to a snapshot.

### Measurement Wait

How long MatchPatch waits just before capturing the loudness measurement.

### Analysis Window

How much audio MatchPatch uses for each loudness measurement.

### Analysis Interval

How often MatchPatch checks loudness inside the recorded audio.

(help-fast-timing-warning)=
## Default And Fast Presets

The Timing tab includes Default and Fast timing presets.

Use Default first. Fast can save time, but it can also be unstable when presets
have delay, reverb, or other trails.

> Warning:
> Fast timing can let one snapshot's delay or reverb tail bleed into the next
> measurement.

## Measurement Time Estimate

MatchPatch shows an estimated time per snapshot and total time for selected
presets. Ignored snapshots are skipped in the estimate.

![Timing tab with measurement estimate](../assets/screenshots/timing-tab.png)

## When To Optimize Timing

Use Determine optimal parameters when:

- repeated measurements do not agree;
- delay or reverb trails are long;
- hardware switching seems slow;
- you want the shortest timing that still measures reliably.

See also: [Optimize Timing](../workflows/optimize-timing.md).


## Next Step

- Run a parameter study: [Optimize Timing](../workflows/optimize-timing.md)
- Fix unstable measurements: [Troubleshooting](../troubleshooting.md)