Round Trip Latency Meter vs variStretch
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Round Trip Latency Meter
This app measures the real-world round trip latency of an iOS audio system. It plays test tones and records their return to calculate latency, requiring a loopback cable connection.
- Measures real-world round trip audio latency
- Plays test tones
- Records returning tones
- Requires loopback cable connection
- Tests iOS audio systems
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>>> Check out the demo videos at onyx3.com/LatencyMeter LatencyMeter app measures the real-world Round Trip Latency (RTL) of a given iOS audio system*. It functions by playing short test tones while simultaneously recording (listening for) the tones to return back to the input. This technique requires patching a loopback cable between audio system’s input and output. (* iOS audio system here refers to the combination of an iPhone/iPad paired with particular external audio interface)
variStretch
This app allows real-time audio speed manipulation without altering pitch. It offers three distinct playback modes and adjustable buffer settings for precise control over sound processing.
- Real-time speed adjustment (0.5-2.0x)
- Tape mode (speed & pitch change)
- Phase Vocoder mode (speed only)
- Adjustable buffer size
- Buffer clear function
- AUv3 host compatibility
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Concept: The app is a so-called time-stretch machine. The user can change the speed (0.5-2.0) of audio source in real-time using keyboard or slider at will. Usage: There are three play modes: 1) Tape (to change the both speed & pitch) 2) Phase Vocoder (to change the speed alone) 3) Thru (no processing) "Buffer Size" slider determines how long the data will be stored. "Buffer Clear" button will reset the buffer to be zero. System Requirements: AUv3 host
Screenshots
Verdict
The clearest difference is rating: variStretch at 5.0 against Round Trip Latency Meter's 1.0. variStretch also leads on update cadence (every 7 months vs every 31 months) and price ($5.99 vs $9.99). On ratings volume, ads, in-app purchases and monetization model there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Round Trip Latency Meter costs $9.99 and variStretch $5.99 up front. Neither carries in-app purchases, so what you see is what you pay.
variStretch holds the better App Store score, 5.0 against 1.0. Both are backed by a comparable volume of ratings — 1 and 1 respectively.
Round Trip Latency Meter ships an update every 31 months, variStretch every 7 months. The most recent releases landed on October 24, 2026 and October 18, 2026 respectively.
| Parameter | Round Trip Latency Meter | variStretch |
|---|---|---|
| Price | $9.99 | $5.99 — better |
| Rating | 1.0 (1 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 0.0% of reviews | — |
| Number of ratings | 1 | 1 |
| Update frequency | Every 31 months | Every 7 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone | iPhone, iPad, iPod — better |
| Requires iOS | 18.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 4 MB | 15 MB |
| Age rating | 4+ | 4+ |
| Developer | ONYX Apps | Satoshi Kajii |
Customer experience
Round Trip Latency Meter
variStretch
In-app purchases
Round Trip Latency Meter
No in-app purchases
variStretch
No in-app purchases
Questions
Is Round Trip Latency Meter free?
Is variStretch free?
Which has better reviews, Round Trip Latency Meter or variStretch?
Do Round Trip Latency Meter or variStretch have ads?
Which is updated more often, Round Trip Latency Meter or variStretch?
Other comparisons
