Description
Multiply frequency by target/source speed ratio, divide duration by it and express ratio as cents.
Frequency ratios express pitch relationships, while cents express their logarithm relative to an octave. Playback speed and pitch-preserving time changes obey different models; the relevant reference and physical assumptions must be supplied.
Multiply frequency by target/source speed ratio, divide duration by it and express ratio as cents.
When to use this tool
Use Archival Disc Speed Pitch Correction when you need a stated pitch-ratio, reference or playback-speed term.
How to use the tool and how it works
- Enter recordedPlaybackRpm, targetPlaybackRpm, measuredFrequency, measuredDuration. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read speedFactor, correctedFrequency, correctedDuration, centsShift. Use the output convention below.
Require positive source/target playback RPM and frequency plus nonnegative duration. Multiply frequency by target/source speed ratio, divide duration by it and express ratio as cents.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| recordedPlaybackRpm | Recorded Playback Rpm | Required. Finite number; strictly above 0. |
| targetPlaybackRpm | Target Playback Rpm | Required. Finite number; strictly above 0. |
| measuredFrequency | Measured Frequency | Required. Finite number; strictly above 0. |
| measuredDuration | Measured Duration | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| speedFactor | Speed Factor | Required. Finite number. |
| correctedFrequency | Corrected Frequency | Required. Finite number. |
| correctedDuration | Corrected Duration | Required. Finite number. |
| centsShift | Cents Shift | Required. Finite number. |
{
"input": {
"recordedPlaybackRpm": 75,
"targetPlaybackRpm": 78,
"measuredFrequency": 400,
"measuredDuration": 120
},
"output": {
"speedFactor": 1.04,
"correctedFrequency": 416,
"correctedDuration": 115.38461538461539,
"centsShift": 67.90023403964102
}
}Limitations and assumptions
- This assumes pitch changes with playback speed. The tool does not process audio, identify an original recording speed or account for independent pitch-preserving time stretch.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use calibrated audio measurements and the appropriate processing method for actual recordings. Retain cultural tuning context and verify reference frequency, speed history and instrument assumptions separately.
References
Similar or alternative tools
- Ethnomusicological Audio Speed Time Factor
Divide duration by speed; retain frequency when preservePitch or multiply it by speed otherwise.
- Public Tuning Reference Pitch Shift Tool
Calculate public tuning reference pitch shift from explicit caller-supplied inputs.