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OpenAudioCopy

Drive offsets

Some drives start reading slightly before or after the requested position. Offset correction shifts the read to align the audio with AccurateRip’s track positions.

The correction is measured in stereo sample frames. One frame contains the left and right sample at one instant. A positive correction tells OpenAudioCopy to read later samples.

Figure 01Offset correction
Offset correctionA read selects x y A B before correction. Moving its start two stereo sample frames later selects A B C D.UncorrectedxyABCDx, y, A, B+2 framesxyABCDA, B, C, D
Offset correctionA read selects x y A B before correction. Moving its start two stereo sample frames later selects A B C D.UncorrectedxyABCDx, y, A, B+2 framesxyABCDA, B, C, D

Correction shown: +2 frames.

Look up the correction

Section titled “Look up the correction”
  1. Load an audio CD in the drive you want to configure.
  2. Choose Help → Configure AccurateRip, or Configure drive offset in Drive Options.
  3. Click Look up drive offset.
  4. Check the drive name and the proposed correction, then click Save.

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Configure drive offset button highlighted.
Open the drive-offset dialogFull-size image

OAC → Drive Options → Offset / Speed

  1. Open Configure drive offset to look up, measure, or enter a correction for this drive.

If lookup finds no match for your drive model, calibrate using your CDs or enter a known correction.

Calibrate using your CDs

Section titled “Calibrate using your CDs”

Calibration measures the correction by comparing audio from your drive with AccurateRip records. Choose a CD with at least six audio tracks.

  1. Load a suitable CD and open Help → Configure AccurateRip.
  2. Click Calibrate using this CD and wait for the result.
  3. Click Save before loading another disc.
  4. Repeat with different albums if more discs are needed.

One suitable disc can confirm a correction found by lookup. Otherwise, three different albums must give the same correction.

If calibration is Inconclusive, try another album. A disc needs six tracks that give the same correction. For a conflicting result, test another disc before changing the saved value.

Enter a known correction manually

Section titled “Enter a known correction manually”

In Configure AccurateRip, enter the value in Stereo sample frames, click Use manual correction, then Save. Check the sign as well as the number.

A correction of zero is valid. Unconfigured means you need to look up or measure the correction.

Disc boundaries and missing samples

Section titled “Disc boundaries and missing samples”

An offset correction may require audio beyond the range OpenAudioCopy can read at the start or end of an audio section.

Figure 02Missing audio at the end of a disc
Missing audio at the end of a discThe corrected read extends past the audio the drive can read. Fill with silence saves silence in that portion and records it in the log. Turning the setting off stops extraction if these samples are missing.Readable audioMissingCorrected read
Missing audio at the end of a discThe corrected read extends past the audio the drive can read. Fill with silence saves silence in that portion and records it in the log. Turning the setting off stops extraction if these samples are missing.Readable audioMissingCorrected read

Choose how to handle missing audio

Section titled “Choose how to handle missing audio”

Under OAC → OAC Options → Extraction, enable Fill up missing offset samples with silence to replace missing audio with silence and record it in the log. With this setting disabled, extraction fails if those samples are required.

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Fill up missing offset samples with silence checkbox enabled.
Fill missing audio with silenceFull-size image

OAC → OAC Options → Extraction

  1. Replaces missing samples at disc boundaries with silence and records them in the log.

The log lists the samples replaced with silence. See AccurateRip coverage for how these samples affect verification.

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