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I am working on a project in which I need to synchronize some audio files, where the audio runs at different speeds and offsets.

To give a little context, I have two versions of an album, one being the standard version which runs at the correct speed and has correct timings, and the other being the "remastered" version which has better sound quality, but is not properly in sync with the standard version. Each song in the "remastered" version runs at a different speed, maybe 98.2%, or 98.4% of the standard version, etc.

Is there a tool that can automatically synchronize these audio files, so that the "remastered" version is in time with the standard version?

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  • idk anything that will do this automatically, but any decent DAW should be able to do it manually [even if a bit fiddly]. I'd also be more inclined to think that the originals were sped up rather than the remasters slowed down. They used to do that a lot to make things a bit more pacy/punchy.
    – Tetsujin
    Jan 16, 2022 at 10:07
  • Where has the speed change come from? If it's from something constant then it should be easy enough to stretch/reduce the tracks by hand. It's from a varying source (like tape stretch) then you're going to need to go through every section/part manually. Either way, you're better of doing it by hand. Jan 16, 2022 at 12:19
  • If each individual track wanders in pitch, the there's always Celemony's Capstan [which comes at a purchase price so eye-watering they've actually removed it from the front page. You can rent it for €199 for 5 days]
    – Tetsujin
    Jan 16, 2022 at 18:21
  • Fortunately the speed of each song is constant Jan 16, 2022 at 21:17
  • If it's constant you've got lots of choices for tools. Personally, I'd reach for Reaper if you don't already own something fancier (iZotope RX has a retime tool; Synchro Arts makes a whole range of products... but those are all overkill when the speed difference is constant) Jan 17, 2022 at 3:00

1 Answer 1

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Pitch shifting or time stretching are the first "go to" tools but this will depend on what is tolerable in terms of artifacts.

Pitch shifting will maintain the integrity of what the sound file reproduces but you will end up with a difference between the original and the new. This also may be due to remastering from tape. Tape machines are supposed to be calibrated but often have very small differences in timing that doesn't reveal itself until later in time.

The benefit of time stretching is that the material will stay at the intended pitch but actually run slower or faster in terms of time depending on the settings made. Downside of stretching is that there is a threshold in which artifacts will be introduced into the sound. The degree of stretching is directly related to how much artifact is introduced. The quality of the stretching algorithm also matters.

In terms of "automatic", I am a heavy user of Ableton live and this program will automatically time match files. The above still applies here though and I almost never use the settings the program provides on import.

The method Some decisions need to be made up front.

  • Is the original pitch of the song crucial? If a little up or down doesn't bother you, Pitch shift it.
  • If the pitch is crucial, time stretch is your only option and you'll have to accept the artifacts that may occur.
  • Take the original audio file and place it in Ableton. I'll use Ableton to describe the method but most DAWs should be able to do this.
  • Turn off Warp. This is the setting that allows you to time stretch with different algorithms.
  • Loop a short section at the beginning of the song.
  • Turn on the metronome.
  • Press play on the transport.
  • The click of the metronome should match the beat of the song for at least one or two bars. If it doesn't...
  • Adjust the project tempo up or down accordingly. Keep doing this until the click matches the song.
  • Once you've got it working over a couple bars, remove the loop and let it roll. The click will probably begin to float off. Keep adjusting the tempo of the project until you can get all the way through the track with the click locked to the song.

Please keep in mind that I am referring to music that has been produced to a machine metronome as most modern music is made today. If you try to do this with a Doobie Brothers song, you'll quickly learn it doesn't work. If this is the case, let me know and I'll explain a method for that.

  • Now that this is done, mute the song track.
  • Import the remastered version.
  • Here's where your decision from earlier comes into play. If a small pitch difference is negligible, turn off Warp. Let's continue with this decision because it tends to yield the highest quality results.
  • Now we have the original muted track and the remastered track audible with the click still active. Press play on the transport.
  • Adjust the pitch of the remastered track, not the project tempo, in small amounts until it is in time with the metronome and make sure it can go all the way through without floating off.
  • Export the remastered track only.
  • Done.

If the rest of the tracks are floating at the same rate, note the pitch adjustment made to the remastered track and apply it to all the remaining songs. If they float off at different paces, it's wash, rinse, repeat of the steps above.

I have to ask... Why is it important for you to have both timed exactly the same? Are you a DJ? What are you doing with both versions open at the same time? What is the project?

I'm curious about the context of your question.

Lastly...good luck.

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