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BPM Accuracy (Software Analysis Vs Studio Value)
post May 17 2012, 01:43
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First post so hi! smile.gif

Recently I've been trying to get high-precision BPM readings for some of my tracks (beyond the realistic accuracy of manual tapping) so I measured them in 5 different programs and collated. One of them was obviously much worse than the rest so I took it out, leaving readings from Rapid Evo, MixMeister, Traktor and something else I forgot the name of. Although there was a surprising amount of dissent given that all 4 programs can be (reasonably) assumed accurate without the need for corroboration, in almost all cases there was clearly a "correct" value (usually matching the studio-quoted BPM precisely).

On some tracks, however, the obviously correct value differs from what I know to be the "actual" BPM (by that I mean the BPM it was meant to be at, as listed by the producers). We're only talking a few hundredths of a unit here really but occasionally that's all it needs to be out by to confuse me when I'm mixing. So my question is this: if I have a track with a quoted BPM of 174.00 and the most accurate analyses (to the best of my knowledge) give me 173.97 (true example), is it more likely that the software is out or that what they actually meant by 174.00 (or thought was the case) was 173.97?

(The tracks all belong broadly to dance music and are from the last, say, 5 years so the production accuracy is likely to be high)

Cheers for any advice!

This post has been edited by ElliottPE: May 17 2012, 01:46
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post May 17 2012, 23:19
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174.00 and the most accurate analyses (to the best of my knowledge) give me 173.97 (true example),
So... By the end of a 5-minute song, the timing is "off" by ~50 milliseconds (1/20th of a second). Obviously, "No human musicians were harmed during the production of this music." biggrin.gif

How does that "confuse" you? You can't hear the difference, can you? I don't know hat you are doing when "mixing", but I would think if any time-alignment needs to be done, you'd be aligning beats & measures rather than worring about the exact BMP clock.

OK, I can think of a couple of possibilities other than a 0.017% clock error, which is certainly possible. Consumer soundcards can be off by a few percent. That's enough to cause pitch errors, and sync errors if you record on one device/soundcard while monitoring the backing track on device/another soundcard. (That assumes there was some actual "recording" somewhere along the line.)

The producer could have used a "humanize" mode that throws-in slight random timing-variations, or maybe a "groove" mode that makes some beats a little early, and other beats a little late.

Or maybe it was re-sampled, and there was an accumulation of teeny-tiny errors.

This post has been edited by DVDdoug: May 17 2012, 23:30
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