Beat Track Out of Sync Using Cat
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Just ran into an odd problem, which I fixed. Charting a song with major changes in tempo near the middle. The chart looked fine, and the Reaper preview looked fine, but the song played poorly. After the change, notes started to slide out of sync, and, maybe 50 measures after the change, notes were off by 1/16th of a measure.
I couldn’t figure it out, and messed around for hours. Finally checked the Beat Track (loaded via CAT), and, after the tempo changes, the beats started drifting a little each measure. I deleted the track and ran CAT again – no change. So I put in the beats by hand, and the song now works.
Just curious. What would cause the beat track to drift like that?
I’m having similar problems with [said song] but saying that i dont really tempo map that well i try to stick to songs with a set or here or there tempo.
I couldn’t figure it out, and messed around for hours. Finally checked the Beat Track (loaded via CAT), and, after the tempo changes, the beats started drifting a little each measure. I deleted the track and ran CAT again – no change. So I put in the beats by hand, and the song now works.BEAT track has nothing to do with syncing of the notes though. The BEAT track draws the lines and controls animations, but the notes flow regardless of the BEAT track.
I can confirm there is an issue with CAT generated beat tracks when songs have tempo changes. I’ve seen two things: Beats that were placed in unquantized positions, and also beats that were placed on the wrong note (downbeat when it should not be.) I should have reported it, but it only took seconds to make the adjustments by hand and figured you knew of the issues.
According to Farottone,
“BEAT track has nothing to do with syncing of the notes though. The BEAT track draws the lines and controls animations, but the notes flow regardless of the BEAT track.”
That’s what I guessed, and I couldn’t figure out why the notes in play kept drifting, yet the preview was fine (and the notes were all quantized, so none should be off). When I saw that the Beats were off by a similar amount, I simply redid the Beat Track, hit “Export MIDI” and ran off an rbcon. Perfect sync. I made no other changes.
I can confirm there is an issue with CAT generated beat tracks when songs have tempo changes.Songs have tempo changes almost every measures, that would make every beat track wrong, and that’s not the case. It’s also not the case for time signature changes: Learning to Live has 107 time signature changes and no issues. I have too seen that issue on 2 songs out of the dozens I did but I never investigated it properly, if you spot the pattern, please say so.
” src=”/wp-content/uploads/invision_emoticons/default_SA_smile.gif”>Maybe it’s covering one of those awful near-0 measure accidents.
This usually happens when going back to modify an existing tempo map – make sure there’s not a skip in the measure numbers. If you add a time signature and you’re not *exactly on* the beat, REAPER will insert a near-zero length measure. Make sure you see consecutive numbers where you expect. If you see a jump (e.g., 62.1, 64.1), you’ll need to undo and try again.
Maybe it’s covering one of those awful near-0 measure accidents.But the notes wouldn’t be off by just a 1/16th, that’s why I ruled it out.
Maybe it’s covering one of those awful near-0 measure accidents.But the notes wouldn’t be off by just a 1/16th, that’s why I ruled it out.
Empirical evidence suggests otherwise. Watch this:
Step 1 Find a spot in between two time signature markers:
http://i.imgur.com/mmeUzTc.png
Step 2 Drag the blue tempo line up 1 pixel. Note how the measure number jumps from M35 to M37. REAPER freaked out and jammed another measure in between, but it’s almost 0 length:
http://i.imgur.com/zga6Lzk.png
Step 3 Use CAT to create a BEAT track (I already had one here, but watch what happens next…)
http://i.imgur.com/QYLrCuv.png
Step 4 Zoomed in a bit – the BEAT track is now all wonky, offset by the amount of the phantom measure. This extends for quite some distance prior to the phantom measure, and through the rest of the song:
http://i.imgur.com/DCR4N9j.png
Moral of the story: WATCH OUT when editing existing tempo maps. Make sure you have the project set to BEATS instead of TIME before you begin:
File / Project Settings / Project Settings / Timebase
If you increase or decrease the tempo of a measure right before a time signature, make sure REAPER doesn’t add a super-secret invisible bonus measure in between.
This is all fascinating. Here are the offending Reaper files:
https://drive.google.com/folderview?id=0B0FHnxeCnFIjMDJKWlhDUWNuXzg&usp=sharing
This is another Nightwish conversion. BeautyMIDI is the original FOF file. Notice all the tempo changes starting around measure 28. These include a tempo of 28 at 33.4, that I had to eliminate.
Beauty is my version, with corrected tempo map and completed guitar chart. The Beat track starts to drift at 29.3 and gets worse and worse, until measure 118, where it is off by nearly 1/16th. There is a tempo change at 119 and it gets close there (I suspect it went over 1/16th and “corrected”).
Beautyv2 is identical, except for a hand-made Beat track.
Again, all this led to a drift in notes played when I export from Beauty, but not from Beautyv2.
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