Re-editing midi files

jonel

New member
Hi All,
I'm not sure if this is the correct forum for the issue that I have, but it looks as near as I can make it.

I have a midi file of a song that that has a 3/4 time signature and I wanted to use this as a back tracking when used with RealBand. The song itself plays beautifully as it stands, but there are two problems that mitigate against it being used in RealBand for backing:

1. The music does not start on a measure (with or without the lead in) and the measure does not fit with 3/4 time either.
2. The file also loads with the default 4/4 time at 120 bpm but modifying these does not make the midi fit the correct measures.

It is almost as if the midi was recorded live.

What I really need to do is to shift the entire midi on to a measure at the beginning of the first beat and then to 'contract' the midi so that it fits the 3/4 measures for a given tempo.

When I set out to do this job I felt like this was really a simple operation to carry out. Well now I'm not sure at all.

I exported the midi to Ableton Live because shifting and stretching were easily available operations in that DAW. But was was unable to do that to all track simultaneously. So I began with the drum track and shifted it to bar 2 (to allow for ant lead-in) and then I easily contracted the midi to fit the correct time signature. If I had been able to do this with all the tracks simultaneously then the job would have now been complete - end of. Unfortunately I had to carry out this operation for all the other tracks, one at a time, and although It didn't take too long, the resulting song was less than impressive with lots of little timing errors that were difficult to work with.

So, I tried another method. I exported the midi to Sonar. The Sonar DAW can time shift midi but it can't stretch it (well not easily). But it could allow me to save it as a type 0 file where all the tracks are merged in to one. I then use this in Ableton to shift and stretch and this had really good results and I suppose I can live with that. But I would like to restore the new midi so that each track had it's own instrument that I can choose appropriately. But I can't seem to do this. I am in the process of giving up and hence this last bid on this forum.

Can anybody suggest a solution to what I can see is, on the face of it, a simple task?


Thanks
 
If it is a true MIDI file...you don't need to do time shifting or stretching...you would just change those things to the MIDI file using your the tools your DAW provides...and if it's not stating on the first beat of a measure...you just drag/move the whole MIDI track to where you want it. Of course, your DAW should be set to the correct time sig and BPM of the MIDI file before you import it...because if you change those things after you import it, the DAW will want to shift the MIDI file.

So...if you know the time sig and the BPM...set that in the DAW. Then load the MIDI file and if you place the DAW cursor where you want it to start, it should load from that point...or just drag it to that point after it is loaded.

I mean...if you're working real hard to get the file where you want it...you're not doing something right, or the DAW is set to something different than the MIDI file, and it is trying to change things as you load or the file and the setting in the DAW are working against each other.
So yeah...it should be a simple task.
 
Somebody pressed record and just played?

Happens often. The solution is dependent on your choice of software and most critically YOUR musical ability.

I can only speak about Cubase. You will have to create a tempo map. There are automated solutions but they usually fail on pieces that are pretty free flowing and played by a decent pianist.

Cubase is very happy stretching audio to fit the tempo track as long as you don't go too far. However, what we always do is build the tempo map for the audio when we're dealing with mainly audio. You can stretch MIDI of course, but you end up still having to break it down and tweak it in.

You start by changing the piece to ¾, then you align the first note of the whole thing to the start of bar 2, to allow a little slippage into bar one if necessary. Then you look carefully at probably bar 3 or 4 with the screen zoomed into that range, and then adjust the tempo so the right note of real bar 3 sits on the bar 3 grid line. Lets say this comes in at 63.5BPM. You then jump the screen to show you bar 3 to around 6 or 7. If you are lucky, bar 6 real note will be sitting on bar 6 grid line, but probably not. Can you see where it drifted? it could be good to bar 5, then slip. You then click on the tempo at bar 5, and then adjust bar 6 to fit and click again. You then go through the entire song. In the end, you have a curve that might have 60bpm as the lowest and perhaps even 70bpm as the maximum. When you replay the song, the tempo will ebb and flow between them.

If you examine the notes in a piano roll style editor, you will see many will be before or after the proper bar gridlines. If played by a good pianist, this is musicality. If played by a poor pianist, they're mistakes. Cubase offers loads of ways to then quantise the midi notes to make them sit on the bar and beat lines - which can improve the poor version, but destroy the good one. Luckily the adjustment can be subtle or hard. Your choice.

A 3 minute song can take 5 minutes or a whole day to do, depending on how well it was played. Real pianists do NOT play in time. Real pianists rarely play chords where each note starts at the same position. Usually right hand chords have the highest notes last, because that's how fingers work.

As far as I know, most sequencers will do this tempo mapping. My experience (as we do this an awful lot on MIDI and audio recordings we are having to fit to a grid) is you cannot predict the effort involved, but the better the pianist, the more work is needed. Bad pianists just benefit from quantisation to correct errors. quantisation ruins good playing.
If the MIDI track was played to audio backing, then the audio backing's tempo track should let the two align better.
 
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