Proper implementation of Stretch

[Dave Connor]

To start at the end of the question: STRETCH [in Audio] when enabled responds to tempo changes. Meaning that if you have it enabled on three tracks out of twenty: they will respond while the others won’t - correct?

My problem is that I’m only using Stretch to fix a few sloppy rhythmic things, not anything related to tempo. But, all my audio was recorded from the MIDI in the sequence which has some tempo changes. Those tempo changes are still there in the conductor track when I playback (and normally wouldn’t effect rendered audio.) So where I may have used stretch to fix a bass note in bar two (hence Stretch is enabled) Stretch will also apply to a later tempo change where the bass is fine. This would seem undesirable and introduce artifacts or other unwanted results.

Is the answer to fix timing problems with Stretch, then Merge that region and disable Stretch to avoid it responding in unwanted ways in other areas?

Thanks!

[bayswater]

There are probably loads of ways to do this, but when I have something like this I do this, which is probably non standard, but for short phrases if usually works. For larger stretches or entire pieces, dragging /adjust beats is what you want.

Note that the tempo changes will be reflected in the bar line in the sequence editor. Presumably your audio doesn’t like up with these lines.

Use the cut tool to chop up the soundbite, with cuts that sit at places beyond which you don’t want stretching to happen. Cut at other places that define specific beats in the audio that are out of time. E.g. if one note is off, you might cut before and after that note.

Now, some of the corrections might be possible by just dragging the new smaller soundbites to earlier and later times. For others, drag the edges of of the soundbites to invoke the stretch functions to put the borders of these little scraps of soundbite where they should be. You have to drag at the correct part of the edge — some places to edge edits and some do fades.

Merge the result. Some very short cross fades might be necessary before merging.

[Dave Connor]

Thank you for responding. Your solutions make sense and I have thought of similar approaches. I suppose what I was ultimately asking is if it’s possible to avoid a lot of work arounds. I have considered making cuts and then just bouncing the stretched sections onto their own new tracks and leaving the remaining files where they are — then disabling the stretch feature on the old and new tracks. Obviously I could drag the bounced files back onto the original track. I really like the new Stretch feature/algorithm and find it easy to work with.

[bayswater]

I didn't consider that process as a work around. More like a process that make sense for small adjustments in specific places, and an extension of exactly what you'd do with MIDI timing tweaks applied to audio. Note that you could even apply quantizing to the chopped up audio, as long as the hit points are defined in each of the dissected soundbite.

I took it that in your case, the sequence, with the MIDI tracks has the tempo you want, and there are a few problems with the timing of a few parts of a soundbite. To that end, tweaking the timing of those bits seems the thing to do, and as of V10, DP does an excellent job of these sorts of stretches without noticeable artifacts.

For general tempo changes over the length of a piece, there is the more general process of creating and moving beats, and the movement of tempo maps from the sequence to the soundbites or the soundbites to the sequence, depending on which has the tempo map you want. In the MOTU area of youtube there is a series of 5 excellent videos by Magic Dave on how to use the tempo adjustment features for the latter process.

[Dave Connor]

I hear you. And I think you’re exactly right in your suggestions. This particular situation seems to require the stretch feature as it’s superior to quantization to rectify it. It’s all string samples so you play with several areas of the audio to adjust the constant behavioral changes in what is essentially an envelope (in order to fix say a single note over 1 second of time where it changes that entire duration.) If you quantized some or all of it you will lose a lot of that with an unnatural sounding result. So you might make three separate adjustments to sculpt it. Stretch is perfect for that. In nearly all other cases it’s pretty straightforward to quantize or snip and slide etc. Stretch is working great, it’s just creating a single problem since one isn’t able to choose to have a track with stretch enabled ignore tempo changes. I should probably contact MOTU and ask for that feature. Thanks again!

[bayswater]

Dave, I’m getting into “look it up in the manual before you speak” mode, but I think you can use the lock setting to make a track follow SMPTE timing and immune to sequence tempo changes. It’s rarely and issue for me, I don’t use setups where tempo changes will change the rate of audio playback, so don’t experience what I think is the specific problem you mentioned. I can see it would get confusing if you are using two different stretch functions at once, and trying to anticipate their combined effect.

[Dave Connor]

Well, you've basically identified the crux of the matter. I've never deliberately setup a scenario where tempo changes change the rate of audio playback either
. The problem is (unless I'm mistaken - but don't think so) you are automatically/unintentionally put in that setup once you enable Stretch on a track. At least for that specific track. Obviously (for now - unless there is a more direct solution) the safest bet is to render/bounce the stretched regions and then disable Stretch. Whatever any viable solutions there are, they all point to disabling Stretch ultimately unless you intend to have the tempo affect audio tracks. As far as locking tracks, I think that would still require that all the stretching work is rendered and done.

I need to read the manual too! I've watched the tutorials where both editing with stretch AND having all tracks enabled to follow the tempo map but those demonstrations were on separate DP sessions. I'll report any answers/findings. Thanks for your input.

[bayswater]

AFAIK, I don’t enable stretch when I do the micro edits on the timing of notes in a sound bite. When I can, I’ll check to see the stretch state of the track containing the edited sound bite.

[Dave Connor]

So I revisited the Stretch tutorial and here’s what’s interesting: When it comes to using the stretch feature for editing, the demos all have consistent tempos. The demo of using Stretch to change tempos is on imported audio. So those two uses have been kept separate even as far as demonstrating them. I recently upgraded to DP11 from 8, so I’ve never worked with stretch and of course they have this much improved algorithm. Anyway, still looking into it.

[bayswater]

Thanks for that. Let me know what you learn after you go through it.

[Dave Connor]

Will do. Thanks for your input!

[waterstrum]

Gentlemen,
I am also curious about the best way to implement Stretch in sequences with lots of audio and multiple tempo changes.
Beyond that, I must compliment you on an exemplary conversation.
Thanks!

[Dave Connor]

Just saw this in coming to read about DP 11.2

I don’t really have anything new to report. As I said, once stretch is enabled, those tracks will respond to tempo changes. The question is, what actually happens when there are tempo changes in DP that were there prior to printing audio and remain afterward?: i.e. no NEW tempo changes (as in my case.) I don’t think my tracks were affected although I thought I heard some oddities during some tempo-change areas. So it may be a non-issue. However, tempo changes done after the fact will no doubt effect stretch-enabled tracks. Perhaps that’s unlikely to occur since there wouldn’t be any reason to change tempo until you have either a master two track bounce or have sort of bounced all stretched tracks in place; and enabled ALL those tracks to follow tempo changes.