Varispeed vs Flex vs Pitch and Time and Pitch Machine

Hi,

 

I need to reduce the tempo of a project by 5% without changing the pitch.

I will then need to share the project (via OMF or AAF) with another DAW, so making permanent (destructive) changes is fine.

 

The project contains multiple drum tracks and upright bass tracks. 8 tracks in total. Each track contains multiple regions with fade information. I prefer to keep these regions as is without merging. If merging regions is necessary, that will be ok.

 

How should I make the tempo changes?

 

With Varispeed I have to bounce each region separately as export does not seem to hold the changes.

With Time and Pitch Machine I need to process each region individually.

 

Is there a way to process the entire project as one most efficiently?

 

the ultimate priority though, would be the best possible sonic quality.

 

Thanks,

Make sure once you have Varispeed added to your Transport (by control Clicking on the Transport area) to set it to Speed only. With 8 tracks you can bounce each track one by one, it wont take long. Just set the cycle range to the range of regions you want Bounced, solo that track and it will render it at the new tempo.

Unless I am missing something, Varispeed is not for quality bounces, exports or anything else other than getting a quick impression of what a song sounds like at a different tempo. (The exception might be if you wanted to bounce all or part of a song that's pitched down, just for the effect of it. But that's not what you're after.)

 

I would flex enable all your audio. Don't bother with editing the transient markers unless something sounds off. Then just change the tempo of your song using a tempo alternative and bounce/export from there. This should give you much smoother and more useful results.

Thanks very much for the info.

If you don't mind a couple follow up questions...

 

Once Flex is enabled on all tracks how do I change the tempo of the song? Is dragging the corner of the region the only method?

 

Which algorithm would be recommended for

a) drums

b) double bass

c) both

 

Thanks again,

Drums: either slicing or rhythmic

 

Bass: Depends on what kind of bass. I've had good results with both monophonic and polyphonic. Sometimes in a bass performance you'll get some accidental harmonies and the polyphonic mode handles that well. I always check the "complex" box when I use polyphonic mode.

 

 

Once Flex is enabled on all tracks how do I change the tempo of the song? Is dragging the corner of the region the only method?

 

Don't do it that way!! That's a great technique to use on a region by region basis within the context of an unchanging tempo for the song as a whole. You want to keep your track's grid reference intact and you'll loose that as soon as you drag the tracks out via left corner drag.

 

Just change the tempo in the transport. Or use a Tempo Alternative in Global Tracks>Tempo. With Tempo Alternatives it's easy to flip back and forth between original tempo and the new one.

 

BTW, Varispeed does have at least one other good use - recording parts that are too difficult to play at the original tempo.

Thanks so much. Fantastic advice. This worked very well to drop the entire tune by 6BPM without any pitch change. No artifacts, everything sounds good. I didn't have to edit any transient markers

 

In total I shifted

DRUM MICS (slicing):

- kick

- snare

- overheads x 2

- room

 

DOUBLE BASS (monophonic):

- 2 mics (1SDC, 1LDC)

 

Thanks again

Unless I am missing something, Varispeed is not for quality bounces, exports or anything else other than getting a quick impression of what a song sounds like at a different tempo.

 

Hi Victor,

 

Just wanted to point out - that's your opinion. Varispeed is a tool, and you can use it for whatever you want. I know some producers use it for speeding up the song, and end up bouncing and releasing the song at the faster speed. If it sounds good, there's nothing to prevent you from using it for a final result, and depending on how you use it and what you use it for, it can sound very good (or very bad).

 

(The exception might be if you wanted to bounce all or part of a song that's pitched down, just for the effect of it. But that's not what you're after.)

The default "speed only" mode doesn't affect the pitch.

When I altered tempo originally with varispeed the results sounded good to me (although without serious critical listening) my problem with that method was having to bounce each track individually rather than being able to export the entire project.

 

I'm going to do a test by exporting the same project after

a) flex

b) varispeed

 

I know that results will vary depending on the material but I'll post my findings here later on...

Just wanted to point out - that's your opinion. Varispeed is a tool, and you can use it for whatever you want. I know some producers use it for speeding up the song, and end up bouncing and releasing the song at the faster speed. If it sounds good, there's nothing to prevent you from using it for a final result, and depending on how you use it and what you use it for, it can sound very good (or very bad).

 

I guess I've only heard it sound very bad! But there's no arguing with results. That's interesting that some have been able to use it like that. I'm guessing that there's lots of people who are reasonably expecting it to be a quick and good solution and I was kind of responding to that. At one point, I was hoping that it would work that way myself but I haven't yet found it to be very flattering on a mostly audio track project. OTOH, a few clients were impressed that I could simply speed a song up that way but even they could hear the artifacts, especially on vocals.

 

I wonder, if it were project with fewer audio tracks and more midi tracks, maybe it would work better? Or in ninedoors case, just drums and bass. It makes sense that material with more transients would fair better.

 

@ninedoors, glad the export worked out for you. I look forward to your test results. If it works well, this may be a tool worth reconsidering.

Hi,

 

Sorry for the delay in posting my results.

 

I used both varispeed and flex.

 

Again, I was only working with drums and double bass. The track was a standard bluegrass tune, so the bass was played with mostly a very staccato 1/5. There were no long, blended notes.

 

Although both versions sounded good. It seemed to my ears the the version done with flex retained a fuller frequency range. The varispeed version seemed to loose just a touch of definition in the highs and lows. It's very close but I do believe there is a difference. I'd be happy to post samples if anyone is interested.

 

That brings me to another question. I'm having difficulty exporting the entire 'flexed' project as an OMF or AAF. Once exported, a) the fades are no longer there and b) the tempo returns to the original tempo.

 

Any thoughts on this?

I also ran a varispeed vs. flextime test. I dropped my tempo down 2.8 bpm vs 1.67% varispeed drop. I found varispeed avoided a phasing problem I was getting in flex. I’m sticking with my varispeed version for my final mix. if I run a more drastic comparison I will post the results.

 

Does anyone know if flex fills the gaps with some algorithm and varispeed resamples? What are the processes?

Ok. Varispeed has a slight pumping artifact. Flex-time has a phazy digital artifact esp when stretching cymbals. My conclusion on a 25% change is stretch/elongate with varispeed and speed up your track with flextime. They are clearly very different processes.

Does anyone know if flex fills the gaps with some algorithm and varispeed resamples? What are the processes?

Flex has different algos that use different processes. For example "slicing" does not do any time-stretching, it just slices the track and spaces out the slices (or brings them closer together), and can fill the gaps if you want to (Track inspector parameters). Other Flex modes perform stretching in different ways. See: Flex Time algorithms and parameters

Thanks David. To slow my track down without pitch changes I ended up using Varispeed with pitch and speed. I clicked the % on display to show how many cents the speed change altered the track. I reimported that audio into a new project and used ceremony’s universal algorithm to shift the pitch + formats back to the original. I could have used logic for the final pitch up and it may well have been as good but this process seemed to yeild an good result.

this process seemed to yeild an good result.

That's all that matters. Good to hear it worked for you!

The time stretching in Logic is something that confuses me as well.

 

It seems there are about 4 different ways to time stretch audio.

 

1-Flex Time

2-Vari Speed

3-File-Functions-Time & Pitch Machine

4-Track-Edit-Time Stretch

 

When do I use each setting and why?

 

Edit - I've done some more background checking and have come up with,

 

1-Flex Time

 

Slicing - Slices audio at transients, then shifts the slices across (not to sure how this works). Does not affect pitch.

Rhythmic - Time Stretches via a looping algorithm, the looping occurs in between any gaps of audio. The gaps are are not the ones present in the audio already, but gaps that occur as a result of time stretching. Does not affect pitch.

Monophonic - Designed for audio playing one note at a time; bass lines, vocals etc (nothing said on how it achieves time stretching). Does not affect pitch.

Polyphonic - Recommended for complex audio (polyphonic audio), may introduce phase artefacts as the process it uses is phase vocoding (not referenced), does not affect pitch.

Tempophone - Imitates a tape time stretching method, introduces many artefacts, metallic sounding. Uses a granular sampling approach, adjusting the size of each sample also affects pitch.

Speed - Time stretches via playing the audio faster or slower, introducing a pitch change, similar to a sampler.

 

Vari-Speed - Speed up or slow down the WHOLE project, in the same manner to Tape Machines (Not clear as to whether it produces artefacts in the same way a tape machine would).

 

Edit Two

 

Interestingly you can slice audio at transient markers in all flex time modes, not only slicing.

The time stretching in Logic is something that confuses me as well.

 

It seems there are about 4 different ways to time stretch audio.

 

1-Flex Time

2-Vari Speed

3-File-Functions-Time & Pitch Machine

4-Track-Edit-Time Stretch

 

When do I use each setting and why?

 

1-Flex Time is non-destructive and loads your audio into RAM. On large audio files and unless you have a lot of RAM it may slow down your Mac. In most scenarios though it yields the most effective and best quality results.

 

2-Varispeed is just like varispeed on a tape machine where you vary the speed of the tape, which changes both the pitch and speed of the entire song at the same time. It also has modes where the pitch remains unchanged. This can be useful for speeding up or slowing down a whole song, for example to record a part that's too hard to play at normal speed, or vocals that are too high to record at the normal pitch. I personally haven't used it like that but I use it when I want to experiment with playing back the song a little faster or slower.

 

3-Time and Pitch Machine is destructive, it actually changes the audio file itself and is an older technology. Rarely used nowadays as far I know.

 

4-Same as Time and Pitch Machine, same algorithms, again rarely used as far I'm concerned.

So 3 and 4 are the same engine, just accessible in two different places, left over from previous versions of logic?

So 3 and 4 are the same engine, just accessible in two different places, left over from previous versions of logic?

Yes, exactly and they offer slightly different functionality (ability to stretch between locators or to nearest bar for example).

Thanks for the confirmation, I'm new to logic and finding all the different places for similar features a little confusing.

You're welcome! Part of the reason for this is that every time they remove ancient functionality, it angers producers who got used to incorporating those functionalities in their workflow. So to keep everyone happy, they keep the old and add the new. That results in many different ways to achieve the same results.