Flex Pitch appears to be distorting audio

[Dave K]

14 minutes ago, polanoid said:

2 hours ago, Dave K said:

Flex is cool and fast, but also known to be buggy and distort audio on occasion.

That distortion is caused because Flex Pitch isn't designed to handle the polyphonic audio material you applied it to. Thats not "buggy".

1) Logic knows that the track is polyphonic and it still presented notes for editing via Flex Pitch in the region where individual notes were played. If modifying the pitch wasn't supported, then it should not have offered the note handles for editing. If it IS supported, then it should not have corrupted my audio. So that's either a bug or a UI failure.

2) many portions of the piano track that were NOT Flex Pitch modified -- such as the chords -- have garbled audio; you can hear it in the project. So the only way that Flex Pitch could have messed it up is if a change elsewhere in the track -- or maybe even just enabling Flex at all -- caused the audio to distort in these spots, when it should not have touched those spots at all. This would be a bug.

Either way, Flex is a point-and-click fully-managed interface. There's no excuse for leaving you with corrupt audio after using Flex. It's not like using a distortion filter, or driving your gain into a clipping region, or editing waveforms by hand -- actions where Logic allows you to shoot yourself in the foot. 

[oscwilde]

46 minutes ago, Dave K said:

Logic knows that the track is polyphonic

How?
Logic doesn't "know" anything until you explicitly tell it what you want to do - be that flex mode, splitting a MIDI region, etc. Even after you've performed an operation, Logic is none the wiser - and will agnostically perform whatever operation it is asked to perform - unless it "can't" do what the user wants to do...in which case, it'll throw a warning dialog....or will ignore the command/operation (as it is not possible)....or the option is greyed out.
 

46 minutes ago, Dave K said:

Either way, Flex is a point-and-click fully-managed interface. There's no excuse for leaving you with corrupt audio after using Flex. It's not like using a distortion filter, or driving your gain into a clipping region, or editing waveforms by hand -- actions where Logic allows you to shoot yourself in the foot. 

Don't disagree with audio corruption....and this may be "fixable" with different algorithms.
Re: the ability to shoot one's own foot - Logic's developers do an amount of hand-holding with warning dialogs, greyed out options, etc. as discussed above - but where is the balance between "nannying" and allowing a user to make choices.....given that Logic is designed for "all" musicians.
The flex distortion may be absolutely the "perfect" option for another musician who is putting together their "Chainsaw, Speak-n-Spell, Bagpipes, and Squeezing the Cat.....in D Minor" symphony.
It's an "off the rack" product that caters to as many users/musical scenarios as possible - and as a result is incredibly flexible. It "can" be as complex or as simple as any user wants it to be - from a "how much the user wants to leverage what's available" perspective - but people think differently....so one person's "simple" is another's labyrinth.

That said....if you have ideas on UI design that you feel could benefit Logic users, let Apple know thru their feedback mechanisms.

[sunbrother]

1 hour ago, polanoid said:

It sure doesn't here, just double checked this

Odd. I just double checked it and it does. Perhaps we’re using it differently. I’m not tempo correcting loops. I’m applying edits with Flex Markers. Doing this, even on a single region marked as Flex and Follow On, enables flex on the track.

Edited March 6 by sunbrother

[Dave K]

1 hour ago, oscwilde said:

1 hour ago, Dave K said:

Logic knows that the track is polyphonic

How?
Logic doesn't "know" anything until you explicitly tell it what you want to do

Not only does it try to detect if it's polyphonic based on the content, it actually got it right, and even so in the context of Flex, where it introduces the distortion:

[David Nahmani]

9 minutes ago, Dave K said:

Not only does it try to detect if it's polyphonic based on the content, it actually got it right

Logic used to detect the type of content and choose the correct algorithm (as described in that link to the user guide), however in recent versions it always sets Flex to polyphonic no matter what the content is (I've even tested it with white noise and a sine wave). 

[polanoid]

7 hours ago, sunbrother said:

Odd. I just double checked it and it does. Perhaps we’re using it differently. I’m not tempo correcting loops. I’m applying edits with Flex Markers. Doing this, even on a single region marked as Flex and Follow On, enables flex on the track.

Your original statement was "Technically, yes, but that forces the track's Flex mode into Automatic" and that is not correct. If the Track is already in Flex mode, it will stay in Flex Mode and the chosen time stretching mode (e.g. Rhythmic) will stay as it is, even if you edit flex markers. Also, the "Flex and Follow" will stay as it is for all regions, also those for which you have in unchecked.

That was my whole point - you can always selectively switch off Flex and Follow for Regions on a Flex track and they will not be flexed. 

[sunbrother]

7 hours ago, polanoid said:

That was my whole point - you can always selectively switch off Flex and Follow for Regions on a Flex track and they will not be flexed. 

So you mean leaving Flex On for the track but individually disabling it for every region you don't want Flexed? Have you tried to use this workflow and found it reliable? I've found that workflow leads to a lot of the undesirable flex artifacts. That's probably why I thought you were talking about selectively turning it On. Otherwise we're just replacing one problematic workflow with another.

Edited March 7 by sunbrother

[polanoid]

1 hour ago, sunbrother said:

Have you tried to use this workflow and found it reliable?

Indeed I did. Regions that have Flex off are not being flexed, so they play like audio regions on a non flex enabled track. Can be verified by a simple phase cancellation test. Can you share a project in which this is not the case?

[Atlas007]

23 hours ago, oscwilde said:

The flex distortion may be absolutely the "perfect" option for another musician who is putting together their "Chainsaw, Speak-n-Spell, Bagpipes, and Squeezing the Cat.....in D Minor" symphony.

😆🤣😂

[Atlas007]

I personally found that doing some flex edits on some regions, enabling flex on some tracks or in general, back and forth, eventually leads to the above reported sonic idiosyncrasies. Is this Logic mishap or user confusion or perhaps both?

Considering the magnitude of the possible situations, that would be very hard if not impossible to determine for sure unless conducting at very large scale a thorough supervised (double-bind) experimentation, IMHO.

Anyhow, in the end, the idea is to find possible viable workflow(s), isn’t?

[Dave K]

8 hours ago, polanoid said:

Regions that have Flex off are not being flexed

If this is true, it sounds like great news for simplifying workflow. 

I tried to summarize in my post above the awesome input offered by everyone, and I'm gonna mark that as the resolution here. If we get consensus here that we get reliable results from disabling flex on all regions in a track except the ones needing edits, then I'll update my post and happily make my life simpler!

[Dave K]

fyi, I have submitted as feedback to Apple this case of Flex Pitch corrupting audio in parts of a region far from any Flex Pitch edits, and I linked back to this post. Let's see if they reach out again for more info.

[sunbrother]

6 hours ago, Atlas007 said:

in the end, the idea is to find possible viable workflow(s), isn’t?

Exactly. Everything you’re saying is technically correct @polanoid and I’m glad you found it reliable but leaving Flex turned on for a track when you don’t need it leads to a lot of unnecessary Flex Analysis being performed. Whether or not you can turn it off for individual regions, I have personally found all this unnecessary analysis to be problematic over the course of a long project with lots of editing. You might view corrupted Flex Analysis as a separate issue, but in the end I do it on a separate track and commit it. YMMV, that’s cool too.

Edited March 8 by sunbrother