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Logic 9 Have Apple Updated Their Algorithms for Flex?

Discussion in 'Logic 9' started by paulnajar, Aug 1, 2009.

  1. paulnajar

    paulnajar Senior member

    I'm curious to know whether Logic 9's audio stretching algorithms have been updated from what was available in 8?

    By the look of the apple videos they have not been updated unless apple have done some work under the hood to the existing algorithms and not bothered to rename them.

    If that's true I'm wondering whether Izotope's Radius will be selectable for flex based functions? Izotope are touting an updated version that's "9 compatible".

    I've never been very happy with the Apple's algorithms offered for elastic audio/ Time Machine etc...

  3. Ginger

    Ginger Member

    The old time stretch algorithms and what happens in FLex is two entirely different things. Earlier, one would actually time stretch the file - either with Logic's own or 3rd part algos - destructively. In Logic 9, you can choose between these Flex modes:


    Neither of these alters the audio file, it's just alters how it is played back, and all stretching happens in real time. This means that you can grab a 32 bar region and stretch it out to 64 bars and hear the result immediately - there's no waiting. You can also change the tempo of the song, and the Flex regions will follow the tempo edits automatically.

    Most of the new algorithms also have editable parameters, like "Percussive" for Monophonic, "Complex" for Polyphonic, Loop Length, Decay and Loop Offset for Rhythmic - and so on.

    Everything Flex related appear to happen in RAM, and are also based on automatic detection of all the transients in the audio files (with manual help, if needed). Flex is an entirely new ballgame.
  4. Orren Merton

    Orren Merton Logic Samurai / Administrator Staff Member

    What Ginger says is correct. But just to be more explicit:

    The Logic 9 developers created completely new algorithms for Flex. These are not reused or re-purposed algorithms from any previous version of Logic.

  5. LivePsy

    LivePsy Member

    Does that mean you can drop a WAV file into a track and Logic automatically stretches it to the song tempo, like say Ableton Live does? So an entire lifetime's worth of loop collecting in plain old WAV format is suddenly like a jam pack?
  6. Orren Merton

    Orren Merton Logic Samurai / Administrator Staff Member

    You have to manually engage Flex for every track. So not quite automatic. But once Flex analyzes an audio file, it will be have like any Apple Loop. In fact, you could save it as an Apple Loop if you wanted using the "Add to Apple Loops library" command if you wanted. :)

  7. LivePsy

    LivePsy Member

    Does the Flex analysis keep a separate file along with the original WAV (like Live)?

    Either way, this is an essential feature and Apple is getting my upgrade money :)
  8. Alan Branch

    Alan Branch Logic Samurai

    I think you'll find the track has to be recorded by Logic for it to have tempo information written into it, so not just any wav file..
  9. Orren Merton

    Orren Merton Logic Samurai / Administrator Staff Member

    Alan is right. The good news is that for non-Logic recorded WAV files, Logic Pro 9 features a new "detect tempo" menu option which will detect the tempo and write it in the file.

    Again, not quite automatic, but a big advance over what was there before!

  10. paulnajar

    paulnajar Senior member

    Thanks Ginger and Orren for the information. This is good to know. Some of the new Flex modes share the same names as their previous Time Machine algorithms.

    Also to LivePsy even Logic 8 could turn audio into Apple Loops but not automatically. You needed the "Open In Apple Loops Utility" (ALU) command or you simply drag hundreds of loops from the finder straight into the ALU which is how I moved all my old loops from EXS and other places into the loop browser.

    I wonder what algorithms Apple Loops used (in 8 and earlier) and whether in 9 they've been updated?

    I also wonder whether using Flex functions somehow requires increased overall latency to do it's stuff?

    Kind regards
  11. Orren Merton

    Orren Merton Logic Samurai / Administrator Staff Member

    There is a nice big enhancement to making Apple Loops using only Logic Pro thanks to Flex Time:

    Previously, the only way to adjust the transient markers in an Apple Loop was to use the Apple Loops Utility. So if you had a MIDI loop, or an audio loop that happened to be perfectly on the beat, you could use the "Add to Apple Loops Library" command to automatically create an Apple Loop in Logic; otherwise, you had to open the ALU, adjust the transient markers, and save it as an Apple Loop there.

    However, now thanks to the Flex Time features, you can adjust the transient markers in the Sample Editor. So you can adjust the transients and save the Apple Loop from within Logic even for Apple Loops that aren't already "beat perfect."

    The ALU is still useful for batch processing.

    I believe that the realtime algorithms used by Apple Loops are not in Logic, since they can be used by any Apple Loop compatible application. Instead, I believe they're part of QuickTime or Core Audio or something. I'm guessing that means they were updated once already in the update from Tiger to Leopard; perhaps even in the latest QuickTime update. I expect them to be updated again in the Snow Leopard update, but that's just a guess/expectation, I don't know for sure.

    I'm confident that it doesn't add to latency; considering that Flex is adjusting timing, if the algorithms themselves knocked the timing out of alignment that would make them unusable. But I'm sure there is a CPU hit.

  12. Janne

    Janne Member

    I've been doing since Logic 7, the addition of AppleLoops have been perhaps the single best feature FOR ME in any version of Logic.
    It totally solved my need for drums.
    I just bought packs of drum loops, and since they often were in WAV format, I'd just dropped them all into the Apple Loops Utillity and batch converted them all to AppleLoops with attributes and all, the ALU makes this very easy...

  13. LivePsy

    LivePsy Member

    But is WAV to Apple Loops doing time stretching or chopping into slices like REX? If its time stretching then perhaps the improvement is in the quality of stretching rather than in the steps to do it. I mean, how much better is Flextime? If it saves a few clicks then its no biggie. But how much better does it sound?

  14. Orren Merton

    Orren Merton Logic Samurai / Administrator Staff Member

    Apple Loops does time and pitch stretching, not slicing.

    "How much" is impossible to quantify. How much better is Led Zeppelin than Foghat? ;) I'd say lots, but a Foghat fan might differ.

    I believe that the Apple Loops algorithms are far more concerned with RAM and CPU efficiency, whereas Flex sacrifices CPU efficiency for sound quality. However, while that may be a general rule, that's not to say that for any specific source material, Apple Loops can't sound "just as good" as Flex. I'm sure it depends on the complexity of the material.

  15. HiGuys,

    A quickie on the subject....

    I've just gone from LP8 to 9, all working well so far. I'm on a Nehelem latest Gen Mac 2x2.66 quad core (os10.5.7 - 12gb ram) using logic with TDM -HD3a alongside an RME fireface 400 on core audio (with its own 8 outs & lightpipe adat link back thru the Digi 192 outs for 8 more)
    I've recorded 2 tracks thru TDM and dropped them onto core audio channels to use flex time (1 gtr & i live Rhodes - both miked thru a neve 1084 mic pre).
    Flex time analysed the waveforms fine, and seems to work like a charm. Only problem is I'm getting sparse random digital clicks or audible 'spikes' thru each track when flex time is active.:mad:
    If I deactivate flex time (thereby losing the timing corrections of flex time) they disappear. I've tried messing with the RME I/O buffer (currently set to 256) with no difference. Freezing the audio with flex time in still left me with clicks in the freeze file.:brkwl:

    There's very little else going on in this song at the mo, just a toontrax Superior 2 drumtrack and EXS midi bass. The core meters are hardly even showing any activity.It's only maybe 1 spike per 3 bars or so, but still a pain.

    Ideas on a postcard much appreciated.:confused:


  16. Orren Merton

    Orren Merton Logic Samurai / Administrator Staff Member

    Try experimenting with different Flex modes. For example, are you using Polyphonic? Try checking "complex." Etc. The right combination of Flex modes/parameters might take care of that for you.

  17. Eli

    Eli Senior member

    I have to say that, now that I am digging deeper into Flex (for some new videos) I am amazed at how good the algorithms sound. Seriously, anything that's still jaw-dropping for a jaded old DAW user like me is something special:D

    Phineas, I'm not sure why you are getting random clicks. I doubt it has anything to do with Flex. Of course it doesn't always work great on all material; but random spikes and clicks are not generally an artifact of bad flexing - at least from what I have seen (and heard) so far.

    Here's an interesting experiment for you: Try launching your project with no TDM hardware (or software). Just run it through the built in Mac core audio driver. See if the random clicks and spikes persist. I have a feeling it's got to do with digital sync somewhere in your chain between your TDM gear and your native audio engine.
  18. Thanx guys,

    Will try your suggestions & get back.


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