A technical support community for Apple Logic Pro users.

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David Nahmani
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Re: PDC broken with external side-chain

Sat Jun 13, 2020 12:22 pm

Go for it. All hands on deck.

David Nahmani
• My Logic Pro X 10.5 book (Apple Pro Training Series)
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EastNashRocker
Posts: 61
Joined: Fri Jan 14, 2011 8:06 pm

Re: PDC broken with external side-chain

Sat Jun 13, 2020 9:00 pm

rfpm wrote:
David Nahmani wrote:
I don't believe the Logic developers go to WWDC. And even if they went I can't imagine they would hold sessions to be in contact with end users. That's not really the point of the WWDC anyway.


Yeah true, I'll keep any eye out anyway. The approach of making this known to well viewed and popular logic platforms might help. Anyone have good examples of sites / channels to contact that get great visibility?


I posted about it today on the facebook group called Apple Logic Pro Tech. I've posted about it before but this is the first time that people acknowledged that this problem exists. I think it's an education thing that a lot of Logic users don't know that it's an issue due to their workflow or because they don't know that the broken PDC is what's causing an issue.

There's another facebook page called Apple Pro X Users Group. I posted the broken PDC video there as well but got zero comments/feedback on it.

This thread on gearslutz has posted five pages of content about this issue since late January. https://www.gearslutz.com/board/apple-l ... tiCKchHwXE

It feels like there's some momentum. I'm still game to keep educating Logic users that they should be frustrated and reaching out to Apple. The most recent video was really helpful to break it down for most Logic users.
 
goombahbeats
Posts: 1
Joined: Thu Feb 20, 2020 1:38 am

Re: PDC broken with external side-chain

Sun Jun 14, 2020 5:07 pm

rfpm wrote:
I have also reported the bug again to Apple. I've done this with every update. This is a serious issue that really renders the DAW unusable for me. How do we get Apples attention and people behind fixing this? Do we need to contact websites or video creators that get a lot of visibility in relation to Logic? Logic Pro Expert, etc.


Maybe start a petition at change.org? Company's seem to pay attention to these.
 
rfpm
Posts: 21
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Re: PDC broken with external side-chain

Tue Jun 23, 2020 5:39 pm

EastNashRocker wrote:
rfpm wrote:

Yeah true, I'll keep any eye out anyway. The approach of making this known to well viewed and popular logic platforms might help. Anyone have good examples of sites / channels to contact that get great visibility?


I posted about it today on the facebook group called Apple Logic Pro Tech. I've posted about it before but this is the first time that people acknowledged that this problem exists. I think it's an education thing that a lot of Logic users don't know that it's an issue due to their workflow or because they don't know that the broken PDC is what's causing an issue.

There's another facebook page called Apple Pro X Users Group. I posted the broken PDC video there as well but got zero comments/feedback on it.

This thread on gearslutz has posted five pages of content about this issue since late January. https://www.gearslutz.com/board/apple-l ... tiCKchHwXE

It feels like there's some momentum. I'm still game to keep educating Logic users that they should be frustrated and reaching out to Apple. The most recent video was really helpful to break it down for most Logic users.


Nice! That's great, the more people are aware the better. Good job
 
rfpm
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Re: PDC broken with external side-chain

Tue Jun 23, 2020 5:41 pm

goombahbeats wrote:
rfpm wrote:
I have also reported the bug again to Apple. I've done this with every update. This is a serious issue that really renders the DAW unusable for me. How do we get Apples attention and people behind fixing this? Do we need to contact websites or video creators that get a lot of visibility in relation to Logic? Logic Pro Expert, etc.


Maybe start a petition at change.org? Company's seem to pay attention to these.


Hmm yeah that might be an idea, would need to get a lot of people aware of the issue first so that the petition would get some traction behind it.
 
jculp3
Posts: 54
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Location: Lititz, PA

Re: PDC broken with external side-chain

Thu Aug 20, 2020 6:43 am

I have the issues as you've all described while using heavy latency plugins, pitch shifters, UAD, upsampling plugins etc. So, when I switch plugin latency in general prefs to "Audio and software instrument tracks" (instead of All), it fixes the sidechain issue, but off course then busses are off. Why would they include both these as options when niether solve the issues? I've submitted my bug report to apple again and now waiting patiently, but also weighing options with other DAW's. Good to see others are getting fed up with this as well. Hopefully they'll fix this soon.
Logic 10.5.1, OS 10.14.6, MBP 15" 2016 2.7 Ghz i7, 16gb ram, UAD Apollo/Twin, LaCie 1TB SSD.
 
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EastNashRocker
Posts: 61
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Re: PDC broken with external side-chain

Thu Aug 20, 2020 7:14 am

jculp3 wrote:
I have the issues as you've all described while using heavy latency plugins, pitch shifters, UAD, upsampling plugins etc. So, when I switch plugin latency in general prefs to "Audio and software instrument tracks" (instead of All), it fixes the sidechain issue, but off course then busses are off. Why would they include both these as options when niether solve the issues? I've submitted my bug report to apple again and now waiting patiently, but also weighing options with other DAW's. Good to see others are getting fed up with this as well. Hopefully they'll fix this soon.


I'll keep using Logic for the current project but I should be fully transitioned over to Studio One 5 in about a month I hope. I'll be checking back here after updates and whenever Logic Pro 11 comes out.
 
Lytz1
Posts: 4
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Logic Sidechain PDC still broken (since years...)

Sat Aug 29, 2020 5:46 am

( --- Thread was merged into here. Sorry, I didn't see this one --- )

So PDC on sidechained signals is broken. Since years.
Probably most of you know this already anyways, maybe not.

However I still want to address this as this doesn't seem to be that well known as it should be.
And is the only major thing that really ***** me off big time.

The .gif down here explains it better than I could write I think.
So please report this s*** to apple. Maybe someday they get their act together and fix this.

Here's the link to the apple logic pro feedback form:
https://www.apple.com/feedback/logic-pro.html

Here's the link to a gearslutz thread where a lot of details are clarified. Also the PDC Automation problem
is explained here as well, as PDC has actually 2 major issues...
https://www.gearslutz.com/board/apple-l ... st14904457

For the people that still don't understand how significant this can get.
I made a .gif where elastique pitch gets the sidechain signal from inst1, you don't even need to hear the audio, you can SEE how far off the sidechain signal is.
In case the image doesn't work, just use the link. You can easily test this yourself by using a plugin that introduces quite some latency and has a sidechain input.


Best,
tL.

Logic_Sidechain_PDC_Bug.gif
Logic_Sidechain_PDC_Bug.gif (631.9 KiB) Viewed 3607 times


( --- Thread was merged into here. Sorry, I didn't see this one --- )
 
en5ca
Posts: 27
Joined: Thu May 06, 2010 12:03 pm

Re: PDC broken with external side-chain

Mon Oct 26, 2020 7:31 pm

Noticed that Plugin (or any) Delay Compensation isn't applied when monitoring input (audio or MIDI). This made me think that the PDC on Logic might not be done at 'online' or 'audio engine runtime' level, but is simply done by adjusting the read timing of channel source data, so that eventually channel outputs end up in sync with each other at summing/output stages, but only after going through their entire signal chains/routes.

This would be more like a design flaw, not a bug, and fixing this would propably require a rewrite of the Logic audio engine itself. At least in situations, where signals need to be in sync before the final output.

While monitoring live inputs through Logic, it seems that Logic just doesn't have the required compensation mechanism, and the signals just pass through, as Logic can't adjust the read timing of live input. If individual chanels and/or their routes have different latencies, the output will then be out of sync. In this respect, auxes and sidechain inputs are also just monitoring their sources 'live'.

The 'proper' way to deal with this propably would be (instead of relying on compensated the raw data read timing) to hold the data (that needs to be PDCd/delayed) in an extra memory buffer during audio engine 'runtime'. The data in memory buffer can be accessed in sync at any 'latency stage' during the audio engine runtime, by adjusting read timing from this memory buffer at the sidechain input/monitoring end. Trade-off being increased use of memory and lower maximum track count. If 100 channel inputs need to be monitored in sync, and one of them has latency inducing plugin, then the 99 other channels need to be held in a memory buffer until the channel with latency has finished filtering/processing.

But now, the Delay Compensation seems to work only at 'visual' level in Logic. 'What you see on Main window tracks is what you get at final output stage'. The signals flowing through their routes may not always be in absolute sync, and when this is required (sidechainin), Logic doesn't seem to have any mechanism to derive the amount of compensation needed at different points ('nodes' ) from it's own signalchains/routes.

A simple test on video:

2 channels/audio tracks.

Both with identical content.

Put a compressor on channel 1, and sidechain it to channel to 2.

Set the compressor to Platinum 1:1.

Put a Linear Phase EQ on chanel 1, after(!) the compressor.

Listen to sidechain input on compressor, while comparing it to channel 2.

It is out of sync. Even though the latency is introduced after(!) the compressor and it's sidechain input, and the tracks seem to visually be in perfect sync on timeline. This would be because instead of delaying the post-fader output ('write') of channel 2 to match channel 1 latency (would require memory buffering), Logic apparently just delays the absolute input ('read') of channel 2 data to match the latency.

In this case, when listening to the sidechain input on channel which later induces latency, the already delayed-at-read sidechain input signal goes through the Linear Phase EQ, and gets delayed by it's processing latency, resulting in sync offset between channel 1 & 2.

In other words, the sidechain input signal is already compensated for the Linear Phase EQ latency, even though it arrives in the compressor before the Linear Phase EQ.

Move the compressor behind the Linear Phase EQs and repeat the experiment. Notice, that now they are in sync. Because the listened sidechain input no longer goes through the Linear Phase EQs, and is the same delayed input signal heard from channel 2. In this situation both signals are delayd to compensate for the Linear Phase EQ latency, but neither of them goes through the LPE, so they are heard in sync, but with unnecessary delay compensation.

Mute channel 2, turn off sidechain input listening and enable sidechain input, and experiment with some compression settings. Then move the compressor back in front of the Linear Phase EQs. The sound changes. In the video the compressor now misses the kick attack completetly. Because the timing of the compressor input signal to be processed depends on the latency of the Linear Phase EQs, but the sidechain input timing is fixed based on the needed total latency compensation amount.

User doesn't even need to setup complex routings with auxes and sidechaining to suffer from this. Simple reordering of sidechained plugins can 'break' the sidechain input sync.

Repeat experiment in Ableton Live, and notice that it works perfectly (later part of video).
 
seewest
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Re: PDC broken with external side-chain

Wed Nov 11, 2020 7:26 am

Fingers crossed this is fixed in the 10.6 update mentioned on apple.com
Logic Pro 10.5.1 2018 Mac Mini 3.2 6 Core i7 Apollo x8
 
seewest
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Re: PDC broken with external side-chain

Thu Nov 12, 2020 3:29 pm

Doesn’t appear to be :(
Logic Pro 10.5.1 2018 Mac Mini 3.2 6 Core i7 Apollo x8
 
rfpm
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Re: PDC broken with external side-chain

Thu Nov 12, 2020 3:39 pm

Was just coming back to ask. How is this still not fixed?
 
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lagerfeldt
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Re: PDC broken with external side-chain

Fri Nov 13, 2020 2:10 am

I don't see this bug mentioned in the new 10.6 release?

I can't test for myself since I'm not going to switch to Catalina (from Mojave) right now, and 10.6 is ≥Catalina only.
Gear Grotto [YouTube]
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I came here to chew bubblegum and kick ass... and I'm all out of bubblegum
 
en5ca
Posts: 27
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Re: PDC broken with external side-chain

Fri Nov 13, 2020 2:19 am

lagerfeldt wrote:
I don't see this bug mentioned in the new 10.6 release?

I can't test for myself since I'm not going to switch to Catalina (from Mojave) right now, and 10.6 is ≥Catalina only.


It is still there.
 
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Ploki
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Re: PDC broken with external side-chain

Fri Nov 13, 2020 2:50 am

sigh
<desktop pending> | 13" M1 Pro | Big Sur 11.1 | Logic 10.6.1
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rfpm
Posts: 21
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Re: PDC broken with external side-chain

Sat Nov 14, 2020 10:01 am

Will this ever be fixed or do we just move to Reaper at this stage? It renders using so many plugins useless.
 
boopie
Posts: 1
Joined: Wed Dec 02, 2020 9:15 am

Re: PDC broken with external side-chain

Wed Dec 02, 2020 9:20 am

Hi i just read the thread and have found sort of a solution. It seems that the Linear Phase EQ has so much latency that it will distort your project. So if you sidechain with a compressor put it after the EQ also you can now change the PDC from Off and All to Audio and Software instrumented tracks. Not sure if it helps but it ''fixed'' my problem.
 
root_sashok
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Re: PDC broken with external side-chain

Sun Dec 06, 2020 3:18 pm

Not fixed in 10.6, reporting a bug again. Maybe we should contact telephone support more often with this?
 
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David Nahmani
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Re: PDC broken with external side-chain

Sun Dec 06, 2020 3:38 pm

root_sashok wrote:
Not fixed in 10.6, reporting a bug again. Maybe we should contact telephone support more often with this?

I don't think it matters how often you contact telephone support about bugs. Instead, I would recommend you report it (again?) at https://www.apple.com/feedback/logic-pro.html
David Nahmani
• My Logic Pro X 10.5 book (Apple Pro Training Series)
Contact me for Private Lessons
Logic Pro X 10.6.1
MacBook Air 1.3 GHz i5 — MacOS X 11.0.1 — 4 GB RAM
iMac 3.2 GHz Quad Core i5 — MacOS X 10.15.4 — 8 GB RAM
 
root_sashok
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Re: PDC broken with external side-chain

Mon Dec 07, 2020 3:05 pm

Reported three times. I think we should start a petition at change.org
Which post has the most summarized and informative description of the bug?
And we should attach two most clear videos with the bugs for ADC & PDC problems, I think.
Then post a link to all topics regarding Logic's ADC & PDC on all forums and maybe in the header of this site and forum?
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