Preserve PDC midi question

[Coachz]

Is a track with PDC enabled (Preserve PDC Delayed Monitoring in Recorded Items) supposed to place the recorded midi later in the track ? Mine does. Also, on playback, neither one sounds right. non-pdc sounds a tick too early and pdc sounds a tick too late.

After testing, I also see that "input manual offset" totally changes where the midi is recorded. So if my audio is sample accurate with my 345 sample offset where does that leave my midi ?

The fine manual says:

3.27 Preserve PDC Delayed Monitoring in Recorded Items If you are monitoring audio on an armed track against previously recorded tracks any of which uses a plug-in that has latency (such as, ReaFir) this will cause the output to be delayed. In this case you may wish to have the recorded output sound exactly as you are hearing it while recording. For example, you might be playing the notes early in order to make it sound right. With this option on, it will play back the same way you heard it as you played it, with the option off it will be earlier (as the PDC of the plug-in will take effect).

So in my example, I'm playing a click audio track with no plugins and recording midi data through a vsti. Since I have NO other tracks (against previously recorded tracks .. as said in the manual) with any plugins and hence latency, then I do NOT need PDC on any tracks yes because I do not need to have Reaper delay any other tracks playing back because they have no plugins with latency on them.

It's just weird to me that PDC is delaying the actual midi I'm recording. Please clear the fog from this old mans' head !

[Goldreap]

Even though you've made clear in your first sentence that by 'PDC' you mean 'Preserve PDC Delayed Monitoring in Recorded Items' I think it might help clarity for readers if we used 'Preserve...' to shorten it, because in these discussions we'll probably want to use 'PDC' to mean what it is > 'Plugin Delay compensation'.
To help clear the fog, yes, 'Preserve...' will move recorded MIDI (or audio) later, but that's all it does...REAPER doesn't choose the setting..doesn't look at PDC and decide that you need 'Preserve...', doesn't know whether you are playing early to try to pull a delayed sound earlier. YOU choose the setting if you think you need it. All it does is move the recorded MIDI or audio later.

[karbomusic]

Originally Posted by Goldreap

doesn't know whether you are playing early to try to pull a delayed sound earlier. YOU choose the setting if you think you need it. All it does is move the recorded MIDI or audio later.

+1 for anyone reading because it's important.

[Coachz]

Originally Posted by karbomusic

+1 for anyone reading because it's important.

But HOW MUCH earlier does it move the midi ? A random amount ? A known amount ? Buffer size dependent ?

[karbomusic]

Can it be accounting for any PDC *and* any existing latency? I ask because the explanation might require that to fully handle the issue it is explaining (I think... until I have more coffee so don't quote me).

Since you have zero PDC latency above, I'd measure the latency you do see between those two tracks and determine if it matches anything else like interface latency. I say that because if this is accounting for what the player is auto-adjusting based on what they hear, their ear won't know/care what kind of latency it is.

[Goldreap]

Coachz,
'Preserve...' moves the MIDI later not earlier.

But by what amount? Good question. Complicated answer. Depends on not just plugin delay (if present) but:
1/ Other audio interface/ MIDI interface latency factors (I say factors, not amounts).
2/ Whether using audio driver reported latency or not.
3/ And if not, the balance of Input vs Output manual offsets you have set.
4/ Whether MIDI is going through audio interface or is separate USB? (Not sure about this).
5/ The affects of variable jitter?
6/ Other things?

Yes complicated....I tested all this some years ago but don't remember specifics.
But look at the screenshot you posted in the other thread. With 'Preserve...' the MIDI has landed about 2ms (?) later. So looks like REAPER has calculated the shift as Plugin Delay (zero) plus the usually expected input MIDI latency, which ties in with what Karbo has just said.

Personally I don't use 'Preserve...' because I don't record with plugins that have latency high enough to 'throw me', and even if I did, it's unlikely that REAPER's preserve amount would be equal (and opposite) to the adjustment I think I'm making consciously or unconsciously....I'd probably have to slip edit the material anyway.

[Coachz]

Originally Posted by Goldreap

Coachz,
'Preserve...' moves the MIDI later not earlier.

But by what amount? Good question. Complicated answer. Depends on not just plugin delay (if present) but:
1/ Other audio interface/ MIDI interface latency factors (I say factors, not amounts).
2/ Whether using audio driver reported latency or not.
3/ And if not, the balance of Input vs Output manual offsets you have set.
4/ Whether MIDI is going through audio interface or is separate USB? (Not sure about this).
5/ The affects of variable jitter?
6/ Other things?

Yes complicated....I tested all this some years ago but don't remember specifics.
But look at the screenshot you posted in the other thread. With 'Preserve...' the MIDI has landed about 2ms (?) later. So looks like REAPER has calculated the shift as Plugin Delay (zero) plus the usually expected input MIDI latency, which ties in with what Karbo has just said.

Personally I don't use 'Preserve...' because I don't record with plugins that have latency high enough to 'throw me', and even if I did, it's unlikely that REAPER's preserve amount would be equal to the adjustment I think I'm making consciously or unconsciously....I'd probably have to slip edit the material anyway.

Thanks for the reply. Preserve is making my midi later even when I have NO plugins. So once I have set my sample accurate offset for audio, I'm still lost on what makes sense for midi.

I set an input manual offset for the audio but when would I set output manual offset ?

I turned off Use audio driver reported latency. Should it be on PLUS the offset ?

[Goldreap]

Bear in mind that Output Manual offsets affect (in tandem) both audio and MIDI, but Input manual offsets only affect audio.

You can therefore juggle the two to get your MIDI and audio landing in sync.

In your case, measure the difference between your audio vs MIDI landing spots.

In your screenshot (other thread) your MIDI (track 11) is landing x samples later than the audio (Track 10), so try Output offset of minus x samples (will move both MIDI and audio earlier) but Input offset of 345 plus x (will move just audio back to where it was).
Leave 'Use audio driver reported latency' off for the above test.
But if 'Use audio driver reported latency' was on, you can still juggle as above, just don't use your 345...put minus x in Output offset and plus x in Input offset.

[Coachz]

Originally Posted by Goldreap

Bear in mind that Output Manual offsets affect (in tandem) both audio and MIDI, but Input manual offsets only affect audio.

You can therefore juggle the two to get your MIDI and audio landing in sync.

In your case, measure the difference between your audio vs MIDI landing spots.

In your screenshot (other thread) your MIDI (track 11) is landing x samples later than the audio (Track 10), so try Output offset of minus x samples (will move both MIDI and audio earlier) but Input offset of 345 plus x (will move just audio back to where it was).
Leave 'Use audio driver reported latency' off for the above test.
But if 'Use audio driver reported latency' was on, you can still juggle as above, just don't use your 345...put minus x in Output offset and plus x in Input offset.

Goldreap, thanks for the info.

1. It seems like a bug if Preserve is moving midi with no plugins being loaded right ?

I had just read that about output manual offset affecting both.

2. Is there any advantage to enabling "use audio driver reported latency" if I know the # samples of latency for my buffer size ?


3. And when does it make sense to enable Preserve on a track ? I am doing both audio and midi recordings. I read testimonials like this one but as an engineer I want to know what Preserve is supposed to be doing.

"The short summary is that if you want your recording to SOUND exactly like what you heard during monitoring, you need to enable 'Preserve PDC delayed monitoring in recorded items' on the track you're recording onto."

[Goldreap]

1. It seems like a bug if Preserve is moving midi with no plugins being loaded right ?
Not a bug, just a misleading name in that it implies an adjustment based only on PDC. As Karbo said above ".. if this is accounting for what the player is auto-adjusting based on what they hear, their ear won't know/care what kind of latency it is."

2. Is there any advantage to enabling "use audio driver reported latency" if I know the # samples of latency for my buffer size ?
I listed ' use audio driver reported latency' being ON or OFF as a consideration because I remembered it affecting the behavior in some way, but I'd have to test again to get at the specifics, but I don't think there is any 'advantage' as such. If you're happy about your actual rather than reported latency then stick with that.

3. And when does it make sense to enable Preserve on a track ? I am doing both audio and midi recordings. I read testimonials like this one but as an engineer I want to know what Preserve is supposed to be doing.
"The short summary is that if you want your recording to SOUND exactly like what you heard during monitoring, you need to enable 'Preserve PDC delayed monitoring in recorded items' on the track you're recording onto."

So many descriptions of 'Preserve...' are confusing, you read them slowly a few times, but even then you're still puzzled. I'll try again with an example where the latency is huge:
Recording a MIDI part> on my track I have a plugin with very obvious latency (say 2000 ms). I play a note, it comes out of the speaker 2000ms late....no,no,no, I want to hear the note in time with the click....so I play the note 2000ms early to get what I'm hearing lined up with the click. Trouble is, my recorded MIDI note will land on REAPER's timeline 2000 ms early. 'Preserve...' moves it later on the grid where it should be for SUBSEQUENT playback (remember that subsequent playback compensates for the plugin latency anyway).

[karbomusic]

"The short summary is that if you want your recording to SOUND exactly like what you heard during monitoring, you need to enable 'Preserve PDC delayed monitoring in recorded items' on the track you're recording onto."

^What GoldReap said. One thing that can be confusing to many is that all players don't make timing decisions the same way. They either...

1. Consider the note they just played based on the timing of it leaving the monitors then hitting their ears... and use that to time the next note they play, rinse/repeat.

2. Consider the vibration in their hands as their timing reference and ignore the slightly latent note that came out of the monitors and use that hand vibration cue to time the next note.

#2 will cause auto-latency compensation (of any kind I think) to undo what the player just did.

This is all about knowing which of the above is being used, and choosing the appropriate setting. Usually, if recording other musicians in the studio, and they are reasonably experienced, they will tell you real quick when you used the wrong setting - they will complain when they hear that what they just recorded is not juxtaposed against the other tracks the same as they intended when playing it. If none of that occurs and you as the engineer don't hear anything wrong, then all of this becomes mostly irrelevant.

So I wouldn't try to cage this animal with absolutes, it's very design is about non-absolutes. IOW, this is not something you calibrate, set and forget, it's there for varying conditions based on the player.

[Coachz]

Originally Posted by Goldreap

1. It seems like a bug if Preserve is moving midi with no plugins being loaded right ?
Not a bug, just a misleading name in that it implies an adjustment based only on PDC. As Karbo said above ".. if this is accounting for what the player is auto-adjusting based on what they hear, their ear won't know/care what kind of latency it is."

2. Is there any advantage to enabling "use audio driver reported latency" if I know the # samples of latency for my buffer size ?
I listed ' use audio driver reported latency' being ON or OFF as a consideration because I remembered it affecting the behavior in some way, but I'd have to test again to get at the specifics, but I don't think there is any 'advantage' as such. If you're happy about your actual rather than reported latency then stick with that.

3. And when does it make sense to enable Preserve on a track ? I am doing both audio and midi recordings. I read testimonials like this one but as an engineer I want to know what Preserve is supposed to be doing.
"The short summary is that if you want your recording to SOUND exactly like what you heard during monitoring, you need to enable 'Preserve PDC delayed monitoring in recorded items' on the track you're recording onto."

So many descriptions of 'Preserve...' are confusing, you read them slowly a few times, but even then you're still puzzled. I'll try again with an example where the latency is huge:
Recording a MIDI part> on my track I have a plugin with very obvious latency (say 2000 ms). I play a note, it comes out of the speaker 2000ms late....no,no,no, I want to hear the note in time with the click....so I play the note 2000ms early to get what I'm hearing lined up with the click. Trouble is, my recorded MIDI note will land on REAPER's timeline 2000 ms early. 'Preserve...' moves it later on the grid where it should be for SUBSEQUENT playback (remember that subsequent playback compensates for the plugin latency anyway).

Does this go for audio tracks too ? If I'm recording guitar through fx with latencies I should put Preserve on ? Other than midi input quantizing, is there ever a reason to turn Preserve off ?

Also this is all to place the notes correctly during record so if I change the plug in later on to a different latency or no latency it is not a problem.

[Coachz]

Originally Posted by karbomusic

^What GoldReap said. One thing that can be confusing to many is that all players don't make timing decisions the same way. They either...

1. Consider the note they just played based on the timing of it leaving the monitors then hitting their ears... and use that to time the next note they play, rinse/repeat.

2. Consider the vibration in their hands as their timing reference and ignore the slightly latent note that came out of the monitors and use that hand vibration cue to time the next note.

#2 will cause auto-latency compensation (of any kind I think) to undo what the player just did.

This is all about knowing which of the above is being used, and choosing the appropriate setting. Usually, if recording other musicians in the studio, and they are reasonably experienced, they will tell you real quick when you used the wrong setting - they will complain when they hear that what they just recorded is not juxtaposed against the other tracks the same as they intended when playing it. If none of that occurs and you as the engineer don't hear anything wrong, then all of this becomes mostly irrelevant.

So I wouldn't try to cage this animal with absolutes, it's very design is about non-absolutes. IOW, this is not something you calibrate, set and forget, it's there for varying conditions based on the player.

Makes total sense. I have 18 songs we have recorded and on mixdown I'm hearing all kinds of timing errors we didn't seem to have while tracking so I'm thinking they got layed down with wrong latency compensation. We were sober !

[karbomusic]

Originally Posted by Coachz

We were sober !

Uh huh.

[Goldreap]

A thought about how to rationalize the wording of "Preserve PDC Delayed Monitoring in Recorded Items"..
..think of it as preserving the usual scenario where during playback PDC takes care of plugin latency, even though YOU have unwittingly messed that up by (if understandably) playing too early (consciously or not) and thus manually doing (more or less) what PDC will do anyway.
Damn, I had to read that a few times!

[Coachz]

Originally Posted by Goldreap

A thought about how to rationalize the wording of "Preserve PDC Delayed Monitoring in Recorded Items"..
..think of it as preserving the usual scenario where during playback PDC takes care of plugin latency, even though YOU have unwittingly messed that up by (if understandably) playing too early (consciously or not) and thus manually doing (more or less) what PDC will do anyway.
Damn, I had to read that a few times!

ok so as I wondered above.......

Does this go for audio tracks too ? If I'm recording guitar through fx with latencies then I should put Preserve on ? Other than midi input quantizing, is there ever a reason to turn Preserve off ?

Also this is all to place the notes correctly during record so if I change the plug in later on to a different latency or no latency it is not a problem.

[Coachz]

I found a test by user Billoon for setting up the input manual offset. It wanted to use 96khz to test and I use 44.1 to record.

Link to Preserve test
https://forums.cockos.com/showpost.p...6&postcount=51

I had to re-enable all of my interface channels as changing to 96khz threw them all out of Reaper.

Check prefs/audio/device to make sure all your channels are available. At 96khz you get 4 chans per digimax and at 44.1 you get 8.

Then I ran his test and got the following.
loopback test at 96khz is 56 samples and changing input manual offset to 56 got everything lined up.

I then ran his tests at 44.1 after resetting my device again in Reaper
loopback test at 44.1 is 115 samples

HOWEVER
at 44.1khz, 54 samples is required to get the clicks to align on loopback
isn't that odd since the loopback test showed 115 samples difference ?

Anyways, I ran his loopback, midi and audio tests and everything seem lined up now so I think that should be that !

[Goldreap]

Originally Posted by Coachz

ok so as I wondered above.......

Does this go for audio tracks too ? If I'm recording guitar through fx with latencies then I should put Preserve on ? Other than midi input quantizing, is there ever a reason to turn Preserve off ?

Also this is all to place the notes correctly during record so if I change the plug in later on to a different latency or no latency it is not a problem.

Yep, audio and MIDI.

Preserve on or off...see Karbo's points 1 and 2 in post #11.

I don't use plugins with latency when recording. I follow the click (or the overall project) and even then my notes tend to land a bit after the beat (in a nice way usually).....I don't want Preserve adding even more lag...I have it OFF.

"Also this is all to place the notes correctly during record so if I change the plug in later on to a different latency or no latency it is not a problem"
Yes that's right...IF you've placed notes incorrectly.
I place notes correctly anyway (where I want them) because I don't go there with latent plugins when recording.

Karbo mentioned earlier that there's no absolute on or off situation. I'd add to that:
Say a plugin has 30 ms delay. Is it bugging me? Can I ignore that? Maybe I can. Maybe I can't, so I start playing a little early...how much early?...can I control that?...can I calibrate each note exactly 30 ms early? Is the material busy or sparse? All very hit and miss/ ballpark.

The only place I'd use 'Preserve...' is if on a track with considerable latency I'm playing a synth with a long swell where I wanted to focus on where the high point of the swell lands in my speakers...I might want to play early to get that swell point sounding where I want it...the sparse notes allow me to accurately time this.

[Goldreap]

^^^
Link to Preserve test
https://forums.cockos.com/showpost.p...6&postcount=51
Thanks for that link....have downloaded...interesting....will check it out later.

[Coachz]

Originally Posted by Goldreap

Yep, audio and MIDI.

Preserve on or off...see Karbo's points 1 and 2 in post #11.

I don't use plugins with latency when recording. I follow the click (or the overall project) and even then my notes tend to land a bit after the beat (in a nice way usually).....I don't want Preserve adding even more lag...I have it OFF.

"Also this is all to place the notes correctly during record so if I change the plug in later on to a different latency or no latency it is not a problem"
Yes that's right...IF you've placed notes incorrectly.
I place notes correctly anyway (where I want them) because I don't go there with latent plugins when recording.

Karbo mentioned earlier that there's no absolute on or off situation. I'd add to that:
Say a plugin has 30 ms delay. Is it bugging me? Can I ignore that? Maybe I can. Maybe I can't, so I start playing a little early...how much early?...can I control that?...can I calibrate each note exactly 30 ms early? All very hit and miss/ ballpark.

The only place I'd use 'Preserve...' is if playing a synth with a long swell where I wanted to focus on where the high point of the swell lands in my speakers...I might want to play early to get that swell point sounding where I want it.

ok cool. I noticed our synth strings with long attacks were off and had to all move left. so maybe pdc would help there.

[Goldreap]

Originally Posted by Coachz

ok cool. I noticed our synth strings with long attacks were off and had to all move left. so maybe pdc would help there.

Sorry, I've edited my post that you just quoted to add that this would be on a track that has considerable latency anyway (as well as the swell). And if your synth part needed moving to the left because of a too long attack you'd just want to move it....'Preserve..' would have actually put it further to the right.

[Coachz]

Originally Posted by Goldreap

Sorry, I've edited my post that you just quoted to add that this would be on a track that has considerable latency anyway (as well as the swell). And if your synth part needed moving to the left because of a too long attack you'd just want to move it....'Preserve..' would have actually put it further to the right.

ahh you're right -----> RIGHT !!!!!

[Goldreap]

Originally Posted by Coachz

ahh you're right -----> RIGHT !!!!!

Been a long day, time for a quiet beer I think.

[Coachz]

After thinking about preserve PDC some more it is clear that when it is enabled then it delays the MIDI that is recorded. As a test I put a click track on the grid and then tried to play a single piano note in time with it with my ear about three feet from the monitors.

I had two tracks, one with preserve PDC enabled and one with it not enabled. The one without preserve PDC enable had the midi lining up very well and the one with preserve PDC enabled and the single-note piano delayed.

Since there is a delay in the audio getting to my ears I would have thought preserve PDC would move the midi up since I would be playing a little bit late due to latency and the distance from the speakers. However preserve PDC is actually delaying the midi even more. It just makes no sense to me and I still can't think of a reason to use it seeing how it behaves.