Delay compensation has me buffaloed

[peppertree]

Originally Posted by O.G. Killa

Go into IO setup and make sure "Compensate for input delays after record pass" in the input tab and "compensate for output delays after record pass" in the output tab are not checked. That might cause this problem, but it's just a guess.

Uhm...wouldn't you want those checked?

(And when would you not want them checked!)

[O.G. Killa]

Originally Posted by peppertree

Uhm...wouldn't you want those checked?

(And when would you not want them checked!)

I don't leave them checked when I record an I don't have any problems. So there might be something about it trying to compensate for recording delays that is moving it ahead by 40ms...

I'm not saying it will definitely fix the problem...but it's something to try as a troubleshooting step.

[Extreme Mixing]

You have to turn Delay Compensation off when you're recording. You'll have to line the midi up manually. Each song will have a different amount of shift needed. since the delay compensation changes depending on what's being used.

Steve

[DigiTechSupt]

Can you test something for me? Create a MIDI track with quantized notes, then route that to a MIDI output and back to a MIDI input and record it to a new track.

Do they line up?

Also, which MIDI interface are you using?

[Steve@ZooWest]

Originally Posted by DigiTechSupt

Can you test something for me? Create a MIDI track with quantized notes, then route that to a MIDI output and back to a MIDI input and record it to a new track.

Do they line up?

Also, which MIDI interface are you using?

I'm using the Midi Timepiece AV.

I created a single note midi track, quantized it, and then routed the midi back through the front of the MTP AV and then to another track as you requested. There are delays as follows:

note 1 about 32 ms.
note 2 about 41 ms.
3 - 49
4 - 58
5 - 67
6 - 76
7 - 3
8 - 11
9 - 20
and so on with increasing delay until
note 16 which was missing in the new track.
note 17 is back to 10 ms delay.

I repeated the experiment to another midi track. Many of the notes that were the same note (ie Bb)extended themselves to the full value they could be until the next Bb was struck, though the original notes were quite short.

The next time yielded results similar to the first time, although the delays seemed to be a bit more random, and this time it skipped note 15.

[DigiTechSupt]

What's your buffer size set to currently and do those values change (re-recording quantized MIDI data) when you adjust the buffer?

Are the values you're giving ahead or behind the original note?

Would you happen to have another MIDI interface you could test with?

Also, let's try this:

Go to MacHD>Users>your account>Library>Preferences>By Host and trash 'com.apple.midi.a bunch of numbers and letters.plist'.

Go to MacHD>Users>your account>Library>Preferences and trash 'com.apple.audio.audiomidisetup.plist'.

Empty the trash and restart, then test again.

[weskoko]

I had the same problem. In ProTools I went under Setup --> MIDI --> MIDI Beat Clock, and enabled MIDI Beat Clock for my Micro Express, All Cables, and set the offset to 100 samples. Your offset will probably be a bit different.

[Sevenlights]

I have a similar issue, when I use EZE drummer. I quantize all the drums and bounce them down to audio tracks and they are always 1180 samples ahead of the beat, so I use time adjuster on my audio tracks to compensate when I want to run EZE drummer 'live' and place the audio tracks on input.

I do have delay compensation on. PT 8.0.1 HD7 in a Digi Chassis

[prophonic]

This is a problem we observed as well with ADC on. We will shortly put a video on the subject to provide you further insight.

Essentially this was the experiment.

1. Create a click track in audio (not click plugin). We used a loop.

2. Create two tracks - one audio to record what is coming from your external instrument (we used an S90). A midi track to record the midi from the instrument.

3. Play the external instrument to the click with LOCAL mode on so that you are not incurring a round trip midi delay thru PT. Turn midi thru off in PT (to avoid doubled notes).


4. Record what you are playing with ADC on.

You will see that (if you are a good player) the audio is more or less where it should be. BUT the midi is delayed by about 1900 samples (our session is 88K) compared to the recorded audio.

In other words the audio is roughly 20ms BEFORE the midi note. If the number of samples is constant, this would mean a 40ms delay in a 44Khz track (as reported in the original post).

You don't get this behaviour if ADC is off - things happen normally as you would expect.

The downside of this is that if you say edit midi and play it back, it will get delayed by around 100 samples again - so you will be out by a whopping 2000 samples compared to what you originally played.

If anyone is interested prior to us posting the video, we have an example session we can email. Please email us at duc AT songphonic DOT com

Our system is 7.4cs10 on 10.4.9 G5 Dual 2Mhz (very stable system).

Global midi offset was set to 0 and we have no compensation enabled for external I/O.

Osman

[prophonic]

We have now uploaded the session which clearly shows the midi timing problem.

You can find it at http://www.songphonic.com/Private/MidiTimingProblem.zip

The moral of the story is that if you want midi to approximate the timing of what you played, record with ADC off (globally).

Osman