MIDI Bombs and Volume Outbursts: Test Results

[nadeama]

Hi everyone,

As I mentioned in another thread, I've now run some tests on a problematic sequence that displays some of the "MIDI bugs" that have been plaguing a number of users for quite a long time now (namely the dreaded MIDI bombs and MIDI volume outbursts). The goal was to see if the problems were reproducible on a very bare system, with minimal sofware and drivers installed.

Test system setup:

- Feshly installed copy of OS X 10.5.4, on a newly formatted partition
- No extra software, or drivers, or startup items, or kernel extensions installed
- DP 6 intalled (that's the only software that didn't come with OS X that I installed)
- All DP plugins disabled except Modulo (which the MIDI tracks in the sequence are assigned to) and the Apple Audio Units plugins that come with OS X (I actually don't know how to disable these)
- The only cables plugged into the computer were the keyboard and mouse cables, as well as one cable plugged into the audio line output of the computer
- All MIDI tracks in the sequence are assigned to several instances of Modulo.
- The computer's built-in Line Output was selected as the audio output in DP's audio driver settings panel
- All other DP preferences left at their default values

You can see other specifics of my system in my signature (although all interfaces were unplugged from the computer during testing).

Testing procedure:

- Hit play so that the sequence starts playing
- After a few seconds, hit the number 1 key on the numeric keypad to rewind the sequence to the beginning
- Repeat until either:
a) You hear some volume outbursts
b) The MIDI data is not being sent as it should at the beginning of the sequence, but instead is sent later on

The procedure may need to be repeated only a few times, or several times in order to experience the problem. This problem is intermittent, so by its nature is unpredictable and it's difficult to say how long it may take on any occasion in order to experience it.

Results of the test:

On this very bare system, the problems were still present and usually quickly (most of the time in a matter of a few minutes) reproducible.


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So here are my questions to forum members:

- Is there anything else that you can think of that I could try before calling MOTU? Anything that could help demonstrate that the problem is not solely with DP, but is due to a conflict with another piece of software/hardware?

- At which version of DP did you start having these problems? In order to avoid any confusion, please answer this question only if you are 100%, positively certain of the answer. Answering "it started with DP 4.5" when in fact your memory might be failing you and it really started with version 5.0 might confuse an issue that is already very complex. Thanks.

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Finally, in order to keep the thread as short and clear as possible, please do not comment to say that you've never experienced these problems. Although everyone's input is always very much appreciated, it's already been covered in many other threads that some users experience the problem while others do not. I would like to keep this particular thread focused on people who are experiencing these issues, so that we can see if there's anything in common in our system setups. Thanks.

[nadeama]

Here is a link to download the file used for testing. Maybe some of you would like to run the test on your own system.

Please see the first post for testing procedures. Also, please repeat the procedure several times before reporting that you don't get the problem. As the problem is intermittent, you might reproduce it on the third try, or it could take 100 tries...

Thanks.

Link to the file:


http://idisk.me.com/nadeama-Public/MIDI ... s_Test.zip

[nadeama]

I'll start the ball rolling by answering one of my own questions:

- I started experiencing these issues with DP 5.0. Last year, on my old computer (PowerMac G5), I could play the test sequence (linked above) in DP 4.6.1 without any problem whatsoever. Playing the same sequence on the same system in DP 5.0 would display the problems.

[nadeama]

Bump.

Nobody is getting volume outbursts anymore?

[Frodo]

Bump.

Nobody is getting volume outbursts anymore?

It's not that, but it takes some dedicated moments to do your test the justice it deserves. Things have gotten busy for me this week, but I'm keenly interested in this issue and will post some results soon.

[nadeama]

Hi Frodo,

Yes it's true that it does take time to look into this. I know it all too well...

I was just surprised that there were no comments at all. But now I look forward to reading your findings.

Thanks for your reply.

[croftish]

Hi Frodo,

Yes it's true that it does take time to look into this. I know it all too well...

I was just surprised that there were no comments at all. But now I look forward to reading your findings.

Thanks for your reply.

What an annoying issue this is!
Has anyone, in your experience, had this issue with older macs? Could it be exclusive to G5/multi core macs?
Just a thought, because everything else seems to point at a bug within DP itself and nothing to do with 3rd party hardware - as I've seen it reported on so many different setups and OS configs.

[Tim]

Could it be exclusive to G5/multi core macs?

It does it on my Dual 2.5 PPC, OS 10.4.11.

[Diazruanova]

I am not sure what you mean with MIDI volume outbursts, but every now and then, on a piano solo sequence using an external synth, I hear something as the sudden appearance of an effect that sounds pretty much as "chorus", you know, as if there are two pianos playing the same passage (out of phase) at the same time for just a couple of bars and of course, the volume increases dramatically.

Could it be the same issue you are referring to?

[monkey man]

That's how it sounds to me, Diazruanova, and a little louder too, as you'd expect.

[nadeama]

Hi Frodo,

Yes it's true that it does take time to look into this. I know it all too well...

I was just surprised that there were no comments at all. But now I look forward to reading your findings.

Thanks for your reply.

What an annoying issue this is!
Has anyone, in your experience, had this issue with older macs? Could it be exclusive to G5/multi core macs?
Just a thought, because everything else seems to point at a bug within DP itself and nothing to do with 3rd party hardware - as I've seen it reported on so many different setups and OS configs.

This is a really good question, and I don't know the answer.

What I can say is that I've had the problem on my previous Mac which was a G5 dual 2Ghz, as well as my new Mac, an 8-core Mac Pro.

As I mentioned above, another interesting thing is that on my G5, I could play the same test sequence in DP 4.6.1 without any problems, and in 5.0 I would get the volume outbursts and MIDI bombs. This would logically seem to point to a bug introduced in DP 5. However, a few users report starting to experience this in DP 4.2 or DP 4.5. This is truely puzzling to me. So much so that I've recently started to wonder whether these posters might just be remembering incorrectly, and maybe their problems might have started with DP 5 after all. I don't want to doubt what anyone is saying, but this issue makes so little sense it's driving me crazy...

Finally, for me this issue is more than just an annoyance. The MIDI bombs are sometimes so severe that with certain sequences the MIDI data sent by DP will crash all 5 of my PC slaves (with a BSOD). This can sometimes happen as often as every half-hour or so. So it's a completely non-workable situation for me. I was hoping for DP6 to provide a fix, but now that we know it's not the case, I have to get to the bottom of this and get MOTU to fix the problem (if it is indeed a bug in DP). Especially since I can't use DP 4.6.1 anymore on my new Intel Mac.

[nadeama]

I am not sure what you mean with MIDI volume outbursts, but every now and then, on a piano solo sequence using an external synth, I hear something as the sudden appearance of an effect that sounds pretty much as "chorus", you know, as if there are two pianos playing the same passage (out of phase) at the same time for just a couple of bars and of course, the volume increases dramatically.

Could it be the same issue you are referring to?

Welcome to the club Enrique. You are officially plagued with the volume outburst issue.

[Diazruanova]

I am not sure what you mean with MIDI volume outbursts, but every now and then, on a piano solo sequence using an external synth, I hear something as the sudden appearance of an effect that sounds pretty much as "chorus", you know, as if there are two pianos playing the same passage (out of phase) at the same time for just a couple of bars and of course, the volume increases dramatically.

Could it be the same issue you are referring to?

Welcome to the club Enrique. You are officially plagued with the volume outburst issue.

Oh well, this is certainly a membership I would love to decline

Anyway, I have noticed that it appears mostly when the passage is a dense one, with many notes, accelerandos , changes in Volume and/or Vel. ON info and for me, it sounds as if there are missing some ALL NOTES OFF controller at some points and the apparent lack of them seem to trigger the effect, very annoying to say the least

[Frodo]

I just tried this with DP6.01 in 10.5.5. While I could get the MIDI notes to act funny, there was a 2-second delay from the time I hit the '1' key until the time the wiper jumped back to the beginning of the sequence. I tried this with pre-rendering on and off-- same result.

Will try this in DP 5.13 under 10.4.11 (MacPro Quad 3G, late 2006, 8GB RAM).

[nadeama]

I just tried this with DP6.01 in 10.5.5. While I could get the MIDI notes to act funny, there was a 2-second delay from the time I hit the '1' key until the time the wiper jumped back to the beginning of the sequence. I tried this with pre-rendering on and off-- same result.

Will try this in DP 5.13 under 10.4.11 (MacPro Quad 3G, late 2006, 8GB RAM).

Hi Frodo,

Thanks so much for trying the test sequence.

I don't have that 2 second delay here. What happens is what I described in the original post: the sequence sometimes plays normally, but other times there is no sound at all. After several seconds of silence, a bunch of MIDI data is sent all at once and the sequence keeps playing, usually normally, after that.

What is it with this bug that everybody's system acts so differently???

For what it's worth, MichKohl in the other thread has been able to reproduce the MIDI bombs with my test sequence. He seems to get the same behavior I'm getting. So at least it's not all in our minds, a problem really does exist.

Thanks again for taking the time to try this out.