.48 Channel rendering oddities

[Litis]

Full Version:
OpenMPT v1.17.02.48


Description of the bug:
Sometimes when I do channel rendering for mixing a final version in Audacity or whatever else, I get the following error message after it renders a few channels: "Could not open file for writing. Is it open in another application?". It only happened with modules that incidentally had 11 channels and I never had such problems with the other tracks which never exceeded nine channels.

How often does it happen?:
I've made two 11-channel modules, and it only happened with these.
It first happened to me when I made a remix and wanted to do some mixing because some parts were too loud and some were too quiet. It had 11 channels and only eight channels rendered before I got the error.
Now it happened with my track "Sane Again" when I was making drum loops for uploading them on ccMixter (like anyone would be interested in them anyway). It originally consisted of eight channels, but I wanted to add three extra channels for the sounds that were of different categories, but instead were shoved inside the existing ones. So I did, and started rendering another loop (with some of the channels muted, as I only wanted a drum loop). But it only rendered four channels, and only one channel remained when the error message popped up.
There were exactly 11 channels, not 32, so I thought this might be the problem and added up for 32 again, but it still happened.

How to reproduce (step by step description):
[list=1]

• Make a track that uses 11 channels or even more.
  
• Do something with it that involves VST.
  
• Try to do channel rendering and see what happens.[/list:o]
  I don't guarantee anything, as I have no idea myself what might be causing it, but I sure want to know what the hell's going on.

[LPChip]

Can it be that modplug is writing to a small harddisc, and the harddisc actually runs out of discspace?

It could be that it goes to C:\temp first where C: has little space left?

That would be my first clue.

Can you test this behavor by exporting a one pattern song (or just one pattern of your song with all the tracks, to see if it still happens?) 1 pattern should illiminate any disk usage problems as the output will be 11x small = still small

EDIT: I have just tested this behavor by rendering a 3 minute lengthy song consistent out of 12 used channels but due to work in progress and lazyness still has 32 channels in total, and it uses VST's and VSTi's. I rendered the track to 32 wave files of each 3 minutes long, resulting in a near 1 GB of space on my harddisc, but no error like mentioning above. Then again, I do have plenty of free space, which could be a trigger for this kind of behavor.

Also if the place you want to render to is on a network location and a glitch occurs, this could happen.

EDIT2: Odd... As I'm finished with the process, I want to remove the directory I created for this purpose. It deletes all files, but it says the directory is in use. Closing MPT does however allow me to remove the directory. Perhaps it has to do something about creating a lock on the directory once a render has started?

[Litis]

I have 4.37 GBs left on the hard drive where I save music, and there's 6.36 gigabytes on the C: drive (where I also install my software). I tried rendering it on C:, but I got the same error.
There's no plug-in both modules use, so it's probably not related to plug-ins.
Also, I did listen to the readily rendered tracks while it was still rendering the rest, but I just tried rendering it again without doing anything related - even opening the folder in Windows Explorer - and I still got the error message.
It does work when I render it as a whole, but I don't want this!

[LPChip]

What if you make a new directory and render there on every new render?

Just to test that its not related. I noticed that when I rendered my series of waves, I couldn't delete that folder until I closed modplug tracker. Maybe its related.

[pelya]

What if you make a new directory and render there on every new render?
Just to test that its not related. I noticed that when I rendered my series of waves, I couldn't delete that folder until I closed modplug tracker. Maybe its related.

When you use File Open/File Save dialog, go to some directory and open/save file, MPT will chande it's current dir to that dir, and when you're opening another file you're still in that dir. And when you're trying to delete it while MPT still running Windows will produce sharing violation (the same in any Linux, you could delete it in Win98 though), Actually this happening with every Windows program - try Notepad .

[Litis]

This is ridiculous. I thought that maybe that MPTM format treats plug-ins in a different way, so I saved a problematic song as one and tried channel render - it still gave me an error.

[bvanoudtshoorn]

Maybe it's something to do with a specific plug you're using; which ones are you using? It could be that if you're using a sampler plug or whatever, it's trying to rescan your hard drive, and grabbing the file's handle while mpt is still trying to write to it...

Alternatively, it might be something to do with how much RAM you have. It could be that MPT bounces the wave files to RAM first, and then copies them to disk. If it fills up your RAM more quickly than it can write to disk, then there might be problems... I'm just guessing here, though. I have no idea if this is what MPT does.

Going back to it maybe being a specific plug... Have you tried rendering each plug in isolation? Maybe make a one-pattern track, and render it using each plug that you use in your tracks.

One question: can you bounce the entire track (that is, not in "channel mode") successfully? What about if you try bouncing the entire track 11 times, soloing each channel each time? If that works, then something's probably going wrong inside mpt itself, and not in your track.

[Sam_Zen]

I remember some earlier reports about problems if a module consists of 11 channels.

[Litis]

My RAM is 256 megabytes. It's a pathetic amount, but I use one of my hard drives to boost it (the one where I save my music to). I don't think it really works, though.
One of the problematic modules is a remix, so it uses some samples in the  normal IT way, and a VST plug-in that allows you to make patterns from your samples (intended for drums and percussion), "Machine II". The other one, however, doesn't use samples in any way.
Yes, I can still make a single WAV.

[bvanoudtshoorn]

What about posting up the track and seeing if other people also have problems rendering it?

[LPChip]

Since there hasn't been any response ever since, I'm closing this bug.

Feel free to make a post so we can reopen the bug for you.