Transpose function chewing resources.

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Glennonator
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Joined: Mon Apr 22, 2013 11:34 pm

Transpose function chewing resources.

Post by Glennonator » Tue Jan 05, 2016 3:56 am

I have been using the transpose function within the midi control panel and very quickly maxing out the cpu on my iPad Air 2. Turning the transpose back to zero for 6 instruments put the cpu back to about 20%. Seems odd that it was using up so much of the resources just to transpose some midi up a few notes.
Any ideas?

Rim
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Joined: Fri Dec 23, 2005 11:08 pm

Re: Transpose function chewing resources.

Post by Rim » Tue Jan 05, 2016 6:16 am

It's not uncommon for transpose to use up more resources on some instruments, because this can cause the instrument to do pitch shifting, which uses more CPU. On large Lyra instruments, this wouldn't happen as every key has its own samples, but I can see this being the case with smaller instruments. Which synth were you using?

Rim

Glennonator
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Posts: 16
Joined: Mon Apr 22, 2013 11:34 pm

Re: Transpose function chewing resources.

Post by Glennonator » Tue Jan 05, 2016 6:51 am

Thanks for the reply rim. I was using the transpose with Lyra on a chello to play up an octave and on twin 2 with various sounds. I was just surprised how much cpu it used. I thought it would just adjust the midi note that is sent through to the instrument and be very light on resources. Cheers.

Rim
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Re: Transpose function chewing resources.

Post by Rim » Tue Jan 05, 2016 7:26 am

You're right, that's all Auria does - it simply changes the MIDI notes up or down, according to the transpose settings. But I'm talking about how this is handled inside each synth. A sampler typically has to perform a pitch shifting algorithm on a sample in order to bring it up or down to the correct pitch. So say you have a test MIDI track with only one very long note on it. You press play, and the CPU usage will be one value, then simply transposing it will change the CPU usage, because now the sampler has to pitch that sample up or down.

In any case, when playing normal MIDI files, you probably won't notice this effect, because it's always pitching notes up or down, as the song plays various notes (regardless of the transpose settings). But if you choose extreme transpose settings, or if your song is only a few notes, there might be a difference.

Rim

Glennonator
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Posts: 16
Joined: Mon Apr 22, 2013 11:34 pm

Re: Transpose function chewing resources.

Post by Glennonator » Tue Jan 05, 2016 4:46 pm

hmmm... so the way I fixed the problem was to move the notes up or down in the piano roll rather than use the transpose. It now uses far less of the resources. It seemed to me to be the midi transposing function that was resource hog. Thanks for your reply.

Rim
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Re: Transpose function chewing resources.

Post by Rim » Tue Jan 05, 2016 5:11 pm

That's interesting. Do you have a project that can demonstrate this? I just created a new project with a simple MIDI region and Lyra playing the default piano sample, and had no increase in CPU usage when transposing up or down with the real time controls. If you have a specific project that has this problem, I'd love to get a copy of it, so I can see what's going on.

Rim

Glennonator
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Posts: 16
Joined: Mon Apr 22, 2013 11:34 pm

Re: Transpose function chewing resources.

Post by Glennonator » Wed Jan 06, 2016 2:00 am

Yes, I have a project I can send to you that has this problem. I'll send it to your drop box and name it TestTranspose. The project is looping. When I hit play the cpu starts at about 20% but climbs steadily to about 70%. When the loop re-starts it generally drops back to 20ish again. If I remove all the transposing it doesn't go over 25%. Hope this helps.

Rim
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Re: Transpose function chewing resources.

Post by Rim » Wed Jan 06, 2016 7:42 am

Perfect, thanks!

Rim

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