Topic by RagtimeMike

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  • RagtimeMike
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  • Registered: 23-10-2007
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Topic: MIDI mapping causes high audio load

Please can someone help with the following?

I have recently started running Pianoteq on a netbook. I have noticed that even when no notes are being played, the % load (top L of the Pianoteq window) is quite high (42%). 

The Pianoteq audio load graph also shows this.  It is at the high (42%) level most of the time, but now and then it flips down to nearly zero, before flipping back up. It spends between 0.5 and 5s at the high level and between 0.1 and 1s at the low level. 

The problem seems somehow related to the MIDI mapping I need to use for my continuous sustain pedal.  The pedal plugs into the continuous pedal socket on my keyboard. The keyboard sends this via MIDI Controller 7 to Pianoteq, where I have mapped that controller to the sustain pedal.  The pedal works fine like this.

If I switch to the default Pianoteq MIDI mapping, the high audio load disappears, but of course my pedal does not work then!

I am concerned that I have less audio load available for piano sounds than I should have.

Here are some parameters of my system that might be relevant:
Roland DP8 continuous sustain pedal
Doepfer PK88 keyboard (with USB connection to netbook)
HP netbook with N2800 CPU
Internal sound card with ASIO4ALL driver
Pianoteq v4.0.4
Preset: D4 Classical AB
Host sample rate = 96kHz
Buffer = 576
Internal sample rate = 32kHz
Polyphony = 32
Reverb on
Pianoteq performance index = 15

Reply by julien

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Re: MIDI mapping causes high audio load

When the load is zero, the engine is fully stopped, but as soon as you move your pedal the piano model is running and it is not too surprising that it consumes 40% of cpu on an Atom netbook (there are a lot of computations going on, even if no note is playing). It is however very likely that you did not turn off energy savings, so your cpu is not always running at its full speed (you should be able to see that in the options/perf panel), and this is not recommended for audio applications. On a slower 1.6GHz N270 Atom netbook, the load is around 30% of cpu when moving the pedal on D4 Classical presets.

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Reply by RagtimeMike

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Re: MIDI mapping causes high audio load

Thanks Julien.  I'm reassured, because the computations you describe obviously have to be done during normal playing.  So it's not a "problem" if Pianoteq still does these computations when I'm not playing.

I notice that Pianoteq is receiving a constant stream of MIDI data from the pedal even when I do not touch the pedal or keyboard.  This may be because because I'm using MIDI mapping for the pedal, as described in my post?

Reply by julien

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Re: MIDI mapping causes high audio load

So your keyboard is sending a constant stream of midi events ? What does it display in the options / MIDI panel of pianoteq, is it always the same CC 64 midi event repeated every 0.01 second , or are there small fluctuations in the message content ?

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