Latency problem

Post here if you are having problems with audio or MIDI hardware within forte

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JohannesD

Latency problem

Postby JohannesD » Wed Sep 01, 2010 9:45 am

Hi,
I have the following problem: When I use NI Akoustik Piano in stand alone mode, and set the audio settings to sample rate 44100, buffer size 128, an output latency of 2ms is displayed. When I switch on the internal sound of my keyboard, too, and play a note, I hear both sounds perfectly at the same time.

Now I start Forte (Demo) instead. In the audio settings, a latency of 10.16ms is displayed. When playing AP within Forte together with the internal keyboard sound, I can hear that the sound of the AP comes later. So, the latency is definately longer with Forte, it is not only about a different computation method.

Is this normal? Can I do anything to get a better performance? My soundcard is an ESI 1010 by the way.

Thanks in advance,
Johannes

MikeG
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Re: Latency problem

Postby MikeG » Wed Sep 01, 2010 1:06 pm

The latency within Forte is 1 buffer longer in order to prevent audio dropouts from making a horrible noise.

However, the 10.16ms you see in Forte is an "estimated MIDI latency" that tries to guess how long it would take to hear the audio from a regular MIDI-cable based controller. Its not the mathematical #buffer*buffer_size thing most apps use.
----------------
Mike (brainspawn)
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PLEASE NOTE that the forum is not monitored as frequently as the support site above. This forum is intended primarily as a way for users to ask other users questions about the use of Forte.

JohannesD

Re: Latency problem

Postby JohannesD » Wed Sep 01, 2010 1:51 pm

And there is no way to change this behaviour (length of the buffer)?

MikeG
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Re: Latency problem

Postby MikeG » Mon Sep 06, 2010 10:40 pm

Using asio mode, the buffer size is controlled by the driver itself. Most asio drivers have control panels that do just this.
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Mike (brainspawn)
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PLEASE NOTE that the forum is not monitored as frequently as the support site above. This forum is intended primarily as a way for users to ask other users questions about the use of Forte.

Dirk Offringa
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Re: Latency problem

Postby Dirk Offringa » Tue Sep 07, 2010 3:37 am

Hi

I think that Johannes is talking about the overall latency in forte which seems to be higher than when using the standalone version with the same ASIO driver settings.

This is true (correct me if I'm wrong) for two reasons:

1: forte adds an extra buffer as explained above
2: forte uses an input buffer for the audio, and incoming midi is buffered for the same amount of time

so in the minimum scenario there are 3 buffers in forte, whereas in the NI standalone version, there's no audio input buffer and (most probably) not the extra buffer, but a very small midi buffer for the input, not tied to the size of the ASIO buffers so the overall latency, with the same ASIO buffersize, is smaller, about half of forte's overall latency.

As Mike just mentioned, the ASIO control panel usually provides a means to adjust the size of a single buffer, so if your hardware can handle it you should try to reduce the value there to 64 samples, which should improve the performance significantly in forte, whereas it'll change just a little bit in the standalone version, relatively speaking.

Dirk
Life would be much easier if I had the source code.


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