Mayou

I would like to understand something with the loading of a buffer~ object via peek~.

If you hit space bar and move the number box until 512 values are displayed, and then press the 'c' key you will load the buffer with this values.

I made it via a coll object and a counter+metro because my values are coming (A1x) with a non constant sampling rate ... (around 200Hz) and I thought that I could load the buffer @200Hz after the coll object.

This was a bad idea. I forgot that Max will load the buffer with the sampling rate in DSP status.

So my question is : If I receive 512 values @ 200Hz from my sensor (so it is around a 2.5 sec buffer), how can I make Max load the buffer with the effective values at the effective sampling rate instead of loading it at 48000 KHz in my case ??

I would like to get the FFT of this buffer, so I would like it to be sampled at the same frequency than my incoming values, and not the frequency of the DSP status. Am I wrong ??

If you hit space bar and move the number box until 512 values are displayed, and then press the 'c' key you will load the buffer with this values. 

This was a bad idea. I forgot that Max will load the buffer with the sampling rate in DSP status. 

I would like to get the FFT of this buffer, so I would like it to be sampled at the same frequency than my incoming values, and not the frequency of the DSP status. Am I wrong ?? 

dsp-sampling-frequency-vs-real-sampling-frequency

You can send buffer~ an [sr 200 ] message to set its sample rate to 200Hz. I'm not totally sure if that will help with what you're asking.

You can send buffer~ an [sr 200 ] message to set its sample rate to 200Hz.  I'm not totally sure if that will help with what you're asking.


Thanks it is better like that, I can get 512 values @ 200Hz in the buffer.

Now it is really complicated to get the sonogram (spectrogram) of my buffer, I start thinking that Max is really good to get frequency content of sounds / music files but maybe I should use Matlab to get the frequency content of continuous data stream from accelerometers sensors ?

Maybe someone have a solution to get the time-frequency content of a 512 values buffer @ 200Hz (when in DSP status I have fs=48000KHz, I/0 vector size =512 and signal vector size = 64).

Here is my actual patch, I have to deal with frequency content after the peek~ object, playing the buffer into a FFT process :

We can see that the buffer is well loaded, with 512 values @ 200 Hz. Could someone give me some directions at this point ? (Record a classical FFT and display it into a LCD or using sonogram to have real time frequency content, I don't know how to start and how to deal with FS, I/O and signal vector size).

Here is my actual patch, I have to deal with frequency content after the peek~ object, playing the buffer into a FFT process : 

In spectroscope~ object reference we can read : " In left inlet: The input signal is analyzed and its spectrum is displayed ". Is there a way to know how the signal is analyzed ?

If you try to make the following patch work, you will see that the sonogram displays something linked to the buffer content :

But it is hard to say what is displayed and how.

Forgive me if this shows a complete ignorance of what you're trying to do but could you not simply represent it as an audio rate signal interpolating between the missing samples?

rampsmooth~ or line~ comes to mind but there are better ways surely. If its just for display I would think this would be accurate enough.

DSP sampling frequency vs. real sampling frequency