# How to use mMeterSender1.ProcessBlock (with sample\*\*)

**URL:** <https://iplug2.discourse.group/t/how-to-use-mmetersender1-processblock-with-sample/491>\
**Category:** Uncategorized\
**Created:** [25 October 2021 09:17 UTC](https://iplug2.discourse.group/t/how-to-use-mmetersender1-processblock-with-sample/491 "2021-10-25T09:17:58Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![billy](https://avatars.discourse-cdn.com/v4/letter/b/ecd19e/32.png) [@billy](https://iplug2.discourse.group/u/billy)\
**Post date:** [25 October 2021 09:17 UTC](https://iplug2.discourse.group/t/how-to-use-mmetersender1-processblock-with-sample/491/1 "2021-10-25T09:17:58Z")

</div>

Hello, I will be very grateful if anyone can help me.

In my plugin, I calculate the white noise level for 30 frequencies. And I want the user to be able to view the values on the GUI (I use IVMeterControl). to display the values I use:  
mLastOutputData1.vals[0] = (double)outputs100[0][s];  
mRTTextSender1.PushData(mLastOutputData1);  
mMeterSender1.ProcessBlock(outputs100, nFrames, kCtrlTagMeter);

but it doesn’t work. I create an output for each frequency as follows: samples\*\* outputs100

Please tell me what I’m doing wrong or if there is a better way to do it

here my code:

```auto
void IPlugEffect::OnIdle()
{  
  mMeterSender1.TransmitData(*this);
  mRTTextSender1.TransmitData(*this);
}
void IPlugEffect::ProcessBlock(sample **inputs, sample** outputs, int nFrames)
{
  const int nChans = NOutChansConnected();
  sample** outputs100;
  for (int s = 0; s < nFrames; s++) {  
    double rausch = (double)((rand() % 32768) / 32768.0 - 0.5); 
    if (s == 0) {
      y_n1[s] = filterbank.terzband(rausch, 100);                    
      y_n12[s] = y_n1[s] * y_n1[s];
    }
    else {
      y_n1[s] = filterbank.terzband(rausch, 100);         
      y_n12[s] = y_n12[s - 1] + y_n1[s] * y_n1[s];        
    }
    if (s == 63) {
      y_nEff1 = sqrt(ringbuffer1(y_n12[s]) / 48000);    
      outputs100[0][s] = 20 * log10(y_nEff1 / 0.1); 

      mLastOutputData1.vals[0] = (double)outputs100[0][s]; 
      mRTTextSender1.PushData(mLastOutputData1); 

      mMeterSender1.ProcessBlock(outputs100, nFrames, kCtrlTagMeter); 
    }
}
```

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<div class="post-metadata">

**Author:** ![stw](https://avatars.discourse-cdn.com/v4/letter/s/8e8cbc/32.png) [@stw](https://iplug2.discourse.group/u/stw)\
**Post date:** [26 October 2021 12:59 UTC](https://iplug2.discourse.group/t/how-to-use-mmetersender1-processblock-with-sample/491/2 "2021-10-26T12:59:50Z")

</div>

Just guessing from what i see…  
This part

> ` if (s == 63) {`

seems a bit strange. Wherever this 63 comes from (i guess you take a fixed 64 frame buffer size into account?). You’re **only** calculating, storing and sending sample 63.

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<div class="post-metadata">

**Author:** ![olilarkin](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/olilarkin/32/2_2.png) [@olilarkin](https://iplug2.discourse.group/u/olilarkin)\
**Post date:** [26 October 2021 16:55 UTC](https://iplug2.discourse.group/t/how-to-use-mmetersender1-processblock-with-sample/491/3 "2021-10-26T16:55:17Z")

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welcome,

In addition to what stw said… what memory does the outputs100 double pointer variable point to? it seems un-initialised. You need to allocate some memory for a “scratch” buffer. [Here](https://gist.github.com/olilarkin/1103fb82de3ace6d4c94660d534100d9) is an example of how I do that using some WDL classes, but you can also do it with, e.g std::vector.

For a 30 channel meter, you could create an IPeakSender member variable in your plug-in class…

```auto
IPeakSender<30> mSender;
WDL_TypedBuf<float> mScratchBufferMemory; // see gist for how to resize
WDL_PtrList<float> mScratchBufferPtrs; // see gist for how to assign

```

Then attach a 30 channel meter in your UI Layout func

` pGraphics->AttachControl(new IVLEDMeterControl<30>(bounds, kCtrlTagMeter);`

Then update the scratch buffer and pass to the sender in ProcessBlock()

```auto
  void ProcessBlock(int nFrames)
  {
    float** frequencyBands = mScratchBufferPtrs.GetList();

    // TODO: for each band, for each sample... update frequencyBands[band][sample] = value;

    mSender.ProcessBlock(frequencyBands, nFrames, kCtrlTagMeter);

```

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<div class="post-metadata">

**Author:** ![billy](https://avatars.discourse-cdn.com/v4/letter/b/ecd19e/32.png) [@billy](https://iplug2.discourse.group/u/billy)\
**Post date:** [27 October 2021 09:06 UTC](https://iplug2.discourse.group/t/how-to-use-mmetersender1-processblock-with-sample/491/4 "2021-10-27T09:06:41Z")

</div>

> [@stw](#):
>
> Just guessing from what i see…  
> This part
> 
> > ` if (s == 63) {`
> 
> seems a bit strange. Wherever this 63 comes from (i guess you take a fixed 64 frame buffer size into account?). You’re **only** calculating, storing and sending sample 63.

exactly, because I need the 64 samples before calculating and displaying the value due level of noise

---

<div class="post-metadata">

**Author:** ![billy](https://avatars.discourse-cdn.com/v4/letter/b/ecd19e/32.png) [@billy](https://iplug2.discourse.group/u/billy)\
**Post date:** [27 October 2021 09:10 UTC](https://iplug2.discourse.group/t/how-to-use-mmetersender1-processblock-with-sample/491/5 "2021-10-27T09:10:46Z")

</div>

thank you for your very quick answer, I try to do it that way. Thank you

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<div class="post-metadata">

**Author:** ![stw](https://avatars.discourse-cdn.com/v4/letter/s/8e8cbc/32.png) [@stw](https://iplug2.discourse.group/u/stw)\
**Post date:** [28 October 2021 10:10 UTC](https://iplug2.discourse.group/t/how-to-use-mmetersender1-processblock-with-sample/491/6 "2021-10-28T10:10:49Z")

</div>

> exactly, because I need the 64 samples before calculating and displaying the value due level of noise

Ok, but even if this is done correctly you’re storing your value to the output100 buffer only every 64 sample. This buffer is transmitted by your meter sender which is most probably an IPeakSender objetc. In ProcessBlock your values then will be averaged over nFrames, so in your case you’ll get an level/64 output (supposed other buffer values are zero inited?) which might not be what you want.

BTW we already have built in DB\<=\>Amp conversions: DBToAmp() and AmpToDB()