sample and hold

[chandrian]

Hello,

First time post so I apologize in advance if the wording is confusing or lacking details.

I was wondering how you might have a system where you can turn on a sample and hold function. Basically I want to be able to sample for 100ms and play that sample, mixed with the current audio input.

I was trying to use feedback delay and a digital input to "take sample" and then hold, but I was not able to figure out how to keep feeding the same sample without adding updated delay signals as well.

Maybe another strategy is much more simple.

Thank you,
Aaron

 

[chandrian]

So I found some code to read in to a buffer/queue and play that buffer, but is there a way to get a bigger buffer so that I can have a 100ms sample and keep playing this over? I had an idea of writing the input buffer (queue2) to a larger array that I can save and play over and over but then I will have to play that array somehow while still playing the original audio input at the same time. I could add the audio output (queue1) to a mixer, but then how do I add the array as another input. Also my SD card stopped working so I am unable to use that right now unfortunately.

(I have not added the new array that stores the input)

#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>
// GUItool: begin automatically generated code
AudioInputI2S            i2s1;           //xy=77,57
AudioRecordQueue         queue2;         //xy=208,57
AudioPlayQueue           queue1;         //xy=327,55
AudioOutputI2S           i2s2;           //xy=459,52
AudioConnection          patchCord1(i2s1, 1, queue2, 0);
AudioConnection          patchCord2(queue1, 0, i2s2, 0);
AudioConnection          patchCord3(queue1, 0, i2s2, 1);
AudioControlSGTL5000     sgtl5000_1;     //xy=446,103
// GUItool: end automatically generated code
int x = 0;
uint16_t buffer[512];

void setup(){
  
  AudioMemory(64);
  sgtl5000_1.enable();
  sgtl5000_1.inputSelect(AUDIO_INPUT_LINEIN);
  sgtl5000_1.volume(0.8);
  sgtl5000_1.lineInLevel(0);
  sgtl5000_1.lineOutLevel(13);
  queue2.begin();
}

void loop(){
  for(x=0;x<100;x++)
  {
  if(queue2.available() >= 2){ //input buffer
    memcpy(buffer, queue2.readBuffer(), 256);
     
  }
   while(1)
    {
    queue2.freeBuffer();      
    int16_t *outBuf = queue1.getBuffer(); //
      memcpy(outBuf, buffer, 256);
      queue1.playBuffer();}
    }
    delay(2000);
}

 

[chandrian]

Im thinking that I have to turn the array into an audio object but do I use something like

audio_block_t

https://www.pjrc.com/teensy/td_libs_AudioNewObjects.html

or

AudioPlayMemor (this one either seems outdated ? or it is just different)

https://www.pjrc.com/teensy/td_libs_AudioPlayMemory.html

Thanks for feedback!

Aaron

 

[chandrian]

Hello again,

So the application I am trying is something like an infinite sustain pedal. Sample the audio or "note" and hold it. You will be able to stop playing the note and it should hold. I also want to mix this note with incoming audio; so essentially you could play different notes while that note is holding.


Here is the code saving to an array and trying to play that. It works for the most part...

I kept bumping up the queue size until I got to:
uint16_t sampleQueue[16384];

and then this did not work (below):
uint16_t sampleQueue[32768];

it just stopped playing audio at that point.

any thoughts?

also i saw other code where this line (below) used queueP + 128 and im not sure why its not 256 since thats the size of the data being copied:
memcpy(queueP + 256*x, queue2.readBuffer(), 256);


please help.

#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>
// GUItool: begin automatically generated code

AudioPlayMemory          mySound;
AudioInputI2S            i2s1;           //xy=77,57
AudioRecordQueue         queue2;         //xy=208,57
AudioPlayQueue           queue1;         //xy=327,55
AudioOutputI2S           i2s2;           //xy=459,52
AudioConnection          patchCord1(i2s1, 1, queue2, 0);
AudioConnection          patchCord2(queue1, 0, i2s2, 0);
AudioConnection          patchCord3(queue1, 0, i2s2, 1);
AudioControlSGTL5000     sgtl5000_1;     //xy=446,103
// GUItool: end automatically generated code
int x = 0;
int y = 0;
int z = 0;
  
void setup(){
//  Serial.begin(9600);
  AudioMemory(64);
  sgtl5000_1.enable();
  sgtl5000_1.inputSelect(AUDIO_INPUT_LINEIN);
  sgtl5000_1.volume(0.5);
  sgtl5000_1.lineInLevel(0);
  sgtl5000_1.lineOutLevel(13);
  queue2.begin();
  pinMode(12, INPUT_PULLUP);

}

void loop()
{  
uint16_t sampleQueue[16384];
//uint16_t sampleQueue[32768];
uint16_t *queueP = sampleQueue; 
  //if(!digitalRead(12))
  {
    for(x=0;x<16;x++)
    {
      if(queue2.available() >= 2)
        {
          memcpy(queueP + 256*x, queue2.readBuffer(), 256);
        }
      queue2.freeBuffer();  
    }  
  }
 
    for(y=0;y<16; y++)
    {
        int16_t *outBuf = queue1.getBuffer(); //
        memcpy(outBuf, queueP + y*256, 256);
        queue1.playBuffer();
    }
  
       
}