playBuffer() has high execution time

[ossi]

In the following sketch I try to copy audio data from a record-queue to a play-queue in the c-main function.
(Later I will do a lot of signalprocessing between input and output).
The code works. I try to measure execution times of the parts using Leds with a scope attached also to
the Led lines. I find that playQueue.playBuffer(); takes more than 2ms. The other times are rather short (as expected).
I don't understand why playBuffer() takes so long. Perhaps I do something
wrong in my way of copying. Is there a way to get the number of free buffers?
I am a total Teensy noob, but I am learning a lot in the 5 dyas since I own a Teensy.

#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>

#include "ossi1.h"

// GUItool: begin automatically generated code
AudioInputI2S            i2s2;           //xy=136,152
AudioPlayQueue           playQueue;         //xy=306,234
AudioRecordQueue         recordQueue;         //xy=309,190
AudioOutputI2S           i2s1;           //xy=499,152
AudioConnection          patchCord1(i2s2, 0, i2s1, 0);
AudioConnection          patchCord2(i2s2, 1, recordQueue, 0);
AudioConnection          patchCord3(playQueue, 0, i2s1, 1);
AudioControlSGTL5000     sgtl5000_1;     //xy=141,54
// GUItool: end automatically generated code

int led33 = 33;
int led34 = 34;
int led35 = 35;

void setup() {
  pinMode(led33, OUTPUT);    
  pinMode(led34, OUTPUT);    
  pinMode(led35, OUTPUT);  
  sgtl5000_1.enable();
  sgtl5000_1.volume(0.9);
  AudioMemory(128) ; 
  recordQueue.begin();
  delay(2000) ;
  }


int16_t *input_L ;  
int16_t *output_L ;  


void doBuffers(int imax){
  for (int i = 0; i < imax; i++) {
    digitalWrite(led35, HIGH);
      input_L = recordQueue.readBuffer();
      output_L = playQueue.getBuffer();
      recordQueue.freeBuffer();
    digitalWrite(led35, LOW);
    digitalWrite(led33, HIGH);
      for(int k=0 ; k<128 ; k++){ output_L[k]=input_L[k] ; }
      delay(1) ;
    digitalWrite(led33, LOW);
    digitalWrite(led34, HIGH);
      playQueue.playBuffer();
    digitalWrite(led34, LOW);
    }
  }
  

void loop() {
  while (recordQueue.available() > 1 ) {
    doBuffers(1) ;
    } 
  }

 

[Frank B]

playBuffer does not play it waits for free space in the queue and thus it may wait until the first qeue entry got played. when there is space, it returns pretty fast.

If you want to learn and have questions like this, it is always good to take a look at the sourcecode.

	while (tail == h) ; // wait until space in the queue

 

[ossi]

Does that mean that I generated the data too fast? Since I generate data as it comes in from the record-queue I had expected that there is alway enough space in the playQueue to cope with the incoming data. But it seems I dont understand the buffer mechanisms. Ok, I will go to the source code.....