Recorder.ino Sped-up

Ceiling

Member
Hey folks-

I've been testing the Recorder example on a Teensy 3.2 with an Audio Shield, however every time I play back the recording it is sped up. After reading online I thought this may have been due to the sampling rate of the audio that I was recording via the line in on the audio board. I've tried multiple sources of audio and tried adjusting the headphone/speaker output on my laptop to 16bit 44.1kHz but the recording is still sped up. Some folks online said I may need to cycle power after changing the audio settings but that didn't give me any different result.

I'm at a loss as to why this is happening and would really appreciate any help.

Thanks!

Code:
// Record sound as raw data to a SD card, and play it back.
//
// Requires the audio shield:
//   http://www.pjrc.com/store/teensy3_audio.html
//
// Three pushbuttons need to be connected:
//   Record Button: pin 0 to GND
//   Stop Button:   pin 1 to GND
//   Play Button:   pin 2 to GND
//
// This example code is in the public domain.

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

// GUItool: begin automatically generated code
AudioInputI2S            i2s2;           //xy=105,63
AudioAnalyzePeak         peak1;          //xy=278,108
AudioRecordQueue         queue1;         //xy=281,63
AudioPlaySdRaw           playRaw1;       //xy=302,157
AudioOutputI2S           i2s1;           //xy=470,120
AudioConnection          patchCord1(i2s2, 0, queue1, 0);
AudioConnection          patchCord2(i2s2, 0, peak1, 0);
AudioConnection          patchCord3(playRaw1, 0, i2s1, 0);
AudioConnection          patchCord4(playRaw1, 0, i2s1, 1);
AudioControlSGTL5000     sgtl5000_1;     //xy=265,212
// GUItool: end automatically generated code

// For a stereo recording version, see this forum thread:
// https://forum.pjrc.com/threads/46150?p=158388&viewfull=1#post158388

// A much more advanced sound recording and data logging project:
// https://github.com/WMXZ-EU/microSoundRecorder
// https://github.com/WMXZ-EU/microSoundRecorder/wiki/Hardware-setup
// https://forum.pjrc.com/threads/52175?p=185386&viewfull=1#post185386

// Bounce objects to easily and reliably read the buttons
Bounce buttonRecord = Bounce(0, 8);
Bounce buttonStop =   Bounce(1, 8);  // 8 = 8 ms debounce time
Bounce buttonPlay =   Bounce(2, 8);


// which input on the audio shield will be used?
const int myInput = AUDIO_INPUT_LINEIN;
//const int myInput = AUDIO_INPUT_MIC;


// Use these with the Teensy Audio Shield
#define SDCARD_CS_PIN    10
#define SDCARD_MOSI_PIN  7
#define SDCARD_SCK_PIN   14

// Use these with the Teensy 3.5 & 3.6 SD card
//#define SDCARD_CS_PIN    BUILTIN_SDCARD
//#define SDCARD_MOSI_PIN  11  // not actually used
//#define SDCARD_SCK_PIN   13  // not actually used

// Use these for the SD+Wiz820 or other adaptors
//#define SDCARD_CS_PIN    4
//#define SDCARD_MOSI_PIN  11
//#define SDCARD_SCK_PIN   13


// Remember which mode we're doing
int mode = 0;  // 0=stopped, 1=recording, 2=playing

// The file where data is recorded
File frec;

void setup() {
  // Configure the pushbutton pins
  pinMode(0, INPUT_PULLUP);
  pinMode(1, INPUT_PULLUP);
  pinMode(2, INPUT_PULLUP);

  // Audio connections require memory, and the record queue
  // uses this memory to buffer incoming audio.
  AudioMemory(60);

  // Enable the audio shield, select input, and enable output
  sgtl5000_1.enable();
  sgtl5000_1.inputSelect(myInput);
  sgtl5000_1.volume(0.5);

  // Initialize the SD card
  SPI.setMOSI(SDCARD_MOSI_PIN);
  SPI.setSCK(SDCARD_SCK_PIN);
  if (!(SD.begin(SDCARD_CS_PIN))) {
    // stop here if no SD card, but print a message
    while (1) {
      Serial.println("Unable to access the SD card");
      delay(500);
    }
  }
}


void loop() {
  // First, read the buttons
  buttonRecord.update();
  buttonStop.update();
  buttonPlay.update();

  // Respond to button presses
  if (buttonRecord.fallingEdge()) {
    Serial.println("Record Button Press");
    if (mode == 2) stopPlaying();
    if (mode == 0) startRecording();
  }
  if (buttonStop.fallingEdge()) {
    Serial.println("Stop Button Press");
    if (mode == 1) stopRecording();
    if (mode == 2) stopPlaying();
  }
  if (buttonPlay.fallingEdge()) {
    Serial.println("Play Button Press");
    if (mode == 1) stopRecording();
    if (mode == 0) startPlaying();
  }

  // If we're playing or recording, carry on...
  if (mode == 1) {
    continueRecording();
  }
  if (mode == 2) {
    continuePlaying();
  }

  // when using a microphone, continuously adjust gain
  if (myInput == AUDIO_INPUT_MIC) adjustMicLevel();
}


void startRecording() {
  Serial.println("startRecording");
  if (SD.exists("RECORD.RAW")) {
    // The SD library writes new data to the end of the
    // file, so to start a new recording, the old file
    // must be deleted before new data is written.
    SD.remove("RECORD.RAW");
  }
  frec = SD.open("RECORD.RAW", FILE_WRITE);
  if (frec) {
    queue1.begin();
    mode = 1;
  }
}

void continueRecording() {
  if (queue1.available() >= 2) {
    byte buffer[512];
    // Fetch 2 blocks from the audio library and copy
    // into a 512 byte buffer.  The Arduino SD library
    // is most efficient when full 512 byte sector size
    // writes are used.
    memcpy(buffer, queue1.readBuffer(), 256);
    queue1.freeBuffer();
    memcpy(buffer+256, queue1.readBuffer(), 256);
    queue1.freeBuffer();
    // write all 512 bytes to the SD card
    //elapsedMicros usec = 0;
    frec.write(buffer, 512);
    // Uncomment these lines to see how long SD writes
    // are taking.  A pair of audio blocks arrives every
    // 5802 microseconds, so hopefully most of the writes
    // take well under 5802 us.  Some will take more, as
    // the SD library also must write to the FAT tables
    // and the SD card controller manages media erase and
    // wear leveling.  The queue1 object can buffer
    // approximately 301700 us of audio, to allow time
    // for occasional high SD card latency, as long as
    // the average write time is under 5802 us.
    //Serial.print("SD write, us=");
    //Serial.println(usec);
  }
}

void stopRecording() {
  Serial.println("stopRecording");
  queue1.end();
  if (mode == 1) {
    while (queue1.available() > 0) {
      frec.write((byte*)queue1.readBuffer(), 256);
      queue1.freeBuffer();
    }
    frec.close();
  }
  mode = 0;
}


void startPlaying() {
  Serial.println("startPlaying");
  playRaw1.play("RECORD.RAW");
  mode = 2;
}

void continuePlaying() {
  if (!playRaw1.isPlaying()) {
    playRaw1.stop();
    mode = 0;
  }
}

void stopPlaying() {
  Serial.println("stopPlaying");
  if (mode == 2) playRaw1.stop();
  mode = 0;
}

void adjustMicLevel() {
  // TODO: read the peak1 object and adjust sgtl5000_1.micGain()
  // if anyone gets this working, please submit a github pull request :-)
}
QMHL9tb.jpg
 
It works for me when playing back the file with the recorder sketch (but on a T4.0). The audio board records and plays back at 44.1kHz. If you are playing the record.raw file with a separate program, you have to tell the program to use 44.1kHz.

Pete
 
Thanks for the reply Pete. I've been playing it back on the Teensy and it's still been sped up. I tried taking it into Audacity and playing with the sampling rate but I ended up with the same result.

I also just tried the PassThroughStereo sketch which worked flawlessly.
 
Last edited:
Can you post an example RECORD.RAW file? You'll need to zip it to attach it here.

I'm wondering if the recorder sketch is dropping packets because of the SD speed. On playback it would sound like it was sped up, but it would also be noisy.

Pete
 
Can you post an example RECORD.RAW file? You'll need to zip it to attach it here.

I'm wondering if the recorder sketch is dropping packets because of the SD speed. On playback it would sound like it was sped up, but it would also be noisy.

Pete

Happy to say that I got it working!

I had changed AUDIO_BLOCK_SAMPLES in Audiostream.h from 128 to 256 when I was messing with another sketch a while back and forgot about it after dealing with other problems. I changed it back and saved but still had the same issue, so I figured I'd just uninstall and reinstall. After reinstalling, the sketch worked but I still had some missing samples. I was using a Kingston 8GB and switched to a Sandisk Ultra 32GB and it performs way better.

It seems like there's still a bit of noise but that might be due to it being USB powered.

View attachment RECORD.zip
 
I think there may be an issue with the sample rate of the USB and of the Teensy audio being slightly different. I can't remember whether that was specifically when using the audio board though.

Pete
 
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