AudioSynthWaveformSine_F32, stereo I2S output to DAC out-of-phase @ sample rate 44100 & 44117 Hz

[psitech]

S/W: Windows 10, Arduino 1.8.19, Teensyduino 1.57, OpenAudio library up to and including commit 88126e2.
H/W: Teensy 3.2 plus PCM5102A DAC.

While playing with the OpenAudio library generating a sine wave, I noticed that for sample rates 44100 & 44117 Hz, the sine output is out-of-phase.
Here is the code used:

#include "OpenAudio_ArduinoLibrary.h"
#include "AudioStream_F32.h"
#include <Audio.h>

// T3.x supported sample rates: 2000, 8000, 11025, 16000, 22050, 24000, 32000, 44100, 44117, 48000,
//                             88200, 88235 (44117*2), 95680, 96000, 176400, 176470, 192000
// T4.x supports any sample rate the codec will handle.

const float sample_rate_Hz = 32000,0f;
const float freq = 1000.0f;
const int   audio_block_samples = 128;

AudioSettings_F32 audio_settings(sample_rate_Hz, audio_block_samples);

AudioSynthWaveformSine_F32    sine1(audio_settings);           
AudioOutputI2S_F32            audioOutI2S1(audio_settings);         
AudioConnection_F32           patchCord1(sine1, 0, audioOutI2S1, 0);
AudioConnection_F32           patchCord2(sine1, 0, audioOutI2S1, 1);

void setup() {
  AudioMemory(20);
  AudioMemory_F32(20);
  sine1.amplitude(1.0);
  sine1.frequency(freq); 
  sine1.begin();
}

void loop() {
}

Output on scope at SR = 32000 Hz:

Output on scope at SR = 44100 Hz:

Output on scope at SR = 44117 Hz:

Output on scope at SR = 48000 Hz:

The logic analyzer on the I2S signals also shows different L&R samples at 44100 & 44117 Hz.

Paul

[psitech]

Running the exact same code on a Teensy 4.0 does not show this out-of-phase behavior at 44100 & 44117 Hz sample rate.

Paul

[boblark]

Paul, I assume the two traces are the left and right outputs.  I will try your code. There is an issue that there is no certainty as to the output order from the SGTL5000 ADC.  It randomly starts up with an ambiguity as to which channel gets to I2S first.  But that is a tiny amount of time and nothing like what you are seeing. Am I right that you are seeing a -1.0 multiplier on one of the channels?  Seems strange. More later, Bob

…

On 1/22/23 03:36, psitech wrote: S/W: Windows 10, Arduino 1.8.19, Teensyduino 1.57, OpenAudio library up to and including commit 88126e2 <88126e2>. H/W: Teensy 3.2 plus PCM5102A DAC. While playing with the OpenAudio library generating a sine wave, I noticed that for sample rates 44100 & 44117 Hz, the sine output is out-of-phase. Here is the code used: |#include "OpenAudio_ArduinoLibrary.h" #include "AudioStream_F32.h" #include <Audio.h> // T3.x supported sample rates: 2000, 8000, 11025, 16000, 22050, 24000, 32000, 44100, 44117, 48000, // 88200, 88235 (44117*2), 95680, 96000, 176400, 176470, 192000 // T4.x supports any sample rate the codec will handle. const float sample_rate_Hz = 32000,0f; const float freq = 1000.0f; const int audio_block_samples = 128; AudioSettings_F32 audio_settings(sample_rate_Hz, audio_block_samples); AudioSynthWaveformSine_F32 sine1(audio_settings); AudioOutputI2S_F32 audioOutI2S1(audio_settings); AudioConnection_F32 patchCord1(sine1, 0, audioOutI2S1, 0); AudioConnection_F32 patchCord2(sine1, 0, audioOutI2S1, 1); void setup() { AudioMemory(20); AudioMemory_F32(20); sine1.amplitude(1.0); sine1.frequency(freq); sine1.begin(); } void loop() { } | Output on scope at SR = 32000 Hz: SDS00073 <https://user-images.githubusercontent.com/27091013/213913550-ff687d17-4c54-4b48-9799-d029c2d82c1d.png> Output on scope at SR = 44100 Hz: SDS00074 <https://user-images.githubusercontent.com/27091013/213913581-ae86860e-11b6-4d61-8cd0-151f604231eb.png> Output on scope at SR = 44117 Hz: SDS00075 <https://user-images.githubusercontent.com/27091013/213913594-dbc44b45-20b9-4648-a3c5-95a7511eed8c.png> Output on scope at SR = 48000 Hz: SDS00076 <https://user-images.githubusercontent.com/27091013/213913602-3a114496-7dd7-4fbb-8036-981fc841a631.png> The logic analyzer on the I2S signals also shows different L&R samples at 44100 & 44117 Hz. Paul — Reply to this email directly, view it on GitHub <#21>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACHP4NGOXCHHQ32X7R2POTTWTULVDANCNFSM6AAAAAAUC55PZQ>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[psitech]

Hi Bob, thanks for looking into this.

I assume the two traces are the left and right outputs

Correct.

Am I right that you are seeing a -1.0 multiplier on one of the channels? Seems strange.

Yes, I fed the RCA cables from the PCM5102A module directly into my scope.

If you want me to run some tests, just let me know.
Paul