STM32 Sine Wave works but Audio file produces static from DAC - stm32

Question

I'm trying to play a simple WAV file using the internal DAC on the STM32F466RE. I have the DMA, writing to a dac by an interval set by Timer4. Using a Sine Wave, this works perfectly:
Sine Wav Example (This works fine):
const uint16_t sine_wave_array[32] = {2047, 1648, 1264, 910, 600, 345,
156, 39, 0, 39, 156, 345,
600, 910, 1264, 1648, 2048, 2447,
2831, 3185, 3495, 3750, 3939, 4056,
4095, 4056, 3939, 3750, 3495, 3185,
2831, 2447};
HAL_DAC_Start(&hdac,DAC_CHANNEL_1);
HAL_DAC_Start_DMA(&hdac, DAC_CHANNEL_1, (uint32_t*)sine_wave_array, 32, DAC_ALIGN_12B_R);
HAL_TIM_Base_Start(&htim4);
//timer config
htim4.Instance = TIM4;
htim4.Init.Prescaler = 0;
htim4.Init.CounterMode = TIM_COUNTERMODE_UP;
htim4.Init.Period = 1136; // (16MHZ /(32 * 440hz))
htim4.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim4.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
//DAC Setup from Stm32cubeIDE
static void MX_DAC_Init(void)
{
/* USER CODE BEGIN DAC_Init 0 */
/* USER CODE END DAC_Init 0 */
DAC_ChannelConfTypeDef sConfig = {0};
/* USER CODE BEGIN DAC_Init 1 */
/* USER CODE END DAC_Init 1 */
/** DAC Initialization
*/
hdac.Instance = DAC;
if (HAL_DAC_Init(&hdac) != HAL_OK)
{
Error_Handler();
}
/** DAC channel OUT1 config
*/
sConfig.DAC_Trigger = DAC_TRIGGER_T4_TRGO;
sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;
if (HAL_DAC_ConfigChannel(&hdac, &sConfig, DAC_CHANNEL_1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN DAC_Init 2 */
/* USER CODE END DAC_Init 2 */
}
The DAC is set to use DMA Stream 5. The DMA is set to half-word (16 bit). The MCU is at 16 MHZ. Everything sounds good.
So now I'm trying to replace that sine_wave with an audio file (headers removed) sampled at 44.1khz form here: hello.h
Here's the modified code:
#include "helo.h"
//HELLO_LENGTH is 57890
HAL_DAC_Start(&hdac,DAC_CHANNEL_1);
HAL_DAC_Start_DMA(&hdac, DAC_CHANNEL_1, (uint32_t*)hello, HELLO_LENGTH, DAC_ALIGN_12B_R);
HAL_TIM_Base_Start(&htim4);
htim4.Init.Period = 362; // (16MHZ /44100)
I also changed the DMA Buffer from Half-word to Byte (8 bit). However, I'm just hearing static now from the speaker. But the static has a repetition to it, almost like the sound is there but all garbled.
I also tried with my own audio file (with headers removed, only the data portion) and I still get the same thing.
Any ideas?

Answer 1

Try to go one step at a time! You have massively ramped up the data rate, and changed the data format and source all at once.
First try the sine wave at the increased rate and verify that you get sensible output. Try different frequencies of sine wave. Start with a low frequency like 1kHz and work up. 44.1kHz sample rate should be able to get close to 20kHz signal.
Each time verify on the oscilloscope that the signal looks correct. If you don't have an oscilloscope then connect up a speaker and listen to the audio with a frequency monitoring app on your phone (eg: this one), or else maybe even an electronic guitar tuner.
Before you hook up a speaker think about how you will filter out the DC bias and amplify the signal. If you don't know what that means then you will have to ask on electronics stack exchange.
I expect that you may find that you are trying to run the sample rate faster that the DAC can go. Internal DACs are not usually meant for audio, also they are very non-linear.
Once you have found a sample rate that works then create a data file in that format. Remember that for wav files the data may be in unsigned or signed integer format. If it is signed then you need to convert to unsigned by adding a bias. Also think about endianness.