Hello, I cannot get SoundSL working to detect the source of a sound direction correctly. To check how the library performs itself, I wrote a little test script.
I assume a 1kHz sine wave to be sampled by a simulated microphone. At a sampling rate of 16kHz, the buffer for 1ms duration consists of 16 samples (per channel) that describe an entire period. At a sound speed of 350m/s and a distance of 0.1m between the microphones, the phase shift should not exceed approximately +/- 90 degrees (+/- 285us). According to my understanding, a phaseshift of [-90 degrees phase shift; 90 degrees phase shift] should result in about [-90 degree angle; 90 degrees angle] where in-phase would be 0 degrees (same distance to both microphones).
In the test script, I compute the sine wave values for a particular offset and feed the values to the library until the result can be calculated. Once one angle is gathered, I increase the phase shift and redo the whole process. The angles are then stored in an array. The results for a phase shift of [0 degrees; 90 degrees] with a 10 degrees increment are shown in the table. The results are not as expected. What am I doing wrong? I use library version 2.2.0.
Thank you.
Solved! I found out that the variable holding the simulated microphone samples was 32-bit instead of 16-bit.
/* USER CODE BEGIN 2 */
float offset = 0.0;
uint32_t err_type;
int32_t est_angle;
AcousticSL_Handler_t h;
AcousticSL_Config_t c;
uint8_t gbl_sound2d_internal_mem[30000];
int32_t glb_test_mic[32]; // 16xL, 16xR
int32_t angles[11];
uint32_t angles_cnt = 0;
h.algorithm = ACOUSTIC_SL_ALGORITHM_GCCP;
h.sampling_frequency = 16000;
h.channel_number = 2;
h.ptr_M1_channels = 2;
h.ptr_M2_channels = 2;
h.ptr_M3_channels = 2;
h.ptr_M4_channels = 2;
h.M12_distance = 100;
h.M34_distance = 100; // Dont care
h.samples_to_process = 512;
h.pInternalMemory = (uint32_t *)gbl_sound2d_internal_mem;
c.resolution = 5;
c.threshold = 1;
err_type = AcousticSL_getMemorySize(&h);
if (err_type)
Error_Handler();
if (h.internal_memory_size > 30000)
Error_Handler();
err_type = AcousticSL_Init(&h);
if (err_type)
Error_Handler();
err_type = AcousticSL_setConfig(&h, &c);
if (err_type)
Error_Handler();
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
for (uint32_t i = 0, j = 0; j < 16; i += 2, j++)
{
glb_test_mic[i] = (int32_t)(1000.0 * cos(2.0 * M_PI / 16 * j));
glb_test_mic[i+1] = (int32_t)(1000.0 * cos(2.0 * M_PI / 16 * j + offset));
}
while(!AcousticSL_Data_Input((int16_t*)&glb_test_mic[0], (int16_t*)&glb_test_mic[1], (int16_t*)&glb_test_mic[0], (int16_t*)&glb_test_mic[0], &h))
;
angles[angles_cnt] = -100;
if(!AcousticSL_Process(&est_angle, &h))
{
angles[angles_cnt] = est_angle;
angles_cnt++;
if(angles_cnt == 11)
{
while(1)
{
asm("nop");
}
}
}
offset += M_PI / (2 * 9);
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}