The discussion revolves around troubleshooting issues with a Fast Fourier Transform (FFT) implementation in C#. Participants are examining the accuracy of FFT results when sampling audio data at a rate of 44100 Hz using 16384 samples. The conversation includes comparisons with MATLAB outputs and considerations of data handling techniques.
Participants express varying opinions on the causes of the discrepancies in FFT results, with no consensus reached on the specific issues affecting the accuracy of the output. Multiple competing views regarding the handling of audio data and FFT implementation remain present throughout the discussion.
Participants mention the importance of ensuring correct data types (e.g., 16-bit vs. 8-bit samples) and the potential impact of windowing on FFT results. There are unresolved questions about the nature of the input signal and how it affects the FFT output.
This discussion may be useful for software developers working with audio signal processing, particularly those implementing FFT algorithms in C# or comparing results with established tools like MATLAB.
Are you looking at stereo information?btb4198 said:however, I am still getting half the Frequencies...
I can just do * by 2 at the very end and get the right Frequencies but I really want to know why it is doing this
I don't know how you are grabbing the information. At some point you must have specified 44100Hz, 16 bits per sample. When you did that, the same data structure should have included whether the signal would be stereo or mono.btb4198 said:I do not know... how can I find out ?
I am using the default microphone on my computer..
what is the different between stereo and mono for a microphone ?
mono is one.. so one mic
so it stereo more that one mic?
how would did affect the input samples ?
int tempint = 0;
for (int index = 0; index < 32768; index += 2)
{
buffer1[tempint] = ((buffer[index + 1] << 8) |
buffer[index + 0]);
if (buffer1[tempint] > 32767)
buffer1[tempint] = buffer1[tempint] - 65536;
tempint++;
} int tempint = 0;
for (int index = 0; index < 32768; index += 2)
{
buffer1[tempint] = ((buffer[index + 1] << 8) |
buffer[index + 0]);
if (buffer1[tempint] > 44100)
buffer1[tempint] = buffer1[tempint] - 88200;
tempint++;