Downsample audio signal am I doing it right?

Hello,

I have an audio file and I want to perform Downsampling

form 44100 to 22050 / from 22050 to 11025 / from 11025 to 8000

Please find bellow my code.

   [samples,fs] = audioread ('piano.wav');
    audiowrite('piano.wav', samples,fs);
        subplot (2,1,1)
        plot(samples)
        xlabel 'audio signal'
% processing second part downsampling

S1 = resample(fs,22050,44100);          % downsample from 44100 to 22050
S2 = resample (S1,11025,22050);         % downsample from 22050 to 11025
S3 = resample (S2,8000,11025);          % doensample from 11025 to 8000

[Walter Roberson]

Looks okay, except that there is no good reason for writing the file you just read from.

Also, you should be using a better x axis for the plot: it should be

x = (0:size(samples,1)-1)/fs;
plot(x, samples);

[Isida Kaloshi]

Dear Mr Roberson,

Thank you very much for your fast reply and for your comment for the x axis.

Kind regards,

[Hari Ijjada]

After resampling the origanl samples how can i listen the resampled file ?

[Henrik Gunnar Sundt]

You probably mean:

S1 = resample(samples,22050,44100);

not:

S1 = resample(fs,22050,44100);

[Walter Roberson]

Good point, Henrik

Answer 1

[Yash Bansod]

I don't think that you are doing it rigt.

The following post describes the correct procedure: https://www.mathworks.com/help/signal/ug/changing-signal-sample-rate.html

To summerize:

% Code to read audio files
[y,Fs] = audioread(filename);

% code to resample audio
Fs_new = 16000;
[Numer, Denom] = rat(Fs_new/Fs);
y_new = resample(y, Numer, Denom);

% Code to play an already read audio file
sound(y, Fs);