De-quantization Audio Signal

This my audio record code and quantization code :

%record code
Fs = 1000;
nBits = 8;
nChannels = 1;
t = 3;
recObj = audiorecorder(Fs,nBits,nChannels);
set(handles.edit4,'String','Start Record');
recordblocking(recObj,t);
set(handles.edit4,'String','Finish');

myRecording = getaudiodata(recObj);
axes(handles.axes1)
plot(myRecording);
grid on;
title('Record Signal')
set(gca, 'YLim', [-2 2])
legend('Audio Signal');
handles.Fs = Fs;
handles.myRecording = myRecording;
guidata(hObject,handles);
soundsc(myRecording, Fs);

%quantization code
normal_sound = (myRecording - min(myRecording))./(max(myRecording)-min(myRecording));

level = 255;
range = 1/level;
quantized_sound = floor(normal_sound ./ range);

My question is how to do de-quantization based on my quantization code? Thanks before

Answer 1

[Pavel Zaviska]

Hi, several algorithms for Audio dequantization based on signal sparsity have been proposed in the paper "Audio Dequantization Using (Co)Sparse (Non)Convex Methods". The MATLAB source codes are freely available on Github: https://github.com/zawi01/audio_dequantization

Even though the quantization scheme used in the paper is slightly different (standard Mid-riser quantizer), the codes can be easily edited (especially the projection functions) to work for arbitrary quantization scheme, assuming that quantization levels are known.