Re: Audio Compressor

On Tue, Aug 18, 2020 at 11:26 AM Renato S. Yamane <[email protected]>
wrote:

> Em ter., 18 de ago. de 2020 às 15:12, Doug Stewart <[email protected]>
> escreveu:
>
>> On Tue, Aug 18, 2020 at 9:41 AM Renato S. Yamane <[email protected]>
>> wrote:
>>
>>> Is there an Audio Compressor available in Octave?
>>> https://www.mathworks.com/help/audio/ref/compressor-system-object.html
>>>
>>> I'm compressing my noises in the worst way, as you can see in the
>>> "while" condition on the example below.
>>>
>>> In my way, the peaks will be "clipped", and I would like to avoid my
>>> stupid workaround:
>>>
>>> ====================
>>> crest_factor = 6;
>>> typenoise = noise(10*44100, 1, 'pink');
>>> [z, p, k] = butter(4, [100/(44100/2), 500/(44100/2)]);
>>> sos = zp2sos (z, p, k);
>>> filtered = sosfilt(sos, typenoise);
>>> normalized = filtered / (rms(filtered) / 10^(-crest_factor/20));
>>>
>>> #{
>>> Now I'm making an stupid workaround, as the audio file must be in
>>> a range from -1 to +1:
>>> #}
>>>
>>> while (normalized(normalized > 1) || normalized(normalized < -1))
>>>   normalized(normalized > 1) = 1;
>>>   normalized(normalized < -1) = -1;
>>>   normalized = normalized / (rms(normalized) / 10^(-crest_factor/20));
>>> endwhile
>>>
>>> audiowrite ('AudioFile.wav', normalized, 44100);
>>>   ====================
>>>
>>>
>> There are many ways to do Audio Compression.
>> Tell us more about what you want to accomplish.
>>
>
> Hi, thanks for your feedback.
> I just need to the user define the crest factor (first line of the code
> above) and the script must generate the noise (wav file) with the
> respective crest factor without clipping.
> I'm expecting the user define the Crest Factor between -6 to -12dB.
>
> Many thanks,
> Renato
>
> But crest factor and clipping are 2 independent things. you can have a
crest factor of some value  and still have clipping or no clipping.


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