# Questions tagged [dynamic-range-compression]

This is for algorithms that compress the dynamic range of a signal, such as used in audio or image processing.

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### Beginner Educational Resources

New member here. Recently got hired into a mid level EE position. Have a BSEE but performed more radar performance analysis at a higher system level previously. In my new group we're doing a lot of ...
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### How does companding compress dynamic range?

Regarding when you 'compress' the signal, I typically see diagrams like this: And the companding curve: I can only see how the companding curve achieves a higher average SQNR by rounding down higher ...
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### How to derive equation for second order interpolation of soft knee cutoff in a compressor?

I am reading Audio effects: theory, implementation and application by Joshua D. Reiss and Andrew McPherson. They explain that, in the simplest case with just a hard cutoff threshold, you have a ...
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### Graphing the response of an envelope follower

First off I want to apologize for not being very clear or technical in describing this question. I haven't had any formal DSP schooling. It will probably be easier to explain what I'm trying to ...
536 views

### Audio: How to measure dynamic range (in sense of dynamic compression/ "loudness war")

I'm about to calculate some quality measures for audio. One important of them is the dynamic range (in sense of "loudness war"). By which in this context is not meant the SNR but the (naive ...
131 views

### What is the best to confirm that the output of a matched filter for a linear FM chirp is correct?

I have written a matched filter in matlab to compress a linear FM chirp signal and would like to confirm that the results of my range compression. My question is what is the best way to do this? I ...
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### How do you perform range compression of SAR data on a 2D matrix?

I am building a Matlab program to process RADARSAT-1 data that came with this book. The book describes the steps to creating SAR image as follows I am currently implement the range compression step. ...
727 views

### Compute dynamic range in a linear quantization system

I know the dynamic range is the ratio between the maximum amplitude and the minimum amplitude of a signal, calculating the dynamic range in dB I get a difference of logarithms: But why the dynamic ...
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### How auto release works in dynamic range compressor

Could anyone help me to understand how auto release mode works in audio dynamic range compressor? After I typed "auto release" in seatch box on that forum I get "0 results".
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### RMS typical length for audio dynamic compressor

I know what does it mean Root Mean Square. But I can’t find any information what is typical portion (length) of audio signal for RMS envelope detector in dynamic audio compressor. Of course I know it ...
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### Sum of cosines as squashed as possible

I have 10 cosine waves of the form $\cos(2\pi(x f_n+\varphi_n))$, where $f_n$, the frequency, is an integer from 1 to 10 and $\varphi_i$, the phase, is a number from 0 to 1: s(x) = \sum\limits_{n=1}...
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### Dynamic range compression - Need pseudo algorithm for normalizing a signal

I have a signal that is NOT an audio signal (but looks like an audio signal - probably you can even "play" it). I would like to amplify the signal in regions where its amplitude is low. In very rare ...
334 views

### Is there any python code for applying a-law/mu-law on 3D numpy array?

I have 3D numpy array of probabilities between [0,1], I need to emphasize on some area with lower probabilities. I was suggested to apply a-law and mu-law. I am wondering if there is python library/...
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### Dynamic compressor - ratio in logarithmic scale problem

I want to use decibels to describe compression ratio. So for example ratio 4:1 means that every 4 input decibels above threshold causes raise of output only 1 decibel. And I also want ratio to be ...
2k views

### peak limiting/audio compression formula needed

I'm looking for a formula to effectively compress an audio waveform to limit peaks. This isn't an "automatic volume control" application where one would control amplifier gain to maintain a volume ...
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### Dynamics processor for speech - apply gain on delayed samples?

A Dynamics processor (limiter, compressor, expander, and gate) is calculating the output gain at some point in time, and it is applying this gain at some delayed point in time. This allows for ...
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### Fast method to decompress huffman and arithmetic encoded data

By nature, when decompressing huffman (and I assume also Arithmetic encoded data) we have to read it in bit by bit and then see how it traverses a huffman code tree that has the actual symbol value at ...
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### Can you recommend an efficient encoding algorithm for sound with long periods of silence?

As a side personal project, I'm coding an Android application that I plan to use to record the sounds of our first baby. I'm kind of new to the world of Android development and sound processing, so ...
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### Gain of resonating filters

I'm trying to make a music instrument based on a resonator with a high Q, such as Ableton's Corpus and Ableton's Resonator (I think the former is based on a simple 2nd order resonant filter while the ...
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### What does the operator 'Range Detector' do in this block diagram? How can it be modeled?

I'm trying to implement a 'Compressor/Expander/Noise gate' for automatic gain control of audio signals. The block diagram of the system is shown below: I don't understand how the 'Range Detector' ...
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### Differences between soft knee and hard knee in Dynamic Range Compression (DRC)?

I want to know more about where it is advantageous to use a soft knee and where and why a hard knee is preferred. Also I would like to get my hands on some good resources which talk about ...
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### A query on the non-uniform quantization

I have read that non-uniform quantization boosts the smaller amplitude signals by a large amount. However the larger amplitude signals receive a small gain. As shown in the below diagram (Compressor ...
211 views

### Map the Amplitude Envelope from [dbmin,dbmax] to [-inf,dbmax]

I would like to map the envelope of a sound (which has max dB level = dbmax, and min dB level = dbmin) from [dbmin,dbmax] to ...