is the algorithmic data conversion, reducing their volume.

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1answer
30 views

What does the word Entropy refer to in Entropy encoding

I have come know of Huffman and Arithmatic encoding that try to curtail redundant data and thus compress data. Why are they called Entropy encoding? What does that mean? Why not just call them ...
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0answers
19 views

Is possible to compress / code data from PDM domain?

I have to compress data with a ADPCM algorithm. The data are in PDM domain at 1.024 MHz. What I'm doing is to down sapling data (decimator+sinc3) of 64 factor from PDM to PCM 16Khz. Then I use the ...
0
votes
2answers
88 views

Linear Predictive Coding and Block Size

I'm experimenting with linear predictive coding as a low-complexity audio compression method, and I'm observing something very odd. I'm compressing a 20 MB mono 16-bit PCM song in different block ...
0
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0answers
26 views

ADPCM: Theory and HIghest Quality Algorithm(s)

Two questions. What is the highest audio quality ADPCM algorithm(s)? IME ADPCM is quite simple, but would I be correct to assume that a multi-sample algorithm (where the previous two samples are ...
2
votes
2answers
99 views

Low-Complexity Audio Compression?

What options exist for discrete audio compression that is good quality, moderate compression (e.g. 3+:1), and low complexity (e.g. hundreds of processing cycles to encode each sample without the use ...
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3answers
93 views

How is data compression possible for audio?

I understand that compression works by exploiting certain psycho-acoustical characteristics of our auditory perception, but I'm still confused. I mean ultimately, the waveform must be recorded ...
0
votes
2answers
100 views

Audio compression with STFT

Let STFT[frame, freqbin] be the short-time Fourier transform of some audio data. (here frame is the index in time, and ...
4
votes
2answers
324 views

Difference between jpg compression and mp3 compression

My understanding of jpg compression is that, if done repeatedly, any image will eventually be reduced to a single flat color, due to the way it deals with neighboring pixels. However, years ago I was ...
0
votes
1answer
56 views

How is compression ratio related to number of dct coefficients

Lets say we have a picture with 6bits/pixel and we use discrete cosine transform with 8x8 blocks of pixels and each coefficient is 8 bits. We can use 2 8x8 masks, a zonal mask A and a zonal bit ...
1
vote
1answer
101 views

compressed/compressive sensing, sensor placement

Given: I have a beam fixed at one end and free at the other. It obviously results in vibrations due to the disturbances in the environment or when induced. This system can be represented using a ...
3
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0answers
61 views

Error bounds in signal compression represented by truncated Moore-Penrose biorthogonal bases using von Neumann wavelets

I was reading and trying to reproduce the results in the arXiv preprint of Periodic Gabor Functions with Biorthogonal Exchange: A Highly Accurate and Efficient Method for Signal Compression by Asaf ...
0
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1answer
83 views

Limitations of Arithmetic coding?

I have been working on an assignment for university in which I have to compress an 80K message consisting of only two symbols, 'a' and 'b', having probability values of 0.6 and 0.4. I have ...
2
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0answers
30 views

Recovering eigenvalues from singular values [closed]

I am dealing with a problem similar to principal component analysis. Aka, I have a matrix and i want to recover the 'most efficient basis' to exaplin the matrix variability. With a square matrix these ...
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0answers
20 views

Sampling from a distribution with arithmetic coding

I'm struggling to implement a sampling scheme where arithmetic decoding is used to generate the samples. This is based on excercise 6.3 from David MacKay's book, where you compare rejection sampling ...
0
votes
1answer
121 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 ...
0
votes
1answer
83 views

Signal quality metric

I have floating point data signal. I apply lossy control to it and I need some kind of metric to determine its quality. In image processing, there is PSNR (or MSE). I tried to use the same for it, It ...
2
votes
2answers
888 views

Help implementing audio dynamic range compression

I am trying to implement audio dynamic range compression in JavaScript (not using web audio API). There is a lot of articles for sound technicians, and some high level documentation, but I couldn't ...
0
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1answer
53 views

What are some techniques to recover an original image from three different compressed versions?

This question is theoretical. Let's say you have three different highly compressed images of a same source image, each compressed with a different algorithm and thus "lossy" in different ways. What ...
2
votes
2answers
106 views

Usage of Digital Cosine Transform in lossy compression of images

I was reading about Digital Cosine Transform (DCT Type-I) and it's use in JPEG. I have the following doubt. My teacher offered an explanation which wasn't very convincing. What property of Digital ...
1
vote
0answers
81 views

How does Golomb-Rice Coding work?

I've read the explanation in http://urchin.earth.li/~twic/Golomb-Rice_Coding.html and http://en.wikipedia.org/wiki/Golomb_coding , however, I still not get the intuition why it is efficient and when ...
2
votes
1answer
242 views

Audible mp3 artifacts?

What kind of compression artifacts would typically be most noticeable to a non-audiophile listener in a low-bit rate mp3 (MPEG-2 Layer III) compressed audio file? What kind of audio signal might one ...
3
votes
1answer
643 views

What are some typical lossless compression ratios?

A client was trying to send me 250 GB worth of files. After attempting various ways of sharing the data, he sent me a zipped folder only 4 GB in size. That sounds like too much compression to me--I ...
3
votes
2answers
237 views

change the frequency component of a spectrum in an audio file

I am working on an audio dynamic range compressor using Matlab. After calculating the FFT of the audio file, I use several bandpass filters to amplify specific bands separately. What I want to do then ...
4
votes
2answers
163 views

Exam Question - end-to-end delay from video capture to video playout

Hi I'm preparing for my exam tomorrow and I've come across a 17 Mark question which seems trivially easy, so I think I'm missing a key point giving the rest of this exam is fairly difficult. The ...
3
votes
1answer
688 views

Speech Compression - In LPC how does the linear predictive filter work on a general level?

Hi I'm taking a multimedia systems course and I'm preparing for my exam on tuesday. I'm trying to get my head around LPC compression on a general level, but I'm having trouble with what is going on ...
8
votes
1answer
447 views

Theory behind Linear Predictive Coding (LPC)

What is the theory behind LPC? Why are(were) certain implementations of LPC said to be more tolerant of transmission or encoding errors quantization than other compressed voice encoding schemes? ...
3
votes
2answers
114 views

A non-lossy aka lossless codec without patent-restrictions for audio?

The term non-lossy codec means the coding thing having no compression lost, more here. I need such format to process the audio, without destroying the quality. ...
2
votes
2answers
153 views

Compressing plotted data with variable sample rate?

I'm currently plotting high sample rate data by down-sampling by a factor and averaging. Most of the time this is working ok, but I am aware that at very low zoom levels (zoomed right out) the ...
4
votes
1answer
490 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 ...
3
votes
1answer
252 views

Determining the resulting pixel value before creating a compressed JPEG image

Is it possible to determine the resulting pixel values and modify them before the compressed jpeg image is actually created? For example, I'm at the stage where I already have the quantized DCT ...
6
votes
1answer
313 views

Non-orthogonal basis which offers better energy compaction in image compression

I am aware of image-independent basis, i.e. DCT, and image-dependent basis, i.e. Karhunen–Loève, which are used in compacting energies for image compression. These bases are orthorgonal. Are there ...
9
votes
1answer
811 views

How does adaptive Huffman coding work?

Huffman coding is a widely used method of entropy coding used for data compression. It assumes that we have complete knowledge of a signal's statistics. However, there are versions of Huffman coding ...