is the algorithmic data conversion, reducing their volume.

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13 views

Speech analysis by using Linear predictive analysis or Discrete wavelet trasform

Could anyone explain the advantages and disadvantages of LPA over DWT for speech signal in term of time, memory, complexity and so on ? Actually my question is related to the field of communication, ...
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3answers
77 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 ...
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2answers
68 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
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2answers
311 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 ...
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1answer
43 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 ...
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1answer
55 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 ...
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0answers
57 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 ...
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1answer
58 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 ...
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0answers
29 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
17 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 ...
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1answer
71 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
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1answer
65 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
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2answers
483 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 ...
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1answer
47 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
98 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
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0answers
68 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
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1answer
208 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
295 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
172 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
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2answers
146 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 ...
2
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1answer
528 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 ...
7
votes
1answer
383 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
106 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
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2answers
133 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
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1answer
389 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
232 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
291 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
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1answer
680 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 ...