Amplitude Compression

Started by bogfrog in comp.dsp12 years ago 12 replies

I am working on audio, samples are 16 bits, values ranging from -1 to +1 for each sample. I want to implement what a paper I am reading...

I am working on audio, samples are 16 bits, values ranging from -1 to +1 for each sample. I want to implement what a paper I am reading calls "amplitude compression." These are the 3 specifications given for the amplitude compression I want to implement: (1) Compression ratio of 8.94:1 for |A| > = -28.6 dB (2) Compression ratio of 1.73:1 for -46.4 dB < |A| < -28.6 dB (3) Compression ratio of


Custom compression methods

Started by Ross Clement (Email address invalid - do not use) in comp.dsp15 years ago 6 replies

Hi. Just out of curiosity, has anyone designed and built their own method for music compression. I realise that the ogg format is open-source...

Hi. Just out of curiosity, has anyone designed and built their own method for music compression. I realise that the ogg format is open-source and relatively unencumbered by licencing issues. But I'm curious if anyone has written their own compression method "because they can". Cheers, Ross-c


Frequency Compression

Started by srikanth.konj in comp.dsp10 years ago

Hi All, Please help me learn more about Frequency Compression. I know the basic concept, but don't know how to achieve it technically. So...

Hi All, Please help me learn more about Frequency Compression. I know the basic concept, but don't know how to achieve it technically. So any material or links which deals with the technical aspects of Frequency compression is welcome. thanks in advance. regards, srikanth


Standard audio compression (LA-2A, not MP3) algorithm

Started by Pat Farrell in comp.dsp15 years ago 1 reply

This may be a FAQ, but I don't see one, and you guys seem pretty smart. Is there a standard algorithm for doing audio compression in a DSP...

This may be a FAQ, but I don't see one, and you guys seem pretty smart. Is there a standard algorithm for doing audio compression in a DSP context? I mean the type of compression that recording studios and radio stations used to use a Universal LA2A or Universal Audio 1176LN. While these are typically thought of as compression (making the loud ampliture software) they usually work by making...


aggressive compression

Started by HyeeWang in comp.dsp12 years ago 8 replies

What is "aggressive" compression technology? How to identify a aggressive compression algo, especially in speech coding domain, which is my...

What is "aggressive" compression technology? How to identify a aggressive compression algo, especially in speech coding domain, which is my interst. Anyway, i am talking the concept of "aggressive " used here. Any comments would be appreciated! HyeeWang


Postdoc position in Image and Waveform Compression

Started by julius in comp.dsp10 years ago

Postdoc position in Image and Waveform Compression A postdoc position is available immediately at Schlumberger- Doll Research in Cambridge,...

Postdoc position in Image and Waveform Compression A postdoc position is available immediately at Schlumberger- Doll Research in Cambridge, Massachusetts. We are looking for a strong PhD graduate for research work in the area of compression of images and waveforms. Experience in image and waveform compression is mandatory, and knowledge of estimation and detection theory is desirable....


AAC compression chips? Other compression chips?

Started by Michal in comp.dsp17 years ago 4 replies

Dear All, I'm looking for inexpensive hardware solution (chips) to encode groups of 6 channel 44/48k signals into streams of preferably AAC....

Dear All, I'm looking for inexpensive hardware solution (chips) to encode groups of 6 channel 44/48k signals into streams of preferably AAC. Or WMA or MP3 or AC-3 if it is simpler. The idea is that signal is input as regular 48k/24bit pcm, than the user can select compression DR (eg 64kbps for 12 channels or 128kpbs for 6 channels) and the circuit will spit out serial encoded data in ...


Anybody using compression option for blackfin loader?

Started by Andre in comp.dsp12 years ago

Hi VDSP-Experts, I am trying to use the "compression" feature of the loader on the BF533 with VDSP5.0 update 4. I have ticked "enable...

Hi VDSP-Experts, I am trying to use the "compression" feature of the loader on the BF533 with VDSP5.0 update 4. I have ticked "enable compression" in project options and selected a zlib init file in load/options. The only thing I modified from the default one (ADSP-BF533_zlib_init_SDRAM.dxe) is the SDRAM bank control register, which I set to my configuration (0x11, using 16MByte). I...


Multiband Amplitude Compression in Freq. Domain

Started by aaab in comp.dsp8 years ago 11 replies

Dear all, I would like to get started on Multiband Amplitude Compression in the Frequency Domain. So basically I would like to do the...

Dear all, I would like to get started on Multiband Amplitude Compression in the Frequency Domain. So basically I would like to do the processing like Compression of the signal on frequency spectra (bins). Can anybody suggest any links or references from where I could get an understanding of how can I do it ? Thanks in advance, AV.


DWT and Data Compression

Started by Umutesi Faith in comp.dsp15 years ago 6 replies

Hello About the DWT: The DWT provides data compression by setting a threshold value and all coefficients that are less than the choosen value...

Hello About the DWT: The DWT provides data compression by setting a threshold value and all coefficients that are less than the choosen value will be reduced to zero or eliminated and the signal can be reconstructed from the thresholded coefficients. Therefore, I would like to ask about the lossless compression , does this involve just the DWT and IDWT without setting any threshold value? or...


Newbie Question

Started by nija in comp.dsp13 years ago 5 replies

Hi all, I am new to the field of DSP/Video Compression. I wanted to learn MPEG 4 Video Compression standard in particular as it is required in...

Hi all, I am new to the field of DSP/Video Compression. I wanted to learn MPEG 4 Video Compression standard in particular as it is required in my current project which is about Live Video streaming using RTSP/RTP protocol on the internet using MPEG 4 codec. I have read some articles/ISO standard about MPEG Video Compression standard.Even though I did my engineering in EE ,I find them ve...


Audio Compression

Started by Udhay in comp.dsp14 years ago 5 replies

Sir, I am udhay. I am a student and i am working on Audio compression for my exam. I want to know how does the compression take place in...

Sir, I am udhay. I am a student and i am working on Audio compression for my exam. I want to know how does the compression take place in audio?? I have doubt in human earing capacity.The maximun hearing capacity of a human is 20-20khz. if a take a sample wave file,its coming around 40khz. what it mean? can anyone help me to clear this doubt.. udhay


Pulse compression implemented by the convolution vs. by fft

Started by tsuyahog in comp.dsp5 years ago 8 replies

Hi there! I'm working on Pulse compression for radar signal using FFT, the echo is N points, and the length of match filter is also N points, then...

Hi there! I'm working on Pulse compression for radar signal using FFT, the echo is N points, and the length of match filter is also N points, then I use N points FFT to calculate the pulse compression result, it seems that I can indeed get the right result. I just get a little confused, since two N-points signals for linear convolution needs L(L> =2N-1) points FFT to get the right thing. Is there


DCT in audio compression

Started by eblade in comp.dsp12 years ago 2 replies

After reading, what seems like a lot of material, I'm still in doubt why DCT isnt used in audio-compression. Seeing as DCT assumes mirror...

After reading, what seems like a lot of material, I'm still in doubt why DCT isnt used in audio-compression. Seeing as DCT assumes mirror symmetry, my only idea for not validating DCT over MDCT is that with real-life signals you can rarely (if ever) expect a signal to have that property? Is that correct or is there a better explanation.


processing in frequency domain & JPEG compression

Started by manishp in comp.dsp8 years ago 1 reply

Sirs, Sometime back there was a dicussion about most of the filtering operating in time domain. Now, in case of JPEG compression, the time...

Sirs, Sometime back there was a dicussion about most of the filtering operating in time domain. Now, in case of JPEG compression, the time domain samples are first converted into frequency domain and then processed further for compression. Why is it not possible to apply direct filtering on the time domain samples? Thanks, Manish


Probably NAIVE question on (lossy?) voice compression

Started by Richard Owlett in comp.dsp17 years ago 1 reply

I'm interested in settling in my own mind what makes speech intelligible. In past wanderings of the WEB I have gathered the impression that...

I'm interested in settling in my own mind what makes speech intelligible. In past wanderings of the WEB I have gathered the impression that there are a wide variety of compression.decompression algorithms available depending on your optimization target. Unfortunately, I don't have a good record of where I've been. I'm doing this on a hobbyist budget ( ie $ = 0 ). Could someone point...


Re: ANNOUNCEMENT: New image format

Started by Thomas Richter in comp.dsp13 years ago

John Costella schrieb: > This might not make sense until you've had a look at what I'm on about > with the format. It does lossless...

John Costella schrieb: > This might not make sense until you've had a look at what I'm on about > with the format. It does lossless compression (pretty well) and lossy > compression (ok, but could probably be tweaked a lot more), but > that's > not the fundamental issue, which is that the format stores images in > a > top-down manner, in such a way that you get damn good progressive > do


"Lena" or similar compression tests

Started by Anonymous in comp.dsp13 years ago 10 replies

Does anyone have source data for any standard image compression images such as "Lena" in integer/unsigned char format? If not - is there an...

Does anyone have source data for any standard image compression images such as "Lena" in integer/unsigned char format? If not - is there an easy way I can obtain this by opening an image in Matlab? Cheers Gary


In what "dimension" does JPEG compression loss occur for color images

Started by Richard Owlett in comp.dsp15 years ago 4 replies

I understand that JPEG is a "lossy" compression method. For color images is loss in: 1. resolution 2. color depth a. would that...

I understand that JPEG is a "lossy" compression method. For color images is loss in: 1. resolution 2. color depth a. would that include contrast 3. resolution AND color depth I intuitively suspect #3. If so is it possible trade off resolution for color depth and vice versa? If not, are there "high" [definition of "high" to be specified by responder] compression algorithm...


Wavelet data compression

Started by Umutesi Faith in comp.dsp14 years ago 3 replies

Hello I am trying to do some data compression using the DWT techniques but i have encoutered some problems. Once i have set the threshold...

Hello I am trying to do some data compression using the DWT techniques but i have encoutered some problems. Once i have set the threshold values, all the DWT coefficients that were less than the chosen value were reduced to zero which was the purpose. But on the other hand i would like to reconstruct the signal using only the remained coefficients without using those coefficients replaced wit...