## Forums Search for: Compression

## OT:advise for developing Codecs

Hello Boys., After a very long time..! Well, coming to my stuff, I'm dividing the subject into two parts I need you people to advise me...

Hello Boys., After a very long time..! Well, coming to my stuff, I'm dividing the subject into two parts I need you people to advise me on the later one. Part-1 [Lossy Technique] ________________ Yeah, I've got my own 'stuff' for Lossy compression techniques. that's it, done. Part-2 [Koding Part] ___________________ As I'm not a Programmer, Two o...

## Data compression that works down to DC

inSo I'm working on a product that logs a bunch of data to flash. Due to physical space constraints (the board is something like 35 x 45mm), I...

So I'm working on a product that logs a bunch of data to flash. Due to physical space constraints (the board is something like 35 x 45mm), I only have 2MB at my disposal, and if I were to log EVERYTHING that's available in uncompressed form, I'd be challenging the amount of space available. The data is mostly captured analog data, and it's often in the form of small-magnitude numbers...

## HELP! DCT is not good enough. How to design my own transform basis matrix for image compression?

inDear all, I want to design a my own transform basis matrix. For 2D case, forward transform is: Y=A*X*B, inverse transform is:...

Dear all, I want to design a my own transform basis matrix. For 2D case, forward transform is: Y=A*X*B, inverse transform is: Z=C*Y*D... let's say X, Y, Z, A, B, C, D are 8x8 matrices... Can anybody tell me what relationship should A, B, C, D have? 1)Orthognality? 2)A=B'? 3)C=D'? 4)A=B^(-1)? 5)C=D^(-1)? 6)B=C? 7)A=D? ... Thank you very much if you can also point me to some r...

## Recovering data (TMS320DM642)

inHi, Soon i will implement a video compression algorithm on DM642. I'd like to recover the compressed data, which will be stored in SDRAM,...

Hi, Soon i will implement a video compression algorithm on DM642. I'd like to recover the compressed data, which will be stored in SDRAM, in order to be able to replay the video on the PC. Can you tell me if Code Composer allows us to recover data stored in external memory and to save them in a file on the PC ? Does RTDX allow to do that ? Could you point me to some example codes ? ...

## algorithms for star field compression

inDear all, I am working on the software of a Star Tracker device which should be capable to compress the images for transmission [1]. The CCD...

Dear all, I am working on the software of a Star Tracker device which should be capable to compress the images for transmission [1]. The CCD is 512x512 and each pixel is digitized with a 12bit ADC and the image frequency is ~10Hz. Since the bandwidth available is rather limited (~1.5 Kb/s) I need to compress the image to a level of few bytes per image to be able to cope with the input...

## Perceived Loudness

inHi Folks, Does anyone know of any good algorithms, papers, web sites, etc., that discuss ways to determine the perceived loudness of an audio...

Hi Folks, Does anyone know of any good algorithms, papers, web sites, etc., that discuss ways to determine the perceived loudness of an audio source? You know, like detecting those nasty over-compressed commercials that sound so loud versus the normal program material? I'm aware of the basic issues such as peak-to-average power ratio (i.e., the effect of compression) and dynamic range di...

## Wavelets for circular data?

Is anyone aware of doing wavelet based compression of arrays of angular data (or phase data)? Instead of normal grau=yscale images, you have...

Is anyone aware of doing wavelet based compression of arrays of angular data (or phase data)? Instead of normal grau=yscale images, you have values from 0-360 degree (which you can quantize between 0-255), but if you have two neighboring pixzels with values of 255 an d0, dont treat it like a discontinuity.. hence this is tricky! Also, would the SAR imagery community (or any other commu...

## Why not set unnecessary frequency components to zero in freq domain?

inThe answer to this one may be obvious, I dont know, but I still couldnt figure it out, so I had to post. To remove an interfering frequency...

The answer to this one may be obvious, I dont know, but I still couldnt figure it out, so I had to post. To remove an interfering frequency from a noisy signal, why don't we simply take the FFT and set the interfering frequency value to zero (in the amplitude spectrum), and then take IFFT again? Something similar seems to be done in JPEG (DCT) compression, where the higher frequencies are simpl...

## hearing aid type algorithms (WDRC, noise reduction, ...)

inHello, does anyone know where I could get speech enhancement algorithms written in C (typically for hearing aids, but I need that to integrate...

Hello, does anyone know where I could get speech enhancement algorithms written in C (typically for hearing aids, but I need that to integrate to a telephony server for my diploma project)? I'm looking for noise reduction algorithms and also for dynamic range compression algorithms... Thank you for reading! M. Meylan

## code compoder studio 3.1 version for TMS320c55x DSK board

inHI , i am satish doing my MS. I need c programming code for audio signal compression. The code should be compatible to run...

HI , i am satish doing my MS. I need c programming code for audio signal compression. The code should be compatible to run on TMS320c55x platform. The software used for this is "code composer studio". Can any help me out fr getting the code for the above topic. Regards satish

## DCT/IDCT implementation in software/hardware

inHi, I came across the following in the book "H.264 and MPEG 4 Video Compression" by Iain E.G. Richardson: "Flowgraph" algorithms are very...

Hi, I came across the following in the book "H.264 and MPEG 4 Video Compression" by Iain E.G. Richardson: "Flowgraph" algorithms are very popular for software CODECS where (in most cases) the best performance is achieved by minimizing the number of computationally expensive multiply operations. For a hardware implementation, "regular data flow" may be more important than the number of o...

## Phase Vocoder

For a school's project, I am programming a standard phase vocoder for time compression/expansion of digital audio. The audiodata is broken up in...

For a school's project, I am programming a standard phase vocoder for time compression/expansion of digital audio. The audiodata is broken up in frames, each frame is multiplied by a window function (in my case a Hann-window) and the result is transformed into frequency-domain by FFT. Now because the frames overlap each other, I was wondering if it's possible to optimize this computatio...

## G.729 with different sampling rates?

inI'm trying to understand G.729. The only compression algorithm I've coded before is ADPCM, and it wasn't keyed to a certain sampling rate - that...

I'm trying to understand G.729. The only compression algorithm I've coded before is ADPCM, and it wasn't keyed to a certain sampling rate - that is, it would be just as happy with 8100 samples per second or 7900 samples per second as it would have been with 8000, just the quality would be slightly higher or lower. With G.729, all the documentation refers to a sampling rate of 8 KHz. Is it ...

## How do I compress an array of floating numbers in Matlab?

inHi all, I have a vector of real numbers in Matlab. How do I compress them? Of course this has to be lossless, since I need to be able to...

Hi all, I have a vector of real numbers in Matlab. How do I compress them? Of course this has to be lossless, since I need to be able to recover them. The goal is to study the Shannon rate and entropy of these real numbers, so I decide to compress them and see how much compression ratio I can have. I don't need to write the result into compressed files, so those headers, etc. are ju...

## Phonemes and FFT (or any other transform good for sound)

inI am interested in this topic any good links with intro and/or in depth incursion to the topic or truly good books? (I am a Mathematician, so I...

I am interested in this topic any good links with intro and/or in depth incursion to the topic or truly good books? (I am a Mathematician, so I don't need any of the basic Math part) ~ A good intro into lossless sound compression of sound I will need as well ~ Thanks lbrtchx

## Wavelets and Reflection image question

Hi all, I've recently begun trying to understand the fundamentals of lossy image compression via transforms such as DCT and...

Hi all, I've recently begun trying to understand the fundamentals of lossy image compression via transforms such as DCT and Wavelets (CDF9/7). In a paper I was reading it suggested that prior to applying a forward transform that a "reflection image" of the original image be created. This involves flipping the image vertically and horizontally and copy those flipped variants above, be...

## Image Compression Using Fourier Transforms

inI was wondering if there was a relatively straightforward algorithm for compressing image using Fourier transforms. I was thinking that I could...

I was wondering if there was a relatively straightforward algorithm for compressing image using Fourier transforms. I was thinking that I could transform an image into frequency space and then perform a lowpass filter on the image to set all the lesser frequencies to zero, then perform a run-length-encoding on the data to pack the zeroes. However, I have been running into trouble with this me...

## Image Processing Algo on Processor

inHi All, I am working on image compression algo,which needs to be finally processor based.i need some suggestion regarding the time taken...

Hi All, I am working on image compression algo,which needs to be finally processor based.i need some suggestion regarding the time taken to code,test the an image processsing algo in a standard DSP processor such as TI's or in Xilinx FPGA.which one would be better???in terms of time taken and performance..??? cheers MIA

## Detecting a shifted peak from two signals

inI'm doing robotics and built a sonar system to detect walls using pulse-compression - this seems to work fine so far. As I'm only interested in...

I'm doing robotics and built a sonar system to detect walls using pulse-compression - this seems to work fine so far. As I'm only interested in the echoes from the front wall, I need to filter out unwanted side echoes (e.g. from floor, ceiling). My approach would be to send out a chirp, and get the echo profile then let the robot move forward and send a second chirp to do a second profile - the...

## signal detection in doppler

inHello People I have been scratching my head on this doppler problem: Because of the doppler effect, the received signal will either be...

Hello People I have been scratching my head on this doppler problem: Because of the doppler effect, the received signal will either be expanded or compressed on time axis. Now, the expansion or compression is sampling rate conversion. So, I tried to use 'resample' function of matlab. The actual length of the signal is 30720 and sampling freq is 48000Hz. Now, when I use y=resample(x,100...