similar to: Steganographic extension to Speex

Hello, Jean-Marc Valin schrieb: >>I am planning on creating a steganographic extension for speex/CELP. >>Since speex/CELP is lossy, there should be quite many bits that one >>can use for hiding data. > > Quite the opposite. Speex uses very few bits, so every bit you corrupt > is likely to be heard. You would need to use "fractions of bits" at a > time.

> I am planning on creating a steganographic extension for speex/CELP. > Since speex/CELP is lossy, there should be quite many bits that one > can use for hiding data. Quite the opposite. Speex uses very few bits, so every bit you corrupt is likely to be heard. You would need to use "fractions of bits" at a time. Even then, it may be hard to hide data efficiently (so it's

Hi, Jean-Marc Valin wrote: > Well, you could change the order in the encoder as long as you reverse > it in the decoder as well. Ok, I see that in the split_cb_shape_sign_unquant function, that each coefficient is tied to it's position in the nb_subvect exc coefficients. Honestly, I have problems understanding what exactly the codebook search works like. If you have the time to to

Hello, playing a little around with speexenc/speexdec, I discovered that if I pass the "-n" or "-w" command line option to speexenc (version 1.1.10), I get a segmentation fault. Looking closely at the code, I found that the line: fprintf (stderr, "Warning: Trying to encode in %s at %d Hz. I'll do it but I suggest you try ultra-wideband instead\n",

Hello, Matthieu Poullet schrieb: > static float cheb_poly_eva(spx_word32_t *coef, float x, int m, char *stack) > { > int k; > float b0, b1, tmp; > int m2=m>>1; > > /* Initial conditions */ > b0=0; /* b_(m+1) */ > b1=0; /* b_(m+2) */ > > x*=2; > > /* Calculate the b_(k) */ > for(k=m2;k>0;k--) > { > tmp=b0;

Hello Jean-Marc and all, I recently had a talk with somebody about CELP. He said, there is this federal standard 1016 (4.8kbps) with a reference implementation of the Department of Defense (only on Sun, unfortunately, if I got this right). This one is noticed in the manual already. He also said, since there is this implementation of the DoD, nobody would voluntarily re-implement CELP. If I read

Hi, After reading the paper entitled "The Computation of Line Spectral Frequencies Using Chebyshev Polynomials", P. Kabal and R. Ramachandran, IEEE Trans. on ASSP, Vol. 34, No. 6, December 1986, I rewrite the function cheb_poly_eva in lsp.c using the Clenshaw's recurrence formula, as described, for example, in Numerical Recipes in C, Second Edition (5.5 and 5.8) : static float

Hi, I have some questions regarding Speex. please reply as soon as possible. where are the two filter loops applied to the raw signal? where is the residue (innovation) signal calculated? where is the innovation mapped on a codebook entry (key)? which bits of a transmitted frame are the two filters, which are codebook keys? Is the codebook from the beginning on static (so already known by

Hi, Jean-Marc Valin wrote: >> 1. What is the point in multiplying a codebook index with some number >> ant adding a loop variable to it as done in the exc unquant function. >> for (j=0;j<subvect_size;j++) >> exc[subvect_size*i+j]+=s*0.03125*shape_cb[ind[i]*subvect_size+j]; > > That's just how you represent a 2D array in C: the codebook has

Hello, Is it possible to adjust the level of the denoiser ? In an old beta, before you change the aggressiveness of the denoiser, it works very well with the noise of a car, a road etc... but not now. The AEC too works very well in a old beta, but now, I think there is a problem... I have tested it with the same sound card (WB 16000). In any case, your project is the best VOIP library in this

Hi everyone, I have got some questions about Speex, I am sorry if my questions are too newbie: 1. For the LP analysis, did Speex use the AR (Autoregressive) model or the ARMA model? 2. Am I right to say that Speex use a multistage VQ (since I believe Speex employs two or more VQ consecutively - based on the manual it says that Speex uses dynamically selectable codebooks (linear

Hello Jean-Marc, Hello speex-dev-people, Jean-Marc Valin wrote: > All I can suggest is having a look at my simple client at: > http://people.xiph.org/~jm/speexclient/ Unfortunately, this does not compile: <<<<< snip >>>>> bjoern@phobos:~/beleg/speex/speexclient-0.0-dev$ ./configure checking for a BSD-compatible install... /usr/bin/install -c checking whether

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Hi, I have one doubt again, that is Vorbis use DCT/MDCT based algorithm and also use psychoacoustic model so this is lossy codec. And I dont think it ca regenerate a better matching waveform than speex. Then there comes FLAC which is the perfect answer to my question, I suppose. But my concern is this that FLAC use simple prediction algorithm and doesnt use any CELP based algo which could have

Hi, I chose speex initially because i had some work in VQ on speex i.e. modifying split VQ to GMM based parametric VQ and I thought If I train the GMM based VQ codebooks with audio signal and then do audio coding with speex, I probably get a better(smaller) residual signal even with speex. But I couldnt get that. I was trying to get a lossless bitstream by MUXing the speex-bitstream and the

Hi all: How to use jitter.c, I see this file is not include in the lib. Sorry for this newbie Q.

Hi, We would like to announce the first release of the Speex project. Speex (http://speex.sourceforge.net) is an open-source (LGPL), patent-free compression format allowing an alternative to expensive proprietary codecs. Unlike Ogg Vorbis which compresses general audio, Speex is designed especially for speech. For that reason, Speex is meant to be a complement to Vorbis. Since it is specialized

hi, thanks for answers to my previous qns. have some more of them. hope it's ok to ask questions on the basics of CELP here. let me know if it's not. 1) synthesized filter stability after interpolation of LSFs I read from some resources that if LSF representation of LPCs is used for interpolation, stability of the synthesis filter is guaranteed. from another source, i read that the

Hello I'm working about audio and video codecs. I'm making a research about the state-of-the-art in coding technologies. My question is about the speex codec 1.0. I would like to know the name of the algorithms that it uses.(LPC,CELP..). It uses more or less the same algorithm for narrowband and wideband? Finally i would like to ask about future codec developement projects. Thanks

Hi, Jean-Marc Valin wrote: > Not sure I understand your question. Change the order of what within what? In cb_search, we iterate nb_subvect times over a codebook, finding nb_subvect codebook entries to quantize the excitation signal. After finding these nb_subvect codebook entries, they're written into the stream: /*save indices*/ for (i=0;i<nb_subvect;i++) {