similar to: More mdct questions

Hi, Can someone tell me which MDCT and invMDCT equation uses? I implemented the invMDCT one given in eusipco.corrected.ps file (handed out by Monty way back) and it produces different time domain samples. I tried both the FFT method and the slow way directly from the equation and couldn't reproduce the results from the original code. This leads me to believe that the forward MDCT used in

...as promised. This describes the mdct used in my d.m.l patch. I think it is the same as the Lee fast-dct. I typed it in a kind of pseudo-TeX, 'cause the ascii art would kill me. Hope you can read TeX source; if not, ask someone who can to make a .ps/.gif/.whatever of the TeX output, and put it on a webpage or something. I'm to lazy to do it (and besides, I don't have access to TeX,

Hi, I'm trying to determine how the frequency data that is passed to the MDCT, and output time domain data obtained from the MDCT, is changed when setting #define MDCT_INTEGERIZED For instance, the trig array, for a size 256 window begins 1.000000 0.000000 0.998795 -0.049068 0.995185 -0.098017 if INTEGERIZED is set, then it begins 16384 0 16364 -803 16305 -1605 which is simply a left shift

Hi vorbis-dev, I'm investigating the mdct* function in libvorbis and writing a small client program to test it. I found that I have to set ARRAYSIZE when mdct_init(lookup, ARRAYSIZE) to minimum value of 62 otherwise it will segfault with mdct_backward. Is there any lower limit or it is more likely that my code has bug? Thank you very much, Pattara -- Please avoid sending me Word or

Hi vorbis-dev! I'm working with Pattara in the oggonachip project, and wondering about the implementation of mdct.c as hardware. According your recomendations about using the floating point version, I would say, we have to implement the integerized version of mdct as a core, and use the fpu only to round the input values. By doing that, you think the result would be still acceptable? How

Hello, I was wondering if someone knows the formula used by the function lm to compute the t-values. I am trying to implement a linear regression myself. Assuming that I have K variables, and N observations, the formula I am using is: For the k-th variable, t-value= b_k/sigma_k With b_k is the coefficient for the k-th variable, and sigma_k =(t(x) x )^(-1) _kk is its standard deviation.

Hi all, I'm attempting to convert all the pointers to arrays the mdct_backward function so it can be partitioned off for a hardware implementation. Although this code is quite short I'm finding it a little tricky. As it stands, mdct_backward is passed values by reference i.e. void mdct_backward(mdct_lookup *init, DATA_TYPE *in, DATA_TYPE *out) o my modified version starts void

Dear all I'm working on the implementation of the MDCT for the processor ARM-Cortex-M4 I'm trying to replicate the behavior of the MDCT for several overlapped values however I realized that current implementation of the MDCT is very close to the theory only in case in which we have and overlap exactly equal to N/2 where N is the size of the input vector as is shown in the examples for

In mdct.c there's some functions including some-point butterfly. In 32-point and 16-point there are calling of smaller-point function everytime twice on each half of data. When I looked on it I found that's just linear algebra. So it can be rewritten to matrix multiplication. Some one can say: there's optimization on in register working. But imagine there's one calling 32-point,

Dear Experts, Can anybody please direct me to proper MDCT theory reference which will help me understand the code better? I'm trying to optimize MDCT for a embedded platform. So need good understanding about theory behind & implementation. Thanks in advance for your time. Warm Regards, Mahantesh -------------- next part -------------- An HTML attachment was scrubbed... URL:

Hi, I have a doubt regarding MDCT window size for OggVorbis decoder. Can the MDCT window size vary from 64 samples to 8192 samples? Specification says that "legal frame sizes are powers of two from 64 to 8192 samples" . Is this same as MDCT window size? Please help me out.. Regards, shikha <p>--- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage:

Dear all, I've only just joined this list, but I can't find any mention of this idea anywhere else, so I thought I'd just post here before getting too deep into programming and possibly reinventing the wheel. Here at Aber, we have around 30 unix and linux servers doing core services. Each one is maintaining its own logfiles and, for various reasons, we want to keep these on the

Hi, as we are trying to implement MDCT in hardware, we are caring now about the "n" (size of input and output vectors to and from MDCT). As I have looked in the code, this "n" is chosen from the Ogg/Vorbis stream data in info.c:_vorbis_unpack_info() which means this "n" can vary aribitrarily (as the power of 2) depending only on the value got from song data? or is

I did composition of butterfly8 and butterfly16 and I found, that these functions are well decomposed - decomposition doesn't lower computional speed. On the other hand the same can be done with butterfly8 - decomposition to butterfly4 (further decomposition is not possible) but there's no reason to do this. I think little improvement can be done by inlining them. Compiler and processor

Is there a weighted median function out there similar to weighted.mean() but for medians? If not, I'll try implement or port it myself. The need for a weighted median came from the following optimization problem: x* = arg_x min (a|x| + sum_{k=1}^n |x - b_k|) where a : is a *positive* real scalar x : is a real scalar n : is an integer b_k: are negative and positive scalars

mdct.c, lines 436 onward (part of mdct_backward) state { DATA_TYPE *oX1=out+n2+n4; DATA_TYPE *oX2=out+n2+n4; DATA_TYPE *iX =out; T =init->trig+n2; do{ oX1-=4; oX1[3] = MULT_NORM (iX[0] * T[1] - iX[1] * T[0]); oX2[0] = -MULT_NORM (iX[0] * T[0] + iX[1] * T[1]); oX1[2] = MULT_NORM (iX[2] * T[3] - iX[3] * T[2]); oX2[1] =

I should'nt have sent the last mail so fast. Same problem with \eqn{u_j = a_j + b x + c x^2, \quad j=1, \ldots, r-1} {u[j] = a[j] + b*x + c*x^2 j = 1,\dots,r-1} I thought the problem in the first case could have to do with the use use of \mbox{} (with the braces) within the arguments of \eqn, but here there are none braces in the arguments of \eqn{}{}. Another case giving the

Hi, I am getting some weird results here and I think I am missing something. I am trying to program a function that for a set of random variables drawn from uniform distributions plots that distribution of the second order statistic of the ordered variables. (ie I have n uniform distributions on [0, w_i] for w_i different w_j and i=1..n. I want to plot the distribution of the second order

Hi, Apologies if this is a known issue, but running make on revision e3187444692195957eb66989622c7b1ad8448b06 fails one of the tests when using fixed point configuration (floating point is ok) on my linux x86. Note that libopus1.1, as extracted from the tar ball, is OK. Specifically, the tests that fail are in celt/tests/test_unit_mdct: nfft=32 inverse=0,snr = 85.341197 nfft=32 inverse=1,snr =

The Vorbis audio format, uses something called the Modified Discrete Cosine Transform (MDCT). I was interested in how this worked, but did not know where to start. Is this the name of a particular algorithm, or does it just mean something like a cosine transform, but not quite right? So I asked the Vorbis mailing list. Nobody answered. It was not a high priority, so I did other things for