similar to: Inverse MDCT formula missing from Specification

void inverse_mdct_slow(float *buffer, int n) { =A0=A0 int i,j; =A0=A0 int n2 =3D n >> 1; =A0=A0 float *x =3D (float *) malloc(sizeof(*x) * n2); =A0=A0 memcpy(x, buffer, sizeof(*x) * n2); =A0=A0 for (i=3D0; i < n; ++i) { =A0=A0=A0=A0=A0 float acc =3D 0; =A0=A0=A0=A0=A0 for (j=3D0; j < n2; ++j) =A0=A0=A0=A0=A0=A0=A0=A0 // formula from paper: =A0=A0=A0=A0=A0=A0=A0=A0 //acc +=3D n/4.0f *

hello, i'm reading the doc at http://xiph.org/ogg/vorbis/doc/Vorbis_I_spec.html and the link to the paper http://www.iocon.com/resource/docs/ps/eusipco_corrected.ps doesn't work. Could anyone correct the link and/or mirror this paper ? Thanks, YG --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list,

Hi, In the course of some work which I describe below, I have found a very significant difference between the BARK function described in the Vorbis specification and its implementation in libvorbis. In the specificationhttp://xiph.org/vorbis/doc/Vorbis_I_spec.pdf bark(x) = 13.1arctan(.00074x) + 2.24arctan(.0000000185x**2 + .0001x) In the libvorbis code

Hi Vorbis-Dev, I'm investigating various WebM/Vorbis bugs in chromium. AFAIK muxing Vorbis inside of WebM does not have an official specification, so I'm using ffmpeg's implementation to try to answer 2 questions: 1. Under what circumstances is it valid to find WebM Blocks containing Vorbis data with zero duration? (This would mean the next Block in the Cluster has the exact

Hey all, friendly ping :) Any help is much appreciated. On Thu, Jun 18, 2015 at 6:56 PM, Chris Cunningham <chcunningham at chromium.org > wrote: > Hi Vorbis-Dev, > > I'm investigating various WebM/Vorbis bugs in chromium. AFAIK muxing > Vorbis inside of WebM does not have an official specification, so I'm using > ffmpeg's implementation to try to answer 2

Hi All, Can any one link me or send me a complete detailed spec of Vorbis encoder? I found the Vorbis_I_spec.pdf but it does not provide much information about encoding procedure. Ravi -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.xiph.org/pipermail/vorbis/attachments/20050829/cf209e5a/attachment.html

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 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

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

Dear all In the paper section describes how CELT and SILK had implemented a look/up head delay of (2.5ms), (5ms) respectively , could you explain me> 1) those values are fixed. 1) how you guarantee those values independent of the architecture's performance. Thanks so much On Tue, Apr 18, 2017 at 10:05 AM, Diego Alejandro Parra Guzman < daparrag at correo.udistrital.edu.co>

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:

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

http://en.wikipedia.org/wiki/Modified_discrete_cosine_transform is an OK place to start. On Mon, Jul 8, 2013 at 7:33 AM, Mahantesh Belakhindi <girishec28 at gmail.com>wrote: > 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

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

In vorbis/lib/mdct.h the following are defined: for integer: #define TRIGBITS 14 #define cPI3_8 6270 #define cPI2_8 11585 #define cPI1_8 15137 #define FLOAT_CONV(x) ((int)((x)*(1<<TRIGBITS)+.5)) for floats: #define cPI3_8 .38268343236508977175F #define cPI2_8 .70710678118654752441F #define cPI1_8 .92387953251128675613F #define FLOAT_CONV(x) = x Could someone explain where these values

Here's an updated version of the MDCT callback patch. -------------- next part --------------

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

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

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] =