similar to: mdct query

Sorry for starting another topic, this is actually a reply to Segher's post on Sun Oct 22 on the 'mdct question' topic. I wasn't subscribed properly and so I didn't get email confirmation and thus can't add to that thread. So Segher, if the equation is indeed what you say it is, then replacing mdct_backward with this version should work, but it doesn't. Am I applying

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

Hi all, The decoder is down 30% execution time, identical bit output. Didn't get the mdct yet; 1024 point mdct is a bit much to brute-force, and I'm not going to hand-unroll the whole thing either (the machine- unrolled version produced a 1.5M executable; understandably, it wasn't very fast. Still waiting for processors with 1.5M L1 code caches ;-) Slowest parts now are: -- mdct --

Thread-split from the vorbis-mailing list ("Vorbis determined to be as good as MPC at 128 kbps!") <p>On Sun, 30 May 2004, Segher Boessenkool wrote: [Steven So] SS>> If iTunes AAC can encode castanets with much less pre-echo at SS>> ABR 128 kbps, then hopefully there will be an imaginative SS>> (and non-patented) way of doing this in Vorbis without the SS>>

I saw some mail go by a bit ago about doubles-vs-floats, but I seem to have lost it. I'm interested in rewriting the mdct code using Altivec on MacOS X. Altivec doesn't support doubles, though -- the only floating point vector type is single precision floats. Vorbis currently has doubles everywhere -- is this really necessary? Doubles are supposedly faster than floats in the PPC

Some thoughts for the new year: 1) MDCT is good for image coding 2) image coding and audio coding are two very different things 3) combine 1 and 2 4) if a psycho model is good, after leaving out what it tells you you can without hurting quality, applying the same model should yield the same results as you got before 5) from 4: decode -> encode -> decode should result in (almost) the

Hey guys, I want to send an email via ROR and I have put this code at the very end in the config/environment.rb file- ActionMailer::Base.delivery_method = :smtp ActionMailer::Base.perform_deliveries = true ActionMailer::Base.logger = nil ActionMailer::Base.raise_delivery_errors = true ActionMailer::Base.smtp_settings = { :address => "[my smtp server]", :port => 25, :domain

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

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:

VorbisHi Any help is appreciate. I have two questions. First, I looked into the vorbis-?-specific and was confused by the floor1 algorithm. I think at last the aim is to derive the piecewise curve with the list X and Y,then when encodering ,why not use the selected point orderly to get the curve ? In other words, the specific use the list of [0,128,64,32,96,16,48,80] , why can not use

I found this sentence in the Ogg format specs: http://www.xiph.org/ogg/vorbis/doc/vorbis-spec-res.html "A residue vector may represent spectral lines, spectral magnitude, spectral phase or hybrids as mixed by channel coupling." But where does the spectral phase information come from ? AFAIK MDCT doesn't provide any phase information. And in OGG-encoding, MDCT is taking place a few

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

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,

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

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

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

...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,

Hello people, Looks like Santa Claus thinks I've been a good boy this year. Here's the third in my performance patch series: d.m.l Apply after applying d.o.n and d.n.m; I don't know how much of those got applied to the CVS tree. What's inside: Request for help! Look in os.h if you're using a compiler or processor I don't use (I use gcc on K5, K7, G3). New MDCT! Now we

Hello Vorbis folks, I'm one of the FFTW authors (www.fftw.org), and a few days ago I was playing with our codelet generator for fun and modified it to spit out hard-coded MDCTs of small sizes. The code (at jdj.mit.edu/~stevenj/mdct_128nr.c) for 256 samples (128 outputs) seems to be almost twice as fast as the Vorbis MDCT code for that size on my 2.2GHz P-IV (gcc 3.2.2 and flags "-O1