search for: imdct

Hi On http://www.xiph.org/ogg/vorbis/doc/vorbis-spec-intro.html there is a link to a document titled 'The use of multirate filter banks for coding of high quality digital audio' that explains window functions for iMDCT. I would very much like to read that document, but the link is broken. If someone would send me the document or a working link to it, I would be very happy. Thanks in advance Morten J --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To...

...ridmp is called . In that function some mathematical computation is done and noise is calculate . ( noise[i] = R - offset ) Can anyone explain me what is the funda behind it . <p>2. NOw about overlap and add . I know very well how overlap add solves the aliasing problem afer IMDCT . I have checked it matematically . Now here , when there is overlapping of unequal size window , ie short - long - short . the window shape is modified . I am clear with that ...But I am not getting the original data after IMDCT and overlap add . Can anyone explain me this .....

I wrote to the list earlier about optimizations of the tremor. Specially replacing the IMDCT with a N/4 FFT. The report is available here: http://www.sandvall.nu/thesis.pdf Short summary: Optimization of the Tremor code under 50kB for a "split" decoder version. ~44 MIPS. Huffman highly unoptimized. IMDCT ~ 8 MIPS. Quick overview of the Ogg/Vorbis format and a psycho acoustic in...

...f performance out of my Vorbis player for Flash. I did several improvements to the Huffman decoder by eliminating function calls and managed after a while to create an AS/haXe hybrid player. The haXe compiler definately produces much more efficient bytecode (at least in some situations) and the iMDCT function is 2.5-3 faster compiled with haXe, compared to the code generated by the Adobe compiler. If someone knows how to generate an SWC library from the haXe code, I would appreciate some help a lot. At the moment, the haXe code is dynamically linked into the AS application at runtime. Over...

...I need this. I'm working on ogg vorbis decoder optimised for SUN SPARC machines. SUN provides library (medialib, mlib) of multimedia functions, which are written in VIS assembly, so they are fast. I want to optimise bacward MDCT, and use medialib function for it. But here is a problem: medialib IMDCT has hard-coded buffer size = 256. It is not possible to use it for larger buffers (I think - I tried to use it twice on two halfes of 512 buffer on many ways). And the second problem is my project deadline is comming soon, so I want to make decoder that works only on files with windows size = 256 :...

Hi, I'm currently working on a paper describing Ogg Vorbis. It is not finished yet. Mostly the decoder is being described. If you have any comments, please send them to me. See: http://www.turbocat.net/~hselasky/math/vorbis/files/ Then I have a question about the function "bark_noise_hybridmp()" which is used in the encoder. Can someone describe what the function does in

Hi All, Currently I am investigating how interesting OGG is for me. The most important requirements are: - Decoding on embedded hardware, ARM7 or ARM9. - Mixing multiple audio streams/files on embedded hardware First of all how difficult is it to decode OGG on an ARM7/9 processor? I read that OGG decoding needs floating point support? Secondly I would like to know how many MIPS are needed to

Hi !! <p> I am just now reading Vorbis I specifications . I ahve some quries in that regading overlap add and sqaure polar mapping . I am writting this mail with the hope that ,some one will resolve my quries. <p> 1. After IMDCT , to remove the aliasing , we do overlap and add . For that the window should have following properties -------------> hk = h2n-1-k and (hk* hk) + (hk+n * hk+n) = 1 . when 2n is the input block size for MDCT in encoder . THis is very imp requirement of overlap add...

Hi I've got serious problem with my Vorbis-Decoder. The error seems to happen in the inverse Mdct. Before the imdct the values seems to be correct (compared with those of jOrbis (www.jcraft.com/jorbis/)). But after the transformation the values shows a strange behaviour. In [0, blocksize/2] the values are correct, but in [blocksize/2, blocksize] the values are wrong. The difference in this interval between...

Hello all, I have recently ported Vorbis to a Texas instruments DSP (TMS320C5510), The problem I have is that it is not decoding the audio in real time( about 50% of real time). Could any one give me a clue in which area I could start to optimize the code. Regards Kevin <p><p><p>--- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage:

...S compiler. I haven't bothered verifying this, but I've profiled my code and there is no "hotspot" where I'm doing something obviously wrong. Time divides between the components in almost the same manner as with my Java decoder, e.g. roughly 40% of the time is spent in the iMDCT code, 35-40% decoding floors and residues and most of the remainer is probably the Huffman code. New attempt (requiring Flash 10 beta player): http://flash.j-ogg.de/10/ Old player: http://flash-j-ogg.de/ Can someone verify that the new player actually causes slightly more CPU load than the...

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1"> </head> <body bgcolor="#ffffff" text="#000000"> Hi,<br> <br> I have been looking into optimising the CELT decoder for speed to make it acceptable for

Hi. When can we expect the next beta version of Vorbis encoder (with some tagging & encoding options I hope)? Also, today I tested MPEG+ encoder which you can download from http://www.stud.uni-hannover.de/user/73884/mppenc.zip (win encoder) http://www.stud.uni-hannover.de/user/73884/in_mpp.zip (winamp plug-in) http://www.stud.uni-hannover.de/user/73884/mppdec.zip (win decoder) It sounds

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