Displaying 20 results from an estimated 3000 matches similar to: "encoder block diagram"
2003 Mar 14
0
encoder block diagram
I've made block diagram of the encoder because I tried to find out, how it works
http://stoffke.freeshell.65535.net/ogg/block.html
Although there are specifiation docs, that give very
detailed information about single aspects of the encoding (or decoding) ,
I'm missing documenations that give a more general overview,
about how the encoder works.
(Vorbis Illuminated seems a bit outdated,
2002 Nov 26
1
floor curve question (whitening filter)
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Hi there,</P>
one step in the encoding process (if I got it right), would becomputing a "floor
2002 Oct 22
3
Spectral phase information in residue vectors
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
2004 Mar 03
1
Matlab implementation
Hello!
I´m just interested if there exists a matlab implementation of the
vorbis encoder / decoder or at least of some parts of it (psychoacoustic model,
MDCT, VQ), would need it for my diploma thesis.
Thanks
Stefan Bayer
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2002 Jul 09
1
Vorbis Block Diagram
Hi,
I have looked through the documentation available from the downloads and the
web and haven't yet come across a block diagram which shows exactly how the
process of going from a .wav file to a .ogg file works. I suspect it is the
same as the mp3 process (with a different psychoacoustic model). I found
this document:
2005 Sep 27
2
***SPAM*** encoder flow chart
Hi
Any help is appreciate!
These days I studied ogg vorbis encoder with sample rate 44.1kbsp,and I thought the whole chart was as follows:
1. read the PCM data and store them in a buffer
2. do MDCT on those PCM data
3. do FFT on those PCM data
4. use both the FFT and MDCT coefficient to the psychoacustic modle and derive an maximum allowable noise curve,
and during this curse ,do the
2003 Jan 24
8
just an idea about quality evaluation
Hello
I had an idea about judging the quality of ogg vorbis
(or any other lossy codec)
I took a wave-file and encoded it to ogg.
Then decoded ogg to wav and inverted it's phase. When mixing the original
wav with the phase-inverted decoded ogg-file, any identic parts of compressed and uncompressed audio should be eliminated.
Of course there's always a "rest" of sound because
2006 Mar 27
2
Speex for sampling freq >48KHz
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
2006 Apr 20
1
Ogg Vorbis questions
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
2001 Sep 05
2
Understanding of Vorbis coder
Hi
I have gone through the document available in the net regarding the
Vorbis encoder /Decoder.
Based on that i have prepared a understanding document on the
encoder/decoder block. I would like to
know whether my understanding of the coder is OK. If there are any
other additional block /information pl. provide me
with the same.
Thanks and regards
S.Padmashri
<HR NOSHADE>
<UL>
1995 Nov 14
1
Vorbis Codebooks
Hello,
Vorbis uses codebooks, for example to do vectorquantization and huffman-encoding.
My question is - are all these codebook dynamicly generated ("trained")
or are there also static codebooks used ?
If yes, what specific tasks are these 2 types used for, during encoding ?
Thanks
Stoffke
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Ogg project
2006 Mar 27
1
Speex for sampling freq >48KHz
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
1999 Aug 15
1
Vorbis transform description
OK, into the nitty-gritty, albeit a high-level version. If it sounds
like I'm glossing important details, you're right. This discusses
only the basic DSP; precise coding, framing, sync, etc, will be in
another mail.
Vorbis is a hybrid transform domain general purpose audio encoder,
like MPEG in some respects (it is rooted in much of the same basic
theory). For the most part, the
2005 Feb 20
1
Well decomposed mdct
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
2004 Jun 02
4
Transient coding: AAC vs. Vorbis
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>>
1999 Nov 19
2
Impulses
After playing with the vorbis code for a while and doing tons of hacks and
analysis on it, I've found it to perform very poorly with impulse signals.
The MDCT seems to cause lots of spreading, and it seems to result in much
worse impulse performance then mp3.
What is the current plan on handling this? Will a smart quantizer be able
to avoid it?
I've been looking at various ways of
2002 Jul 08
1
Vorbis Block Diagram
Hi,
I have looked through the documentation available from the downloads and the
web and haven't yet come across a block diagram which shows exactly how the
process of going from a .wav file to a .ogg file works. I suspect it is the
same as the mp3 process (with a different psychoacoustic model). I found
this document:
2005 Sep 29
2
stereo couple
Dear All:
I studied the stereo couple documents and now confused, I wonder
why it can be done like that, and what is the principle behind that.
I think i am confused perhaps because i have no background knowledge,
can you help me out?
Also, when doing the T/F transform,we used MDCT, so it means no imaginary part.
And i am much puzzled about the angle in the stereo couple,what does it mean?
2003 Sep 10
1
A new introduction attempt.
I have been using libvorbis for the past few weeks and have been asked to
summarise what I have discovered about the codec. There is an early draft
of the document at
http://www.geocities.com/gatewaystation/vorbis/vorbis.htm - Please forgive
the dodgy formatting (it was formerly a MS word document that got converted
with their 'save as html' feature). I still have some additions to
2005 Sep 23
1
***SPAM*** help
vorbisHi
Sorry if it is too stupid to ask the following questions.
I am just confused by the pychoacoustics model. I think the computation in the psy.c is to
derive a curve which stands for the threshold for the mdct coefficient. Is it right ?
If it is right , then what can we do with the curve ? I refered to several articles and find the aim of
most pychoacoustics model was to derive the SMR