Displaying 20 results from an estimated 3000 matches similar to: "Fixed Quantizer - Fixed Quality"
2007 Feb 20
0
Standardized residual variances in SEM
Hello,
I'm using the "sem" package to do a confirmatory factor analysis on data
collected with a questionnaire. In the model, there is a unique factor G
and 23 items. I would like to calculate the standardized residual
variance of the observed variables. "Sem" only gives the residual
variance with the "summary" function, or the standardized loadings with
the
2002 Sep 01
2
Seperating Forground from Background
One thing I have noticed when encoding VCDs is that often videos with
complex backgrounds don't compress nearly as well as those with simple
ones. Part of the problem is that TV cameras seam to have the focus so
that the entire image is clear rather than focusing on the foreground (and
blurring the backgrounds). The result is that a good number of bits are
wasted trying to perfectly
2002 Aug 28
5
Analogue artifact estimation
Hi List,
Just batting a few ideas around here, but would it be possible to include in to the codec, estimation for common video artifacts that occur in the analogue world?
For example, anything that's gone through a composite stage will likely have dot-crawl and false colour - if we can recognise this effect in the encoder, we can treat it as a special case.
Other artifacts that come to
2003 Mar 23
6
A comparison of VP3, and two MPEG-4 variants
a couple points before I look at this too hard:
"For VP3, since you can't do a constant quality encode"
what? that should not be the case. Could be a QT-specific bug. Theora at any rate is certainly capable of doing constant-quality encode. This probably explains your standard deviation complaint -- VP3 is running a rate control alg, where the other codecs are just shooting for
2007 Aug 25
1
Theora vs MPEG vs H264
Hi all,
I have to compare the theora codec with MPEG and H264.
I was googling and I found that the PSNR is a common used parameter.
How can I do this with Theora?
Thanks
--
Leonardo de Paula Rosa Piga
Undergraduate Computer Engineering Student
LSC - IC - UNICAMP
http://www.students.ic.unicamp.br/~ra033956
2009 Nov 12
1
Transforming a dataframe into a response/predictor matrix
I currently have a data frame whose rows correspond to each student and whose columns are different variables for the student, as shown below:
Lastname Firstname CATALOG_NBR Email StudentID EMPLID Start
1 alastname afirstname 1213 *@uark.edu 10295236 # 12/2/2008
2 anotherlastname anotherfirstname 1213 **@uark.edu ## 10295236 9/3/2008
Xattempts Q1
2000 Sep 07
9
Video codec
Hi,
I guess this is a good time to start putting together a wish list for a
video codec.
I see that for audio the compression is around 10X for reasonable quality.
I am sure this will start its own thread of conversation.
For video you can do 40X fairly easily and the big task is to go to 80X or
100X with reasonable picture quality, say, a peak luma SNR of more than 30
dB. Uncompressed
2011 Apr 11
2
lpcSize
Okay,
Not exactly the answer I was looking for. This sounds like a big change. I don't mind re-writing the LSP quantizer but re-training code books and breaking compatibility is not what I want to do. I am working on an optimization for an ARM cortex-A8. It is desirable to process things in 4 element blocks. Is there a simpler approach you could recommend?
Vasant Shridhar
2013 May 29
1
NHW Image codec - 2 lower quality settings
Hello,
I have finally added 2 lower quality settings for the NHW codec: -l1 (-5Ko)
and -l2 (-10Ko).I use a quantization of 0.935 and 0.88 (kind of
quantization), and I decrease residual coding on the first order wavelet
image.
I have updated the demo page: http://nhwcodec.blogspot.com/ .
These 2 lower quality settings are still experimental.If you could find
time, would be interested in any
2011 Nov 20
2
Adding two or more columns of a data frame for each row when NAs are present.
I am fairly new to R and would like help with the problem below. I am
trying to sum and count several rows in the data frame yy below. All works
well as in example 1. When I try to add the columns, with an NA in Q21, I
get as NA as mySum. I would like NA to be treated as O, or igored.
I wrote a function to try to count an NA element as 0, Example 3 function.
It works with a few warnings,
2004 Sep 10
2
Fixed: ERROR: mismatch in decoded data, verify FAILED!
> Also, Kai has been kind enough to send me a copy of his file which
> has a
> problem only on -8, which I'll be looking into soon.
After some intense debugging, I found the problem. One
block in the file triggered a very rare bug in the LPC
coefficient quantizer caused by insufficient floating
point precision. There is a snippet to compute the
log(base 2) of a number:
2009 Feb 26
1
using predict method with an offset
Hi,
I have run into another problem using offsets, this time with
the predict function, where there seems to be a contradiction
again between the behavior and the help page.
On the man page for predict.lm, it says
Offsets specified by offset in the fit by lm will not be included in
predictions, whereas those specified by an offset term in the formula
will be.
While it indicates nothings about
1999 Aug 25
1
Vorbis/Lame
Hi,
I think that it would be a good thing to know more about those 2 projects
(and also the future patent free format).
I think that many people as me know about Lame, but not about Vorbis, and
vice-versa.
It would be fine that someone (perhaps the maintainer) of every project
would introduce to both group of people those projects. 2 things would be
interesting (to my mind):
- to know about the
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>>
2001 Oct 25
1
Fwd: Re: Clarification on pshycho-acoustic in Vorbis (your non-MP3 guide)
After reading http://mp3.radified.com/mp3.htm I sent Rad an explanation of
some things as I understand them. He liked it and posted it on his site
(still unlinked, use the URL below). Can somebody with better
understanding of psycho-acoustic terms and the vorbis model check it and
comment on it? In particular I didn't know how vorbis handles
quantization noise. If you reply with
2003 May 07
2
VP30
Hi,
Can anyone tell me the significant differences between VP30 and
VP31 (or are you allowed to)? Are there different token and quantizer
tables? Are there algorithmic differences? I have a VP30-encoded file that
plays with the VP3 VfW DLL but not with the open source decoder.
Thanks...
--
-Mike Melanson
--- >8 ----
List archives: http://www.xiph.org/archives/
Ogg project
2009 Mar 18
2
Octagon Coding
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Dear Celts,
I've become intrigued by the problem of spherical quantizers, so I decided
to see if I could come up with something better than PVQ. What I wound up
writing is something I call an "octagon quantizer. In two dimensions, PVQ
uses a "diamond" (square) shape. An octagon code (OVQ) uses an octagon,
which is a much better
2000 Dec 26
4
Thought for the new year
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
2003 Nov 03
1
svm in e1071 package: polynomial vs linear kernel
I am trying to understand what is the difference between linear and
polynomial kernel:
linear: u'*v
polynomial: (gamma*u'*v + coef0)^degree
It would seem that polynomial kernel with gamma = 1; coef0 = 0 and degree
= 1
should be identical to linear kernel, however it gives me significantly
different results for very simple
data set, with linear kernel
2007 Aug 29
1
Fast quality reduction transcoding
Hi,
After a quick read of the Theora spec, I became curious about the
possibility of fast quality reduction of Theora videos. The idea is to
decode through the Huffman and reverse prediction steps, and then to
truncate the coefficients and reencode. My questions are:
* Is this a reasonable way to reduce the quality and bitrate of a
stream? Will it be comparable in quality to a complete