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Topic: Codebook


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In the News (Wed 15 Feb 12)

  
  Codebook - Wikipedia, the free encyclopedia
In cryptography, a codebook is a document used for implementing a code.
The distribution and physical security of codebooks presents a special difficulty in the use of codes, compared to the secret information used in ciphers, the key, which is typically much shorter.
NSA documents sometimes use "codebook" to mean 'block cipher'; compare their use of "combiner-type algorithm" to mean 'stream cipher'.
en.wikipedia.org /wiki/Codebook   (143 words)

  
 RFC 3951 (rfc3951) - Internet Low Bit Rate Codec (iLBC)   (Site not responding. Last check: 2007-10-20)
The codebook search method employs noise shaping derived from the LPC filters, and the main decision criterion is to minimize the squared error between the target vector and the code vectors.
As codebook encoding with squared-error matching is known to produce a coded signal of less power than does the scalar quantized start state signal, a gain re-scaling method is implemented by a refined search for a better set of codebook gains in terms of power matching after encoding.
The construction of the adaptive codebook memory in the decoder is identical to the method outlined in section 3.6.3, except that it is done on the codebook memory without perceptual weighting.
www.faqs.org /rfcs/rfc3951.html   (10647 words)

  
 Stata help for codebook
See codebook problems for a discussion of these problems and advice on overcoming them.
It indicates that the codebook pertains to the languages in namelist or to all defined languages if no such list is specified as an argument to languages().
The output of codebook lists the data label and variable labels in these languages and which value labels are attached to variables in these languages.
www.stata.com /help.cgi?codebook   (442 words)

  
 Encryption - Open Encyclopedia   (Site not responding. Last check: 2007-10-20)
Historically, cryptography was split into a dichotomy of codes and ciphers, and coding had its own terminology, analogous to that for ciphers: "encoding, codetext, decoding" and so on.
However, codes have a variety of drawbacks, including susceptibilty to cryptanalysis and the difficulty of managing a cumbersome codebook.
Because of this, codes have fallen into disuse in modern cryptography, and ciphers are the dominant paradigm.
open-encyclopedia.com /Encryption   (494 words)

  
 FRB: 1989 SCF Codebook, part1
This codebook serves as the authoritative guide to the variables included on the public use version of the 1989 SCF cross-section dataset.
In this codebook, many variables have been grouped in a way different from the way that they were originally asked (e.g., lines of credit for homeowners and non-homeowners were originally asked separately -- as noted in the codebook below, these responses have been merged in a single set of variables).
Because question ordering is important in understanding the effective meaning of many questions, users of the data are encouraged to consult the questionanaire (available separately) for a precise guide to where and how the underlying questions were asked.
www.federalreserve.gov /pubs/oss/oss2/89/codebk89pt1.html   (1839 words)

  
 How many kinds of Kohonen networks exist?
Let the codebook vectors be indexed by a subscript j, and let the index of the codebook vector nearest to the current training case be n.
A SOM works by smoothing the codebook vectors in a manner similar to kernel estimation methods, but the smoothing is done in neighborhoods in the grid space rather than in the input space (Mulier and Cherkassky 1995).
In particular, local-linear smoothing eliminates the notorious "border effect", whereby the codebook vectors near the border of the grid are compressed in the input space.
www.faqs.org /faqs/ai-faq/neural-nets/part1/section-11.html   (3517 words)

  
 IP.com's Prior Art Database
Fixed-rate codebooks are designed using a modified version of the general- ized Lloyd algorithm.
Codebooks are optimized for the Gaussian distribu- tion.
Codebook design uses a modified version of the generalized Lloyd algorithm in a training-sequence- based iterative scheme.
www.priorartdatabase.com /IPCOM/000009715   (584 words)

  
 Vorbis I specification
Codebooks are a self-contained abstraction that perform entropy decoding and, optionally, use the entropy-decoded integer value as an offset into an index of output value vectors, returning the indicated vector of values.
This packed configuration consists of multiple 'codebooks', each containing a specific Huffman-equivalent representation for decoding compressed codewords as well as an optional lookup table of output vector values to which a decoded Huffman value is applied as an offset, generating the final decoded output corresponding to a given compressed codeword.
Both the codebooks themselves and the codewords they decode are unrolled from a packet as a series of arbitrary-width values read from the stream according to Section 2, “Bitpacking Convention”.
www.xiph.org /vorbis/doc/Vorbis_I_spec.html   (12396 words)

  
 DESIGN OF AN ARTICULATORY CODEBOOK   (Site not responding. Last check: 2007-10-20)
Because of these reasons, attempts have been made at reducing the size of the codebook ([8]) and at vocal tract shape clustering ([5]) in order to reduce codebook access time.
The inversion of the articulatory-to-acoustic mapping is processed during the building of the articulatory codebook as follows.
Once the codebook is built, the access task simply requires estimating the acoustic parameters for each frame of the speech signal, determining the coordinates of the corresponding cluster node in the network using the sub-sampling period of each parameter, and retrieving all possible vocal tract model shapes to which the acoustic node points.
www.caip.rutgers.edu /~chenoukh/Articles/EuroSpeech97/node2.html   (433 words)

  
 Codebook DTD Version 2.0   (Site not responding. Last check: 2007-10-20)
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