Technologies for Packet-Based Voice Applications in Visual C#.NET

Recognizing PDF 417 in Visual C#.NET Technologies for Packet-Based Voice Applications

Technologies for Packet-Based Voice Applications
Recognizing PDF 417 In C#.NET
Using Barcode scanner for Visual Studio .NET Control to read, scan PDF-417 2d barcode image in VS .NET applications.
www.OnBarcode.com
PDF 417 Reader In C#
Using Barcode scanner for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
The key blocks of the encoder are
Barcode Recognizer In Visual C#
Using Barcode decoder for Visual Studio .NET Control to read, scan barcode image in VS .NET applications.
www.OnBarcode.com
Decoding Barcode In C#.NET
Using Barcode decoder for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
I I I I I I I I I I I I I I I I
PDF 417 Decoder In C#.NET
Using Barcode decoder for VS .NET Control to read, scan PDF 417 image in .NET framework applications.
www.OnBarcode.com
Recognizing PDF 417 In .NET
Using Barcode recognizer for ASP.NET Control to read, scan PDF 417 image in ASP.NET applications.
www.OnBarcode.com
Framer High-pass filter LPC analysis Line spectral pair (LSP) quantizer LSP decoder LSP interpolation Format perceptual weighting filter Pitch estimation Subframe processing Harmonic noise shaping Impulse response calculator Zero input response and ringing subtraction Pitch predictor High-rate excitation (MP-MLQ) Excitation decoder Decoding of the pitch information
PDF-417 2d Barcode Decoder In .NET Framework
Using Barcode reader for VS .NET Control to read, scan PDF417 image in Visual Studio .NET applications.
www.OnBarcode.com
Read PDF 417 In VB.NET
Using Barcode recognizer for Visual Studio .NET Control to read, scan PDF-417 2d barcode image in Visual Studio .NET applications.
www.OnBarcode.com
26 ITU-T Recommendation G728
QR Code Reader In Visual C#.NET
Using Barcode reader for Visual Studio .NET Control to read, scan Denso QR Bar Code image in Visual Studio .NET applications.
www.OnBarcode.com
Scanning Universal Product Code Version A In C#
Using Barcode reader for .NET Control to read, scan GS1 - 12 image in VS .NET applications.
www.OnBarcode.com
The ITU-T Recommendation G728106 contains the description of an algorithm for the coding of speech signals at 16 Kbps using LD-CELP The LDCELP algorithm consists of an encoder and a decoder, as illustrated in Figure 2-18 The essence of the CELP technique, which is an analysis-bysynthesis approach search, is retained in LD-CELP The LD-CELP, however, uses backward adaptation of predictors and gain to achieve an algorithmic delay of 0625 ms Only the index to the excitation code book is transmitted The predictor coefficients are updated through an LPC analysis of previously quantized speech The excitation gain is updated by using the gain information embedded in the previously quantized excitation The block size for the excitation vector and gain adaptation is only five samples A perceptual weighting filter is updated using LPC analysis of the unquantized speech G728 uses short excitation vectors (5 samples, or 0625 ms) and backward-adaptive linear predictors The algorithmic delay of the resulting coder is 0625 ms, resulting in an achievable end-to-end delay of less than 2 ms The G728 standard was designed to provide speech quality equivalent
Decode EAN / UCC - 13 In Visual C#
Using Barcode reader for .NET framework Control to read, scan UCC-128 image in Visual Studio .NET applications.
www.OnBarcode.com
Data Matrix 2d Barcode Decoder In Visual C#.NET
Using Barcode scanner for .NET framework Control to read, scan Data Matrix ECC200 image in Visual Studio .NET applications.
www.OnBarcode.com
Figure 2-18 Example of G728 speech coder/decoder
UPC-E Supplement 5 Recognizer In C#
Using Barcode scanner for .NET Control to read, scan UCC - 12 image in .NET framework applications.
www.OnBarcode.com
Barcode Recognizer In .NET Framework
Using Barcode reader for ASP.NET Control to read, scan barcode image in ASP.NET applications.
www.OnBarcode.com
Input Signal Excitation VQ Code book + Gain Synthesis Filter
Recognizing Data Matrix 2d Barcode In Visual Studio .NET
Using Barcode recognizer for ASP.NET Control to read, scan Data Matrix image in ASP.NET applications.
www.OnBarcode.com
Recognize USS Code 39 In Objective-C
Using Barcode recognizer for iPad Control to read, scan Code39 image in iPad applications.
www.OnBarcode.com
2
UCC.EAN - 128 Decoder In Visual C#
Using Barcode decoder for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Scan Universal Product Code Version A In None
Using Barcode recognizer for Font Control to read, scan UCC - 12 image in Font applications.
www.OnBarcode.com
Perceptual Weighting Filter
Reading UCC - 12 In C#.NET
Using Barcode reader for Visual Studio .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Decoding Code39 In None
Using Barcode recognizer for Font Control to read, scan Code 3/9 image in Font applications.
www.OnBarcode.com
VQ Mean Index Source Error
Backward Gain Adapter
Backward Synthesis Filter Adapter Encoder
Backward Perceptual Weighting Filter Adapter
VQ Index
Excitation VQ Code book
Gain
Synthesis Filter
Postfilter
Coded Speech
Backward Gain Adapter Decoder
Backward Synthesis Filter Adapter
to or better than that of the G721 32-Kbps ADPCM international standard, even after three tandem connections107 The G728 encoder is a CELP coder utilizing a gain-shape VQ code book of 1,024 candidate code vectors Three linear predictors are used to generate a perceptual weighting filter, a synthesis filter, and a gain predictor For all three, backward adaptation is used to minimize coding delay Backwardadaptive prediction attempts to predict the current set of samples from the previous ones Thus, there is no buffering delay as is required for forward prediction The predictor coefficients for the synthesis filter and the gain predictor are generated at the decoder in the same backward-adaptive fashion In an error-free environment, the same coded speech and gain samples are available at the decoder as at the encoder, so the LPC filters will be the same Thus, the only information sent from the encoder to the decoder is the excitation index A hybrid windowing technique, based on Barnwell s recursive autocorrelation method, can be used to enable the generation of LPC coefficients without the delays associated with standard windowed autocorrelation The input speech is buffered into five sample vectors for processing Four vectors comprise a 20-sample frame The three linear predictors are updated once per frame Note, however, that the basic algorithmic delay is only one vector because backward adaptation is used The encoder then selects the code book VQ vector that minimizes a perceptually weighted mean-squared error distortion measure with this input vector The perceptual weighting function is based on a tenth-order LPC analysis of the input speech Each VQ code vector in turn is scaled by an adaptive
Technologies for Packet-Based Voice Applications
excitation gain factor, and then passed through the synthesis filter; a weighted error measure is produced for each No explicit LT predictor is used in G728 Instead, a relatively high-order (fiftieth-order) synthesis filter is used, which picks up some of the long-term structure of the speech signal The synthesis filter is generated by backward-adaptive LPC analysis of the coded speech The gain predictor generates a gain factor for each input vector; this predictor is based on a tenth-order LPC analysis of the gains of the previously selected code vectors The 10-bit VQ code book is structured as a 7-bit shape code book and a 3-bit gain code book to reduce the complexity of the code book search operation These two code book components are jointly optimized in the search procedure, which selects the gain-shape code vector combination to minimize the error measure Once the optimal code vector has been selected, its index is transmitted At the decoder, the code vector index is used to generate the gain-shape code vector, which is then scaled by the adaptive gain factor and passed through the synthesis filter to generate the coded speech The gain predictor and synthesis filter are again generated by backward LPC analysis of the previous excitation gains and the previous coded speech signal Finally, adaptive ST and LT postfilters are applied to the coded speech vector The ST postfilter emphasizes the formant structure of the speech, working in a similar (but opposite) fashion to the perceptual weighting filter to deemphasize the perceived noise in the spectral valleys The LT postfilter emphasizes the pitch structure of the speech The ST postfilter is formed during the synthesis filter adaptation; the LT postfilter, adapted using a pitch detector that operates on the coded speech in the decoder, is updated once per frame107
Copyright © OnBarcode.com . All rights reserved.