Log area ratio

Log area ratios (LAR) can be used to represent reflection coefficients (another form for linear prediction coefficients) for transmission over a channel. While not as efficient as line spectral pairs (LSPs), log area ratios are much simpler to compute. Let $r_k$ be the kth reflection coefficient of a filter, the kth LAR is:

A_k = \log{1-r_k \over 1+r_k}

Use of Log Area Ratios have now been mostly replaced by Line Spectral Pairs, but older codecs, such as GSM-FR use LARs.

Entropy type	Unary Arithmetic Golomb Huffman Adaptive Canonical Modified Range Shannon Shannon–Fano Shannon–Fano–Elias Tunstall Universal Exp-Golomb Fibonacci Gamma Levenshtein

Dictionary type	Byte pair encoding DEFLATE Lempel–Ziv LZ77 / LZ78 (LZ1 / LZ2) LZJB LZMA LZO LZRW LZS LZSS LZW LZWL LZX LZ4 Statistical

Other types	BWT CTW Delta DMC MTF PAQ PPM RLE

Audio

Concepts	Bit rate average (ABR) constant (CBR) variable (VBR) Companding Convolution Dynamic range Latency Nyquist–Shannon theorem Sampling Sound quality Speech coding Sub-band coding

Codec parts	A-law μ-law ACELP ADPCM CELP DPCM Fourier transform LPC LAR LSP MDCT Psychoacoustic model WLPC

Image

Concepts	Chroma subsampling Coding tree unit Color space Compression artifact Image resolution Macroblock Pixel PSNR Quantization Standard test image

Methods	Chain code DCT EZW Fractal KLT LP RLE SPIHT Wavelet

Video

Concepts	Bit rate average (ABR) constant (CBR) variable (VBR) Display resolution Frame Frame rate Frame types Interlace Video characteristics Video quality

Codec parts	Lapped transform DCT Deblocking filter Motion compensation

Theory

Compression formats
Compression software (codecs)

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Log area ratio

See also