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Audio Coding

  All lossy source coding techniques can be interpreted as vector quantization (VQ) with variable length coding gif. The coding scheme used in this coder uses an orthonormal transform (see 4.1.3) as a fixed codebook for vector quantization of MDCT (see 4.1.1) transform coefficients. Variable length coding is done by a number of Huffman codes on the VQ coefficients.

Since this is an experiment, the coder does not have a specified file format and does not output a bitstream. The produced bits are counted in the coder, and a new audio output file is produced with the resulting quantized data. The coder reads and writes raw wav files.

Before I move on to the actual coding, I introduce the transforms used in the coder.

Figure 6: A schematic view of the coder.

Bosse Lincoln
Sat Mar 7 16:27:43 PST 1998