spandsp: GSM 06.10 encoding and decoding

spandsp 0.0.6

GSM 06.10 encoding and decoding

# What does it do?

The GSM 06.10 module is an version of the widely used GSM FR codec software available from http://kbs.cs.tu-berlin.de/~jutta/toast.html. This version was produced since some versions of this codec are not bit exact, or not very efficient on modern processors. This implementation can use MMX instructions on Pentium class processors, or alternative methods on other processors. It passes all the ETSI test vectors. That is, it is a tested bit exact implementation.

This implementation supports encoded data in one of three packing formats:

- Unpacked, with the 76 parameters of a GSM 06.10 code frame each occupying a separate byte. (note that none of the parameters exceed 8 bits).
- Packed the the 33 byte per frame, used for VoIP, where 4 bits per frame are wasted.
- Packed in WAV49 format, where 2 frames are packed into 65 bytes.

# How does it work?

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