AF_gain_table_u(3)

NAME
AF_gain_table_u, AF_gain_table_a - ULAW and ALAW gain tables

SYNTAX
#include <AF/AFUtils.h>

extern int AF_gain_min_u, AF_gain_max_u;

extern unsigned char *AF_gain_table_u[];

extern int AF_gain_min_a, AF_gain_max_a;

extern unsigned char *AF_gain_table_a[];

DESCRIPTION
is an array of precomputed gain tables for ULAW samples. is the same thing, but for ALAW samples. These tables are useful for effectivly decompressing a sample, multiplying by a constant, and recompressing. The tables are available in 1 dB steps from to for ULAW samples. (or from to for ALAW samples.)

EXAMPLES
Typical usage is:

unsigned char *gain_table; unsigned char input, output; /* first select a particular table, for 5 dB gain */ gain_table = AF_gain_table_u[ 5 - AF_gain_min_u ]; /* now translate the sample */ output = gain_table[ input ];

DIAGNOSTICS
If you index the table with an out-of-range linear value you may cause a protection fault and crash your application.

SEE ALSO
AF(1)

BUGS
If you encounter a reproducible bug, please submit a problem report to (af-bugs@crl.dec.com).

COPYRIGHT
Copyright 1990-1994, Digital Equipment Corporation.
See AF(1) for a full statement of rights and permissions.

AUTHORS
Tom Levergood and Larry Stewart, Digital Cambridge Research Lab