man3/AF_power_af.3

#

    AF_power_uf(3)						       AF_power_uf(3)

    NAME
      AF_power_uf, AF_power_af - ULAW and ALAW power tables

    SYNTAX
      #include <AF/AFUtils.h>

      extern float AF_power_uf[];

      extern float AF_power_af[];

    DESCRIPTION
      AF_power_uf and AF_power_af are precomputed tables you can link with your
      application.	They are indexed by a ULAW or ALAW sample respectively.	 The
      tables contain, effectively, the square of the linearized sample value,
      scaled to the	range from 0.0 to 1.0.	 These tables are useful for comput-
      ing the power	in a block of ULAW or ALAW compressed samples.	This is
      important for	figuring out if	the signal is silent or	not, for example.

    EXAMPLES
      Typical usage	is:

      unsigned char	ulaw;
      float	power;
      power	= AF_power_uf[ ulaw ];

    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