buffer.c

speech signal process tools

/*
 ********************************************************************************
 *
 *  This material contains proprietary software of Entropic Speech, Inc.
 *  Any reproduction, distribution, or publication without the the prior
 *  written permission of Entropic Speech, Inc. is strictly prohibited.
 *  Any public distribution of copies of this work authorized in writing
 *  by Entropic Speech, Inc. must bear the notice:
 *
 *     "Copyright (c) 1987 Entropic Speech, Inc.; all rights reserved"
 *
 *  Program: buffer
 *
 *  Written by: Jim Elliott
 *
 *  Computes buffer statistics for encode program.
 *
 ********************************************************************************
 */

/*
 *  SCCS program and date keywords.
 */

#ifndef lint
static char *sccs_id = "@(#)buffer.c	1.2	10/6/87 ESI";
#endif

/*
 *  System include files.
 */

#include <stdio.h>

/*
 *  ESPS include files.
 */

#include <esps/esps.h>
#include <esps/anafea.h>
#include <esps/encode.h>
#include <esps/fea.h>

/*
 *  Defines.
 */

#define MAX_FRM 120		/* Number of frames in circular buffer */

/*
 ********************************************************************************
 *  Subroutine to update buffer statistics.
 ********************************************************************************
 */

update_buffer( bs, buf_hist, max_delay, samp_freq, chan_rate,
    anafea_rec )

float chan_rate, samp_freq;
int buf_hist[], *max_delay;
struct anafea *anafea_rec;
struct bit_stats *bs;
{
    static float
	bits[ MAX_FRM ];	/* Circular buffer for frame bit counts */

    static int
	rd = 0,			/* Read pointer for circular buffer */
	samp[MAX_FRM],		/* Circular buffer for frame samples */
	wr = 0;			/* Write pointer for circular buffer */

    int
	i,			/* Scratch index */
	samp_in;		/* Samples input to buffer during frame */

    float
	bits_in,		/* Bits input to buffer during frame */
	bits_out;		/* Bits output from buffer during frame */

    bits_in = (float) bs->frm_bits;
    bits_out = (float) *anafea_rec->frame_len / samp_freq * chan_rate;
    samp_in = *anafea_rec->frame_len;

/*
 *  Add input bits to circular buffer and advance write pointer. Check for
 *  wrap-around and abort if it has occurred.
 */

    bits[wr] = bits_in;
    samp[wr] = samp_in;

    wr++;
    if ( wr == MAX_FRM )
        wr = 0;

    spsassert( wr != rd, "crossover in read and write pointers" );

/*
 *  Deduct output bits from circular buffer, advancing the read pointer as we
 *  go. If the read pointer catches up with the write pointer, the buffer is
 *  empty, and we are finished.
 */

    while ( bits_out >= bits[rd] )
    {
	bits_out -= bits[rd];

	rd++;
	if ( rd == MAX_FRM )
	    rd = 0;

	if ( rd == wr )
	    break;
    }

/*
 *  Adjust the numbers of bits in the frame addressed by the read pointer,
 *  unless the buffer is empty (pointers equal).
 */

    if ( rd != wr )
	bits[rd] -= bits_out;

/*
 *  Now, figure out the number of bits and the number of input samples
 *  remaining in the buffer.
 */

    i = rd;
    bs->buf_bits = 0.0;
    bs->buf_samp = 0;

    while ( i != wr )
    {
	bs->buf_bits += bits[i];
	bs->buf_samp += samp[i];

	i++;
	if ( i == MAX_FRM )
	    i = 0;
    }

/*
 *  Update the maximum buffer delay, and the buffer-delay histogram.
 */

    if ( bs->buf_samp > *max_delay )
	*max_delay = bs->buf_samp;

    i = bs->buf_samp / 100;
    if ( i > 10 )
	i = 10;
    buf_hist[i]++;
}