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convert_linear.c

/*
 * FILE:    convert_linear.c
 * PROGRAM: RAT
 * AUTHOR:  O.Hodson <O.Hodson@cs.ucl.ac.uk>
 *
 * Copyright (c) 1998-2001 University College London
 * All rights reserved.
 */
 
#ifndef HIDE_SOURCE_STRINGS
static const char cvsid[] = 
      "$Id: convert_linear.c,v 1.12 2001/01/18 00:24:23 ucacoxh Exp $";
#endif /* HIDE_SOURCE_STRINGS */

#include "config_unix.h"
#include "config_win32.h"
#include "audio_types.h"
#include "converter_types.h"
#include "convert_linear.h"
#include "convert_util.h"
#include "util.h"
#include "memory.h"
#include "debug.h"

/* Linear Interpolation Conversion *******************************************/

struct s_filter_state;
typedef void (*inter_cf)(int offset, int channels, sample *src, int src_len, sample *dst, int dst_len, struct s_filter_state *s);

typedef struct s_filter_state {
        int      scale;
        sample  *tmp_buf;
        int      tmp_len;
        sample  *last;
        int      last_len;
        inter_cf convert_f;
} filter_state_t;

typedef struct s_linear_state {
        int       steps;
      filter_state_t    fs[2];
} linear_state_t;

static void 
linear_upsample(int offset, int channels, 
                sample *src, int src_len, 
                sample *dst, int dst_len, 
                filter_state_t *l)
{
        register int r, loop;
        register short *sp, *dp;
        short *last = l->last + offset;

        sp = src + offset;
        dp = dst + offset;
        
        loop = min(src_len/channels, dst_len/(channels*l->scale));

        /* On some platforms divisions by powers of 2 is way quicker */
        /* than other divisions.  To improve interpolation perf.     */
        /* approximate fractions which are not powers of two         */
        /* i.e. 1 / 3 ->  5 / 16                                     */
        /*      1 / 5 ->  6 / 32                                     */
        /*      1 / 6 -> 11 / 64                                     */

        switch (l->scale) {
        case 6:
                while(loop--) {
                        register int il, ic;
                        il = *last; ic = *sp;

                        r = 55 * il + 11 * ic; r /= 64; *dp = (sample)r; dp += channels;
                        r = 44 * il + 22 * ic; r /= 64; *dp = (sample)r; dp += channels;
                        r = 33 * il + 33 * ic; r /= 64; *dp = (sample)r; dp += channels;
                        r = 22 * il + 44 * ic; r /= 64; *dp = (sample)r; dp += channels;
                        r = 11 * il + 55 * ic; r /= 64; *dp = (sample)r; dp += channels;
                        r =           66 * ic; r /= 64; *dp = (sample)r; dp += channels;
                        last = sp;
                        sp += channels;
                }
                break;
        case 5:
                while(loop--) {
                        register int il, ic;
                        il = *last; ic = *sp;
                        r = 24 * il +  6 * ic; r /= 32; *dp = (sample)r; dp += channels;
                        r = 18 * il + 12 * ic; r /= 32; *dp = (sample)r; dp += channels;
                        r = 12 * il + 18 * ic; r /= 32; *dp = (sample)r; dp += channels;
                        r =  6 * il + 24 * ic; r /= 32; *dp = (sample)r; dp += channels;
                        r =           30 * ic; r /= 32; *dp = (sample)r; dp += channels;
                        last = sp;
                        sp  += channels;
                }
                break;
        case 4:
                while(loop--) {
                        register int il, ic;
                        il = *last; ic = *sp;
                        r = 3 * il + 1 * ic; r /= 4; *dp = (sample)r; dp += channels;
                        r = 2 * il + 2 * ic; r /= 4; *dp = (sample)r; dp += channels;
                        r = 1 * il + 3 * ic; r /= 4; *dp = (sample)r; dp += channels;
                        *dp = (sample)ic; dp += channels;
                        last = sp;
                        sp  += channels;
                }
                break;
        case 3:
                while(loop--) {
                        register int il, ic;
                        il = *last; ic = *sp;
                        r = 10 * il +  5 * ic; r /= 16; *dp = (sample)r; dp += channels;
                        r =  5 * il + 10 * ic; r /= 16; *dp = (sample)r; dp += channels;
                        r =           15 * ic; r /= 16; *dp = (sample)r; dp += channels;
                        last = sp;
                        sp  += channels;
                }
                break;
        case 2:
                while(loop--) {
                        register int il, ic;
                        il = *last; ic = *sp;
                        r = il + ic; r /= 2; *dp = (sample)r; dp += channels;
                        *dp = (sample)ic; dp += channels;
                        last = sp;
                        sp  += channels;
                }
                break;
        default:
                assert(0); /* Should never get here */
        }
        l->last[offset] = src[src_len - channels + offset];
}

static void
linear_downsample(int offset, int channels, 
                  sample *src, int src_len, 
                  sample *dst, int dst_len, 
                  filter_state_t *l)
{
        register int loop, r, c, lim;
        register short *sp, *dp;

        loop = min(src_len / (channels * l->scale), dst_len / channels);
        sp = src + offset;
        dp = dst + offset;
        lim = l->scale - 1;
        while(loop--) {
                r  = (int)*sp; sp+=channels;
                c  = lim;
                while(c--) {
                        r += (int)*sp; sp+=channels;
                } 
                r /= l->scale;
                *dp = (short)r;
                dp+= channels;
        }
}

static void
linear_init_state(filter_state_t *l, const converter_fmt_t *cfmt)
{
        if (cfmt->src_freq > cfmt->dst_freq) {
                l->scale = cfmt->src_freq / cfmt->dst_freq;
                l->last_len = 0;
                l->convert_f = linear_downsample;
        } else if (cfmt->src_freq < cfmt->dst_freq) {
                l->scale = cfmt->dst_freq / cfmt->src_freq;
                l->last_len = cfmt->src_channels;
                l->convert_f = linear_upsample;
                l->last = (sample*)xmalloc(sizeof(sample) * l->last_len);
                memset(l->last, 0, sizeof(sample) * cfmt->src_channels);
        }
}

int 
linear_create (const converter_fmt_t *cfmt, u_char **state, uint32_t *state_len)
{
      converter_fmt_t   sfmt, ufmt;
      linear_state_t    *l;
        int       g;

      if (((cfmt->src_freq % 8000) == 0 && (cfmt->dst_freq % 8000)) ||
          ((cfmt->src_freq % 11025) == 0 && (cfmt->dst_freq % 11025))) {
            /* 11025 - 8000 not supported */
            return FALSE;
      }

      xmemchk();
        g = gcd(cfmt->src_freq, cfmt->dst_freq);        

      l = (linear_state_t*)xmalloc(sizeof(linear_state_t));
        memset(l, 0 , sizeof(linear_state_t));
        l->steps = conversion_steps(cfmt->src_freq, cfmt->dst_freq);
      xmemchk();

      sfmt = *cfmt;

      if (sfmt.src_channels != sfmt.dst_channels) {
            /* In addition to rate conversion, this requires
             * channel number conversion, this can happen
             * either side of rate conversion - see sinc_convert() */
            if (sfmt.src_channels == 2 && sfmt.dst_channels == 1) {
                  sfmt.src_channels = 1; /* Stereo->Mono, R1->R2 */
            } 
      }

        switch(l->steps) {
        case 1:
                linear_init_state(l->fs, &sfmt);
                break;
        case 2:
            ufmt = sfmt;
            ufmt.dst_freq = g;
                linear_init_state(l->fs,     &ufmt);
            ufmt = sfmt;
            ufmt.src_freq = g;
                linear_init_state(l->fs + 1, &ufmt);
                break;
        }
      xmemchk();
        *state     = (u_char*)l;
        *state_len = sizeof(linear_state_t);
        return TRUE;
}

void
linear_convert (const converter_fmt_t *cfmt, 
                u_char *state, 
                sample* src_buf, int src_len, 
                sample *dst_buf, int dst_len)
{
        linear_state_t *l;
        int         channels, i;

        channels = cfmt->src_channels;

        l = (linear_state_t*)state;

        if (cfmt->src_channels == 2 && cfmt->dst_channels == 1) {
                /* stereo->mono then sample rate change */
                if (l->steps) {
                        /* inplace conversion needed */
                        converter_change_channels(src_buf, src_len, 2, src_buf, src_len / 2, 1); 
                        src_len /= 2;
                } else {
                        /* this is only conversion */
                        converter_change_channels(src_buf, src_len, 2, dst_buf, dst_len, 1);
                        return;
                }
                channels = 1;
        } else if (cfmt->src_channels == 1 && cfmt->dst_channels == 2) {
                dst_len /= 2;
        }
        
        switch(l->steps) {
        case 1:
                assert(l->fs->convert_f);
                for(i = 0; i < channels; i++) {
                        l->fs->convert_f(i, channels, src_buf, src_len, dst_buf, dst_len, l->fs);
                }
                break;
        case 2:
                /* first step is always downsampling for moment */
                if (l->fs->tmp_buf == NULL) {
                        l->fs->tmp_len  = src_len / l->fs->scale;
                        l->fs->tmp_buf = (sample*)xmalloc(sizeof(sample) * l->fs->tmp_len);
                }
                assert(l->fs[0].convert_f);
                assert(l->fs[1].convert_f);

                for(i = 0; i < channels; i++)
                        l->fs[0].convert_f(i, channels, src_buf, src_len, l->fs->tmp_buf, l->fs->tmp_len, l->fs);
                for(i = 0; i < channels; i++)
                        l->fs[1].convert_f(i, channels, l->fs->tmp_buf, l->fs->tmp_len, dst_buf, dst_len, l->fs + 1);
                break;
        }
        
        if (cfmt->src_channels == 1 && cfmt->dst_channels == 2) {
                /* sample rate change before mono-> stereo */
                if (l->steps) {
                        /* in place needed */
                        converter_change_channels(dst_buf, dst_len, 1, dst_buf, dst_len * 2, 2);
                } else {
                        /* this is our only conversion here */
                        converter_change_channels(src_buf, src_len, 1, dst_buf, dst_len * 2, 2);
                }
        }
}

void 
linear_destroy (u_char **state, uint32_t *state_len)
{
        linear_state_t *l = (linear_state_t*)*state;
        int i;

        assert(*state_len == sizeof(linear_state_t));
        
        for(i = 0; i < l->steps; i++) {
                if (l->fs[i].last)    xfree(l->fs[i].last);
                if (l->fs[i].tmp_buf) xfree(l->fs[i].tmp_buf);
        }
        xfree(l);
        *state     = NULL;
        *state_len = 0;
}




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