static int start(sox_format_t * ft)
{
priv_t *p = (priv_t *) ft->priv;
ft->signal.channels = 1;
lsx_rawstart(ft, sox_true, sox_false, sox_true, SOX_ENCODING_CVSD, 1);
p->last_n_bits = 5; /* 101 */
p->step_mult = exp((-1 / .005 / ft->signal.rate));
p->step_add = (1 - p->step_mult) * (.1 * SOX_SAMPLE_MAX);
lsx_debug("step_mult=%g step_add=%f", p->step_mult, p->step_add);
return SOX_SUCCESS;
}
static void cvsdstartcommon(sox_format_t * ft)
{
priv_t *p = (priv_t *) ft->priv;
p->cvsd_rate = (ft->signal.rate <= 24000) ? 16000 : 32000;
ft->signal.rate = 8000;
ft->signal.channels = 1;
lsx_rawstart(ft, sox_true, sox_false, sox_true, SOX_ENCODING_CVSD, 1);
/*
* initialize the decoder
*/
p->com.overload = 0x5;
p->com.mla_int = 0;
/*
* timeconst = (1/e)^(200 / SR) = exp(-200/SR)
* SR is the sampling rate
*/
p->com.mla_tc0 = exp((-200.0)/((float)(p->cvsd_rate)));
/*
* phase_inc = 32000 / SR
*/
p->com.phase_inc = 32000 / p->cvsd_rate;
/*
* initialize bit shift register
*/
p->bit.shreg = p->bit.cnt = 0;
p->bit.mask = 1;
/*
* count the bytes written
*/
p->bytes_written = 0;
p->com.v_min = 1;
p->com.v_max = -1;
lsx_report("cvsd: bit rate %dbit/s, bits from %s", p->cvsd_rate,
ft->encoding.reverse_bits ? "msb to lsb" : "lsb to msb");
}
static int raw_start(sox_format_t * ft) {
return lsx_rawstart(ft, sox_false, sox_false, sox_true, SOX_ENCODING_UNKNOWN, 0);
}
