ref: 19144759ff0bc03f470689c61a15fac88caacd7d
dir: /src/vol.c/
/* * (c) 20/03/2000 Fabien COELHO <fabien@coelho.net> for sox. * * Change volume of sound file, with basic linear amplitude formula. * Pretty redundant with -v general option. * Beware of saturations! clipping is checked and reported. * Cannot handle different number of channels. * Cannot handle rate change. */ #include "st_i.h" #include <math.h> /* exp(), sqrt() */ static st_effect_t st_vol_effect; #define LOG_10_20 ((double)(0.1151292546497022842009e0)) typedef struct { double gain; /* amplitude gain. */ int uselimiter; /* boolean: are we using the limiter? */ double limiterthreshhold; double limitergain; /* limiter gain. */ int limited; /* number of limited values to report. */ int totalprocessed; } * vol_t; /* * Process options: gain (float) type (amplitude, power, dB) */ static int st_vol_getopts(eff_t effp, int n, char **argv) { vol_t vol = (vol_t) effp->priv; vol->gain = 1.0; /* default is no change */ vol->uselimiter = 0; /* default is no limiter */ if (n && (!sscanf(argv[0], "%lf", &vol->gain))) { st_fail(st_vol_effect.usage); return ST_EOF; } /* adjust gain depending on type (what a great parser;-) */ if (n>1) { switch (argv[1][0]) { case 'd': /* decibels to amplitude */ case 'D': vol->gain = exp(vol->gain*LOG_10_20); break; case 'p': case 'P': /* power to amplitude, keep phase change */ if (vol->gain > 0.0) vol->gain = sqrt(vol->gain); else vol->gain = -sqrt(-vol->gain); break; case 'a': /* amplitude */ case 'A': default: break; } } if (n>2) { if ((fabs(vol->gain) < 1.0) || !sscanf(argv[2], "%lf", &vol->limitergain) || !((vol->limitergain > 0.0) && (vol->limitergain < 1.0))) { st_fail(st_vol_effect.usage); return ST_EOF; } vol->uselimiter = 1; /* ok, we'll use it */ /* The following equation is derived so that there is no * discontinuity in output amplitudes */ /* and a ST_SAMPLE_MAX input always maps to a ST_SAMPLE_MAX output * when the limiter is activated. */ /* (NOTE: There **WILL** be a discontinuity in the slope * of the output amplitudes when using the limiter.) */ vol->limiterthreshhold = ST_SAMPLE_MAX * (1.0 - vol->limitergain) / (fabs(vol->gain) - vol->limitergain); } return ST_SUCCESS; } /* * Start processing */ static int st_vol_start(eff_t effp) { vol_t vol = (vol_t) effp->priv; if (effp->outinfo.channels != effp->ininfo.channels) { st_warn("VOL cannot handle different channels (in=%d, out=%d)" " use avg or pan", effp->ininfo.channels, effp->outinfo.channels); } if (effp->outinfo.rate != effp->ininfo.rate) { st_fail("VOL cannot handle different rates (in=%ld, out=%ld)" " use resample or rate", effp->ininfo.rate, effp->outinfo.rate); return ST_EOF; } vol->limited = 0; vol->totalprocessed = 0; return ST_SUCCESS; } /* * Process data. */ static int st_vol_flow(eff_t effp, const st_sample_t *ibuf, st_sample_t *obuf, st_size_t *isamp, st_size_t *osamp) { vol_t vol = (vol_t) effp->priv; register double gain = vol->gain; register double limiterthreshhold = vol->limiterthreshhold; register double sample; register st_size_t len; len = min(*osamp, *isamp); /* report back dealt with amount. */ *isamp = len; *osamp = len; if (vol->uselimiter) { vol->totalprocessed += len; for (;len>0; len--) { sample = *ibuf++; if (sample > limiterthreshhold) { sample = (ST_SAMPLE_MAX - vol->limitergain * (ST_SAMPLE_MAX - sample)); vol->limited++; } else if (sample < -limiterthreshhold) { sample = -(ST_SAMPLE_MAX - vol->limitergain * (ST_SAMPLE_MAX + sample)); /* FIXME: MIN is (-MAX)-1 so need to make sure we * don't go over that. Probably could do this * check inside the above equation but I didn't * think it thru. */ if (sample < ST_SAMPLE_MIN) sample = ST_SAMPLE_MIN; vol->limited++; } else { sample = gain * sample; } ST_SAMPLE_CLIP_COUNT(sample, effp->clippedCount); *obuf++ = sample; } } else { /* quite basic, with clipping */ for (;len>0; len--) { sample = gain * *ibuf++; ST_SAMPLE_CLIP_COUNT(sample, effp->clippedCount); *obuf++ = sample; } } return ST_SUCCESS; } /* * Do anything required when you stop reading samples. * Don't close input file! */ static int st_vol_stop(eff_t effp) { vol_t vol = (vol_t) effp->priv; if (vol->limited) { st_warn("limited %d values (%d percent).", vol->limited, (int) (vol->limited * 100.0 / vol->totalprocessed)); } return ST_SUCCESS; } static st_effect_t st_vol_effect = { "vol", "Usage: vol gain [ type [ limitergain ] ]" " (default type=amplitude: 1.0 is constant, <0.0 change phase;\n" " type=power 1.0 is constant; type=dB: 0.0 is constant, +6 doubles ampl.)\n" " The peak limiter has a gain much less than 1.0 (ie 0.05 or 0.02) which is only\n" " used on peaks to prevent clipping. (default is no limiter)", ST_EFF_MCHAN, st_vol_getopts, st_vol_start, st_vol_flow, st_effect_nothing_drain, st_vol_stop }; const st_effect_t *st_vol_effect_fn(void) { return &st_vol_effect; }