ref: c28e759b03dd2a3d74adecf9658775835c006aa0
parent: 93eed5cd3459c8c32cccf9aef8113bdca255221d
author: robs <robs>
date: Mon Jun 30 17:04:54 EDT 2008
Recent synth speed-up lost spectral purity in some cases. This fixed version should be as fast as possible whilst remaining pure. Also added a new pure exponential sweep, and a squared sweep.
--- a/ChangeLog
+++ b/ChangeLog
@@ -83,7 +83,8 @@
o Improved `rate' resampling effect; resample, polyphase, & rabbit
now deprecated. (robs)
o New `spectrogram' effect; creates a PNG (if built with PNG lib). (robs)
- o `synth' can now sweep linearly (as well as logarithmically). (robs)
+ o `synth' can now sweep linearly and squarely (as well as
+ exponentially). (robs)
o Fix synth max. level setting for some output encodings. (robs)
o Fix crash on 64-bit arch. with tempo & key effects. (Sami Liedes)
o `gain' alias for the vol effect. (robs)
--- a/soxeffect.7
+++ b/soxeffect.7
@@ -1160,6 +1160,8 @@
.IP \fB\-o\ \fItext\fR
Name of the spectrogram output PNG file, default `spectrogram.png'.
.RE
+.TP
+\
For the ability to perform off-line processing of spectral data, see the
.B stat
effect.
@@ -1301,7 +1303,7 @@
will overwrite channel 1 with channel 2; creating a stereo
file with both channels containing the same audio.
.TP
-\fBsynth\fR [\fIlen\fR] {[\fItype\fR] [\fIcombine\fR] [\fIfreq\fR[\fBk\fR][\fI\-freq2\fR[\fBk\fR]|\fI~freq2\fR[\fBk\fR]]] [\fIoff\fR] [\fIph\fR] [\fIp1\fR] [\fIp2\fR] [\fIp3\fR]}+\fBsynth\fR [\fIlen\fR] {[\fItype\fR] [\fIcombine\fR] [[\fB%\fR]\fIfreq\fR[\fBk\fR][\fB:\fR\^|\^\fB+\fR\^|\^\fB/\fR\^|\^\fB\-\fR[\fB%\fR]\fIfreq2\fR[\fBk\fR]]] [\fIoff\fR] [\fIph\fR] [\fIp1\fR] [\fIp2\fR] [\fIp3\fR]}This effect can be used to generate fixed or swept frequency audio tones
with various wave shapes, or to generate wide-band noise of various
`colours'.
@@ -1382,10 +1384,22 @@
is given, then
.I len
must also have been given and the generated tone will be swept between
-the given frequencies. If
-.I freq2
-is preceded with `-', the tone will change by a fixed number of octaves
-per second; if `~', a fixed number of hertz per second.
+the given frequencies. The two given frequencies must be separated by
+one of the characters `:', `+', `/', or `-'. This character is used to
+specify the sweep function as follows:
+.RS
+.IP \fB:\fR
+Linear: the tone will change by a fixed number of hertz per second.
+.IP \fB+\fR
+Square: a second-order function is used to change the tone.
+.IP \fB/\fR
+Exponential: the tone will change by a fixed number of semitones per second.
+.IP \fB\-\fR
+Exponential: as `/', but initial phase always zero, and stepped (less
+smooth) frequency changes.
+.RE
+.TP
+\
Not used for noise.
.SP
\fIoff\fR is the bias (DC-offset) of the signal in percent; default=0.
--- a/src/synth.c
+++ b/src/synth.c
@@ -1,7 +1,7 @@
/* libSoX synth - Synthesizer Effect.
*
* Copyright (c) Jan 2001 Carsten Borchardt
- * Copyright (c) 2001-2007 SoX contributors
+ * Copyright (c) 2001-2008 SoX contributors
*
* This source code is freely redistributable and may be used for any purpose.
* This copyright notice must be maintained. The authors are not responsible
@@ -145,12 +145,14 @@
+typedef enum {Linear, Square, Exp, Exp_cycle} sweep_t;+
typedef struct {/* options */
type_t type;
combine_t combine;
double freq, freq2, mult;
- sox_bool log_sweep;
+ sweep_t sweep;
double offset, phase;
double p1, p2, p3; /* Use depends on synth type */
@@ -280,13 +282,15 @@
/* read frequencies if given */
if (isdigit((int) argv[argn][0]) ||
argv[argn][0] == '.' || argv[argn][0] == '%') {+ static const char sweeps[] = ":+/-";
+
chan->freq2 = chan->freq = lsx_parse_frequency(argv[argn], &end_ptr);
if (chan->freq < 0) { sox_fail("invalid freq");return SOX_EOF;
}
- if (*end_ptr == '-' || *end_ptr == '~') { /* freq2 given? */- chan->log_sweep = *end_ptr == '-';
+ if (*end_ptr && strchr(sweeps, *end_ptr)) { /* freq2 given? */+ chan->sweep = strchr(sweeps, *end_ptr) - sweeps;
chan->freq2 = lsx_parse_frequency(end_ptr + 1, &end_ptr);
if (chan->freq2 < 0) { sox_fail("invalid freq2");@@ -301,8 +305,8 @@
sox_fail("frequency: invalid trailing character");return SOX_EOF;
}
- if (chan->log_sweep && chan->freq * chan->freq2 == 0) {- sox_fail("invalid frequency for logarithmic sweep");+ if (chan->sweep >= Exp && chan->freq * chan->freq2 == 0) {+ sox_fail("invalid frequency for exponential sweep");return SOX_EOF;
}
@@ -366,9 +370,23 @@
channel_t chan = &synth->channels[i];
*chan = synth->getopts_channels[i % synth->getopts_nchannels];
set_default_parameters(chan, i);
- chan->mult = chan->log_sweep ?
- synth->samples_to_do? (log(chan->freq2) - log(chan->freq)) / synth->samples_to_do : 1 :
- synth->samples_to_do? (chan->freq2 - chan->freq) / synth->samples_to_do / 2 : 0;
+ switch (chan->sweep) {+ case Linear: chan->mult = synth->samples_to_do?
+ (chan->freq2 - chan->freq) / synth->samples_to_do / 2 : 0;
+ break;
+ case Square: chan->mult = synth->samples_to_do?
+ sqrt(fabs(chan->freq2 - chan->freq)) / synth->samples_to_do / sqrt(3.) : 0;
+ if (chan->freq > chan->freq2)
+ chan->mult = -chan->mult;
+ break;
+ case Exp: chan->mult = synth->samples_to_do?
+ log(chan->freq2 / chan->freq) / synth->samples_to_do * effp->in_signal.rate : 1;
+ chan->freq /= chan->mult;
+ break;
+ case Exp_cycle: chan->mult = synth->samples_to_do?
+ (log(chan->freq2) - log(chan->freq)) / synth->samples_to_do : 1;
+ break;
+ }
sox_debug("type=%s, combine=%s, samples_to_do=%u, f1=%g, f2=%g, ""offset=%g, phase=%g, p1=%g, p2=%g, p3=%g mult=%g",
find_enum_value(chan->type, synth_type)->text,
@@ -381,158 +399,162 @@
-static sox_sample_t do_synth(sox_sample_t synth_input, priv_t * synth, unsigned c, double elapsed_time_s)
+#define sign(d) ((d) < 0? -1. : 1.)
+#define elapsed_time_s synth->samples_done / effp->in_signal.rate
+
+static int flow(sox_effect_t * effp, const sox_sample_t * ibuf, sox_sample_t * obuf,
+ sox_size_t * isamp, sox_size_t * osamp)
{- channel_t chan = &synth->channels[c];
- double synth_out; /* [-1, 1] */
+ priv_t * synth = (priv_t *) effp->priv;
+ unsigned len = min(*isamp, *osamp) / effp->in_signal.channels;
+ unsigned c, done;
+ int result = SOX_SUCCESS;
- if (chan->type < synth_noise) { /* Need to calculate phase: */- double phase; /* [0, 1) */
+ for (done = 0; done < len && result == SOX_SUCCESS; ++done) {+ for (c = 0; c < effp->in_signal.channels; c++) {+ sox_sample_t synth_input = *ibuf++;
+ channel_t chan = &synth->channels[c];
+ double synth_out; /* [-1, 1] */
- if (!chan->log_sweep) {- double f = chan->freq + synth->samples_done * chan->mult;
- phase = f * elapsed_time_s;
- }
- else {- double f = chan->freq * exp(synth->samples_done * chan->mult);
- double cycle_elapsed_time_s = elapsed_time_s - chan->cycle_start_time_s;
- if (f * cycle_elapsed_time_s >= 1) { /* move to next cycle */- chan->cycle_start_time_s += 1 / f;
- cycle_elapsed_time_s = elapsed_time_s - chan->cycle_start_time_s;
- }
- phase = f * cycle_elapsed_time_s;
- }
- phase = fmod(phase + chan->phase, 1.0);
+ if (chan->type < synth_noise) { /* Need to calculate phase: */+ double phase; /* [0, 1) */
+ switch (chan->sweep) {+ case Linear:
+ phase = (chan->freq + synth->samples_done * chan->mult) *
+ elapsed_time_s;
+ break;
+ case Square:
+ phase = (chan->freq + sign(chan->mult) *
+ sqr(synth->samples_done * chan->mult)) * elapsed_time_s;
+ break;
+ case Exp:
+ phase = chan->freq * exp(chan->mult * elapsed_time_s);
+ break;
+ case Exp_cycle: {+ double f = chan->freq * exp(synth->samples_done * chan->mult);
+ double cycle_elapsed_time_s = elapsed_time_s - chan->cycle_start_time_s;
+ if (f * cycle_elapsed_time_s >= 1) { /* move to next cycle */+ chan->cycle_start_time_s += 1 / f;
+ cycle_elapsed_time_s = elapsed_time_s - chan->cycle_start_time_s;
+ }
+ phase = f * cycle_elapsed_time_s;
+ break;
+ }
+ }
+ phase = fmod(phase + chan->phase, 1.0);
- switch (chan->type) {- case synth_sine:
- synth_out = sin(2 * M_PI * phase);
- break;
+ switch (chan->type) {+ case synth_sine:
+ synth_out = sin(2 * M_PI * phase);
+ break;
- case synth_square:
- /* |_______ | +1
- * | | |
- * |_______|__________| 0
- * | | |
- * | |__________| -1
- * | |
- * 0 p1 1
- */
- synth_out = -1 + 2 * (phase < chan->p1);
- break;
+ case synth_square:
+ /* |_______ | +1
+ * | | |
+ * |_______|__________| 0
+ * | | |
+ * | |__________| -1
+ * | |
+ * 0 p1 1
+ */
+ synth_out = -1 + 2 * (phase < chan->p1);
+ break;
- case synth_sawtooth:
- /* | __| +1
- * | __/ |
- * |_______/_____| 0
- * | __/ |
- * |_/ | -1
- * | |
- * 0 1
- */
- synth_out = -1 + 2 * phase;
- break;
+ case synth_sawtooth:
+ /* | __| +1
+ * | __/ |
+ * |_______/_____| 0
+ * | __/ |
+ * |_/ | -1
+ * | |
+ * 0 1
+ */
+ synth_out = -1 + 2 * phase;
+ break;
- case synth_triangle:
- /* | . | +1
- * | / \ |
- * |__/___\__| 0
- * | / \ |
- * |/ \| -1
- * | |
- * 0 p1 1
- */
+ case synth_triangle:
+ /* | . | +1
+ * | / \ |
+ * |__/___\__| 0
+ * | / \ |
+ * |/ \| -1
+ * | |
+ * 0 p1 1
+ */
- if (phase < chan->p1)
- synth_out = -1 + 2 * phase / chan->p1; /* In rising part of period */
- else
- synth_out = 1 - 2 * (phase - chan->p1) / (1 - chan->p1); /* In falling part */
- break;
+ if (phase < chan->p1)
+ synth_out = -1 + 2 * phase / chan->p1; /* In rising part of period */
+ else
+ synth_out = 1 - 2 * (phase - chan->p1) / (1 - chan->p1); /* In falling part */
+ break;
- case synth_trapezium:
- /* | ______ |+1
- * | / \ |
- * |__/________\___________| 0
- * | / \ |
- * |/ \_________|-1
- * | |
- * 0 p1 p2 p3 1
- */
- if (phase < chan->p1) /* In rising part of period */
- synth_out = -1 + 2 * phase / chan->p1;
- else if (phase < chan->p2) /* In high part of period */
- synth_out = 1;
- else if (phase < chan->p3) /* In falling part */
- synth_out = 1 - 2 * (phase - chan->p2) / (chan->p3 - chan->p2);
- else /* In low part of period */
- synth_out = -1;
- break;
+ case synth_trapezium:
+ /* | ______ |+1
+ * | / \ |
+ * |__/________\___________| 0
+ * | / \ |
+ * |/ \_________|-1
+ * | |
+ * 0 p1 p2 p3 1
+ */
+ if (phase < chan->p1) /* In rising part of period */
+ synth_out = -1 + 2 * phase / chan->p1;
+ else if (phase < chan->p2) /* In high part of period */
+ synth_out = 1;
+ else if (phase < chan->p3) /* In falling part */
+ synth_out = 1 - 2 * (phase - chan->p2) / (chan->p3 - chan->p2);
+ else /* In low part of period */
+ synth_out = -1;
+ break;
- case synth_exp:
- /* | | | +1
- * | | | |
- * | _| |_ | 0
- * | __- -__ |
- * |____--- ---____ | f(p2)
- * | |
- * 0 p1 1
- */
- synth_out = dB_to_linear(chan->p2 * -100); /* 0 .. 1 */
- if (phase < chan->p1)
- synth_out = synth_out * exp(phase * log(1 / synth_out) / chan->p1);
- else
- synth_out = synth_out * exp((1 - phase) * log(1 / synth_out) / (1 - chan->p1));
- synth_out = synth_out * 2 - 1; /* map 0 .. 1 to -1 .. +1 */
- break;
+ case synth_exp:
+ /* | | | +1
+ * | | | |
+ * | _| |_ | 0
+ * | __- -__ |
+ * |____--- ---____ | f(p2)
+ * | |
+ * 0 p1 1
+ */
+ synth_out = dB_to_linear(chan->p2 * -100); /* 0 .. 1 */
+ if (phase < chan->p1)
+ synth_out = synth_out * exp(phase * log(1 / synth_out) / chan->p1);
+ else
+ synth_out = synth_out * exp((1 - phase) * log(1 / synth_out) / (1 - chan->p1));
+ synth_out = synth_out * 2 - 1; /* map 0 .. 1 to -1 .. +1 */
+ break;
- default: synth_out = 0;
- }
- } else switch (chan->type) {+ default: synth_out = 0;
+ }
+ } else switch (chan->type) {#define RAND (2. * rand() * (1. / RAND_MAX) - 1)
- case synth_whitenoise:
- synth_out = RAND;
- break;
+ case synth_whitenoise:
+ synth_out = RAND;
+ break;
- case synth_pinknoise:
- synth_out = GeneratePinkNoise(&(chan->pink_noise));
- break;
+ case synth_pinknoise:
+ synth_out = GeneratePinkNoise(&(chan->pink_noise));
+ break;
- case synth_brownnoise:
- do synth_out = chan->brown_noise + RAND * (1. / 16);
- while (fabs(synth_out) > 1);
- chan->brown_noise = synth_out;
- break;
+ case synth_brownnoise:
+ do synth_out = chan->brown_noise + RAND * (1. / 16);
+ while (fabs(synth_out) > 1);
+ chan->brown_noise = synth_out;
+ break;
- default: synth_out = 0;
- }
+ default: synth_out = 0;
+ }
- /* Add offset, but prevent clipping: */
- synth_out = synth_out * (1 - fabs(chan->offset)) + chan->offset;
+ /* Add offset, but prevent clipping: */
+ synth_out = synth_out * (1 - fabs(chan->offset)) + chan->offset;
- switch (chan->combine) {- case synth_create: return synth_out * synth->max;
- case synth_mix : return (synth_out * synth->max + synth_input) * 0.5;
- case synth_amod : return (synth_out + 1) * synth_input * 0.5;
- case synth_fmod : return synth_out * synth_input;
- }
- return 0;
-}
-
-
-
-static int flow(sox_effect_t * effp, const sox_sample_t * ibuf, sox_sample_t * obuf,
- sox_size_t * isamp, sox_size_t * osamp)
-{- priv_t * synth = (priv_t *) effp->priv;
- unsigned len = min(*isamp, *osamp) / effp->in_signal.channels;
- unsigned c, done;
- double sample_period = 1 / effp->in_signal.rate;
- int result = SOX_SUCCESS;
-
- for (done = 0; done < len && result == SOX_SUCCESS; ++done) {- double elapsed_time_s = synth->samples_done * sample_period;
- for (c = 0; c < effp->in_signal.channels; c++)
- *obuf++ = do_synth(*ibuf++, synth, c, elapsed_time_s);
+ switch (chan->combine) {+ case synth_create: *obuf++ = synth_out * synth->max; break;
+ case synth_mix : *obuf++ = (synth_out * synth->max + synth_input) * 0.5; break;
+ case synth_amod : *obuf++ = (synth_out + 1) * synth_input * 0.5; break;
+ case synth_fmod : *obuf++ = synth_out * synth_input; break;
+ }
+ }
if (++synth->samples_done == synth->samples_to_do)
result = SOX_EOF;
}
@@ -564,7 +586,7 @@
const sox_effect_handler_t *sox_synth_effect_fn(void)
{ static sox_effect_handler_t handler = {- "synth", "[len] {type [combine] [freq[k][-freq2[k]|~freq2[k]] [off [ph [p1 [p2 [p3]]]]]]}",+ "synth", "[len] {type [combine] [[%]freq[k][:|+|/|-[%]freq2[k]] [off [ph [p1 [p2 [p3]]]]]]}",SOX_EFF_MCHAN | SOX_EFF_PREC |SOX_EFF_LENGTH,
getopts, start, flow, 0, stop, kill, sizeof(priv_t)
};