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volume: change pa_volume_t mapping to cubic

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This commit is contained in:
Lennart Poettering 2009-05-22 01:30:54 +02:00
parent e7bca90775
commit 000bdb8d25
2 changed files with 33 additions and 15 deletions
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42
src/pulse/volume.c
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@ -120,20 +120,28 @@ pa_volume_t pa_sw_volume_divide(pa_volume_t a, pa_volume_t b) {
return pa_sw_volume_from_linear(pa_sw_volume_to_linear(a) / v);
}
#define USER_DECIBEL_RANGE 90
/* Amplitude, not power */
static double linear_to_dB(double v) {
return 20.0 * log10(v);
}
static double dB_to_linear(double v) {
return pow(10.0, v / 20.0);
}
pa_volume_t pa_sw_volume_from_dB(double dB) {
if (isinf(dB) < 0 || dB <= -USER_DECIBEL_RANGE)
if (isinf(dB) < 0 || dB <= PA_DECIBEL_MININFTY)
return PA_VOLUME_MUTED;
return (pa_volume_t) lrint(ceil((dB/USER_DECIBEL_RANGE+1.0)*PA_VOLUME_NORM));
return pa_sw_volume_from_linear(dB_to_linear(dB));
}
double pa_sw_volume_to_dB(pa_volume_t v) {
if (v == PA_VOLUME_MUTED)
if (v <= PA_VOLUME_MUTED)
return PA_DECIBEL_MININFTY;
return ((double) v/PA_VOLUME_NORM-1)*USER_DECIBEL_RANGE;
return linear_to_dB(pa_sw_volume_to_linear(v));
}
pa_volume_t pa_sw_volume_from_linear(double v) {
@ -141,18 +149,28 @@ pa_volume_t pa_sw_volume_from_linear(double v) {
if (v <= 0.0)
return PA_VOLUME_MUTED;
if (v > .999 && v < 1.001)
return PA_VOLUME_NORM;
/*
* We use a cubic mapping here, as suggested and discussed here:
*
* http://www.robotplanet.dk/audio/audio_gui_design/
* http://lists.linuxaudio.org/pipermail/linux-audio-dev/2009-May/thread.html#23151
*/
return pa_sw_volume_from_dB(20.0*log10(v));
return (pa_volume_t) (cbrt(v) * PA_VOLUME_NORM);
}
double pa_sw_volume_to_linear(pa_volume_t v) {
double f;
if (v == PA_VOLUME_MUTED)
if (v <= PA_VOLUME_MUTED)
return 0.0;
return pow(10.0, pa_sw_volume_to_dB(v)/20.0);
if (v == PA_VOLUME_NORM)
return 1.0;
f = ((double) v / PA_VOLUME_NORM);
return f*f*f;
}
char *pa_cvolume_snprint(char *s, size_t l, const pa_cvolume *c) {
@ -225,7 +243,7 @@ char *pa_sw_cvolume_snprint_dB(char *s, size_t l, const pa_cvolume *c) {
l -= pa_snprintf(e, l, "%s%u: %0.2f dB",
first ? "" : " ",
channel,
isinf(f) < 0 || f <= -USER_DECIBEL_RANGE ? -INFINITY : f);
isinf(f) < 0 || f <= PA_DECIBEL_MININFTY ? -INFINITY : f);
e = strchr(e, 0);
first = FALSE;
@ -249,7 +267,7 @@ char *pa_sw_volume_snprint_dB(char *s, size_t l, pa_volume_t v) {
f = pa_sw_volume_to_dB(v);
pa_snprintf(s, l, "%0.2f dB",
isinf(f) < 0 || f <= -USER_DECIBEL_RANGE ? -INFINITY : f);
isinf(f) < 0 || f <= PA_DECIBEL_MININFTY ? -INFINITY : f);
return s;
}