[Pkg-alsa-devel] Bug#663090: [alsa-devel] amixer: convert percentage into db wrongly
Takashi Iwai
tiwai at suse.de
Fri Mar 9 11:33:19 UTC 2012
At Fri, 9 Mar 2012 18:06:17 +0800,
Adam Lee wrote:
>
> On Fri, Mar 09, 2012 at 10:30:27AM +0100, Takashi Iwai wrote:
> > At Fri, 9 Mar 2012 17:07:17 +0800,
> > Adam Lee wrote:
> > >
> > > On Fri, Mar 09, 2012 at 07:40:27AM +0100, Takashi Iwai wrote:
> > > > At Fri, 9 Mar 2012 12:22:47 +0800,
> > > > Adam Lee wrote:
> > > > >
> > > > > Add Vincent in cc, because conky read amixer's result.
> > > > >
> > > > > On Thu, Mar 08, 2012 at 05:45:14PM +0100, Takashi Iwai wrote:
> > > > > > > * Adam Lee <adam8157 at gmail.com> [2012-03-08 20:36 +0800]:
> > > > > > >
> > > > > > > Package: alsa-utils
> > > > > > > Version: 1.0.25-1
> > > > > > > Severity: important
> > > > > > >
> > > > > > >
> > > > > > > db is not linear, but amixer believe it is.
> > > > > > >
> > > > > > > "amixer get Master" says "Limits: Playback 0 - 74", then everytime I run
> > > > > > > "amixer -q sset Master 10%-", there is 8db dec.
> > > > > > >
> > > > > > > For example, at first Master is 100% and 0db, both alsamixer and amixer
> > > > > > > think it is, and after I run "amixer -q sset Master 10%-", both
> > > > > > > alsamixer and amixer says Master is -8.00db, but alsamixer says it is
> > > > > > > 72%, amixer says it is 89%.
> > > > > > >
> > > > > > > alsamixer is right, amixer calc and set wrongly.
> > > > > >
> > > > > > No, both are correct. You are dreaming too much on the world unified
> > > > > > percentage representation :)
> > > > > >
> > > > > > The percentage in amixer has nothing to do with dB level.
> > > > > > It's just the percentage of the raw value range of that mixer
> > > > > > element. Thus showing 89% is correct. It's 10% down from 100%
> > > > > > (1% is because of the resolution of the raw values).
> > > > > >
> > > > > > Now, alsamixer shows the percentage in a different way. It's
> > > > > > explained well in the source code (alsamixer/volume_mapping.c), but
> > > > > > not mentioned in the man page, unfortunately.
> > > > > >
> > > > > > * The mapping is designed so that the position in the interval is proportional
> > > > > > * to the volume as a human ear would perceive it (i.e., the position is the
> > > > > > * cubic root of the linear sample multiplication factor). For controls with
> > > > > > * a small range (24 dB or less), the mapping is linear in the dB values so
> > > > > > * that each step has the same size visually. Only for controls without dB
> > > > > > * information, a linear mapping of the hardware volume register values is used
> > > > > > * (this is the same algorithm as used in the old alsamixer).
> > > > > >
> > > > > > The percentage representation in alsamixer corresponds to this
> > > > > > mapping, thus it's neither dB nor linear percent.
> > > > > >
> > > > >
> > > > > Hi, Takashi
> > > > >
> > > > > Thank you for replying. But I still insist this is a bug. Three
> > > > > questions:
> > > > >
> > > > > 1, several months ago, it's OK, both amixer and alsamixer use the human
> > > > > mapping(0-10% and 90%-100% are the same change by a human ear), why not
> > > > > now?
> > > >
> > > > amixer hasn't been changed until yet. It handles either in raw values
> > > > or in dB. No human-ear mapping at all. It's never changed since
> > > > years, and won't be changed. If the volume mapping would be
> > > > implemented to amixer in future, it must be only optional.
> > > >
> > > > Only the recent alsamixer introduced the volume mapping to visualize
> > > > the volumes reasonably.
> > > >
> > >
> > > OK, thank you. Maybe an optional will make everyone happy.
> > >
> > > > > 2, conky(Vincent, I mean ${mixer}), some other software, lot of user's
> > > > > scripts use amixer to set or get volume, expecting the human mapping,
> > > > > why change the behavior?
> > > >
> > > > You must be smoking something bad. The behavior of amixer hasn't been
> > > > changed.
> > > >
> > >
> > > I figured out a reason probably, when the limits range is wide, like
> > > 0-65536, amixer's mapping and alsamixer's human-ear mapping are close.
> > >
> > > If I remember right, my hardware's limits was 0-65536, but it becomes
> > > 0-74 after I run "alsactl init", but unfortunately, I don't know how to
> > > modify it back.
> > >
> > > > > 3, alsamixer and amixer use the same dB value, why there is difference
> > > > > in percentage? If alsa-utils developer think the human mapping sucks,
> > > > > why you guys still use it in alsamixer? There is no "both correct", the
> > > > > difference confuses user...
> > > >
> > > > That's true. alsamixer should have stopped showing the stupid
> > > > percentage.
> > > >
> > > > The biggest understand is that people (including you) think there is
> > > > an absolutely perfect percentage definition for the sound level. It's
> > > > an illusion.
> > > >
> > >
> > > I don't expect an absolutely perfect percentage definition. I want a
> > > human-ear mapping, which alsamixer does well, 100% is about as ten times
> > > loud as 10%.
> >
> > How did you measure _quantitatively_ it's exactly ten times louder?
> > And you think 50% is ten times loud as 5% volume, 10% is ten times
> > loud as 1%? Things aren't so easy, unfortunately.
> >
> > > But amixer doesn't work like that, amixer's 100% is about
> > > as *one hundred times* as amixer's 10%.
> >
> > Yes, this is what's amixer expected to behave. It's a value just
> > representing the percentage of a "raw value" of the mixer element.
> > It never says it's corresponding to any practical volume. This is the
> > misunderstanding first of all.
> >
> > For example, I guess in your 64k case, the raw value is even not in dB
> > unit but it's a linear volume. amixer doesn't care. 10% means only
> > the 6553 of 65536. That's all. So simple.
> > (In addition, amixer can handle dB, e.g. amixer set Master +10dB or
> > such. But it's not suitable for percentage unit because dB level
> > can't be represented in the absolute percent volume -- what is 10% in
> > dB?)
> >
> > > Maybe it is beautiful, and alsamixer's human-ear mapping is stupid in
> > > the sound science universe. But as a common user, I don't think so. And
> > > I don't know how you guys put up with it :(
> >
> > No, you misunderstand what I wrote. alsamixer's mapping is really an
> > improvement. That's why it was implemented recently. But if it shows
> > a different number, user may wonder, just like you did. If you didn't
> > see a number, you didn't notice the difference :)
> >
> > But amixer wasn't changed. amixer is a tool to manipulate raw
> > values. Of course, it'd be also nice to implement the same percentage
> > expression, but as already mentioned, it should be activated only via
> > an option. The default behavior of amixer must not be changed for
> > compatibility reason.
> >
>
> OK.
>
> Looking forward to the option, if your time and other capacity allow :)
The implementation isn't too hard. I wrote a quick patch now as below.
It became bigger than I thought since it contains many clean-ups that
are needed to adapt the mapped volume.
With the patch, amixer shows and reads the percent value with -M
option just like in alsamixer.
Takashi
---
diff --git a/amixer/Makefile.am b/amixer/Makefile.am
index fcd0e81..ba67a57 100644
--- a/amixer/Makefile.am
+++ b/amixer/Makefile.am
@@ -4,7 +4,7 @@ LDADD = -lm
# CFLAGS += -g -Wall
bin_PROGRAMS = amixer
-amixer_SOURCES = amixer.c
+amixer_SOURCES = amixer.c ../alsamixer/volume_mapping.c
noinst_HEADERS = amixer.h
man_MANS = amixer.1
EXTRA_DIST = amixer.1
diff --git a/amixer/amixer.c b/amixer/amixer.c
index 9d2855d..a0a7387 100644
--- a/amixer/amixer.c
+++ b/amixer/amixer.c
@@ -29,7 +29,9 @@
#include <assert.h>
#include <alsa/asoundlib.h>
#include <sys/poll.h>
+#include <stdint.h>
#include "amixer.h"
+#include "../alsamixer/volume_mapping.h"
#define LEVEL_BASIC (1<<0)
#define LEVEL_INACTIVE (1<<1)
@@ -68,6 +70,8 @@ static int help(void)
printf(" -i,--inactive show also inactive controls\n");
printf(" -a,--abstract L select abstraction level (none or basic)\n");
printf(" -s,--stdin Read and execute commands from stdin sequentially\n");
+ printf(" -R,--raw-volume Use the raw value (default)\n");
+ printf(" -M,--mapped-volume Use the mapped volume\n");
printf("\nAvailable commands:\n");
printf(" scontrols show all mixer simple controls\n");
printf(" scontents show contents of all mixer simple controls (default command)\n");
@@ -187,9 +191,9 @@ static int convert_db_range(int val, int omin, int omax, int nmin, int nmax)
/* Fuction to convert from volume to percentage. val = volume */
-static int convert_prange(int val, int min, int max)
+static int convert_prange(long val, long min, long max)
{
- int range = max - min;
+ long range = max - min;
int tmp;
if (range == 0)
@@ -204,29 +208,6 @@ static int convert_prange(int val, int min, int max)
#define convert_prange1(val, min, max) \
ceil((val) * ((max) - (min)) * 0.01 + (min))
-static const char *get_percent(int val, int min, int max)
-{
- static char str[32];
- int p;
-
- p = convert_prange(val, min, max);
- sprintf(str, "%i [%i%%]", val, p);
- return str;
-}
-
-#if 0
-static const char *get_percent1(int val, int min, int max, int min_dB, int max_dB)
-{
- static char str[32];
- int p, db;
-
- p = convert_prange(val, min, max);
- db = convert_db_range(val, min, max, min_dB, max_dB);
- sprintf(str, "%i [%i%%] [%i.%02idB]", val, p, db / 100, abs(db % 100));
- return str;
-}
-#endif
-
static long get_integer(char **ptr, long min, long max)
{
long val = min;
@@ -288,26 +269,83 @@ struct volume_ops {
int (*get)(snd_mixer_elem_t *elem, snd_mixer_selem_channel_id_t c,
long *value);
int (*set)(snd_mixer_elem_t *elem, snd_mixer_selem_channel_id_t c,
- long value);
+ long value, int dir);
};
-enum { VOL_RAW, VOL_DB };
+enum { VOL_RAW, VOL_DB, VOL_MAP };
struct volume_ops_set {
int (*has_volume)(snd_mixer_elem_t *elem);
- struct volume_ops v[2];
+ struct volume_ops v[3];
};
static int set_playback_dB(snd_mixer_elem_t *elem,
- snd_mixer_selem_channel_id_t c, long value)
+ snd_mixer_selem_channel_id_t c, long value, int dir)
{
- return snd_mixer_selem_set_playback_dB(elem, c, value, 0);
+ return snd_mixer_selem_set_playback_dB(elem, c, value, dir);
}
static int set_capture_dB(snd_mixer_elem_t *elem,
- snd_mixer_selem_channel_id_t c, long value)
+ snd_mixer_selem_channel_id_t c, long value, int dir)
+{
+ return snd_mixer_selem_set_capture_dB(elem, c, value, dir);
+}
+
+static int set_playback_raw_volume(snd_mixer_elem_t *elem,
+ snd_mixer_selem_channel_id_t c,
+ long value, int dir)
+{
+ return snd_mixer_selem_set_playback_volume(elem, c, value);
+}
+
+static int set_capture_raw_volume(snd_mixer_elem_t *elem,
+ snd_mixer_selem_channel_id_t c,
+ long value, int dir)
+{
+ return snd_mixer_selem_set_capture_volume(elem, c, value);
+}
+
+/* FIXME: normalize to int32 space to be compatible with other types */
+#define MAP_VOL_RES (INT32_MAX / 100)
+
+static int get_mapped_volume_range(snd_mixer_elem_t *elem,
+ long *pmin, long *pmax)
+{
+ *pmin = 0;
+ *pmax = MAP_VOL_RES;
+ return 0;
+}
+
+static int get_playback_mapped_volume(snd_mixer_elem_t *elem,
+ snd_mixer_selem_channel_id_t c,
+ long *value)
+{
+ *value = (rint)(get_normalized_playback_volume(elem, c) * MAP_VOL_RES);
+ return 0;
+}
+
+static int set_playback_mapped_volume(snd_mixer_elem_t *elem,
+ snd_mixer_selem_channel_id_t c,
+ long value, int dir)
{
- return snd_mixer_selem_set_capture_dB(elem, c, value, 0);
+ return set_normalized_playback_volume(elem, c,
+ (double)value / MAP_VOL_RES, dir);
+}
+
+static int get_capture_mapped_volume(snd_mixer_elem_t *elem,
+ snd_mixer_selem_channel_id_t c,
+ long *value)
+{
+ *value = (rint)(get_normalized_capture_volume(elem, c) * MAP_VOL_RES);
+ return 0;
+}
+
+static int set_capture_mapped_volume(snd_mixer_elem_t *elem,
+ snd_mixer_selem_channel_id_t c,
+ long value, int dir)
+{
+ return set_normalized_capture_volume(elem, c,
+ (double)value / MAP_VOL_RES, dir);
}
static const struct volume_ops_set vol_ops[2] = {
@@ -315,29 +353,42 @@ static const struct volume_ops_set vol_ops[2] = {
.has_volume = snd_mixer_selem_has_playback_volume,
.v = {{ snd_mixer_selem_get_playback_volume_range,
snd_mixer_selem_get_playback_volume,
- snd_mixer_selem_set_playback_volume },
+ set_playback_raw_volume },
{ snd_mixer_selem_get_playback_dB_range,
snd_mixer_selem_get_playback_dB,
- set_playback_dB }},
+ set_playback_dB },
+ { get_mapped_volume_range,
+ get_playback_mapped_volume,
+ set_playback_mapped_volume },
+ },
},
{
.has_volume = snd_mixer_selem_has_capture_volume,
.v = {{ snd_mixer_selem_get_capture_volume_range,
snd_mixer_selem_get_capture_volume,
- snd_mixer_selem_set_capture_volume },
+ set_capture_raw_volume },
{ snd_mixer_selem_get_capture_dB_range,
snd_mixer_selem_get_capture_dB,
- set_capture_dB }},
+ set_capture_dB },
+ { get_mapped_volume_range,
+ get_capture_mapped_volume,
+ set_capture_mapped_volume },
+ },
},
};
+static int std_vol_type = VOL_RAW;
+
static int set_volume_simple(snd_mixer_elem_t *elem,
snd_mixer_selem_channel_id_t chn,
char **ptr, int dir)
{
long val, orig, pmin, pmax;
char *p = *ptr, *s;
- int invalid = 0, err = 0, vol_type = VOL_RAW;
+ int invalid = 0, percent = 0, err = 0;
+ int vol_type = std_vol_type;
+ double scale = 1.0;
+ int correct = 0;
if (! vol_ops[dir].has_volume(elem))
invalid = 1;
@@ -347,10 +398,6 @@ static int set_volume_simple(snd_mixer_elem_t *elem,
if (*p == '\0' || (!isdigit(*p) && *p != '-'))
goto skip;
- if (! invalid &&
- vol_ops[dir].v[VOL_RAW].get_range(elem, &pmin, &pmax) < 0)
- invalid = 1;
-
s = p;
val = strtol(s, &p, 10);
if (*p == '.') {
@@ -358,32 +405,37 @@ static int set_volume_simple(snd_mixer_elem_t *elem,
strtol(p, &p, 10);
}
if (*p == '%') {
- if (! invalid)
- val = (long)convert_prange1(strtod(s, NULL), pmin, pmax);
+ percent = 1;
p++;
} else if (p[0] == 'd' && p[1] == 'B') {
- if (! invalid) {
- val = (long)(strtod(s, NULL) * 100.0);
- vol_type = VOL_DB;
- if (vol_ops[dir].v[vol_type].get_range(elem, &pmin, &pmax) < 0)
- invalid = 1;
- }
+ vol_type = VOL_DB;
p += 2;
- }
+ scale = 100;
+ } else
+ vol_type = VOL_RAW;
+
+ val = (long)(strtod(s, NULL) * scale);
+ if (vol_ops[dir].v[vol_type].get_range(elem, &pmin, &pmax) < 0)
+ invalid = 1;
+ if (percent)
+ val = (long)convert_prange1(val, pmin, pmax);
if (*p == '+' || *p == '-') {
if (! invalid) {
if (vol_ops[dir].v[vol_type].get(elem, chn, &orig) < 0)
invalid = 1;
- if (*p == '+')
+ if (*p == '+') {
val = orig + val;
- else
+ correct = -1;
+ } else {
val = orig - val;
+ correct = 1;
+ }
}
p++;
}
if (! invalid) {
val = check_range(val, pmin, pmax);
- err = vol_ops[dir].v[vol_type].set(elem, chn, val);
+ err = vol_ops[dir].v[vol_type].set(elem, chn, val, correct);
}
skip:
if (*p == ',')
@@ -711,15 +763,33 @@ static int controls(int level)
return 0;
}
+static void show_selem_volume(snd_mixer_elem_t *elem,
+ snd_mixer_selem_channel_id_t chn, int dir,
+ long min, long max)
+{
+ long raw, val;
+ vol_ops[dir].v[VOL_RAW].get(elem, chn, &raw);
+ if (std_vol_type == VOL_RAW)
+ val = convert_prange(raw, min, max);
+ else {
+ vol_ops[dir].v[std_vol_type].get(elem, chn, &val);
+ val = convert_prange(val, 0, MAP_VOL_RES);
+ }
+ printf(" %li [%li%%]", raw, val);
+ if (!vol_ops[dir].v[VOL_DB].get(elem, chn, &val)) {
+ printf(" [");
+ print_dB(val);
+ printf("]");
+ }
+}
+
static int show_selem(snd_mixer_t *handle, snd_mixer_selem_id_t *id, const char *space, int level)
{
snd_mixer_selem_channel_id_t chn;
long pmin = 0, pmax = 0;
long cmin = 0, cmax = 0;
- long pvol, cvol;
int psw, csw;
int pmono, cmono, mono_ok = 0;
- long db;
snd_mixer_elem_t *elem;
elem = snd_mixer_find_selem(handle, id);
@@ -868,13 +938,7 @@ static int show_selem(snd_mixer_t *handle, snd_mixer_selem_id_t *id, const char
mono_ok = 1;
}
if (snd_mixer_selem_has_common_volume(elem)) {
- snd_mixer_selem_get_playback_volume(elem, SND_MIXER_SCHN_MONO, &pvol);
- printf(" %s", get_percent(pvol, pmin, pmax));
- if (!snd_mixer_selem_get_playback_dB(elem, SND_MIXER_SCHN_MONO, &db)) {
- printf(" [");
- print_dB(db);
- printf("]");
- }
+ show_selem_volume(elem, SND_MIXER_SCHN_MONO, 0, pmin, pmax);
}
if (snd_mixer_selem_has_common_switch(elem)) {
snd_mixer_selem_get_playback_switch(elem, SND_MIXER_SCHN_MONO, &psw);
@@ -891,13 +955,7 @@ static int show_selem(snd_mixer_t *handle, snd_mixer_selem_id_t *id, const char
if (snd_mixer_selem_has_playback_volume(elem)) {
printf(" Playback");
title = 1;
- snd_mixer_selem_get_playback_volume(elem, SND_MIXER_SCHN_MONO, &pvol);
- printf(" %s", get_percent(pvol, pmin, pmax));
- if (!snd_mixer_selem_get_playback_dB(elem, SND_MIXER_SCHN_MONO, &db)) {
- printf(" [");
- print_dB(db);
- printf("]");
- }
+ show_selem_volume(elem, SND_MIXER_SCHN_MONO, 0, pmin, pmax);
}
}
if (!snd_mixer_selem_has_common_switch(elem)) {
@@ -919,13 +977,7 @@ static int show_selem(snd_mixer_t *handle, snd_mixer_selem_id_t *id, const char
if (snd_mixer_selem_has_capture_volume(elem)) {
printf(" Capture");
title = 1;
- snd_mixer_selem_get_capture_volume(elem, SND_MIXER_SCHN_MONO, &cvol);
- printf(" %s", get_percent(cvol, cmin, cmax));
- if (!snd_mixer_selem_get_capture_dB(elem, SND_MIXER_SCHN_MONO, &db)) {
- printf(" [");
- print_dB(db);
- printf("]");
- }
+ show_selem_volume(elem, SND_MIXER_SCHN_MONO, 1, cmin, cmax);
}
}
if (!snd_mixer_selem_has_common_switch(elem)) {
@@ -946,13 +998,7 @@ static int show_selem(snd_mixer_t *handle, snd_mixer_selem_id_t *id, const char
continue;
printf("%s%s:", space, snd_mixer_selem_channel_name(chn));
if (!pmono && !cmono && snd_mixer_selem_has_common_volume(elem)) {
- snd_mixer_selem_get_playback_volume(elem, chn, &pvol);
- printf(" %s", get_percent(pvol, pmin, pmax));
- if (!snd_mixer_selem_get_playback_dB(elem, chn, &db)) {
- printf(" [");
- print_dB(db);
- printf("]");
- }
+ show_selem_volume(elem, chn, 0, pmin, pmax);
}
if (!pmono && !cmono && snd_mixer_selem_has_common_switch(elem)) {
snd_mixer_selem_get_playback_switch(elem, chn, &psw);
@@ -964,13 +1010,7 @@ static int show_selem(snd_mixer_t *handle, snd_mixer_selem_id_t *id, const char
if (snd_mixer_selem_has_playback_volume(elem)) {
printf(" Playback");
title = 1;
- snd_mixer_selem_get_playback_volume(elem, chn, &pvol);
- printf(" %s", get_percent(pvol, pmin, pmax));
- if (!snd_mixer_selem_get_playback_dB(elem, chn, &db)) {
- printf(" [");
- print_dB(db);
- printf("]");
- }
+ show_selem_volume(elem, chn, 0, pmin, pmax);
}
}
if (!snd_mixer_selem_has_common_switch(elem)) {
@@ -988,13 +1028,7 @@ static int show_selem(snd_mixer_t *handle, snd_mixer_selem_id_t *id, const char
if (snd_mixer_selem_has_capture_volume(elem)) {
printf(" Capture");
title = 1;
- snd_mixer_selem_get_capture_volume(elem, chn, &cvol);
- printf(" %s", get_percent(cvol, cmin, cmax));
- if (!snd_mixer_selem_get_capture_dB(elem, chn, &db)) {
- printf(" [");
- print_dB(db);
- printf("]");
- }
+ show_selem_volume(elem, chn, 1, cmin, cmax);
}
}
if (!snd_mixer_selem_has_common_switch(elem)) {
@@ -1927,6 +1961,8 @@ int main(int argc, char *argv[])
{"version", 0, NULL, 'v'},
{"abstract", 1, NULL, 'a'},
{"stdin", 0, NULL, 's'},
+ {"raw-volume", 0, NULL, 'R'},
+ {"mapped-volume", 0, NULL, 'M'},
{NULL, 0, NULL, 0},
};
@@ -1934,7 +1970,7 @@ int main(int argc, char *argv[])
while (1) {
int c;
- if ((c = getopt_long(argc, argv, "hc:D:qidnva:s", long_option, NULL)) < 0)
+ if ((c = getopt_long(argc, argv, "hc:D:qidnva:sRM", long_option, NULL)) < 0)
break;
switch (c) {
case 'h':
@@ -1987,6 +2023,12 @@ int main(int argc, char *argv[])
case 's':
read_stdin = 1;
break;
+ case 'R':
+ std_vol_type = VOL_RAW;
+ break;
+ case 'M':
+ std_vol_type = VOL_MAP;
+ break;
default:
fprintf(stderr, "Invalid switch or option needs an argument.\n");
morehelp++;
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