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libobs: Add Logarithmic fader type

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This adds the conversion function used by the old obs based on a
logarithmic scale.
This commit is contained in:
fryshorts 2014-11-27 21:01:26 +01:00
parent 119d77e176
commit 1b034569f0
2 changed files with 45 additions and 1 deletions
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40
libobs/obs-audio-controls.c
View File

@ -155,6 +155,36 @@ static float iec_db_to_def(const float db)
return def;
}
#define LOG_OFFSET_DB 6.0f
#define LOG_RANGE_DB 96.0f
/* equals -log10f(LOG_OFFSET_DB) */
#define LOG_OFFSET_VAL -0.77815125038364363f
/* equals -log10f(-LOG_RANGE_DB + LOG_OFFSET_DB) */
#define LOG_RANGE_VAL -2.00860017176191756f
static float log_def_to_db(const float def)
{
if (def >= 1.0f)
return 0.0f;
else if (def <= 0.0f)
return -INFINITY;
return -(LOG_RANGE_DB + LOG_OFFSET_DB) * powf(
(LOG_RANGE_DB + LOG_OFFSET_DB) / LOG_OFFSET_DB, -def)
+ LOG_OFFSET_DB;
}
static float log_db_to_def(const float db)
{
if (db >= 0.0f)
return 1.0f;
else if (db <= -96.0f)
return 0.0f;
return (-log10f(-db + LOG_OFFSET_DB) - LOG_RANGE_VAL)
/ (LOG_OFFSET_VAL - LOG_RANGE_VAL);
}
static void signal_volume_changed(signal_handler_t *sh,
struct obs_fader *fader, const float db)
{
@ -289,6 +319,12 @@ obs_fader_t *obs_fader_create(enum obs_fader_type type)
fader->max_db = 0.0f;
fader->min_db = -INFINITY;
break;
case OBS_FADER_LOG:
fader->def_to_db = log_def_to_db;
fader->db_to_def = log_db_to_def;
fader->max_db = 0.0f;
fader->min_db = -96.0f;
break;
default:
goto fail;
break;
@ -475,6 +511,10 @@ obs_volmeter_t *obs_volmeter_create(enum obs_fader_type type)
volmeter->pos_to_db = iec_def_to_db;
volmeter->db_to_pos = iec_db_to_def;
break;
case OBS_FADER_LOG:
volmeter->pos_to_db = log_def_to_db;
volmeter->db_to_pos = log_db_to_def;
break;
default:
goto fail;
break;

6
libobs/obs-audio-controls.h
View File

@ -61,7 +61,11 @@ enum obs_fader_type {
[ 2.5 %, 0 % ] | [ -60 dB, -inf dB ]
@endcode
*/
OBS_FADER_IEC
OBS_FADER_IEC,
/**
* @brief Logarithmic fader
*/
OBS_FADER_LOG
};
/**