librespot/playback/src/mixer/alsamixer.rs
2022-07-27 23:31:11 +02:00

288 lines
11 KiB
Rust

use crate::player::{db_to_ratio, ratio_to_db};
use super::mappings::{LogMapping, MappedCtrl, VolumeMapping};
use super::{Mixer, MixerConfig, VolumeCtrl};
use alsa::ctl::{ElemId, ElemIface};
use alsa::mixer::{MilliBel, SelemChannelId, SelemId};
use alsa::{Ctl, Round};
use std::ffi::CString;
#[derive(Clone)]
#[allow(dead_code)]
pub struct AlsaMixer {
config: MixerConfig,
min: i64,
max: i64,
range: i64,
min_db: f64,
max_db: f64,
db_range: f64,
has_switch: bool,
is_softvol: bool,
use_linear_in_db: bool,
}
// min_db cannot be depended on to be mute. Also note that contrary to
// its name copied verbatim from Alsa, this is in millibel scale.
const SND_CTL_TLV_DB_GAIN_MUTE: MilliBel = MilliBel(-9999999);
const ZERO_DB: MilliBel = MilliBel(0);
impl Mixer for AlsaMixer {
fn open(config: MixerConfig) -> Self {
info!(
"Mixing with Alsa and volume control: {:?} for device: {} with mixer control: {},{}",
config.volume_ctrl, config.device, config.control, config.index,
);
let mut config = config; // clone
let mixer =
alsa::mixer::Mixer::new(&config.device, false).expect("Could not open Alsa mixer");
let simple_element = mixer
.find_selem(&SelemId::new(&config.control, config.index))
.expect("Could not find Alsa mixer control");
// Query capabilities
let has_switch = simple_element.has_playback_switch();
let is_softvol = simple_element
.get_playback_vol_db(SelemChannelId::mono())
.is_err();
// Query raw volume range
let (min, max) = simple_element.get_playback_volume_range();
let range = i64::abs(max - min);
// Query dB volume range -- note that Alsa exposes a different
// API for hardware and software mixers
let (min_millibel, max_millibel) = if is_softvol {
let control = Ctl::new(&config.device, false)
.expect("Could not open Alsa softvol with that device");
let mut element_id = ElemId::new(ElemIface::Mixer);
element_id.set_name(
&CString::new(config.control.as_str())
.expect("Could not open Alsa softvol with that name"),
);
element_id.set_index(config.index);
let (min_millibel, mut max_millibel) = control
.get_db_range(&element_id)
.expect("Could not get Alsa softvol dB range");
// Alsa can report incorrect maximum volumes due to rounding
// errors. e.g. Alsa rounds [-60.0..0.0] in range [0..255] to
// step size 0.23. Then multiplying 0.23 by 255 incorrectly
// returns a dB range of 58.65 instead of 60 dB, from
// [-60.00..-1.35]. This workaround checks the default case
// where the maximum dB volume is expected to be 0, and cannot
// cover all cases.
if max_millibel != ZERO_DB {
warn!("Alsa mixer reported maximum dB != 0, which is suspect");
let reported_step_size = (max_millibel - min_millibel).0 / range;
let assumed_step_size = (ZERO_DB - min_millibel).0 / range;
if reported_step_size == assumed_step_size {
warn!("Alsa rounding error detected, setting maximum dB to {:.2} instead of {:.2}", ZERO_DB.to_db(), max_millibel.to_db());
max_millibel = ZERO_DB;
} else {
warn!("Please manually set `--volume-range` if this is incorrect");
}
}
(min_millibel, max_millibel)
} else {
let (mut min_millibel, max_millibel) = simple_element.get_playback_db_range();
// Some controls report that their minimum volume is mute, instead
// of their actual lowest dB setting before that.
if min_millibel == SND_CTL_TLV_DB_GAIN_MUTE && min < max {
debug!("Alsa mixer reported minimum dB as mute, trying workaround");
min_millibel = simple_element
.ask_playback_vol_db(min + 1)
.expect("Could not convert Alsa raw volume to dB volume");
}
(min_millibel, max_millibel)
};
let min_db = min_millibel.to_db() as f64;
let max_db = max_millibel.to_db() as f64;
let reported_db_range = f64::abs(max_db - min_db);
// Synchronize the volume control dB range with the mixer control,
// unless it was already set with a command line option.
let db_range = if config.volume_ctrl.range_ok() {
let db_range_override = config.volume_ctrl.db_range();
if db_range_override.is_normal() {
db_range_override
} else {
reported_db_range
}
} else {
config.volume_ctrl.set_db_range(reported_db_range);
reported_db_range
};
if reported_db_range == db_range {
debug!("Alsa dB volume range was reported as {}", reported_db_range);
if reported_db_range > 100.0 {
debug!("Alsa mixer reported dB range > 100, which is suspect");
debug!("Please manually set `--volume-range` if this is incorrect");
}
} else {
debug!(
"Alsa dB volume range was reported as {} but overridden to {}",
reported_db_range, db_range
);
}
// For hardware controls with a small range (24 dB or less),
// force using the dB API with a linear mapping.
let mut use_linear_in_db = false;
if !is_softvol && db_range <= 24.0 {
use_linear_in_db = true;
config.volume_ctrl = VolumeCtrl::Linear;
}
debug!("Alsa mixer control is softvol: {}", is_softvol);
debug!("Alsa support for playback (mute) switch: {}", has_switch);
debug!("Alsa raw volume range: [{}..{}] ({})", min, max, range);
debug!(
"Alsa dB volume range: [{:.2}..{:.2}] ({:.2})",
min_db, max_db, db_range
);
debug!("Alsa forcing linear dB mapping: {}", use_linear_in_db);
Self {
config,
min,
max,
range,
min_db,
max_db,
db_range,
has_switch,
is_softvol,
use_linear_in_db,
}
}
fn volume(&self) -> u16 {
let mixer =
alsa::mixer::Mixer::new(&self.config.device, false).expect("Could not open Alsa mixer");
let simple_element = mixer
.find_selem(&SelemId::new(&self.config.control, self.config.index))
.expect("Could not find Alsa mixer control");
if self.switched_off() {
return 0;
}
let mut mapped_volume = if self.is_softvol {
let raw_volume = simple_element
.get_playback_volume(SelemChannelId::mono())
.expect("Could not get raw Alsa volume");
raw_volume as f64 / self.range as f64 - self.min as f64
} else {
let db_volume = simple_element
.get_playback_vol_db(SelemChannelId::mono())
.expect("Could not get Alsa dB volume")
.to_db() as f64;
if self.use_linear_in_db {
(db_volume - self.min_db) / self.db_range
} else if f64::abs(db_volume - SND_CTL_TLV_DB_GAIN_MUTE.to_db() as f64) <= f64::EPSILON
{
0.0
} else {
db_to_ratio(db_volume - self.max_db)
}
};
// see comment in `set_volume` why we are handling an antilog volume
if mapped_volume > 0.0 && self.is_some_linear() {
mapped_volume = LogMapping::linear_to_mapped(mapped_volume, self.db_range);
}
self.config.volume_ctrl.as_unmapped(mapped_volume)
}
fn set_volume(&self, volume: u16) {
let mixer =
alsa::mixer::Mixer::new(&self.config.device, false).expect("Could not open Alsa mixer");
let simple_element = mixer
.find_selem(&SelemId::new(&self.config.control, self.config.index))
.expect("Could not find Alsa mixer control");
if self.has_switch {
if volume == 0 {
debug!("Disabling playback (setting mute) on Alsa");
simple_element
.set_playback_switch_all(0)
.expect("Could not disable playback (set mute) on Alsa");
} else if self.switched_off() {
debug!("Enabling playback (unsetting mute) on Alsa");
simple_element
.set_playback_switch_all(1)
.expect("Could not enable playback (unset mute) on Alsa");
}
}
let mut mapped_volume = self.config.volume_ctrl.to_mapped(volume);
// Alsa's linear algorithms map everything onto log. Alsa softvol does
// this internally. In the case of `use_linear_in_db` this happens
// automatically by virtue of the dB scale. This means that linear
// controls become log, log becomes log-on-log, and so on. To make
// the controls work as expected, perform an antilog calculation to
// counteract what Alsa will be doing to the set volume.
if mapped_volume > 0.0 && self.is_some_linear() {
mapped_volume = LogMapping::mapped_to_linear(mapped_volume, self.db_range);
}
if self.is_softvol {
let scaled_volume = (self.min as f64 + mapped_volume * self.range as f64) as i64;
debug!("Setting Alsa raw volume to {}", scaled_volume);
simple_element
.set_playback_volume_all(scaled_volume)
.expect("Could not set Alsa raw volume");
return;
}
let db_volume = if self.use_linear_in_db {
self.min_db + mapped_volume * self.db_range
} else if volume == 0 {
// prevent ratio_to_db(0.0) from returning -inf
SND_CTL_TLV_DB_GAIN_MUTE.to_db() as f64
} else {
ratio_to_db(mapped_volume) + self.max_db
};
debug!("Setting Alsa volume to {:.2} dB", db_volume);
simple_element
.set_playback_db_all(MilliBel::from_db(db_volume as f32), Round::Floor)
.expect("Could not set Alsa dB volume");
}
}
impl AlsaMixer {
pub const NAME: &'static str = "alsa";
fn switched_off(&self) -> bool {
if !self.has_switch {
return false;
}
let mixer =
alsa::mixer::Mixer::new(&self.config.device, false).expect("Could not open Alsa mixer");
let simple_element = mixer
.find_selem(&SelemId::new(&self.config.control, self.config.index))
.expect("Could not find Alsa mixer control");
simple_element
.get_playback_switch(SelemChannelId::mono())
.map(|playback| playback == 0)
.unwrap_or(false)
}
fn is_some_linear(&self) -> bool {
self.is_softvol || self.use_linear_in_db
}
}