Skip to content

[ALSA] Improve stream setup parameters. #520

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
alexmoon wants to merge 1 commit into from
Closed

[ALSA] Improve stream setup parameters. #520

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
70 changes: 37 additions & 33 deletions src/host/alsa/mod.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -251,11 +251,8 @@ impl Device {
Err((e, _)) => return Err(e.into()),
Ok(handle) => handle,
};
let can_pause = {
let hw_params = set_hw_params_from_format(&handle, conf, sample_format)?;
hw_params.can_pause()
};
let (_buffer_len, period_len) = set_sw_params_from_format(&handle, conf)?;
let can_pause = set_hw_params_from_format(&handle, conf, sample_format)?;
let period_len = set_sw_params_from_format(&handle, conf, stream_type)?;

handle.prepare()?;

Expand All @@ -277,7 +274,9 @@ impl Device {
_ => None,
};

handle.start()?;
if let alsa::Direction::Capture = stream_type {
handle.start()?;
}

let stream_inner = StreamInner {
channel: handle,
Expand Down Expand Up @@ -387,7 +386,7 @@ impl Device {
}
}

if rates.len() == 0 {
if rates.is_empty() {
vec![(min_rate, max_rate)]
} else {
rates
Expand Down Expand Up @@ -420,14 +419,14 @@ impl Device {
supported_formats.len() * supported_channels.len() * sample_rates.len(),
);
for &sample_format in supported_formats.iter() {
for channels in supported_channels.iter() {
for &channels in supported_channels.iter() {
for &(min_rate, max_rate) in sample_rates.iter() {
output.push(SupportedStreamConfigRange {
channels: channels.clone(),
channels,
min_sample_rate: SampleRate(min_rate as u32),
max_sample_rate: SampleRate(max_rate as u32),
buffer_size: buffer_size_range.clone(),
sample_format: sample_format,
sample_format,
});
}
}
Expand Down Expand Up @@ -859,14 +858,13 @@ fn stream_timestamp(
None => {
let trigger_ts = status.get_trigger_htstamp();
let ts = status.get_htstamp();
let nanos = timespec_diff_nanos(ts, trigger_ts)
.try_into()
.unwrap_or_else(|_| {
panic!(
"get_htstamp `{:?}` was earlier than get_trigger_htstamp `{:?}`",
ts, trigger_ts
);
});
let nanos = timespec_diff_nanos(ts, trigger_ts);
if nanos < 0 {
panic!(
"get_htstamp `{:?}` was earlier than get_trigger_htstamp `{:?}`",
ts, trigger_ts
);
}
Ok(crate::StreamInstant::from_nanos(nanos))
}
Some(creation) => {
Expand Down Expand Up @@ -963,11 +961,11 @@ impl StreamTrait for Stream {
}
}

fn set_hw_params_from_format<'a>(
pcm_handle: &'a alsa::pcm::PCM,
fn set_hw_params_from_format(
pcm_handle: &alsa::pcm::PCM,
config: &StreamConfig,
sample_format: SampleFormat,
) -> Result<alsa::pcm::HwParams<'a>, BackendSpecificError> {
) -> Result<bool, BackendSpecificError> {
let hw_params = alsa::pcm::HwParams::any(pcm_handle)?;
hw_params.set_access(alsa::pcm::Access::RWInterleaved)?;

Expand All @@ -990,7 +988,10 @@ fn set_hw_params_from_format<'a>(
hw_params.set_channels(config.channels as u32)?;

match config.buffer_size {
BufferSize::Fixed(v) => hw_params.set_buffer_size(v as alsa::pcm::Frames)?,
BufferSize::Fixed(v) => {
hw_params.set_period_size_near((v / 4) as alsa::pcm::Frames, alsa::ValueOr::Nearest)?;
hw_params.set_buffer_size(v as alsa::pcm::Frames)?;
}
BufferSize::Default => {
// These values together represent a moderate latency and wakeup interval.
// Without them we are at the mercy of the device
Expand All @@ -1001,37 +1002,40 @@ fn set_hw_params_from_format<'a>(

pcm_handle.hw_params(&hw_params)?;

Ok(hw_params)
Ok(hw_params.can_pause())
}

fn set_sw_params_from_format(
pcm_handle: &alsa::pcm::PCM,
config: &StreamConfig,
) -> Result<(usize, usize), BackendSpecificError> {
stream_type: alsa::Direction,
) -> Result<usize, BackendSpecificError> {
let sw_params = pcm_handle.sw_params_current()?;
sw_params.set_start_threshold(0)?;

let (buffer_len, period_len) = {
let period_len = {
let (buffer, period) = pcm_handle.get_params()?;
if buffer == 0 {
return Err(BackendSpecificError {
description: "initialization resulted in a null buffer".to_string(),
});
}
sw_params.set_avail_min(period as alsa::pcm::Frames)?;
let buffer = buffer as usize * config.channels as usize;
let period = period as usize * config.channels as usize;
(buffer, period)

let start_threshold = match stream_type {
alsa::Direction::Playback => buffer - period,
alsa::Direction::Capture => 1,
};
sw_params.set_start_threshold(start_threshold.try_into().unwrap())?;

period as usize * config.channels as usize
};

sw_params.set_tstamp_mode(true)?;
// TODO:
// Pending new version of alsa-sys and alsa-rs getting published.
// sw_params.set_tstamp_type(alsa::pcm::TstampType::MonotonicRaw)?;
sw_params.set_tstamp_type(alsa::pcm::TstampType::MonotonicRaw)?;

pcm_handle.sw_params(&sw_params)?;

Ok((buffer_len, period_len))
Ok(period_len)
}

impl From<alsa::Error> for BackendSpecificError {
Expand Down