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audio: reduce alsa and pulseaudio latency to 30ms

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Closes #928

Change contributed by Ali in https://github.com/hexops/mach/pull/1138
I am just cleaning up the commit.

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
This commit is contained in:
Stephen Gutekanst 2024-04-16 10:47:58 -07:00
parent 74595362d3
commit b0d6c88f3b
2 changed files with 11 additions and 8 deletions
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17
src/sysaudio/pulseaudio.zig
View file

@ -57,6 +57,9 @@ const Lib = struct {
pa_cvolume_set: *const fn ([*c]c.pa_cvolume, c_uint, c.pa_volume_t) callconv(.C) [*c]c.pa_cvolume,
pa_sw_volume_from_linear: *const fn (f64) callconv(.C) c.pa_volume_t,
pa_usec_to_bytes: *const fn (t: c.pa_usec_t, spec: [*c]const c.pa_sample_spec) usize,
pa_stream_get_sample_spec: *const fn (s: ?*c.pa_stream) [*c]const c.pa_sample_spec,
pub fn load() !void {
lib.handle = std.DynLib.openZ("libpulse.so") catch return error.LibraryNotFound;
inline for (@typeInfo(Lib).Struct.fields[1..]) |field| {
@ -311,9 +314,10 @@ pub const Context = struct {
var status: StreamStatus = .{ .main_loop = ctx.main_loop, .status = .unknown };
lib.pa_stream_set_state_callback(stream, streamStateOp, &status);
const buffer_len = lib.pa_usec_to_bytes(main.default_latency, lib.pa_stream_get_sample_spec(stream));
const buf_attr = c.pa_buffer_attr{
.maxlength = std.math.maxInt(u32),
.tlength = std.math.maxInt(u32),
.tlength = @intCast(buffer_len),
.prebuf = 0,
.minreq = std.math.maxInt(u32),
.fragsize = std.math.maxInt(u32),
@ -322,8 +326,7 @@ pub const Context = struct {
const flags =
c.PA_STREAM_START_CORKED |
c.PA_STREAM_AUTO_TIMING_UPDATE |
c.PA_STREAM_INTERPOLATE_TIMING |
c.PA_STREAM_ADJUST_LATENCY;
c.PA_STREAM_INTERPOLATE_TIMING;
if (lib.pa_stream_connect_playback(stream, device.id.ptr, &buf_attr, flags, null, null) != 0) {
return error.OpeningDevice;
@ -378,19 +381,19 @@ pub const Context = struct {
var status: StreamStatus = .{ .main_loop = ctx.main_loop, .status = .unknown };
lib.pa_stream_set_state_callback(stream, streamStateOp, &status);
const buffer_len = lib.pa_usec_to_bytes(main.default_latency, lib.pa_stream_get_sample_spec(stream));
const buf_attr = c.pa_buffer_attr{
.maxlength = std.math.maxInt(u32),
.tlength = std.math.maxInt(u32),
.prebuf = 0,
.prebuf = std.math.maxInt(u32),
.minreq = std.math.maxInt(u32),
.fragsize = std.math.maxInt(u32),
.fragsize = @intCast(buffer_len),
};
const flags =
c.PA_STREAM_START_CORKED |
c.PA_STREAM_AUTO_TIMING_UPDATE |
c.PA_STREAM_INTERPOLATE_TIMING |
c.PA_STREAM_ADJUST_LATENCY;
c.PA_STREAM_INTERPOLATE_TIMING;
if (lib.pa_stream_connect_record(stream, device.id.ptr, &buf_attr, flags) != 0) {
return error.OpeningDevice;