From 2692a7d22c0b691f7f27f969c91e7af05c8ede7d Mon Sep 17 00:00:00 2001
From: dec05eba <dec05eba@protonmail.com>
Date: Sun, 14 Apr 2024 00:02:47 +0200
Subject: Testing audio latency compensation
---
include/sound.hpp | 2 +-
src/main.cpp | 9 ++++++---
src/sound.cpp | 19 +++++++++++++++----
3 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/include/sound.hpp b/include/sound.hpp
index 731e787..c0d0465 100644
--- a/include/sound.hpp
+++ b/include/sound.hpp
@@ -55,7 +55,7 @@ void sound_device_close(SoundDevice *device);
Returns the next chunk of audio into @buffer.
Returns the number of frames read, or a negative value on failure.
*/
-int sound_device_read_next_chunk(SoundDevice *device, void **buffer, double timeout_sec);
+int sound_device_read_next_chunk(SoundDevice *device, void **buffer, double timeout_sec, double *latency_sec);
std::vector<AudioInput> get_pulseaudio_inputs();
diff --git a/src/main.cpp b/src/main.cpp
index 5aacd8b..eb90e91 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2417,12 +2417,15 @@ int main(int argc, char **argv) {
while(running) {
void *sound_buffer;
int sound_buffer_size = -1;
+ double latency_seconds = 0.0;
+ const double time_before_read = clock_get_monotonic_seconds();
if(audio_device.sound_device.handle)
- sound_buffer_size = sound_device_read_next_chunk(&audio_device.sound_device, &sound_buffer, timeout_sec);
+ sound_buffer_size = sound_device_read_next_chunk(&audio_device.sound_device, &sound_buffer, 1.0, &latency_seconds);
const bool got_audio_data = sound_buffer_size >= 0;
-
- const double this_audio_frame_time = clock_get_monotonic_seconds() - paused_time_offset;
+ const double time_after_read = clock_get_monotonic_seconds();
+ latency_seconds = time_after_read - time_before_read; // TODO: Remove this
+ const double this_audio_frame_time = (time_after_read - paused_time_offset) - latency_seconds;
if(paused) {
if(got_audio_data)
diff --git a/src/sound.cpp b/src/sound.cpp
index 485548b..8be32b2 100644
--- a/src/sound.cpp
+++ b/src/sound.cpp
@@ -41,6 +41,7 @@ struct pa_handle {
size_t output_index, output_length;
int operation_success;
+ double latency_seconds;
};
static void pa_sound_device_free(pa_handle *s) {
@@ -79,8 +80,9 @@ static pa_handle* pa_sound_device_new(const char *server,
p->read_data = NULL;
p->read_length = 0;
p->read_index = 0;
+ p->latency_seconds = 0.0;
- const int buffer_size = attr->maxlength;
+ const int buffer_size = attr->fragsize;
void *buffer = malloc(buffer_size);
if(!buffer) {
fprintf(stderr, "failed to allocate buffer for audio\n");
@@ -161,6 +163,9 @@ static int pa_sound_device_read(pa_handle *p, double timeout_seconds) {
bool success = false;
int r = 0;
int *rerror = &r;
+ pa_usec_t latency = 0;
+ int negative = 0;
+
CHECK_DEAD_GOTO(p, rerror, fail);
while (p->output_index < p->output_length) {
@@ -193,6 +198,10 @@ static int pa_sound_device_read(pa_handle *p, double timeout_seconds) {
CHECK_DEAD_GOTO(p, rerror, fail);
continue;
}
+
+ if(pa_stream_get_latency(p->stream, &latency, &negative) >= 0) {
+ p->latency_seconds = (negative ? -(int64_t)latency : (int64_t)latency) * 0.000001;
+ }
}
const size_t space_free_in_output_buffer = p->output_length - p->output_index;
@@ -255,8 +264,8 @@ int sound_device_get_by_name(SoundDevice *device, const char *device_name, const
buffer_attr.tlength = -1;
buffer_attr.prebuf = -1;
buffer_attr.minreq = -1;
- buffer_attr.maxlength = period_frame_size * audio_format_to_get_bytes_per_sample(audio_format) * num_channels; // 2/4 bytes/sample, @num_channels channels
- buffer_attr.fragsize = buffer_attr.maxlength;
+ buffer_attr.maxlength = -1;
+ buffer_attr.fragsize = period_frame_size * audio_format_to_get_bytes_per_sample(audio_format) * num_channels; // 2/4 bytes/sample, @num_channels channels
int error = 0;
pa_handle *handle = pa_sound_device_new(nullptr, description, device_name, description, &ss, &buffer_attr, &error);
@@ -276,13 +285,15 @@ void sound_device_close(SoundDevice *device) {
device->handle = NULL;
}
-int sound_device_read_next_chunk(SoundDevice *device, void **buffer, double timeout_sec) {
+int sound_device_read_next_chunk(SoundDevice *device, void **buffer, double timeout_sec, double *latency_sec) {
pa_handle *pa = (pa_handle*)device->handle;
if(pa_sound_device_read(pa, timeout_sec) < 0) {
//fprintf(stderr, "pa_simple_read() failed: %s\n", pa_strerror(error));
+ *latency_sec = 0.0;
return -1;
}
*buffer = pa->output_data;
+ *latency_sec = pa->latency_seconds;
return device->frames;
}
--
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