+++ /dev/null
-From 0c232229f3dc6b0cdf02ef44ae212b256c1828a3 Mon Sep 17 00:00:00 2001
-From: George Kiagiadakis <george.kiagiadakis@collabora.com>
-Date: Tue, 9 Jul 2019 18:06:18 +0300
-Subject: [PATCH] alsa: make corrections on the timeout based on how fast ALSA
- consumes samples
-
-This feels a bit hacky, but it actually makes huge difference when pipewire is
-running in qemu.
-
-The idea is that it keeps track of how much samples are in the device
-(fill level) and calculates how many are consumed when a timeout occurs.
-Then it converts that into a time based on the sample rate and compares it to
-the system clock time that elapsed since the last write to the device.
-The division between the two gives a rate (drift) that can be used to shorten
-the timeout window.
-
-So for instance, if the timeout window was 21.3 ms, but the device actually
-consumed an equivalent of 28 ms in samples, the drift will be 21.3/28 = 0.76
-and the next timeout window will be approximately 21.3 * 0.76 = 16.1 ms
-
-To avoid making things worse, the drift is clamped between 0.6 and 1.0.
-Min 0.6 was arbitrarily chosen, but sometimes alsa does report strange numbers,
-causing the drift to be very low, which in turn causes an early wakeup.
-Max 1.0 basically means that we don't care if the device is consuming samples
-slower. In that case, the early wakeup mechanism will throttle pipewire.
-
-Fixes #163
-
-Upstream-Status: Submitted [https://github.com/PipeWire/pipewire/pull/166]
----
- spa/plugins/alsa/alsa-utils.c | 29 +++++++++++++++++++++++++----
- spa/plugins/alsa/alsa-utils.h | 2 ++
- 2 files changed, 27 insertions(+), 4 deletions(-)
-
-diff --git a/spa/plugins/alsa/alsa-utils.c b/spa/plugins/alsa/alsa-utils.c
-index 7cf1d0d2..e8548345 100644
---- a/spa/plugins/alsa/alsa-utils.c
-+++ b/spa/plugins/alsa/alsa-utils.c
-@@ -624,7 +624,21 @@ static int get_status(struct state *state, snd_pcm_uframes_t *delay, snd_pcm_ufr
- static int update_time(struct state *state, uint64_t nsec, snd_pcm_sframes_t delay,
- snd_pcm_sframes_t target, bool slave)
- {
-- double err, corr;
-+ double err, corr, drift;
-+ snd_pcm_sframes_t consumed;
-+
-+ consumed = state->fill_level - delay;
-+ if (state->alsa_started && consumed > 0) {
-+ double sysclk_diff = nsec - state->last_time;
-+ double devclk_diff = ((double) consumed) * 1e9 / state->rate;
-+ drift = sysclk_diff / devclk_diff;
-+ drift = SPA_CLAMP(drift, 0.6, 1.0);
-+
-+ spa_log_trace_fp(state->log, "cons:%ld sclk:%f dclk:%f drift:%f",
-+ consumed, sysclk_diff, devclk_diff, drift);
-+ } else {
-+ drift = 1.0;
-+ }
-
- if (state->stream == SND_PCM_STREAM_PLAYBACK)
- err = delay - target;
-@@ -677,11 +691,11 @@ static int update_time(struct state *state, uint64_t nsec, snd_pcm_sframes_t del
- state->clock->next_nsec = state->next_time;
- }
-
-- spa_log_trace_fp(state->log, "slave:%d %"PRIu64" %f %ld %f %f %d", slave, nsec,
-- corr, delay, err, state->threshold * corr,
-+ spa_log_trace_fp(state->log, "slave:%d %"PRIu64" %f %ld %f %f %f %d", slave, nsec,
-+ corr, delay, err, state->threshold * corr, drift,
- state->threshold);
-
-- state->next_time += state->threshold / corr * 1e9 / state->rate;
-+ state->next_time += state->threshold / corr * drift * 1e9 / state->rate;
- state->last_threshold = state->threshold;
-
- return 0;
-@@ -812,6 +826,10 @@ again:
- goto again;
-
- state->sample_count += total_written;
-+ state->fill_level += total_written;
-+
-+ clock_gettime(CLOCK_MONOTONIC, &state->now);
-+ state->last_time = SPA_TIMESPEC_TO_NSEC (&state->now);
-
- if (!state->alsa_started && total_written > 0) {
- spa_log_trace(state->log, "snd_pcm_start %lu", written);
-@@ -981,6 +999,8 @@ static int handle_play(struct state *state, uint64_t nsec,
- if ((res = update_time(state, nsec, delay, target, false)) < 0)
- return res;
-
-+ state->fill_level = delay;
-+
- if (spa_list_is_empty(&state->ready)) {
- struct spa_io_buffers *io = state->io;
-
-@@ -1120,6 +1140,7 @@ int spa_alsa_start(struct state *state)
-
- state->threshold = (state->duration * state->rate + state->rate_denom-1) / state->rate_denom;
- state->last_threshold = state->threshold;
-+ state->fill_level = 0;
-
- init_loop(state);
- state->safety = 0.0;
-diff --git a/spa/plugins/alsa/alsa-utils.h b/spa/plugins/alsa/alsa-utils.h
-index 110d4204..bab0f67b 100644
---- a/spa/plugins/alsa/alsa-utils.h
-+++ b/spa/plugins/alsa/alsa-utils.h
-@@ -141,7 +141,9 @@ struct state {
- int64_t sample_time;
- uint64_t next_time;
- uint64_t base_time;
-+ uint64_t last_time;
-
-+ snd_pcm_uframes_t fill_level;
- uint64_t underrun;
- double safety;
-
---
-2.23.0
-
Code Review / AGL / meta-agl-devel.git / blobdiff