diff options
Diffstat (limited to 'meta-pipewire/recipes-multimedia/pipewire/pipewire/0007-alsa-make-corrections-on-the-timeout-based-on-how-fa.patch')
| -rw-r--r-- | meta-pipewire/recipes-multimedia/pipewire/pipewire/0007-alsa-make-corrections-on-the-timeout-based-on-how-fa.patch | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/meta-pipewire/recipes-multimedia/pipewire/pipewire/0007-alsa-make-corrections-on-the-timeout-based-on-how-fa.patch b/meta-pipewire/recipes-multimedia/pipewire/pipewire/0007-alsa-make-corrections-on-the-timeout-based-on-how-fa.patch new file mode 100644 index 00000000..86495014 --- /dev/null +++ b/meta-pipewire/recipes-multimedia/pipewire/pipewire/0007-alsa-make-corrections-on-the-timeout-based-on-how-fa.patch @@ -0,0 +1,130 @@ +From 05a3a926df4906cdf60f7978843c637bbf37714a 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 | 31 ++++++++++++++++++++++++++----- + spa/plugins/alsa/alsa-utils.h | 2 ++ + 2 files changed, 28 insertions(+), 5 deletions(-) + +diff --git a/spa/plugins/alsa/alsa-utils.c b/spa/plugins/alsa/alsa-utils.c +index 87582c1c..872969bf 100644 +--- a/spa/plugins/alsa/alsa-utils.c ++++ b/spa/plugins/alsa/alsa-utils.c +@@ -593,7 +593,21 @@ static int get_status(struct state *state, snd_pcm_sframes_t *delay) + + static int update_time(struct state *state, uint64_t nsec, snd_pcm_sframes_t delay, 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 - state->last_threshold; +@@ -650,11 +664,11 @@ static int update_time(struct state *state, uint64_t nsec, snd_pcm_sframes_t del + state->clock->rate_diff = corr; + } + +- 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; +@@ -783,6 +797,10 @@ 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); +@@ -935,7 +953,7 @@ static int handle_play(struct state *state, uint64_t nsec, snd_pcm_sframes_t del + { + int res; + +- if (delay >= state->last_threshold * 2) { ++ if (delay > state->last_threshold * 2) { + spa_log_trace(state->log, "early wakeup %ld %d", delay, state->threshold); + state->next_time = nsec + (delay - state->last_threshold) * SPA_NSEC_PER_SEC / state->rate; + return -EAGAIN; +@@ -944,6 +962,8 @@ static int handle_play(struct state *state, uint64_t nsec, snd_pcm_sframes_t del + if ((res = update_time(state, nsec, delay, false)) < 0) + return res; + ++ state->fill_level = delay; ++ + if (spa_list_is_empty(&state->ready)) { + struct spa_io_buffers *io = state->io; + +@@ -1072,6 +1092,7 @@ int spa_alsa_start(struct state *state) + + state->slaved = is_slaved(state); + 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 a862873f..b53890b5 100644 +--- a/spa/plugins/alsa/alsa-utils.h ++++ b/spa/plugins/alsa/alsa-utils.h +@@ -134,7 +134,9 @@ 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; + +-- +2.20.1 + |