From b43844e7c67afbce92235608e931ccd28e3b72b9 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wtaymans@redhat.com>
Date: Fri, 26 Apr 2019 15:48:21 +0200
Subject: [PATCH] alsa: improve capture resync

Make sure we capture enough data even when the ringbuffer wraps
around.
Use the clock nsec to get timing, we don't need to get the new time.
Improve sync in capture.
---
 spa/plugins/alsa/alsa-utils.c | 45 ++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 19 deletions(-)

diff --git a/spa/plugins/alsa/alsa-utils.c b/spa/plugins/alsa/alsa-utils.c
index 183f71518..fa197c415 100644
--- a/spa/plugins/alsa/alsa-utils.c
+++ b/spa/plugins/alsa/alsa-utils.c
@@ -671,7 +671,6 @@ int spa_alsa_write(struct state *state, snd_pcm_uframes_t silence)
 		uint64_t nsec;
 		snd_pcm_sframes_t delay;
 
-		clock_gettime(CLOCK_MONOTONIC, &state->now);
 		if ((res = get_status(state, &delay)) < 0)
 			return res;
 
@@ -691,7 +690,7 @@ int spa_alsa_write(struct state *state, snd_pcm_uframes_t silence)
 			state->alsa_sync = false;
 		}
 
-		nsec = SPA_TIMESPEC_TO_NSEC(&state->now);
+		nsec = state->position->clock.nsec;
 		if ((res = update_time(state, nsec, delay, true)) < 0)
 			return res;
 	}
@@ -807,7 +806,7 @@ push_frames(struct state *state,
 		size_t n_bytes;
 		struct buffer *b;
 		struct spa_data *d;
-		uint32_t index, offs, avail, l0, l1;
+		uint32_t avail, l0, l1;
 
 		b = spa_list_first(&state->free, struct buffer, link);
 		spa_list_remove(&b->link);
@@ -823,19 +822,17 @@ push_frames(struct state *state,
 		src = SPA_MEMBER(my_areas[0].addr, offset * state->frame_size, uint8_t);
 
 		avail = d[0].maxsize / state->frame_size;
-		index = 0;
-		total_frames = SPA_MIN(avail, frames);
+		total_frames = SPA_MIN(avail, state->threshold);
 		n_bytes = total_frames * state->frame_size;
 
-		offs = index % d[0].maxsize;
-		l0 = SPA_MIN(n_bytes, d[0].maxsize - offs);
+		l0 = SPA_MIN(n_bytes, frames * state->frame_size);
 		l1 = n_bytes - l0;
 
-		spa_memcpy(SPA_MEMBER(d[0].data, offs, void), src, l0);
+		spa_memcpy(d[0].data, src, l0);
 		if (l1 > 0)
-			spa_memcpy(d[0].data, src + l0, l1);
+			spa_memcpy(d[0].data, my_areas[0].addr, l1);
 
-		d[0].chunk->offset = index;
+		d[0].chunk->offset = 0;
 		d[0].chunk->size = n_bytes;
 		d[0].chunk->stride = state->frame_size;
 
@@ -857,24 +854,30 @@ int spa_alsa_read(struct state *state, snd_pcm_uframes_t silence)
 	if (state->position && state->threshold != state->position->size)
 		state->threshold = state->position->size;
 
-	if (state->slaved) {
-		uint64_t nsec, master;
+	if (state->slaved && state->alsa_started) {
+		uint64_t nsec;
 		snd_pcm_sframes_t delay;
 
-		master = state->position->clock.position + state->position->clock.delay;
-		nsec = master * SPA_NSEC_PER_SEC / state->rate;
-
 		if ((res = get_status(state, &delay)) < 0)
 			return res;
 
-		if (delay > state->threshold * 2) {
+		if (delay < state->threshold || delay > state->threshold * 2) {
 			spa_log_warn(state->log, "slave: resync %f %f %f",
 					state->z1, state->z2, state->z3);
-			snd_pcm_forward(state->hndl, delay - state->threshold);
-			delay = state->threshold;
 			init_loop(state);
+			state->alsa_sync = true;
+		}
+		if (state->alsa_sync) {
+			if (delay < state->threshold)
+				snd_pcm_rewind(state->hndl, state->threshold - delay);
+			else if (delay > state->threshold)
+				snd_pcm_forward(state->hndl, delay - state->threshold);
+
+			delay = state->threshold;
+			state->alsa_sync = false;
 		}
 
+		nsec = state->position->clock.nsec;
 		if ((res = update_time(state, nsec, delay, true)) < 0)
 			return res;
 	}
@@ -899,7 +902,11 @@ again:
 			return res;
 	}
 
-	to_read -= read;
+	if (to_read > read)
+		to_read -= read;
+	else
+		to_read = 0;
+
 	if (read > 0 && to_read >= state->threshold && !spa_list_is_empty(&state->free))
 		goto again;