[pulseaudio-discuss] [PATCH] rtp: Do all receive side rate calculations in sink-input domain

[arun at accosted.net]

From: Arun Raghavan <git at arunraghavan.net>

The code was mixing sink and sink input domain rate updates, and that
only works if the rate of the RTP stream is the same as the rate of the
sink. This changes all the calcuations to be on the sink-input rate,
since that's the rate we are trying to guess (and resample for).
---
 src/modules/rtp/module-rtp-recv.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/modules/rtp/module-rtp-recv.c b/src/modules/rtp/module-rtp-recv.c
index dc42f7c..528b6d8 100644
--- a/src/modules/rtp/module-rtp-recv.c
+++ b/src/modules/rtp/module-rtp-recv.c
@@ -106,6 +106,7 @@ struct session {
     pa_usec_t intended_latency;
     pa_usec_t sink_latency;
 
+    unsigned int base_rate;
     pa_usec_t last_rate_update;
     pa_usec_t last_latency;
     double estimated_rate;
@@ -284,7 +285,6 @@ static int rtpoll_work_cb(pa_rtpoll_item *i) {
 
     if (s->last_rate_update + RATE_UPDATE_INTERVAL < pa_timeval_load(&now)) {
         pa_usec_t wi, ri, render_delay, sink_delay = 0, latency;
-        uint32_t base_rate = s->sink_input->sink->sample_spec.rate;
         uint32_t current_rate = s->sink_input->sample_spec.rate;
         uint32_t new_rate;
         double estimated_rate, alpha = 0.02;
@@ -351,12 +351,12 @@ static int rtpoll_work_cb(pa_rtpoll_item *i) {
         new_rate = (uint32_t) ((double) (RATE_UPDATE_INTERVAL + latency/4 - s->intended_latency/4) / (double) RATE_UPDATE_INTERVAL * s->avg_estimated_rate);
         s->last_latency = latency;
 
-        if (new_rate < (uint32_t) (base_rate*0.8) || new_rate > (uint32_t) (base_rate*1.25)) {
-            pa_log_warn("Sample rates too different, not adjusting (%u vs. %u).", base_rate, new_rate);
-            new_rate = base_rate;
+        if (new_rate < (uint32_t) (s->base_rate*0.8) || new_rate > (uint32_t) (s->base_rate*1.25)) {
+            pa_log_warn("Sample rates too different, not adjusting (%u vs. %u).", s->base_rate, new_rate);
+            new_rate = s->base_rate;
         } else {
-            if (base_rate < new_rate + 20 && new_rate < base_rate + 20)
-              new_rate = base_rate;
+            if (s->base_rate < new_rate + 20 && new_rate < s->base_rate + 20)
+              new_rate = s->base_rate;
             /* Do the adjustment in small steps; 2‰ can be considered inaudible */
             if (new_rate < (uint32_t) (current_rate*0.998) || new_rate > (uint32_t) (current_rate*1.002)) {
                 pa_log_info("New rate of %u Hz not within 2‰ of %u Hz, forcing smaller adjustment", new_rate, current_rate);
@@ -521,8 +521,6 @@ static struct session *session_new(struct userdata *u, const pa_sdp_info *sdp_in
     s->intended_latency = u->latency;
     s->last_rate_update = pa_timeval_load(&now);
     s->last_latency = u->latency;
-    s->estimated_rate = (double) sink->sample_spec.rate;
-    s->avg_estimated_rate = (double) sink->sample_spec.rate;
     pa_atomic_store(&s->timestamp, (int) now.tv_sec);
 
     if ((fd = mcast_socket((const struct sockaddr*) &sdp_info->sa, sdp_info->salen)) < 0)
@@ -554,6 +552,10 @@ static struct session *session_new(struct userdata *u, const pa_sdp_info *sdp_in
         goto fail;
     }
 
+    s->base_rate = (double) s->sink_input->sample_spec.rate;
+    s->estimated_rate = (double) s->sink_input->sample_spec.rate;
+    s->avg_estimated_rate = (double) s->sink_input->sample_spec.rate;
+
     s->sink_input->userdata = s;
 
     s->sink_input->parent.process_msg = sink_input_process_msg;
-- 
2.5.0