[pulseaudio-discuss] [PATCH] echo-cancel: Fix assert with webrtc's built-in drift compensation

[Arun Raghavan]

The webrtc canceller seems to have changed to require that the
set_stream_drift_samples() method be called before every call of
ProcessStream().

So we now call ec->set_stream_drift_samples() before calling
ec->record() by:

1. Always calling do_push_drift_comp() instead of only when the sink is
   running

2. Calling set_stream_drift_samples() in the loop with record() instead
   of outside

We do kind of leak this quirk of the webrtc canceller into the generic
bits of module-echo-cancel, but this should not be harmful in the
general case either.
---
 src/modules/echo-cancel/module-echo-cancel.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/modules/echo-cancel/module-echo-cancel.c b/src/modules/echo-cancel/module-echo-cancel.c
index 0a9f290..2c7449a 100644
--- a/src/modules/echo-cancel/module-echo-cancel.c
+++ b/src/modules/echo-cancel/module-echo-cancel.c
@@ -736,9 +736,6 @@ static void do_push_drift_comp(struct userdata *u) {
     u->sink_rem = plen % u->sink_blocksize;
     u->source_rem = rlen % u->source_output_blocksize;
 
-    /* Now let the canceller work its drift compensation magic */
-    u->ec->set_drift(u->ec, drift);
-
     if (u->save_aec) {
         if (u->drift_file)
             fprintf(u->drift_file, "d %a\n", drift);
@@ -778,6 +775,7 @@ static void do_push_drift_comp(struct userdata *u) {
         cchunk.memblock = pa_memblock_new(u->source->core->mempool, cchunk.length);
         cdata = pa_memblock_acquire(cchunk.memblock);
 
+        u->ec->set_drift(u->ec, drift);
         u->ec->record(u->ec, rdata, cdata);
 
         if (u->save_aec) {
@@ -946,8 +944,8 @@ static void source_output_push_cb(pa_source_output *o, const pa_memchunk *chunk)
         u->sink_skip -= to_skip;
     }
 
-    /* process and push out samples, do drift compensation only if the sink is actually running */
-    if (u->ec->params.drift_compensation && u->sink->thread_info.state == PA_SINK_RUNNING)
+    /* process and push out samples */
+    if (u->ec->params.drift_compensation)
         do_push_drift_comp(u);
     else
         do_push(u);
-- 
2.9.3