acap/coreaudio: fix outputting empty frames

a race condition

Prior to e511f898 (2024-11-14) and still in the stable branch, it
produces:
[Audio decompress] 2 empty channel(s) returned!

Author: MartinPulec

FIXES.md

@@ -1,3 +1,10 @@
+#### 1.9.10
+
+* fix macOS >= 15.4 init crashes (LC_RPATH dups)
+* build fixes (XIMEA, PCP)
+* fix manual port assignment with send+recv over lo in single process
+* few other less important fixes
+
 #### 1.9.9
 
 * build fixes: switch to U22, PCP

configure.ac

@@ -1,6 +1,6 @@
 dnl Process this file with autoconf to produce a configure script.
 
-AC_INIT([UltraGrid],[1.9.9],[ultragrid-dev@cesnet.cz])
+AC_INIT([UltraGrid],[1.9.10],[ultragrid-dev@cesnet.cz])
 configure_flags="$*"
 AC_CANONICAL_TARGET
 AM_INIT_AUTOMAKE([1.10])

src/audio/capture/coreaudio.m

@@ -409,13 +409,13 @@ static void (^cb)(BOOL) = ^void(BOOL granted) {
         pthread_mutex_lock(&s->lock);
         ret = ring_buffer_read(s->buffer, s->frame.data, s->frame.max_size);
         if(!ret) {
+                s->data_ready = FALSE;
                 s->boss_waiting = TRUE;
                 while(!s->data_ready) {
                         pthread_cond_wait(&s->cv, &s->lock);
                 }
                 s->boss_waiting = FALSE;
                 ret = ring_buffer_read(s->buffer, s->frame.data, s->frame.max_size);
-                s->data_ready = FALSE;
         }
         pthread_mutex_unlock(&s->lock);