ffplay: force setting alsa buffer size

Signed-off-by: Marton Balint <cus@passwd.hu>

ffplay.c

@@ -3781,6 +3781,7 @@ int main(int argc, char **argv)
     int flags;
     VideoState *is;
     char dummy_videodriver[] = "SDL_VIDEODRIVER=dummy";
+    char alsa_bufsize[] = "SDL_AUDIO_ALSA_SET_BUFFER_SIZE=1";
 
     av_log_set_flags(AV_LOG_SKIP_REPEATED);
     parse_loglevel(argc, argv, options);
@@ -3818,6 +3819,12 @@ int main(int argc, char **argv)
     flags = SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER;
     if (audio_disable)
         flags &= ~SDL_INIT_AUDIO;
+    else {
+        /* Try to work around an occasional ALSA buffer underflow issue when the
+         * period size is NPOT due to ALSA resampling by forcing the buffer size. */
+        if (!SDL_getenv("SDL_AUDIO_ALSA_SET_BUFFER_SIZE"))
+            SDL_putenv(alsa_bufsize);
+    }
     if (display_disable)
         SDL_putenv(dummy_videodriver); /* For the event queue, we always need a video driver. */
 #if !defined(_WIN32) && !defined(__APPLE__)