From 25b5096400b2fd578e059eb4a5d2aba8f3cfddfb Mon Sep 17 00:00:00 2001
From: Pavel Koshevoy <pkoshevoy@gmail.com>
Date: Sun, 3 Sep 2017 20:44:31 -0600
Subject: [PATCH] lavfi/atempo: Avoid false triggering an assertion failure

Steps to reproduce:
1. revert 4240e5b047379b29c33dd3f4438bc4e610527b83
2. ./ffmpeg -f lavfi -i sine=d=1 -af aselect=e=0,atempo=0.5 -y atempo.wav

Signed-off-by: Marton Balint <cus@passwd.hu>
---
 libavfilter/af_atempo.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavfilter/af_atempo.c b/libavfilter/af_atempo.c
index 9eee8a63a8..8b214bccd7 100644
--- a/libavfilter/af_atempo.c
+++ b/libavfilter/af_atempo.c
@@ -914,6 +914,11 @@ static int yae_flush(ATempoContext *atempo,
 
     atempo->state = YAE_FLUSH_OUTPUT;
 
+    if (!atempo->nfrag) {
+        // there is nothing to flush:
+        return 0;
+    }
+
     if (atempo->position[0] == frag->position[0] + frag->nsamples &&
         atempo->position[1] == frag->position[1] + frag->nsamples) {
         // the current fragment is already flushed: