From ca47e9ffdc656f31d5a79df74ec7a78fc4a938ee Mon Sep 17 00:00:00 2001
From: Michael Roitzsch <reactorcontrol@icloud.com>
Date: Sat, 18 Nov 2017 13:33:08 +0100
Subject: [PATCH] lavfi/af_pan: fix sign handling in channel coefficient parser

When a channel formula ends with a subtraction, the next formula will
otherwise have its first coefficient negated.

(cherry picked from commit 4f4e19914ddca5096bf7639c7c99a9045e436e8b)
---
 libavfilter/af_pan.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libavfilter/af_pan.c b/libavfilter/af_pan.c
index a477bde460..e54f715147 100644
--- a/libavfilter/af_pan.c
+++ b/libavfilter/af_pan.c
@@ -166,6 +166,7 @@ static av_cold int init(AVFilterContext *ctx)
             goto fail;
         }
         /* gains */
+        sign = 1;
         while (1) {
             gain = 1;
             if (sscanf(arg, "%lf%n *%n", &gain, &len, &len))