From b1a213ab5d84085ae2b98452daa8feda01881cbf Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Thu, 8 Jun 2023 21:33:44 +0200
Subject: [PATCH] fftools/ffmpeg_filter: reject filtergraphs with zero outputs

Nothing useful can be done with them currently.
---
 fftools/ffmpeg_filter.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
index 4f7565e44e..54c7ed1f5c 100644
--- a/fftools/ffmpeg_filter.c
+++ b/fftools/ffmpeg_filter.c
@@ -845,6 +845,12 @@ FilterGraph *fg_create(char *graph_desc)
         ofilter->name      = describe_filter_link(fg, cur, 0);
     }
 
+    if (!fg->nb_outputs) {
+        av_log(fg, AV_LOG_FATAL, "A filtergraph has zero outputs, this is not supported\n");
+        ret = AVERROR(ENOSYS);
+        goto fail;
+    }
+
 fail:
     avfilter_inout_free(&inputs);
     avfilter_inout_free(&outputs);