ffmpeg: check for unconnected outputs

Fixes e.g.:

ffmpeg -f lavfi -i testsrc -f lavfi -i testsrc -filter_complex "[0:v][1:v]psnr[out]" -f null none

1 files changed, 15 insertions, 0 deletions

diff --git a/ffmpeg_filter.c b/ffmpeg_filter.c
index 896161a869..817f48f473 100644
--- a/ffmpeg_filter.c
+++ b/ffmpeg_filter.c
@@ -678,6 +678,21 @@ int configure_output_filter(FilterGraph *fg, OutputFilter *ofilter, AVFilterInOu
     }
 }
 
+void check_filter_outputs(void)
+{
+    int i;
+    for (i = 0; i < nb_filtergraphs; i++) {
+        int n;
+        for (n = 0; n < filtergraphs[i]->nb_outputs; n++) {
+            OutputFilter *output = filtergraphs[i]->outputs[n];
+            if (!output->ost) {
+                av_log(NULL, AV_LOG_FATAL, "Filter %s has an unconnected output\n", output->name);
+                exit_program(1);
+            }
+        }
+    }
+}
+
 static int sub2video_prepare(InputStream *ist, InputFilter *ifilter)
 {
     AVFormatContext *avf = input_files[ist->file_index]->ctx;