@@ -39,6 +39,18 @@ static int force_one_stream(AVFormatContext *s)

                s->oformat->name);

         return AVERROR(EINVAL);

     }

+    if (   s->oformat->audio_codec != AV_CODEC_ID_NONE

+        && s->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_AUDIO) {

+        av_log(s, AV_LOG_ERROR, "%s files have exactly one audio stream\n",

+               s->oformat->name);

+        return AVERROR(EINVAL);

+    }

+    if (   s->oformat->video_codec != AV_CODEC_ID_NONE

+        && s->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_VIDEO) {

+        av_log(s, AV_LOG_ERROR, "%s files have exactly one video stream\n",

+               s->oformat->name);

+        return AVERROR(EINVAL);

+    }

     return 0;

 }