avformat/segafilmenc: Postpone check for existence of video stream

Up until now, the Sega FILM muxer complained if the first stream wasn't a
video stream that there is no video stream at all which is of course
nonsense. So postpone this check.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/segafilmenc.c

@@ -183,11 +183,11 @@ static int film_init(AVFormatContext *format_context)
             }
             film->video_index = i;
         }
+    }
 
-        if (film->video_index == -1) {
-            av_log(format_context, AV_LOG_ERROR, "No video stream present.\n");
-            return AVERROR(EINVAL);
-        }
+    if (film->video_index == -1) {
+        av_log(format_context, AV_LOG_ERROR, "No video stream present.\n");
+        return AVERROR(EINVAL);
     }
 
     if (audio != NULL && get_audio_codec_id(audio->codecpar->codec_id) < 0) {