@@ -1635,6 +1635,7 @@ static void show_help_muxer(const char *name)

         show_help_children(fmt->priv_class, AV_OPT_FLAG_ENCODING_PARAM);

 }

+#if CONFIG_AVFILTER

 static void show_help_filter(const char *name)

 {

 #if CONFIG_AVFILTER

@@ -1682,6 +1683,7 @@ static void show_help_filter(const char *name)

            "can not to satisfy request\n");

 #endif

 }

+#endif

 int show_help(void *optctx, const char *opt, const char *arg)

 {

@@ -1703,8 +1705,10 @@ int show_help(void *optctx, const char *opt, const char *arg)

         show_help_demuxer(par);

     } else if (!strcmp(topic, "muxer")) {

         show_help_muxer(par);

+#if CONFIG_AVFILTER

     } else if (!strcmp(topic, "filter")) {

         show_help_filter(par);

+#endif

     } else {

         show_help_default(topic, par);

     }

@@ -212,6 +212,11 @@ static int flv_write_header(AVFormatContext *s)

             } else {

                 framerate = 1 / av_q2d(s->streams[i]->codec->time_base);

             }

+            if (video_enc) {

+                av_log(s, AV_LOG_ERROR,

+                       "at most one video stream is supported in flv\n");

+                return AVERROR(EINVAL);

+            }

             video_enc = enc;

             if (enc->codec_tag == 0) {

                 av_log(s, AV_LOG_ERROR, "Video codec '%s' for stream %d is not compatible with FLV\n",

@@ -220,6 +225,11 @@ static int flv_write_header(AVFormatContext *s)

             }

             break;

         case AVMEDIA_TYPE_AUDIO:

+            if (audio_enc) {

+                av_log(s, AV_LOG_ERROR,

+                       "at most one audio stream is supported in flv\n");

+                return AVERROR(EINVAL);

+            }

             audio_enc = enc;

             if (get_audio_flags(s, enc) < 0)

                 return AVERROR_INVALIDDATA;