diff --git a/lib/flv_tag.cpp b/lib/flv_tag.cpp
index 939a96c6..520929e5 100644
--- a/lib/flv_tag.cpp
+++ b/lib/flv_tag.cpp
@@ -933,11 +933,14 @@ char * FLV::Tag::getData(){
 /// Returns the length of the raw media data for this packet.
 unsigned int FLV::Tag::getDataLen(){
   if (data[0] == 0x08 && (data[11] & 0xF0) == 0xA0) {
+    if (len < 17){return 0;}
     return len - 17;
   }
   if (data[0] == 0x09 && (data[11] & 0x0F) == 7) {
+    if (len < 20){return 0;}
     return len - 20;
   }
+  if (len < 16){return 0;}
   return len - 16;
 }
 
@@ -993,10 +996,8 @@ JSON::Value FLV::Tag::toJSON(DTSC::Meta & metadata, AMF::Object & amf_storage, u
     char audiodata = data[11];
     metadata.tracks[reTrack].trackID = reTrack;
     metadata.tracks[reTrack].type = "audio";
-    if (metadata.tracks[reTrack].codec == "") {
+    if (metadata.tracks[reTrack].codec == "" || metadata.tracks[reTrack].codec != getAudioCodec()) {
       metadata.tracks[reTrack].codec = getAudioCodec();
-    }
-    if (!metadata.tracks[reTrack].rate) {
       switch (audiodata & 0x0C) {
         case 0x0:
           metadata.tracks[reTrack].rate = 5512;
@@ -1014,8 +1015,6 @@ JSON::Value FLV::Tag::toJSON(DTSC::Meta & metadata, AMF::Object & amf_storage, u
       if (amf_storage.getContentP("audiosamplerate")) {
         metadata.tracks[reTrack].rate = (long long int)amf_storage.getContentP("audiosamplerate")->NumValue();
       }
-    }
-    if (!metadata.tracks[reTrack].size) {
       switch (audiodata & 0x02) {
         case 0x0:
           metadata.tracks[reTrack].size = 8;
@@ -1027,8 +1026,6 @@ JSON::Value FLV::Tag::toJSON(DTSC::Meta & metadata, AMF::Object & amf_storage, u
       if (amf_storage.getContentP("audiosamplesize")) {
         metadata.tracks[reTrack].size = (long long int)amf_storage.getContentP("audiosamplesize")->NumValue();
       }
-    }
-    if (!metadata.tracks[reTrack].channels) {
       switch (audiodata & 0x01) {
         case 0x0:
           metadata.tracks[reTrack].channels = 1;
@@ -1124,6 +1121,11 @@ JSON::Value FLV::Tag::toJSON(DTSC::Meta & metadata, AMF::Object & amf_storage, u
         break; //the video info byte we just throw away - useless to us...
     }
     pack_out["time"] = tagTime();
+    if (!getDataLen()){
+      //empty packet
+      pack_out["data"] = "";
+      return pack_out;
+    }
     if ((videodata & 0x0F) == 7) {
       switch (data[12]) {
         case 1:
diff --git a/src/input/input_flv.cpp b/src/input/input_flv.cpp
index b6163aa7..6b0d9b59 100644
--- a/src/input/input_flv.cpp
+++ b/src/input/input_flv.cpp
@@ -105,6 +105,9 @@ namespace Mist {
       thisPacket.null();
       return;
     }
+    if (!tmpTag.getDataLen()){
+      return getNext();
+    }
     thisPacket.genericFill(tmpTag.tagTime(), tmpTag.offset(), tmpTag.getTrackID(), tmpTag.getData(), tmpTag.getDataLen(), lastBytePos, tmpTag.isKeyframe); //init packet from tmpTags data
   }
 
diff --git a/src/output/output_rtmp.cpp b/src/output/output_rtmp.cpp
index 387a3aac..68936ad3 100644
--- a/src/output/output_rtmp.cpp
+++ b/src/output/output_rtmp.cpp
@@ -198,6 +198,35 @@ namespace Mist {
       }
       if (track.codec == "MP3"){
         dataheader[0] += 0x20;
+        if (track.rate == 8000){
+          dataheader[0] |= 0xE0;
+        }else{
+          dataheader[0] |= 0x20;
+        }
+      }
+      if (track.codec == "ADPCM") {
+        dataheader[0] |= 0x10;
+      }
+      if (track.codec == "PCM") {
+        dataheader[0] |= 0x30;
+      }
+      if (track.codec == "Nellymoser") {
+        if (track.rate == 8000){
+          dataheader[0] |= 0x50;
+        }else if(track.rate == 16000){
+          dataheader[0] |= 0x40;
+        }else{
+          dataheader[0] |= 0x60;
+        }
+      }
+      if (track.codec == "G711a") {
+        dataheader[0] |= 0x70;
+      }
+      if (track.codec == "G711mu") {
+        dataheader[0] |= 0x80;
+      }
+      if (track.codec == "Speex") {
+        dataheader[0] |= 0xB0;
       }
       if (track.rate >= 44100){
         dataheader[0] |= 0x0C;
@@ -824,6 +853,7 @@ namespace Mist {
             break;
           }
           F.ChunkLoader(next);
+          if (!F.getDataLen()){break;}//ignore empty packets
           AMF::Object * amf_storage = 0;
           if (F.data[0] == 0x12 || pushMeta.count(next.cs_id) || !pushMeta.size()){
             amf_storage = &(pushMeta[next.cs_id]);