diff --git a/lib/mp4.cpp b/lib/mp4.cpp
index a95eab7e..b32efba2 100644
--- a/lib/mp4.cpp
+++ b/lib/mp4.cpp
@@ -250,6 +250,15 @@ namespace MP4 {
       case 0x61766331:
         return ((AVC1*)this)->toPrettyString(indent);
         break;
+      case 0x65647473:
+        return ((EDTS*)this)->toPrettyString(indent);
+        break;
+      case 0x73747373:
+        return ((STSS*)this)->toPrettyString(indent);
+        break;
+      case 0x75647461:
+        return ((UDTA*)this)->toPrettyString(indent);
+        break;
       case 0x75756964:
         return ((UUID*)this)->toPrettyString(indent);
         break;
@@ -4014,6 +4023,59 @@ namespace MP4 {
     return r.str();
   }
 
+  EDTS::EDTS(){
+    memcpy(data + 4, "edts", 4);
+  }
+
+  std::string EDTS::toPrettyString(uint32_t indent){
+    return toPrettyContainerString(indent, std::string("[edts] Edit Box"));
+  }
+  
+  UDTA::UDTA(){
+    memcpy(data + 4, "udta", 4);
+  }
+
+  std::string UDTA::toPrettyString(uint32_t indent){
+    return toPrettyContainerString(indent, std::string("[udta] User Data Box"));
+  }
+
+  STSS::STSS(){
+    memcpy(data + 4, "stss", 4);
+  }
+  
+  void STSS::setEntryCount(uint32_t newVal){
+    setInt32(newVal, 4);
+  }
+  
+  uint32_t STSS::getEntryCount(){
+    getInt32(4);
+  }
+  
+  void STSS::setSampleNumber(uint32 newVal, uint32_t index){
+    if (index+1 > getEntryCount()){
+      setEntryCount(index);
+    }
+    setInt32(newVal, 8 + (index * 4));
+  }
+  
+  uint32_t STSS::getSampleNumber(uint32_t index){
+    if (index >= getEntryCount()){
+      return 0;
+    }
+    return getInt32(8 + (index * 4));
+  }
+  
+  std::string STSS::toPrettyString(uint32_t indent){
+    std::stringstream r;
+    r << std::string(indent, ' ') << "[stss] Sync Sample Box (" << boxedSize() << ")" << std::endl;
+    r << fullBox::toPrettyString(indent);
+    r << std::string(indent + 1, ' ') << "EntryCount: " << getEntryCount() << std::endl;
+    for (int i = 0; i < getEntryCount(); i++){
+      r << std::string(indent + 1, ' ') << "SampleNumber[" << i <<"] : " << getSampleNumber(i) << std::endl;
+    }
+    return r.str();
+  }
+
   static char c2hex(int c){
     if (c >= '0' && c <= '9') return c - '0';
     if (c >= 'a' && c <= 'f') return c - 'a' + 10;
diff --git a/lib/mp4.h b/lib/mp4.h
index cbecd429..094f6d15 100644
--- a/lib/mp4.h
+++ b/lib/mp4.h
@@ -786,6 +786,28 @@ namespace MP4 {
       std::string toPrettyString(uint32_t indent = 0);
   };
   
+  class EDTS: public containerBox{
+    public:
+      EDTS();
+      std::string toPrettyString(uint32_t indent = 0);
+  };
+
+  class UDTA: public containerBox{
+    public:
+      UDTA();
+      std::string toPrettyString(uint32_t indent = 0);
+  };
+  
+  class STSS: public fullBox{
+    public:
+      STSS();
+      void setEntryCount(uint32_t newVal);
+      uint32_t getEntryCount();
+      void setSampleNumber(uint32 newVal, uint32_t index);
+      uint32_t getSampleNumber(uint32_t index);
+      std::string toPrettyString(uint32_t indent = 0);
+  };
+      
   class UUID: public Box{
     public:
       UUID();