for ExoPlayer, remove duration for live.

@@ -336,6 +336,7 @@ Remark:
 
 ## History
 
+* v2.0, 2015-10-28, for [ExoPlayer #828][exo #828], remove duration for live.
 * v2.0, 2015-10-28, for [ExoPlayer #828][exo #828], add av tag in flv header. 2.0.197
 * v2.0, 2015-10-27, for [#512][bug #512] partical hotfix the hls pure audio. 2.0.196
 * <strong>v2.0, 2015-10-08, [2.0 alpha2(2.0.195)][r2.0a2] released. 89358 lines.</strong>

@@ -1400,6 +1400,11 @@ int SrsSource::on_meta_data(SrsCommonMessage* msg, SrsOnMetaDataPacket* metadata
 
     SrsAmf0Any* prop = NULL;
     
+    // when exists the duration, remove it to make ExoPlayer happy.
+    if (metadata->metadata->get_property("duration") != NULL) {
+        metadata->metadata->remove("duration");
+    }
+    
     // generate metadata info to print
     std::stringstream ss;
     if ((prop = metadata->metadata->ensure_property_number("width")) != NULL) {

@@ -513,6 +513,24 @@ SrsAmf0Any* SrsUnSortedHashtable::ensure_property_number(string name)
     return prop;
 }
 
+void SrsUnSortedHashtable::remove(string name)
+{
+    std::vector<SrsAmf0ObjectPropertyType>::iterator it;
+    
+    for (it = properties.begin(); it != properties.end();) {
+        std::string key = it->first;
+        SrsAmf0Any* any = it->second;
+        
+        if (key == name) {
+            srs_freep(any);
+            
+            it = properties.erase(it);
+        } else {
+            ++it;
+        }
+    }
+}
+
 void SrsUnSortedHashtable::copy(SrsUnSortedHashtable* src)
 {
     std::vector<SrsAmf0ObjectPropertyType>::iterator it;
@@ -787,6 +805,11 @@ SrsAmf0Any* SrsAmf0Object::ensure_property_number(string name)
     return properties->ensure_property_number(name);
 }
 
+void SrsAmf0Object::remove(string name)
+{
+    properties->remove(name);
+}
+
 SrsAmf0EcmaArray::SrsAmf0EcmaArray()
 {
     _count = 0;

@@ -405,6 +405,10 @@ public:
     * @remark user should never free the returned value, copy it if needed.
     */
     virtual SrsAmf0Any* ensure_property_number(std::string name);
+    /**
+     * remove the property specified by name.
+     */
+    virtual void remove(std::string name);
 };
 
 /**
@@ -803,6 +807,7 @@ namespace _srs_internal
         virtual SrsAmf0Any* get_property(std::string name);
         virtual SrsAmf0Any* ensure_property_string(std::string name);
         virtual SrsAmf0Any* ensure_property_number(std::string name);
+        virtual void remove(std::string name);
     public:
         virtual void copy(SrsUnSortedHashtable* src);
     };