Improved seek function for real-time protocols

src/output/output.cpp

@@ -592,7 +592,8 @@ namespace Mist{
   }
 
   /// Prepares all tracks from selectedTracks for seeking to the specified ms position.
-  void Output::seek(unsigned long long pos){
+  /// If toKey is true, clips the seek to the nearest keyframe if the main track is a video track.
+  void Output::seek(unsigned long long pos, bool toKey){
     sought = true;
     if (!isInitialized){
       initialize();
@@ -602,6 +603,25 @@ namespace Mist{
     if (myMeta.live){
       updateMeta();
     }
+    if (toKey){
+      long unsigned int mainTrack = getMainSelectedTrack();
+      //abort toKey if there are no keys in the main track
+      if (!myMeta.tracks.count(mainTrack) || !myMeta.tracks[mainTrack].keys.size()){
+        WARN_MSG("Sync-seeking impossible (main track invalid); performing regular seek instead");
+        seek(pos);
+        return;
+      }
+      DTSC::Track & Trk = myMeta.tracks[mainTrack];
+      if (Trk.type == "video"){
+        unsigned long long seekPos = 0;
+        for (std::deque<DTSC::Key>::iterator it = Trk.keys.begin(); it != Trk.keys.end(); ++it){
+          unsigned long long currPos = it->getTime();
+          if (currPos > pos){break;}//stop if we're past the point we wanted
+          seekPos = currPos;
+        }
+        pos = seekPos;
+      }
+    }
     MEDIUM_MSG("Seeking to %llums", pos);
     std::set<long unsigned int> seekTracks = selectedTracks;
     for (std::set<long unsigned int>::iterator it = seekTracks.begin(); it != seekTracks.end(); it++){

src/output/output.h

@@ -43,7 +43,7 @@ namespace Mist {
       //non-virtual generic functions
       virtual int run();
       virtual void stats(bool force = false);
-      void seek(unsigned long long pos);
+      void seek(unsigned long long pos, bool toKey = false);
       bool seek(unsigned int tid, unsigned long long pos, bool getNextKey = false);
       void stop();
       uint64_t currentTime();

src/output/output_rtmp.cpp

@@ -711,7 +711,7 @@ namespace Mist {
       amfReply.getContentP(3)->addContent(AMF::Object("details", "DDV"));
       amfReply.getContentP(3)->addContent(AMF::Object("clientid", (double)1337));
       sendCommand(amfReply, playMessageType, playStreamId);
-      seek((long long int)amfData.getContentP(3)->NumValue());
+      seek((long long int)amfData.getContentP(3)->NumValue(), true);
 
       //send a status reply
       AMF::Object amfreply("container", AMF::AMF0_DDV_CONTAINER);