change it from a queue to a list. Implement a clearQueue that keeps some frames, and a function clear out unwanted frames

src/zm_packetqueue.cpp

@@ -34,7 +34,7 @@ zm_packetqueue::~zm_packetqueue() {
 }
 
 bool zm_packetqueue::queuePacket( ZMPacket* zm_packet ) {
-	pktQueue.push( zm_packet );
+	pktQueue.push_back( zm_packet );
 
 	return true;
 }
@@ -42,7 +42,7 @@ bool zm_packetqueue::queuePacket( AVPacket* av_packet ) {
     
   ZMPacket *zm_packet = new ZMPacket( av_packet );
  
-	pktQueue.push( zm_packet );
+	pktQueue.push_back( zm_packet );
 
 	return true;
 }
@@ -53,17 +53,57 @@ ZMPacket* zm_packetqueue::popPacket( ) {
 	}
 
 	ZMPacket *packet = pktQueue.front();
-	pktQueue.pop();
+	pktQueue.pop_front();
 
 	return packet;
 }
 
+unsigned int zm_packetqueue::clearQueue( unsigned int frames_to_keep, int stream_id ) {
+  
+  Debug(3, "Clearing all but %d frames", frames_to_keep );
+  frames_to_keep += 1;
+
+	if ( pktQueue.empty() ) {
+    Debug(3, "Queue is empty");
+    return 0;
+  } else {
+    Debug(3, "Queue has (%d)", pktQueue.size() );
+  }
+
+  list<ZMPacket *>::reverse_iterator it;
+  ZMPacket *packet = NULL;
+
+  for ( it = pktQueue.rbegin(); it != pktQueue.rend() && frames_to_keep; ++it ) {
+    ZMPacket *zm_packet = *it;
+    AVPacket *av_packet = &(zm_packet->packet);
+       
+    Debug(3, "Looking at packet with stream index (%d) with keyframe (%d), frames_to_keep is (%d)", av_packet->stream_index, ( av_packet->flags & AV_PKT_FLAG_KEY ), frames_to_keep );
+    
+    // Want frames_to_keep video keyframes.  Otherwise, we may not have enough
+    if ( ( av_packet->stream_index == stream_id) && ( av_packet->flags & AV_PKT_FLAG_KEY ) ) {
+      if (!frames_to_keep)
+        break;
+      frames_to_keep --;
+    }
+  }
+  unsigned int delete_count = 0;
+  while ( it != pktQueue.rend() ) {
+    Debug(3, "Deleting a packet from the front, count is (%d)", delete_count );
+
+    packet = pktQueue.front();
+    pktQueue.pop_front();
+    delete packet;
+
+    delete_count += 1;
+  }    
+  return delete_count; 
+} // end unsigned int zm_packetqueue::clearQueue( unsigned int frames_to_keep, int stream_id )
+
 void zm_packetqueue::clearQueue() {
   ZMPacket *packet = NULL;
 	while(!pktQueue.empty()) {
-  
     packet = pktQueue.front();
-    pktQueue.pop();
+    pktQueue.pop_front();
     delete packet;
 	}
 }
@@ -71,3 +111,42 @@ void zm_packetqueue::clearQueue() {
 unsigned int zm_packetqueue::size() {
   return pktQueue.size();
 }
+
+
+void zm_packetqueue::clear_unwanted_packets( timeval *recording_started, int mVideoStreamId ) {
+  // Need to find the keyframe <= recording_started.  Can get rid of audio packets.
+	if ( pktQueue.empty() ) {
+		return;
+	}
+
+  // Step 1 - find keyframe < recording_started.
+  // Step 2 - pop packets until we get to the packet in step 2
+  list<ZMPacket *>::reverse_iterator it;
+
+  for ( it = pktQueue.rbegin(); it != pktQueue.rend(); ++ it ) {
+    ZMPacket *zm_packet = *it;
+    AVPacket *av_packet = &(zm_packet->packet);
+Debug(1, "Looking for keyframe after start" );
+    if ( 
+        ( av_packet->flags & AV_PKT_FLAG_KEY ) 
+        && 
+        ( av_packet->stream_index == mVideoStreamId )
+        && 
+        timercmp( &(zm_packet->timestamp), recording_started, < )
+       ) {
+Debug(1, "Found keyframe before start" );
+      break;
+    }
+  }
+  if ( it == pktQueue.rend() ) {
+    Debug(1, "Didn't find a keyframe packet keeping all" );
+    return;
+  }
+
+  ZMPacket *packet = NULL;
+  while ( pktQueue.rend() != it ) {
+    packet = pktQueue.front();
+    pktQueue.pop_front();
+    delete packet;
+  }
+}

src/zm_packetqueue.h

@@ -23,7 +23,7 @@
 //#include <boost/interprocess/managed_shared_memory.hpp>
 //#include <boost/interprocess/containers/map.hpp>
 //#include <boost/interprocess/allocators/allocator.hpp>
-#include <queue>
+#include <list>
 #include "zm_packet.h"
 
 extern "C" {
@@ -40,10 +40,12 @@ public:
     ZMPacket * popPacket( );
     bool popVideoPacket(ZMPacket* packet);
     bool popAudioPacket(ZMPacket* packet);
+    unsigned int clearQueue( unsigned int video_frames_to_keep, int stream_id );
     void clearQueue( );
     unsigned int size();
+    void clear_unwanted_packets( timeval *recording, int mVideoStreamId );
 private:
-    std::queue<ZMPacket *>    pktQueue;
+    std::list<ZMPacket *>    pktQueue;
 
 };