demux: dash: only look for index on segment start

modules/demux/adaptative/http/Chunk.cpp

@@ -107,8 +107,11 @@ block_t * AbstractChunk::read(size_t sizehint, mtime_t *time)
 
     if(block)
     {
+	if(getBytesRead() == 0)
+            block->i_flags |= BLOCK_FLAG_HEADER;
         setBytesRead(getBytesRead() + block->i_buffer);
         onDownload(&block);
+        block->i_flags ^= BLOCK_FLAG_HEADER;
     }
 
     return block;

modules/demux/dash/mpd/DASHSegment.cpp

@@ -43,7 +43,7 @@ DashIndexSegment::DashIndexSegment(ICanonicalUrl *parent) :
 
 void DashIndexSegment::onChunkDownload(block_t **pp_block, SegmentChunk *, BaseRepresentation *rep)
 {
-    if(!rep)
+    if(!rep || ((*pp_block)->i_flags & BLOCK_FLAG_HEADER) == 0 )
         return;
 
     IndexReader br(rep->getPlaylist()->getVLCObject());