Bug 149248

Summary:	First and last chunk download priority
Product:	[Applications] ktorrent	Reporter:	Byte Smythe <bytesmythe>
Component:	general	Assignee:	Joris Guisson <joris.guisson>
Status:	RESOLVED FIXED
Severity:	wishlist
Priority:	NOR
Version:	unspecified
Target Milestone:	---
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	Patch to download first and last 1 percent of file chunks

Description Byte Smythe 2007-08-27 08:35:45 UTC

Version:           2.1 (using KDE KDE 3.5.6)
Installed from:    Ubuntu Packages
Compiler:          gcc 4.1.2 
OS:                Linux

When downloading exceptionally long AVIs (such as TV programs), there are not enough beginning and ending chunks downloaded to get an idea of the video quality. On one torrent, I had over 90% of the file downloaded, but could not watch more than 3 to 4 seconds of the video. I notice that chunk priority has been addressed before, but I don't think ktorrent accounts for the large number of chunks needed by such large files to successfully preview them.

By way of example, the above torrent I mentioned had over 2700 chunks. Chunk numbers 2, 3, and 6 were some of the last 20 chunks downloaded. Another torrent I'm downloading right now is almost 700 MB and nearly 55% done, but I have less than one second of video. I'd much rather have, say, the first and last 10 chunks of such a large file so I can get a good idea of what I'm seeing.

Comment 1 Byte Smythe 2007-08-27 14:57:31 UTC

Created attachment 21489 [details]
Patch to download first and last 1 percent of file chunks

This is probably a somewhat naive attempt, but I tried it out and, for the size
files I'm downloading, it does what I want. With this in place, I can easily
preview 700 MB files in a short amount of time. Perhaps some tweaking could be
done to allow the user to select the percentage of the end chunks to prioritize
(maybe from 1 to 5 percent).

Comment 2 Joris Guisson 2007-08-31 18:57:23 UTC

SVN commit 706964 by guisson:

Prioritise at least 1 % of multimedia files instead of the 1 chunk we currently do.

Initial patch was provided by Byte Smythe with some modifications from myself.

BUG: 149248



 M  +32 -10    chunkmanager.cpp  


--- branches/extragear/kde3/network/ktorrent/libktorrent/torrent/chunkmanager.cpp #706963:706964
@@ -93,22 +93,38 @@
 			for(Uint32 i=0; i<tor.getNumFiles(); ++i)
 			{
 				bt::TorrentFile & file = tor.getFile(i);
-				if (file.isMultimedia() && file.getPriority() != bt::ONLY_SEED_PRIORITY) 
+				if (!file.isMultimedia() || file.getPriority() == bt::ONLY_SEED_PRIORITY) 
+					continue;
+
+				if (file.getFirstChunk() == file.getLastChunk())
 				{
-					prioritise(file.getFirstChunk(), file.getFirstChunk()+1, PREVIEW_PRIORITY);
-					if (file.getLastChunk() - file.getFirstChunk() > 2)
-						prioritise(file.getLastChunk() -1,file.getLastChunk(), PREVIEW_PRIORITY);
+					// prioritise whole file 
+					prioritise(file.getFirstChunk(),file.getLastChunk(),PREVIEW_PRIORITY);
 				}
+				else
+				{
+					Uint32 chunkOffset;
+					chunkOffset = ((file.getLastChunk() - file.getFirstChunk()) / 100) + 1;
+					prioritise(file.getFirstChunk(), file.getFirstChunk()+chunkOffset, PREVIEW_PRIORITY);
+					if (file.getLastChunk() - file.getFirstChunk() > chunkOffset)
+					{
+						prioritise(file.getLastChunk() - chunkOffset, file.getLastChunk(), PREVIEW_PRIORITY);
+					}
+				}
 			}
 		}
 		else
 		{
 			if(tor.isMultimedia())
 			{
-				prioritise(0,1,PREVIEW_PRIORITY);
-				if (tor.getNumChunks() > 2)
-					prioritise(tor.getNumChunks() - 2,tor.getNumChunks() - 1,PREVIEW_PRIORITY);
-				//this->prioritise(getNumChunks()-2, getNumChunks()-1);
+				Uint32 chunkOffset;
+				chunkOffset = (tor.getNumChunks() / 100) + 1;
+
+				prioritise(0,chunkOffset,PREVIEW_PRIORITY);
+				if (tor.getNumChunks() > chunkOffset)
+				{
+					prioritise(tor.getNumChunks() - chunkOffset, tor.getNumChunks() - 1,PREVIEW_PRIORITY);
+				}
 			}
 		}
 	}
@@ -791,9 +807,15 @@
 			// if it is a multimedia file, prioritise first and last chunks of file
 			if (tf->isMultimedia())
 			{
-				prioritise(first,first+1,PREVIEW_PRIORITY);
+				Uint32 chunkOffset;
+				chunkOffset = ((last - first) / 100) + 1;
+
+				prioritise(first,first+chunkOffset,PREVIEW_PRIORITY);
 				if (last - first > 2)
-					prioritise(last -1,last, PREVIEW_PRIORITY);
+				{
+					prioritise(last - chunkOffset, last, PREVIEW_PRIORITY);
+					//prioritise(last -1,last, PREVIEW_PRIORITY);
+				}
 			}
 		}
 		else