how to download the file range pieces?

[pangoo-reuse]

like .torrent contains 2 files , file1,file2.
file1 is a video file.
for example ,file1 has 60 pieces , i want to play file1 when download,
i want to play third seconds first,or fast jump 5th seconds ,
i want bt downloader download 5th seconds (like 5 -10 pieces) first,so what shoud i do ?thx a lot

[jokechen102]

Did your question solved? I have the same question ,too.

[pvishnyakov]

Implement FilePrioritySkipSelector to select the file and PieceSelector to tell BtClient what pieces you need, several hints:

	private final FilePrioritySkipSelector filePrioritySkipSelector =
			torrentFile ->
					torrent.getFiles().indexOf(torrentFile)==selectedFileIndex
							? FilePriority.HIGH_PRIORITY
							: FilePriority.SKIP;

	private final PieceSelector pieceSelector = new PieceSelector() {
		@Override
		public IntStream getNextPieces(BitSet bitSet, PieceStatistics pieceStatistics) {
			return IntStream.of(piecesToDownload);
		}
	};

	private boolean piecesDownloaded() {
		for (int i:piecesToDownload) if (!pieceMap[i]) return false;
		return true;
	}

	private BtClient createClient(URI uri) {
		try {
			return Bt.client(runtime)
					.storage(storage)
					.torrent(uri.toURL())
					.afterTorrentFetched(tf -> {
...
						pieceMap = new boolean[piecesInTorrent];
					        piecesToDownload = IntStream.concat(IntStream.range(firstFilePiece, firstFilePiece+piecesToPrepare), IntStream.rangeClosed(lastFilePiece-criticalEndPieces+1, lastFilePiece)).toArray();
						runtime.getEventSource().onPieceVerified(torrent.getTorrentId(), event -> {
							pieceMap[event.getPieceIndex()]=true;
							if (piecesDownloaded()) {
                                                             // update piecesToDownload array to supply next portion of pieces
							}
						});
					})
					.fileSelector(filePrioritySkipSelector)
					.selector(pieceSelector)
					.stopWhenDownloaded()
					.build();
		} catch (Exception e) {
			log("Error creating BT client", e);
			return null;
		}
	}