Oppaitime : News

Policy
Bittorrent v1 and hybrid torrents are allowed. v2-only torrents are not allowed.

Context
Bittorrent v2 has been gaining significant support over the last few years. Bittorrent v2 torrent files are specified in such a way that they can coexist with bittorrent v1 data in the same file, creating a so-called "hybrid" torrent file. Newer versions of qBittorrent have started producing these hybrid torrents by default. While hybrid torrents are meant to be completely backwards compatible with v1 torrents, their sudden unexpected appearance has caused some minor problems which I will go over below.

Problems
Bittorrent v2 metadata makes use of zero-length keys. This has always been allowed, but this is pretty much the first time we're seeing it used. Transmission was unable to handle this and nobody had ever run into it before, so hybrid files are unable to load at all in some (now obsolete) versions of Transmission, despite having valid v1 metadata. If you use an old version of Transmission, be aware of this bug.
Oppaitime was modifying uploaded torrents in a v2-unaware way, which would cause some (but not all) of the v2 metadata to be removed from hybrid torrents. These torrents remained valid v1 torrents, but were not valid v2 torrents. Unfortunately, the heuristic that qBittorrent uses to determine whether to load a file as v1 or v2 would notice this partial v2 data, try to load the torrent as v2, and fail because the torrent was not actually a valid v2 file. Oppaitime has recently been updated to properly preserve v2 metadata in hybrid torrents, so this issue in qBittorrent should not be triggered going forward.


Conclusion
No clients as far as I know produce v2-only torrents by default, so this policy should not affect any uploaders. Some other trackers have banned hybrid torrents, but we have not. Whether your client produces v1 torrents or hybrid torrents, both are acceptable to upload.
All known issues in loading hybrid torrents in clients have been fixed by the client or mitigated by changes to OT, so hybrid torrents should work fine for everyone.