Subsonic Forum

If modify tags on mp3s, will that screw up seeding torrents as the files have been modified and won't pass the hash test.?

--disclaimer-- This reply is not meant to imply or infer any acknowledgement or support for file exchanges in violation of copyright laws in respective areas. --disclaimer--



The short technical answer is yes. Torrent chunks the file collection into blocks and each block is verified by an md5 hash or some other parity-checking algorithm, so that when the download of a block is finished, it can checksum the bytes against that hash value and declare that the block is complete, or got corrupted and needs to be resent.

it also continues to test those blocks against files you already have because if they are detected to be corrupted or deleted, your 'seed' has to be removed from the valid seed list. Otherwise, serving a block from your modified file won't mesh right with a block from someone else's unmodified copy and the file to all subsequent receivers is hosed.

So yeah, you need to have your subsonic server be looking at copies of the files that are not being served by torrent.

Another technical note is that ID3.2 (as opposed to the original ID3.1) has variable length string content, and, of course, the embedded album art. As such, changing a file would actually change the entire size of the blocks that contain it, which torrent can't do: it would need to generate a new batch of blocks instead, but again those wouldn't mesh with existing blocks from others.

Excellent replies from both of you. Thank you.

I think I'd like to make a request then:

While organizing ID tags in subsonic, check a box so original FLAC/MP3s are not modified, and additional track, album, sorting info is put in an additional file in that directory. If that's even possible. ?

Subsonic loads the ID3 info on scan and saves it in the database for easier searching and retrieval. The request would be to have a way to edit the database copy of things without touching the original file, rather than an additional file on the file system. You should make the post over in the Feature Requests board, rather than Help.

Done. Thank you for your replies subsonic community. You are the greatest.
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