libdvdnav has a problem in that it is difficult to gracefully recover from a read error and continue on to subsequent blocks on the disc. An application would like to seek forward past the current block after getting a read error in order to attempt to get past the bad block(s). But dvdnav_sector_search() does not guarantee that a requested forward seek will actually move the current position forward. It truncates down to the nearest VOBU which will almost always cause a forward seek request by a single block (or a small number of blocks) to move the current position backward. This behaviour puts the application into a loop of: read failure, attempted forward seek (which results in backward seek), read failure ... Attached is a patch to dvdnav_sector_search which guarantees that an attempted forward seek always moves the current position forward.