Doom9's Forum - View Single Post - BDSup2Sub - convert and tweak bitmap subtitle streams (VobSub,BD-SUP,BDN XML,HD-SUP)

0xdeadbeef · 17th March 2009, 02:37

Regarding the MKVMerge issue, I got a little more insight what causes this problem. Indeed MKVMerge doesn't complain about a time overlap, but about a "wrong" offset. This seems to happen for each subtitle that doesn't fit into one 0x800 bytes packet and thus uses an RLE buffer split over multiple (usually 2) packets.

While I'm not so keen to claim that there is no chance that I messed something in my implementation, chances are that MKVMerge doesn't consider multi-packets at all. At least the fact that VobSync is able to decode the multi-packet subtitles created by BDSup2Sub hints that the command buffer and the offset can't be that wrong. Besides, I'm pretty sure I saw multi-packet subtitles displayed correctly when used to create a DVD.

So this might be an issue of MKVMerge. I'm not yet 100% sure though.

17th March 2009, 02:37	#83 \| Link
0xdeadbeef Author of BDSup2Sub Join Date: Jun 2003 Posts: 478	Regarding the MKVMerge issue, I got a little more insight what causes this problem. Indeed MKVMerge doesn't complain about a time overlap, but about a "wrong" offset. This seems to happen for each subtitle that doesn't fit into one 0x800 bytes packet and thus uses an RLE buffer split over multiple (usually 2) packets. While I'm not so keen to claim that there is no chance that I messed something in my implementation, chances are that MKVMerge doesn't consider multi-packets at all. At least the fact that VobSync is able to decode the multi-packet subtitles created by BDSup2Sub hints that the command buffer and the offset can't be that wrong. Besides, I'm pretty sure I saw multi-packet subtitles displayed correctly when used to create a DVD. So this might be an issue of MKVMerge. I'm not yet 100% sure though.