[Matroska-devel] Tagging MKV files
pkoshevoy at gmail.com
Thu Aug 16 17:15:21 CEST 2012
On 8/15/2012 3:27 PM, Dan Hinsley wrote:
> So, I'm working on a library to allow tagging of MKV files and I have
> a question. What I'd like to do is write all the tags at the end of
> the file, so that I don't have to rewrite the entire file. But it
> looks like I have to update the SeekPosition to point to the new
> location of the tags. The problem is that this will increase the
> number of bytes to specify the offset, and since there doesn't appear
> to be any padding in this section (I'm using the cover_art.mkv test
> file), that prevents me from just updating this.
> And even if I rewrite the entire file, calculating the offsets is
> tough because the offset is going to depend on the size of the
> SeekPosition lengths, which depends on the offset.
To calculate the exact number of bytes required to store an offset you
would need to implement a 2-pass mechanism. However, you can also avoid
all this and simply assume that all offsets require 8-bytes for storage.
> Am I missing something obvious here?
You could take a look at http://sourceforge.net/projects/yamka/, it may
work for you.
> Also (not that it matters for me at the moment) how are the Seek UID's
The SeekID [AB] stored in the Seek Entry is the EBML ID of the
element that the seek entry points to.
> Also, is there a forum anywhere for developers working to
> create/play/modify MKV files?
This is it.
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