[Matroska-devel] Hi, question about the MKV tags

Santiago Jimeno sjimeno at ya.com
Tue Feb 15 18:47:43 CET 2011


I suppose that you now have seen the problem closely and you understand 
better what I am meaning from my first message .
But you have surrendered soon.

I take 2 months studying and working about Matroska Tags for writing an 
editor without remux.
The code is very advanced. I have prepared everithing necessary for editing 
(reading, showing and writing of Tags and Attachments blocks and also 
handling of SeekHead and SegmentSize)
I only have to finish writing one function "ApplyChanges"
Here, all aspects related with the Tags edition are already developed. Also 
the relative thing to the Pictures deletion.
In spite of the complexity of Tags edition, with nested tags, etc, I don't 
have problem.
The true difficulty is Attachments, its independencie of Tags, its size, its 
file position and also the multiple locations that suppose the addición of 
this for the whole.
Also Attachments (thanks to random apps) may have Pictures and Fonts blended 
in any order, independently of what Order Guidelines says.

I summarize the situation:
If there is only Tags ->  there are 3 edition possibilities with two 
location combinations. Total (without repeating) 5 possibilities. Already 
implemented
If Pics + Tags ->  there are 10 edition possibilities with 4 location 
combinations.  Total (without repeating) 34 possibilities. I only have 
written 7 of them.

Surely the code already written could cover 80% or more than our 
necessities. But I should write code until for the less likely thing.
Example: what happens if the space after SeekHead is only of 1 byte when 
VOID needs 2 bytes at least (ID and Length=0)

For this reason I am proposing the changes that I said in my previous 
messages.
Of them, the simple integration of Pictures inside Tags would suppose an 
enormous redución of complexity (from 34 to 5 possibilities)
And still less complexity if we also fix a definitive location.
Then: Pictures or Tags? Or both together in one block?
But the decision doesn't correspond me.

Regards. Santiago

----- Original Message ----- 
From: "Steve Lhomme" <slhomme at matroska.org>
To: "Discussion about the current and future development of Matroska" 
<matroska-devel at lists.matroska.org>
Sent: Tuesday, February 15, 2011 4:01 PM
Subject: Re: [Matroska-devel] Hi, question about the MKV tags


> So there is no tag support now, so you're going to use a proprietary
> and limited and undocumented way to do it just for yourself ? Hoping
> the problem of doing it the clean way will solve by itself ?
>
> On Tue, Feb 15, 2011 at 1:45 PM, Boris Juraga <boris.juraga at gmail.com> 
> wrote:
>> Well from the conversation till now i have one conclusion - no proper
>> tags support is near, not without full remux. So i will use a
>> workaround i was using before trying to use the tag system. I will
>> create spec complying xml file containing the tags and called
>> tags.xml, and instead of adding it to mkvmerge as a global tags xml
>> file - i will add it as attachment. And it will be fixed size xml
>> document. I think 5KB is more than enough for tags for movie or
>> episode. and as it is fixed size, i will use my current tag\attachment
>> reader to seek to it and simply over write it with the new tags.xml.
>> As the files are exactly the same size no problems will occur. Simply
>> if the new tags are bigger than 5KB i will remux.
>>
>> I cant think of a single problem with this solution, no one is reading
>> tags at the moment so my app will work.
>> _______________________________________________
>> Matroska-devel mailing list
>> Matroska-devel at lists.matroska.org
>> http://lists.matroska.org/cgi-bin/mailman/listinfo/matroska-devel
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>> http://dir.gmane.org/gmane.comp.multimedia.matroska.devel
>>
>
>
>
> -- 
> Steve Lhomme
> Matroska association Chairman
> _______________________________________________
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> http://lists.matroska.org/cgi-bin/mailman/listinfo/matroska-devel
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> 





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