[Matroska-devel] Matroska-devel Digest, Vol 83, Issue 4

[Shashank Tulsyan]

Thanks for that quick reply, I really appreciate it.

@Mosu
> But there's no way to get the exact position of all those blocks without
> reading the whole cluster.
>    
In AVVVAVVV ..
Let's say I am in some A part. I move forward and now i am V part.
So what you are telling is i can't i know the length of this V part 
without reading this entire V part?
I expected a vint to be present as the first thing in V block, that tell 
the size of the block.
With what u are saying, I think it is not so in mkv.

I don't think a simple size field would havetaken much space.
Compared to the block size, for a 256kbps video, 2sec should be like 
64Kilobytes, a vint for that would take 3 bytes, 3bytes in 64kilobytes 
seems quit small
and i think 256kbps is pretty small.

And with what i understand it seems it is something that cannot be added 
as an extra feature to mkv without making in backward incompatible.
Please tell me if i am wrong.
Any suggestion, is welcome.

> So what you're trying to achieve is probably not possible for Matroska
> files.
>
> Regards,
> Mosu
>
>    


@Steve
> Unless you write a little app that would extract the file position+length of
> each block for the track you want to extract.
Basically my app can save and download a given range, and save this and 
distribute
to save time of other people. But it cannot understand file formats.
It totally relies on other software.

It's sad that I can extract audio portion in AVI without touching video 
parts but not in MKV.

> Also note that for some codecs
> like Vorbis the raw extracted data may not work in most program, as they
> usually expect it in Ogg. AAC may not be handled well as a raw stream in
> many programs.
>
> Steve
>    
See my software doesn't do the extracting part.
It just downloads what is requested.
So let's say i have vorbis audio in some file,
for extracting it I would use a demuxer, and then mux it.
While running the demuxer, only those portions of the file will be given 
to the demuxer
that it asks for. As long as the demuxer gives a format that is 
playable, which can be ogg, this should work for vorbis as well.