[Matroska-devel] WavPack in Matroska

Steve Lhomme steve.lhomme at free.fr
Sat Jul 3 15:22:43 CEST 2004

Christian HJ Wiesner a écrit :
> Steve Lhomme wrote:
>> Well, that's how it's done now. But without any container. The .wvc 
>> file has no tags, no nothing, just the complementary data. These data 
>> mean nothing wihtout the original .wv file. That's why from our point 
>> of view it's better to have everything in the same file.
> Forgive me my ignorance, but who has a use for 2 tracks of a hybrid 
> encoding in the same file ? Normally those HAVE to be 2 files, so that 
> they can fulfil their purpose ? The idea is :

It is very consistent to store related content in the same file. You 
could use TAR which is a very easy format. But Matroska offer such a 
possibility too. Imagine the mess if you have 2 files for each track you 
rip. And when moving these files to another folder, where filenames 
would matter (to match pairs). It's really not good... As I'm thinking 
about CoreSync, an application to automate such a job, it is really not 
convenient to have this special case.

The idea is that it should be stored as if it was a basic lossless file 
(ie both in the same file). And when needed you can only keep the lossy 
part only in another file (like peeling for Vorbis).

Which leads to another problem. If we store all the data in the same 
track (see previous email) we have to have a codec interaction when we 
want to create a lossy-only version of the file. So it might be a good 
idea to have it at the container level instead... I couldn't imagine a 
clean DShow graph if it was at the codec level, but it's easy on the 
container level.

> - to have a small lossy file, that you can copy quickly to your laptop, 
> portable unit, etc.
> - to have the complementary file @ home on the server, saving some 20 - 
> 30% space compared to a real lossless file, but still you are able to 
> restore the original track, without losses

Of course, for such operations, it's dead easy to have a separate file. 
But in the other hand it is harder to maitain consistency. (another good 
reason to have CoreSync doing the ugly job when needed)

> I dont see ANY sense in storing them both together in one single file ? 
> Do i miss something ? Maybe for creation of the tracks ? Please 
> enlighten me ....

A good example is music distribution. It's easier to "sell" a track in 
one file than in 2 files. I'd personally wouldn't like to have both 
files separate on my HD. But would like to split then easily on demand 
(and when you think of WavPack muxed with video it's also better if this 
operation is done at the container level).

robUx4 on blog <http://robux4.blogspot.com/>

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