Re: [hatari-users] AVI Record problem -> ODML 64 bit support added

[Anders Eriksson <ae@xxxxxx>]

On Mon, 28 Aug 2017, Nicolas Pomarède wrote:

> Le 11/07/2017 à 15:50, Nicolas Pomarède a écrit :
>
> > I see AVI specs 2.0 can have extra AVIX chunks to have > 2GB in the end. I 
> > will try to look at this someday (but it might not be soon)
> Hi,
>
> good news, Hatari now support the "OpenDML AVI File Format Extensions 
> Specification" which extends the basic AVI format limited to 32 bit file size 
> to handle file size of any size > 4GB.
>
> I made some tests and successfully recorded a 7 GB file which I could read 
> using VLC (including seeking anywhere using the indexes), some avi validation 
> programs also reported a correct structure of the file.
>
> For the technical details, the ODML format divides the AVI file in several 
> RIFF AVI or RIFF AVIX (X=extension) chunks. Each chunks should be < 4GB but 
> you can have as many as you like and some new "super indexes" are added to 
> allow referencing position using 64 bit offset.
>
> In Hatari, I arbitrarily fixed the super index size to 256 entries, each 
> entries would then reference a 1 GB 'movi' chunk.
>
> This requires an OS capable of handling 64 bit file offset, but all modern 
> OSes will do it.
>
> This means the current limit for an AVI file will now be 256 GB in Hatari :)

Great stuff Nicholas!

I really appreciate the effort.


--
Anders Eriksson
ae@xxxxxx     http://www.dhs.nu/
ae@xxxxxxxxx  http://www.atari.org/