wwp@yahoogroups.com:
Re: Does the image width have to be divisible by 2 to join correctly?
Markus Altendorff 2005-Sep-28 19:10:00
centreofengland wrote:
>
> Thanks for explaining, Now I know that I need to resize my jpg
> correctly before I use pano2qtvr otherwise its going to go wrong.
>
> I am new to making qtvr's, what exactly are these tiles things?
> Is a smaller number better for the tile value or a larger number?
> It does not say on here.. http://www.pano2qtvr.com/
>
> There is little info on the detailed side of things like this, so
> any help would be great.
A little history of QTVR, as told from memory ;)
"Inside" a QTVR file is always a simple movie made of
individual frames, only that the frames are not shown one
after the other, but side by side. That's why some software
that claims to know how to handle MOV files shows the frames
as a movie turned sideways... ignoring the QTVR type, and
playing back the track data it knows.
The large panorama picture (larger than a single frame of a
movie was allowed to be, i think the frame limit was
2048x2048) was split into these tiles. A side effect is that
if RAM becomes tight, the QTVR player may conserve memory by
only uncompressing the tiles visible in the viewer window.
The two size factors (96 and 4) are based on Apple's
QuickDraw engine that : groups of 4 pixels are "nice" to
work with (OK, 8 pixels would've been even nicer ;), and 96
is simply 24 * 4 - with 24 being the "default" tile number.
Later versions of Quicktime overcame the tile number
limitation, and the size setting of the tiles became a
question of performance:
Low number of tiles = little time loss, but needs more RAM
to keep the uncompressed tile.
High number of tiles = more decompression overhead, but
needs less RAM.
That's about all i remember from the QTVR Authoring Studio
days ;)
-Markus