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Re: overhead when using a LOT of non-overlapping tracks ?

Hi Ando,

Thanks for your reply.

What I mean with storage is that we use the quicktime movie
as a way to describe our project. We want to be able to save it
(with all the tracks, including effect tracks), then load it later,
and still be able to modify the effect settings.

The reason why we have so many tracks is that we want to
play the effects in real time. Thus, we cannot render those effect
tracks and we must keep them as this.

If we understood the way effects work correctly, we are only able
to apply an effect to a WHOLE track, which means that, for example,
if a clip A has a transition with another clip B, and if B has a transition
effect with C, we need to split them into several tracks, one track for
each effect + 2 source tracks for each of those effects + the remaining
parts of the clips that are NOT part of the transition.

Would it be possible maybe to apply an effect to only a well defined
time range in a track ? That would indeed lessen the need for many of
those tracks.

Of course we also allow the user to export the movie as a one-video track
movie, but we keep the version with many tracks for edition purposes
(that's what we call the "storage" version of the movie, which is part of the
application document folder).

best,

Benjamin-


On Friday, September 20, 2002, at 04:57 PM, Ando Sonenblick wrote:

Hi....

QT was definitely not designed to work with nearly that many tracks.
Doesn't mean it won't work - and obviously there will be a lot more overhead
and memory usage the more tracks you have involved. However, while QT has
some rough spots, it also has some nifty tricks that make it work better
than you'd think at times...

One question I have is: I don't quite understand what you mean by "storage"
vs "export". Are you wanting to make a movie with all these elements only
for yourself, on your own drive? Or will others receive this movie?

I also think, "why not author a single movie from all of your hundreds of
clips - you may have a large resulting movie, but qt handles that
wonderfully..."

Ando


Dear list members,

I would like to save a movie made of several clips with transitions
(like iMovie does)
and I wonder if it is possible to use QT as a storage for this (I'm not
talking about
export here, but storing the movie with its structure)

The way it's implemented now is :
- 1 track for each video clip (perhaps more than 1 track if parts
of this clip (beginning or end) are in a transition).
- Those tracks overlap only where there is a transition effect between
those two clips.

The problem with this approach is that the number of clips quickly
increases.

It's not uncommon to have as many as 400 or 500 tracks for a single
movie.

My question is : what exactly is the overhead of dealing with movies
with an
awful lot of tracks like these (both memory and cpu usage) ?

Was QuickTime designed to be able to handle a lot of tracks without too
many
troubles (let's say more than 100 and less than 3000) ? Are there many
QT
functions (adding tracks, prerolling, etc...) that depend upon the
TOTAL number
of tracks in the movie ?

I would like to avoid wirting benchmarking code if someone has a clear
answer to give me.

Thank you

Benjamin Golinvaux
www.arboretum.com
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