>
> Date: Sun, 26 Nov 2000 12:57:25 +0100
> From: jean-louis valero <[EMAIL PROTECTED]>
> Subject: <lingo-l> quicktime framerate
>
> hello list
> Is it possible to know the real framerate of a quicktime movie? I tried
> everything(of course may be not...) between digitalVideoTimescale and
> the timescale of member but I can't establish by lingo the number of
> frames per second a quicktime movie has been compressed with. I do need
> that information just after the opening of the digital movie.
> It seems not to be evident, because when I use Quicktime player itself,
> and ask it that information, it says it needs a playing file to answer
> to my question.
There are a few things to consider here.
Firstly, a Quicktime movie may have more than one video track, and each
track may have a different frame rate, so your question might better be
'How do I get the frame rate of a Quicktime video track?'
Next, Quicktime is all about sync. It is designed to drop frames to
'keep up' on hardware that is being strained. That way, the frames that
you *do* see will be visible at the right moment. This is critical for
audio synchronised with video.
(Compare this to Director or Flash which will play every frame, even if
it means that playback is much slower on slower hardware).
This means that you might end up with a frame rate of 12 when the video
track was saved at 30. That's why Quicktime needs to have the movie
playing to give you an accurate answer.
Quicktime movies have a setting 'Play every frame' which will force the
video to behave more like Director or Flash - you'll see every frame,
but because this would make the audio sound dreadful on slower computers
(lots of gaps between samples), the sound will be turned off in this mode.
So, if you look in Quicktime player with 'get info' (you'll need a Pro
license!) you can select a video track and see the frame rate that the
track was saved at, and (while playing) you can see the frame rate it
can get to on a particular machine. Note, that if you play more than one
movie at once or do some other machine intensive task, the playing FPS
will most likely drop, so don't assume that the value you see there will
remain constant under all conditions.
> I do need that information, because my Premiere-like application must
> inform the user about the framerate of every movie s(he) uses, to be
> frame-accurate (30,29.97,25,24, 15 im/sec) when s(he) derushes.
> If I can't obtain that, bye-bye my app, it's not serious to let the user
> guess the framerate!
Well, you may be stretching Director quite a bit if you want to make a
Premiere-like application. For one thing, Director apps can not export
Quicktime movies, and for another, Director apps have plenty of
overheads which would slow everything down.
If you use a tool which is 'closer' to Quicktime, such as RealBasic, you
will have access to the movie toolbox, and all this stuff will be
available to you. Director's Quicktime support is ok, but does not run
deep enough for this kind of thing.
I wish it were otherwise. Quicktime is astonishingly rich, but Director
users don't get access to the really cool stuff (such as changing the
'quad' of individual tracks) because the QT3 Xtra is so basic.
--
_____________
Brennan Young
Artist, Composer and Multimedia programmer
mailto:[EMAIL PROTECTED]
Hofstadters law:
"It always takes longer than you think, even when you consider
Hofstadter's law."
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