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Re: How reliable is GetMovieTime()
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Re: How reliable is GetMovieTime()

On Saturday, February 16, 2002, at 12:57 PM, Bob Sabiston wrote:
In my application, I am trying to set some markers as a quicktime movie
plays. I start the movie with StartMovie and then use GetMovieTime as it
plays to find out how far along it is. This is not working too well,
though; the times that I get do not correspond well with where the movie
really is when I request the time. Is there a more accurate way to
determine exactly where the quicktime movie is at any given moment?

It seems to be a drifting problem. The times start out pretty accurate, but
after a couple of minutes they are off by about a second. There should be
some way to tell exactly what frame or time value is playing exactly right
now--is there?

How are you deciding that they are off? That timevalue should correspond to the time QT is using to play the movie back.

QT usually will derive this timing from the samplerate of sound playback, so if you are using the computer's clock as an external reference to compare with, you may be seeing the drift of your sound card against its notional samplerate.

Another possibility is that if the movie is overtaxing the CPU, the displayed frame may be slightly behind the current time, with QT in catch-up mode trying to restore sync. In this case you will likely see some dropped frames.
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 >How reliable is GetMovieTime() (From: "Bob Sabiston" <email@hidden>)



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