Calculating Final Cut Pro X xml sequence duration

Question

Final Cut Pro X xml (fcpxml documentation, page 19) elements have duration attributes like these "duration=264100/2400s". Denumerator should mean frame rate (24 frames per second). How can I calculate item duration in frames or in seconds and frames?

excerpt from documentation: "Time values are expressed as a rational number of seconds with a 64-bit numerator and a 32-bit denominator. Frame rates for NTSC-compatible media, for example, use a frame duration of 1001/30000s (29.97 fps) or 1001/60000s (59.94 fps). If a time value is equal to a whole number of seconds, the fraction may be reduced into whole seconds (for example, 5s)."

edit: actually duration is so obvious... eg. duration="4500/2400s" is: 4500 // 2400 is 1 second; 4500 % 2400 is 2100 or 21 frames, meaning duration is 00:00:01:21.

but still I can't find out how to calculate item time code in the timeline with all these other attributes like this (title starts at 00:00:04:22 in the timeline, the timeline duration is 00:01:50:11, all @24fps):

<title name="Basic Title: The Big Lebowski" lane="1" offset="8651800/2400s" ref="r2" duration="6000/2400s" start="3600s">

score 0 · Answer 1 · answered Aug 04 '16 at 17:40

I'm not sure I understand your question, but from your example, I get this:

The timeline starts 01:00:00:00
The title appears at 01:00:04:22
And stays for a duration of 00:00:02:12 (60 frames @24fps)

I got these results from the following Perl function, which takes the frame rate as second argument.

sub fcptime2tc {
    my ($t, $fps) = @_;

    # extract $x, $y from stuff like "8651800/2400s" or "3600s"
    my ($x, $y) = $t =~ m!^(\d+)(/\d+)s$!;

    $y =~ s!^/!!; # delete "/"
    $y ||= 1;

    my $seconds = $x / $y;

    my $f  = sprintf( "%02.0f", ( $seconds - int($seconds) ) * $fps );

    my $z  = int($seconds);
    my $s  = sprintf( "%02d", $z % 60 ); $z /= 60;
    my $m  = sprintf( "%02d", $z % 60 ); $z /= 60;
    my $h  = sprintf( "%02d", $z % 24 );

    return join(":", $h, $m, $s, $f);
}

It should be trivial to translate to any other language if you like.

What this doesn't take into account is silly drop-frame timecodes.

Calculating Final Cut Pro X xml sequence duration

1 Answers1