Time Unit Calculation

[Michael Gissing]

My guess is samples in kHz. Is the clip 60 seconds approx? If you divide the number by 48 it is just over 60 seconds. That is assuming a sample rate of 48kHz.

Also the clip is mp3, a codec badly handled by FCP. It should have been converted to aif or wav 16 or 24 bit 48khz before editing.

[Pie Mal]

Thanks for the post.

The duration of this whole track is actually 25:06 min

I think you’re on to something though, I’m thinking that number is somehow related to the frame/bit rate. These XMLs are meant for tagging video at a particular point in time (relative to audio). If you have any further insight as to the formula I would use to deduce the actual point in time (preferably in units of seconds/milliseconds/minutes) that would be awesome.

Thanks!

[Pie Mal]

Here is another example of one of a video track:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE fcpxml>
<fcpxml version="1.0">
<project>
<resources>
<format id="f1" frameDuration="1/29s" width="640.000000" height="480.000000"/>
<asset id="r1" name="1985-11-10-Berkeley_part_2.m4v" uid="O2wWMxasJdyRavHND5dJ" src="video/1985/1985-11-10-Berkeley_part_2.m4v" start="0/29s" duration="136647/29s" hasVideo="1" hasAudio="1" audioSources="1" audioChannels="2" audioRate="48000.000000"/>
</resources>
<clip name="1985-11-10-Berkeley_part_2.m4v" start="0/29s" duration="136647/29s" format="f1">
<video ref="r1" start="0/29s" duration="136647/29s" offset="0/29s">
<audio lane="-1" ref="r1" start="0/29s" duration="136647/29s" offset="0/29s" role="dialogue"/>
</video>
<marker start="43703/29s" duration="1/29s" value="final thought"/>
</clip>
</project>
</fcpxml>

[Pie Mal]

okay so…from developer documentation, this only partially answers my question but a start:

“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”).”

I found this by googling “fcpxml audio tag” and clicking on the pdf

[Michael Gissing]

Being a video edit XML I imagine that there is a formula based on frame rate. I know broadcast wav timecode data is based purely on number of samples from a zero point. I am guessing it is for FCPX as roles are mentioned.

However I have no real skill in this area apart from some involvement in beta testing and software development with some audio companies.

[Nick Meyers]

if you ask at the apple developer site, you will definitely get your answer.

nick

[Milivoj Ivkovic]

Many years later, maybe it’s still worth replying in case others stumble onto this post.

In .fcpxml files, the start, offset and duration numbers are real-time seconds (as hinted to by the “s” at the end). They are not related to framerate. You only need the framerate if you need to convert these times to a frame number or to standard timecode which uses frames.

An example from a title in a .fcpxml file:




[Pie Mal]

Still more years later that Reply was helpful thanks a lot Milivoj Ivkovic