Re: Scope of id attributes
Re: Scope of id attributes
- Subject: Re: Scope of id attributes
- From: Helena Ju <email@hidden>
- Date: Thu, 24 Jul 2008 13:34:01 -0700
Hey Bruce,
Lotsa good questions!
Your approach is right (number (3) anyway), and Gregory Clarke is also
right. Ids live only for the duration of an XML file, and in that XML
file they are unique. Certainly if you have played around with a
project and exported the XML a few times throughout that, you'll see
the id change.
The masterclip is identified in the XML via the masterclipid, but
internally we use other methods to persist the relationship. You can
think of the id attribute as a pointer to the object.
All of the above being said, how do you use it practically? If you
make up a uuid and use it as a 'id' attribute, you won't need to
inspect the project to look to make sure your id value will be
distinct. OR, you can look at the id attribute on the master clip
you'd like to connect an affiliate clip with, and use that.
Best Luck!
Helena
On Jul 24, 2008, at 11:44 AM, Bruce Sharpe wrote:
But if id attributes have no existence outside of the XML, then how do
I create an affiliate clip in XML? It needs to refer to a
masterclipid. As an experiment, I exported an affiliate clip as XML
and sure enough it has a masterclipid value that is not defined
anywhere else in the XML. If I export the whole project then I can
see the clip with that id value.
So, barring some new definitive information about this, my strategy
will be to:
(1) Either not create any new ids, or
(2) examine the project XML and choose id values that are distinct
from those already used.
(3) In any case, if I want to create an affiliate clip, I will assume
that it is safe to refer to the masterclipid that shows up in the
export of an existing clip.
Bruce
On Thu, Jul 24, 2008 at 10:00 AM, Gregory Clarke
<email@hidden> wrote:
I agree with you that case 1 is probably true. And here's why:
don't forget
that in FCP a clip is not actually a piece of media, but rather a
pointer to
a piece of media. Analogous to a QuickTime reference movie rather
than a
video file. So my guess is that the id attribute is just an XML
representation of that same pointer "link" and doesn't exist in the
FCP
project because QuickTime handles that.
Of course, we could be wrong...
Greg
Thanks, Greg. I think I get the concept of the id, but my question
is, if I create one in a component and then import the XML to a
project, will there be a problem if the id I have created happens to
be the same as one that already existed in the project?
Case 1: It is possible that there is no concept of id in a
project, it
only exists in XML imports and exports. In that case there is no
problem.
Case 2: But it is also possible that the id values that I see when I
export the project do exist in the project regardless of whether it
has been exported or not. In that case, not only do I need to avoid
conflicts when I create an id, but I may be able to reference other
project elements through their id.
Unless I hear otherwise I am going to assume that Case 1 is true.
Bruce
On Thu, Jul 24, 2008 at 9:03 AM, Gregory Clarke
<email@hidden> wrote:
Hi Bruce,
The explanation of the id Attribute on p16 of the Final Cut Pro XML
should
help - it's meant for sharing common info, so it's not meant to be
unique.
Here's the example from the PDF:
For example, the clip information for a video track in a
sequence may be
identical to the clip information
in an audio track in the same sequence. Rather than repeating this
information for both tracks, you
can encode it once and then reference the information using the id
attribute.
Hope that helps,
Greg
On Jul 24, 2008, at 12:23 AM, Bruce Sharpe wrote:
Suppose I am creating a clip, sequence or other object in XML
with the
intention of importing it into an existing project. I want to
use id
attributes in my object. Do I need to be careful not to
conflict with
any ids that are already in use in the project?
Bruce
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