final cut pro 5.x HDV rendering
 

Hi all,

Was wondering if you were all experiencing the same thing. If I have an HDV clip and just want to cut it with the blade tool final cut pro wants me to re-render the clip is something you have had happen also. I do have filters on the clip but I thought once its rendered its rendered. Any help?

If your filters required render (non-real time filters), any changes made to the clip will require re-render, including a blade cut. I haven't worked with HDV, but with SD that's how it works.

However, a cool trick I use to view non-rendered transitions, filters, etc... is to press Option+P and it will play back your timeline in "pseudo" real time. That way you see if the changes you made are the right look without having to wait for a render. That way I can make changes to my heart's content and don't have the downtime of waiting to render every small change. Then I just render the entire clip before I export. Real time saver.

Grant

Hi Jourdan,
This is due to the nature of HDV; compression are made between a bunch of frames called GOP (group of pictures). A group starts with an I-frame which contains all information in the picture (compressed) then the rest of the frames only need to contain changes to the I-frame and not fully pictures to save space on the media.

(This is why you can have four times more resolution in the HDV images than on DV images and still not use more bandwith/space. This also explains why HDV is much more sensitive to drop-outs. But DV is only compressed inside each frame.)

When you use the razor tool you cut away the existent I-frame. So FCP now has to recalculate the frames to get a cut starting with all information it needs for the first frame. Otherwise you may get a cut starting with blocky frames which are not complete until you get to the next I-frame. Hope you could understand this. /Johan

Thanks alot guys. Makes perfect sense.

Johan's answer gave a nice "behind the scene's" description. I've wondered what the reason was, I just knew it required re-render when altering, not why it did. Thanks for that detailed answer.

Does the Option+P trick work with HDV?

Grant

I used to capture HDV via the SDI port and then transcode to DVCProHD.

But since the new FCP version I find that I can capture HDV 1080f and edit it perfectly well without any delays for rendering simple cuts and trims and general alterations.

Note that I have not applied any effects yet.

So I personally don't experience any rendering delays attributable to this GOP business.

I wonder why ....

Best

Harry.

Mac G5 Dual. 2 gigs RAM. Decklink HD Pro (sl).

Works fine in HDV 24F!

In FCS 2, the new FCP 6 will allow any HDV rendering to be rendered as ProRes 422. I think this was a great idea.