Best workflow for alpha overlays? Also HDV or AIC?
by Andrew Rollo
on
Jul 21, 2008 at 9:31:30 am
I am using HDV footage and I have some transparent overlays in PNG format.
Currently I edit in HDV native but adding the overlay means I have to render and I have to re-render every time I move it.
The render time are so slow. Surely I should be able to get real-time playback with basic transparency on a high end quad workstation in Final Cut.
I was also considering changing from HDV to AIC. DVCPro file sizes are too high but AIC isn't bad vs HDV. Have people noticed significant performance improvement in renders changing from HDV to an I-frame compressor?
I suspect the issue with alpha is that these codecs don't support an alpha channel so the render has to happen. I don't want to change my workflow to something like Sheer, which supports alpha as I don't use transparency all that much. Do I maybe have to store the color part of the overlay as the same format as the timeline and use the alpha as a mask layer? Or is the only way to avoid rendering an alpha overlay to have all clips in a format that supports an alpha channel?
Re: Best workflow for alpha overlays? Also HDV or AIC? by Lee Berger on Jul 21, 2008 at 2:09:19 pm
Andrew,
The only format in FCP that supports alpha is Animation, an uncompressed format that produces very large file sizes. If you want to stay with HDV files sizes and if you are in FCP 6.0.2 I would suggest you continue to edit natively in HDV, but render in ProRes 422. Go to your Sequence Settings (CMD+0), Render Control Tab. In the Codec drop down, choose Apple ProRes 422. As it indicates this only works with HDV and XDCam. Your renders will be faster then rendering in the Same as Sequence Codec setting. You will probably still have to render your PNG overlays, but it will take less time and the quality will be better.
The other option is to capture or transcode directly to ProRes 422, but that will double your file sizes.
Re: Best workflow for alpha overlays? Also HDV or AIC? by Andrew Rollo on Jul 22, 2008 at 1:36:56 pm
Thanks for the reply, I only have Final Cut 5.1.4 - I don't think the ProRes option is available. I tried out the transcode idea using Apple intermediate though (there is a capture option called HDV-Apple intermediate) and the capture worked but HDV 720p25 comes out as 50fps Apple Intermediate. The clips are playing at twice the speed. I also don't get any logging - it's just a raw capture. It also hangs up randomly doing this.
I can setup a sequence as 25 fps Apple Intermediate, I'm not sure why it captures as 50fps.
I think for the moment, I will have to stick to HDV. I set the playback to unlimited in the preferences rather than safe so it previews the overlays, it just stutters a bit but good enough for previewing overlay positioning.
