HDV to DV widescreen?

vicmilt wrote on 8/29/2007, 8:18 PM
Hey guys -

Have finally gotten to test rendering my latest longform - shot primarily in HDV (Sony z1).

Wow - even with a Q6600 and a SATA Raid setup the final render from the timeline (primarily M2t with some Cineform intermediates) takes 6 hours for an hour and ten minutes of source - with functionally no effects. This is sort of limiting me to only one test render a day (overnight) - which bites.

So I'm wondering... if I prerendered to a new track in DV Widescreen...
A - can I do this without losing final quality?
B - can I do this considering the project itself is 1080i?

The theorectical reason for this question stems from my old workflow in SD. There, I would regularly pre-render (to a new treack) - completed sections to DV. The final render of DV to MPEG2 was by and large a one-to-one affair, timewise. That is, an hour of source (pre-rendered on timeline) would take about an hour to encode.

That would enable a number of test discs and revisions in the course of a working day.

Thoughts?
Comments?

v

Comments

riredale wrote on 8/29/2007, 9:09 PM
It seems to me that something is seriously wrong for you to have such a slow render, but I don't have a quad setup. Hopefully others on this board with such a PC will be able to offer their own render times for comparison.

Rendering to DVwidescreen is a great idea for editing purposes. Even with a fast PC, I think working with DV files is much more fluid than with m2t. That said, you will lose color resolution if your final format is MPEG2 and if you are working with NTSC files. All that wonderful 1080i image information is squashed into 4:1:1 DV, meaning that the color resolution is very high in a vertical direction but only 1/4 in the horizontal direction. Then an MPEG2 encoder will chop it even further, since its format is 4:2:0 (equal color resolution of 1/2 in vertical and horizontal directions). So the final result is a pretty poor 4:1:0.

If, instead, you edit in DV using GearShift to shift back to m2t for the final MPEG2 render, then color resolution will be as good as it gets. Or you could use a format other than DV that had higher color resolution, such as DV50, Mjpeg, or Cineform.
Spot|DSE wrote on 8/29/2007, 9:46 PM
Something is seriously wrong.
HDV to DV widescreen MPEG should not be significantly more than realtime if you haven't added temporal FX or you're not keying.
FWIW, I have a long form piece rendering right now that contains 75 mins of keyed XDCAM and HDV, plus DV and HD PIP. The full project is 2:38:10. It generally takes around 8.5 hours to render from an HD timeline to widescreen MPEG. Render to DV should be faster. This is a *much* slower machine than the new machine you've posted earlier. This is a dual 270 machine.
farss wrote on 8/29/2007, 10:02 PM
Render to DV should be faster

I'm not so certain about that, keep in mind that when downscaling you really want to be rendering at Best and that can slow things down signifcantly.
As I'm in PAL land I usually render to SD DV before the edit but I do recall rendering all the camera tapes down taking quite a while, thanks to Multirenderer not too much of a pain though.

Bob.