HDV 1080i 25fps
by Simon Cawthorne
on
Jun 22, 2009 at 10:20:51 am
Hi All,
A general question.
I've successfully completed an edit using HDV for the first time: Using HDV was a test run for the future, and the final product is web based, however, I took the opportunity to look at HDV workflows and editing set ups.
This has left me with one question: I wish to create a master file for HDV and had originally assumed I could render for HDV 1080i 25fps, which was the format I captured from and have worked in throughout. However, as the AE render options only offer 1080p at 25fps, this has left me unclear on whether, as it looks, I should render progressive if I want to hold a 25fps master, or does setting up the field render option in the AE dialogue override this?
Re: HDV 1080i 25fps by Dave LaRonde on Jun 22, 2009 at 4:08:52 pm
[Simon Cawthorne]"...I wish to create a master file for HDV and had originally assumed I could render for HDV 1080i 25fps, which was the format I captured from and have worked in throughout..."
That's not quite correct. When you captured your video, it resulted in a quicktime file, an mpeg4 file, an avi file, or perhaps even an mxf file. Within this broad range of multimedia containers, it probably was compressed by a codec such as h.264.
Before we can give you a straight answer, we'd need to know more about the nature of the footage you imported into AE. You can find learn more about it by highlighting the footage in the project window and looking at the top.
And know this: any -- repeat, ANY -- kind of native HDV, still in its acquisition codec, is intended to be used only for the most basic kinds of editing... and certainly not effects work which implies re-rendering. Acquisition codecs are lossy, so called because they LOSE picture information. Best practices involve capturing in a higher-quality codec than the capture codec. For additional information on this topic, you should check in the appropriate COW forum for the NLE you used to capture the footage.
Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA
Re: HDV 1080i 25fps by Kevin Camp on Jun 22, 2009 at 4:18:34 pm
actually, you won't want to work with hdv in ae... either bring hdv into ae or rendering out from ae. i'm not saying that you can't, but rather you shouldn't.
hdv (and codecs like mpeg-2, mpeg-4, h.264) use temporal compression. with this type of compression, there are very few whole frames, most frames are composited from data from other frames, this helps reduce file size and data rates, but it means that ae has to do a lot of work to composite a frame to then effect... good for nle's bad for compositors. also, since the compression relies on looking at frames that have been rendered and will be rendered in the future, ae can't actually render using temporal compression, so, to maintain data rate it will increase the intraframe (jpeg-like) compression which will hurt your image quality when you render.
what your workflow should incorporate is converting the hdv to a codec that uses no compression or only intraframe compression when you go to ae, then, to go back to the nle, render to a codec that does not use temporal compression (probably the same that you exported from your nle), and let your nle convert it to hdv, if needed.
Re: HDV 1080i 25fps by Kevin Camp on Jun 22, 2009 at 4:25:15 pm
i forgot a short list of hd capable codecs that use only intraframe compression (or no compression) that work well in ae:
uncompressed avi
quicktime lossless animation
quicktime photo-jpeg
apple's pro res 422 (need fcp)
avid's dnxhd (free from avid)
dvcprohd
Re: HDV 1080i 25fps by Kevin Camp on Jun 22, 2009 at 4:32:13 pm
and to answer your question about 1080i, when you send your comp to the render queue, you can click the render settings and choose the render with fields by setting the field order to render to (upper for 1080, here in the states, anyway).
also, if you render to fields, make sure that any imported footage is being handled by ae to correctly separate fields in the first place, or you'll have a real mess... select the footage in the project window, at the top of that window it should say '(separating even)' some place... if not, the choose file>interpret footage>main and set it to separate fields.
Re: HDV 1080i 25fps by Simon Cawthorne on Jun 22, 2009 at 6:24:57 pm
Hi Dave, Kevin,
thanks for the input.
this is the route I took:
Captured the footage to FCP using Qt, Apple pro Res 422, 1080i 25fps.
In FCP, set up the timeline for this codec for the base edit.
I then rendered out a version for AE that was not self contained to cut down recompressions and disk usage. Took care that AE/I interpreted the footage properly for AE on import.
I then went to work with AE, and finally set up for render. That's where I'm at for the moment (having rendered a web version out with no problem to complete the job at hand of course.)
From what you've both said for an HDV master, it seems I should go back to FCP and adjust the settings to render either a No codec or animation codec in FCP, then set up the referenced QT movie again so that AE handles this instead of the Pro Res codec it is currently dealing with. Then render a no compression/animation codec back out for FCP to create a master (?) - or render out from AE at high quality for my master? I'm not sure on this final aspect.
I see that with the route I have taken thus far, I am currently attempting to compress Pro res 422 footage twice, as well as potentially asking AE to render Interlaced as progressive.
Of course, you also indicate that in the first instance, it may be better to create effects in AE and then import them into FCP (alpha channels/screen) etc.
For information, there is a good article about GOP problems, editing in Pro res, and also capturing Pro res 422 from cameras into FCP on Creative Cow. I'll try to find it and link to it.
Re: HDV 1080i 25fps by Dave LaRonde on Jun 22, 2009 at 6:29:54 pm
[Simon Cawthorne]"Captured the footage to FCP using Qt, Apple pro Res 422, 1080i 25fps.... I then rendered out a version for AE that was not self contained"
That's a very good way to do it. Don't forget that when you export by reference (not self-contained), you can't move the file to a different machine or move the original media files to different folders.
Render out from AE as ProRes, and life should be good!
Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA
Re: HDV 1080i 25fps by Simon Cawthorne on Jun 22, 2009 at 6:50:46 pm
I added a post as you were writng by the looks of it, but I'll drop it in here too -
wouldn't compressing Pro res lose quality if it is compressed again with pro res?
Also is it really as simple as taking the 1080p 25fps option and selecting the render fields option? It can't be that easy -- surely? I seem to recal pro res give an interlace option too - I set that up as "yes"
Re: HDV 1080i 25fps by Simon Cawthorne on Jun 22, 2009 at 6:31:43 pm
"I see that with the route I have taken thus far, I am currently attempting to compress Pro res 422 footage twice, as well as potentially asking AE to render Interlaced as progressive."
correction: attempting to compress footage already encoded in pro res on capture with Pro Res at the output stage from AE, which must be detrimental to quality?
