DNxHD for filmout?

M

Michael Chen

Member
Hi guys,
I am currently making a feature for theatrical release, and has just finished the offline for my film. We shot the film on the Sony HDCAM F900, and I am getting conflicting advice on how we should do our online.

We edited our offline on avid xpress pro HD. Our post-production supervisor said we should finish the online on avid adrenaline, using the DNxHD codecs for finishing and outputting DPX files for filmout purpose.

Another techical friend of ours told us that we should do the online on uncompressed HD as our final output is for film and cinema release and we should not have any compression.

Both insisted that their way is the proper way, as our post-production supervisor said that there will be no noticeable difference between the 2 ways on the big screen.
And of course, we are also working on a tight budget, and if DNxHD codec is decent, we'll most likely stick with it.

Will be great if anyone can help me out. Am worried that we may make mistakes in our workflow. Thanks in advance.
 
I'd say Ideally Uncompressed would be the way to go, on a Avid Ds Nitris or a similar system, but in the end the Post Supervisor is right, there wouldn't be a big difference between the two. If you can, use an Avid Media Composer Adrenaline HD with physical break-out-box, as that hardware will help. When I finally get my film shot, this will be my workflow for a film out, but that's mostly because I can't afford the Nitris system. I'm just one person though, so don't take my advice to be the right way, you should probably get quite a few more views on this, but it may take sometime. Have you tried posting on the Avid.com message boards too? If not, try there and maybe put a post on DVinfo.com also.

Also, this may sound out there, but try getting an e-mail to Robert Rodriguez, he's done many many filmouts from HDCam Cameras....
http://troublemakerstudios.com/contact/
(This is Trouble Maker Publishing so I don't know who this will actually go to, but maybe you could ask for it to be fowarded since it's a technical question.)

I don't know if you'll actually get a response back but if you do, he'll have the insight and the know how. Anything from Spykids two on was shot with a HDCam Camera.
 
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uncompressed is the way to go if you can afford. The DNxHD board is simply a way to compress content so you don't have to use as much hard drive space. It may be minimal, but once you've done your master, there is really no going back, so you have to live with the compromise.
 
Of course, doing a brief test with a maximal post process (color correct, VFX, titling, whatevah) and comparing the two, zoomed in and looking for artifacting differences. Uncompressed is of course preferable, but will you be able to tell much difference considering it started life as a 22.5 MB/sec compressed 3:1:1 stream in the first place?
My gut says if budget is an issue, spend the money on better color correction etc. rather than uncompressed over DNxHD (and if you do go DNxHD, for God's Sake use 220 not 145!!!!!!)

-mike
 
You should try to do a quick film-out test before you decide. compression normally shows up in scenes with high detail levels like foliage etc.
DNxHD is a really great compression scheme but its designed to work best with the gamma of a broadcast monitor, I would be concerned that the non linear gamma of the film-out process would reveal some previously unseen artifacting. Obviously your source footage is already highly compressed at 144 Mbit/s

Michael Chen said:
Both insisted that their way is the proper way, as our post-production supervisor said that there will be no noticeable difference between the 2 ways on the big screen.
Click to expand...
Can he back that claim up? Can he show you some DNx that went to film?
Movie screens are slightly larger then broadcast screens.

I've posted a few 8bit HDcam, to uncompressed 8bit files, to film projects, that have looked OKish
DNx is not a chance I would take with my project without testing, filmouts are expensive!

FYI at 23.976 the current top DNx compression is 175 Mbits/s and HDcam is 144 Mbits/s

Dont forget "Compression Leads to Depression"tm
 
Thanks for all the feedback. Appreciate all the advice given.

I actually found another thread titled "Avid uncompressed HD" in this forum posted by MichaelP, where he speaks about going for DNxHD as a good alternative.

The film transfer house does not use avid and uses a system known as DVS CLIPSTER which I am not familiar with.
Therefore, I intend to bring our computer over to capture online footages under DNxHD, and if the results is bad, we'll have to redo the whole process again in uncompressed format.

But from the looks of all the comments, I guess perhaps it's worth taking a risk to capture in DNxHD 220 and see the result in big screen and hopefully it will hold up well. I don't think I can edit uncompress HD in Avid Adrenaline if I am not mistaken, and we can't afford the Nitris system as well. It's a whole new budget for us doing uncompress, unless there is an affordable way to do it.

By the way, Mike Curtis, are you the same Mike from hdforindies?

Punkmetaldrummer, so you'll be using this workflow as well? Guess we are in the same boat, we can't afford the nitris system.
 
The DVS Clipster is a serious high bandwidth system the tool set is a little limited in comparsion to its competitors but it will playback 4k if need be.

Adrenalines will only do compressed HD, Symphony nitris will do uncompressed.

Good luck, I'll be interested in your findings
 
Will keep you updated on the results.

By the way just to double confirm,
what is the storage space required for 2 hours of footages captured on DNxHD 220?
 
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