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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

HD to SD; lot's of aliasing...

Hi Leo

We have yet to take delivery of our Red but this is an issue that we have already experienced while working with HDCAM footage. Looks great in HD but when we down convert with get lots of problems with line twitter and zinging! Sorry for the non technical description but you get the picture.

We down convert by dropping our completed HD timeline into a 8 bit uncompressed one and rendering out. Like you, the only method that we've found successful is to use the FCP Flicker Filter.

Without having to resort to sending our footage out of house to be run through a Snell & Wilcox Alchemist Ph.C - HD or similar, we're on the hunt for an affordable solution.

Ideas welcome!

Scott
 
Results so far...

Results so far...

I'm not sure I'm getting anywhere...

I've run so many tests, with so many different combinations of settings, I'm getting suite-fatigue & suite-blindness.

The latest wrinkle is that a highly respected guy around here told me that 4K 16x9 couldn't work and that is my problem. Said he couldn't get 4K 16x9 to process in RedCine and recommends using only 4K 2:1.

Very strange, because it's working fine for me; the R3D files open easily and process fairly quickly on my 8 core Mac. Using latest Apple software, 16GB RAM.

I'd like to know if others are using 4K 16x9 successfully.

As I've said, the 4K 16x9 files look great in the flavors of HD I've tried, but I've not been successful in making SD files from them using FCS or Compressor.

I've sent files to the smart guys here at Red and also to Assimilate. I am considering a hardware converter, but that really add complexity to the post flow.

Can't believe I'm stumbling over this...

Many thanks and best regards to all who are helping!

Leo
 
I give up for today...

I give up for today...

First, I want to sincerely thank those who generously gave of their time to help with the HD to SD issue.

When I haven't been at RedCine vainly trying various settings to produce acceptable SD files or HD files that could be converted to acceptable files, I've been emailing or on the phone with equipment and software developers. I've learned a lot, received occasional misinformation, and am now trying to sort it all out.

Either I'm doing something very wrong (quite possible) or, as some much wiser than I have suggested, the Red HD file is so non-standard that the typical conversion software can't produce a good down-conversion. I have not yet tried running through After Effects or Shake.

I do have an awkward hardware work-around, exporting 720p from RedCine and down-converting with a Panasonic HD deck, so my Red is not useless, but this is a quite inconvenient fix.

It is, however, to my eye much more pleasing than applying blurring filters to mask the horrible aliasing artifacts.

I've sent my files to a couple of people, including the Boxx/Scratch guys, and am waiting to hear how they are handling the down-convert. I won't be pleased if I have to invest in hardware, but it's better than where I am with this now.

So, here's my plea; if you know how to produce high-quality SD video from Red footage, please share. I do appreciate the theoretical suggestions, but would sure like to hear actually success methods.

I'd like Red to make a definitive statement on this issue. Surely many, if not most, Red users have a need for SD deliverable video.

I hope a post will arrive that will make me whack myself on the head for not realizing what I should be doing.

My thanks and best regards to all,

Leo
 
most, Red users have a need for SD deliverable video
Click to expand...

Much of what I do will end up SD. This is a big issue. I have just received my
mac pro and I'm awaiting a Kona LH. It is disappointing to hear that it does not down convert well.

I will be following this thread closely.

Best of luck.

Frank
 
Hi Leo
Something to watch out for with Quicktime and FCP on a Mac is the RGB to YUV conversion. Apple in there wisdom apply all sort of horrible filtering in this conversion which can produce banding, aliasing, sharpening and also often produce gamut errors. Simple create a red circle on white in photoshop and render it on a uncompressed 4:2:2 timeline in FCP and you see what I mean. DS, Flame and other systems handle this much better. I can reproduce what FCP and Quicktime do in Combustion by applying a .5 sharpening filter to the same red circle with the same results.

If we have a problem down converting we do it in a program with good filtering ie shake, combustion and render to a rgb format not uncompressed 4:2:2. We then use BM old 2Vuy codec and set the timeline processing to RGB and let the BM hardware to the RGB to YUV conversion. Not the worlds best solution but it certain helps with some aliasing issues and gamut errors.

Cheers, Chris
 
A salesmen gets lost in a small town and asks for directions. After explaining where he needs to go he is told he can't get there from here. I have had the same experience and I am using the same work around with the DVCPro HD deck with the addition of using after effects to add a little unsharp mask as I make the 720p from the 1080p Redcine made. What a convaluted work flow to get good SD. SD sucks, it needs special anti alias treatment to look good. Remember the early character generator from Chyron. The fonts were jaggy because anti alias technology had not been invented. Red is concerned about HD not SD. When you transfer 35 to SD tape the Spirit has anti alias technology. Without it your film transfer would be filled with jaggies. I do not know of any software solution for down converting HD with the same kind of quality you get from a quality hardware converter. Teranex may be just the ticket. Until I see for myself that a better final product is possible, from software or hardware I will continue with my convaluted workflow.
 
Leo - if you like, make some r3d with particularly bad aliasing issues available to me and perhaps I can be of some help in coming up w. appropriate settings or software-based workflow for this.

I'll be running it through Scratch, not RC, but to the best of my knowledge the algorithms are the same, so once I've determined the correct settings the workflow should translate.

cheers,

john t.
 
Thank you, John!

You have a PM directing you to the file via ftp.

I'm speaking with the Teranex guys this morning as well.

Best regards,

Leo
 
I don't know of any NLE with what I'd call good downconversion abilities. They are simple because that's fast.

Downconversion is a two step process:

1) filtering
2) decimation

Filtering is the process of removing any frequencies /detail in the source image that are too high to exist in the desired downsample. Say you're going from HD to SD, you must remove any "HD only" detail before you decimate. If you don't, you get aliasing.

Decimation just means dropping pixels to get to the desired output resolution. That's the easy bit, but without the correct filter, you'll get aliasing.

RED has a very high resolution, more than HD, much more than SD. You need very strong anti alias filters in your downconversion to remove those extra high details or else you'll get aliasing in the downconversion. Consequently, you'll also get the sharpest SD you've ever seen.... They are two sides of the same coin.

If your software does not anti-alias enough, standard trick is to pre-blur the image slightly to drop the detail to the level where the in-built filter can handle it.

To see an example of this all in action, http://www.cambridgeincolour.com/tutorials/image-resize-for-web.htm

The design of an downsample filter is tricky - you must make it:
preserve resolution,
remove detail that can cause aliasing,
and avoid ringing or other artifacts.

Graeme
 
Thanks, Mark, I've seen that demo and talked with the Teranex guys; the problem with this solution is that the Teranex doesn't deal with files.

To make this work we would have to play the HD out of FCS into the Teranex and use another Mac to record the down-converted SDI.

Talking with Boxx now; they claim they can do a "beautiful" down-convert, and although this is much more expensive, it's a much simpler solution. I'm now downloading their test conversion of my footage.

I'm very grateful to Graeme's assistance, but applying his suggested filter settings produces unacceptably soft results.

Best regards to all,

Leo
 
Hi Leo,

Can you make a review about the result from BOXX.

Thanks.
 
I downloaded the SD test files that were processed by Scratch/Boxx and, unfortunately, the aliasing problem is as bad as with the other software solutions we've attempted.

I'm not so happy.

Best regards to all,

Leo
 
Leo can you post some footage for us to look at?
I'd like to see the images you are talking about, and try to establish what isn't acceptable about them, and hence try and work out the best way to make them acceptable.

Simple frame grabs would suffice.
 
Hi Ed,

A frame grab won't show the problem. Picture looks good as still frame; it's the motion that shows the issue.

Best regards,

Leo
 
The plan at our facility is to use the Teranex Mini. We have a Red HD finishing room and we will send the finished program/spot or scenes that need to be in SD into the Teranex at 1080P. The Teranex will output a down converted 480i 59.94 and we will recapture in our SD room. Seperate masters HD and SD will be created in each room. It blows. But I do not see any other way.
 
You know, this may sound stupid, but I found while working on a series in HD and staring at HD monitors all day, that the digibetas we were making continually looked shockingly bad on the SD monitors until we got used to looking at them. So there is a perceptual problem going back and forth between HD and SD, I think. Just a thought. Maybe the psychological factor is making things look worse than they do, particularly if you have been beating your head against the wall over and over again over this. Maybe you should get a second opinion from somebody else.
Rob Gardner
 
The aliasing is real. Not imagined. We get it the same here. We make TV spots. We have a Varicam and we can A B the footage and it aliases big time. The HD version is smashingly clean. The SD version aliases. It would be great is there was a software down converter that did what Teranex does. Teranex says they are working on a software solution but it may be as far as two years out. Til then I'll be hardware converting.
 
The aliasing is not only real, it's your worse nightmare. Let me state this as plainly as possible; the software down-converts from Red footage are unusable. This is the very bitter reality until someone can demonstrate an acceptable software down-convert solution.

Mark, I also talked to Mike Poirier at Teranex; he was quite convincing that a software solution does not exist. We're planning the Teranex route as well.

What happens to the people putting together Red packages on a modest budget? What happens to the legion of Scarlet users if the down-converts from that camera look as bad as from the Red One? Ladies and gentlemen, this is serious.

If I were directing the R&D efforts at Red, making a suitable down-converter application would be my top priority.

Please, please, no fan-boy flames. I'm here to honestly report my experiences with Red and to learn from others. I'm not Red-bashing; I firmly believe this camera changes everything, but the SD problem is something I never counted on.

Best regards to all,

Leo
 
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