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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...

GFIRob said:
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
Click to expand...

If you want a second opinion, I was there. It is far from some minor "little" issue. This is not pulldown related, it is not looking at a lower-rez movie, this is an issue of motion producing all sorts of jaggies on EVERYTHING in the clip. The only cure that we could find so far was to hit the pause button. Its that bad. What would help is if any other RED owners who are delivering SD spots on Beta would reveal how they're down-converting (be it through FCP, through some sort of hardware device, etc.
 
You have my attention Leo.

70% of what I will do ends up SD. Is there a way you can show us the problems caused by down conversion ?

If all the benefits of Red are lost in down conversion, I'm in trouble too.
 
I've posted the R3D file to our ftp server.

ftp.ltpro.com

User Name: redcine
Password: redcine

The file is named: A013_C057_080505_001.R3D

I sincerely hope someone can process this through RedCine and software down-convert it to SD at an acceptable quality.

I'll gladly apologize to all for the waste of bandwidth with this thread, immediately adopt your method, and send you a big thank-you!

Best regards to all,

Leo
 
I'm processing the car footage in RC right now (just installed) with identically acceptable results re. scaling as I did in Scratch, which is not surprising since they are the same basic engine.

I think one solution for aliasing problems is in the RC settings. This is where scaling and as much other processing as possible needs to happen for optimal results. Make sure you set the filter to Lanczos (sharpest), Gaussian (softest), or Mitchell (inbetween) if aliasing is an issue during downconvert.

And if downscaling needs to happen in other software (not sure why, though), then definitely use software like Shake, Nuke, or Scratch that has proper scaling tools. In my experience NLE scalers are TERRIBLE, and AE is only slightly better.

I'm not entirely surprised that Teranex is telling you there is no software solution (considering they mfg & sell dedicated hardware), but that is, in my experience, just not true. There are plenty of software solutions out there with highly advanced scaling tools, one just needs to know what they are and how to use them.

And it gets down to another issue - not everyone is up to speed on digital post processing of images at professional levels. Nor should they need to be.

All of us who do this sort of thing for a living are not surprised by this. Would you expect me, a camera layperson (though I've shot w. various film & digital cameras in the past) to walk on set and be able to match your abilities with Red One? I know I wouldn't be able to w/o at least several years of dedicated training and hard work. Post at professional levels is no less complex than DP'ing or operating. It all requires experience and skill if you want professional results.

cheers

jt
 
Initially, I'm getting gorgeous downconverts 1080 to SD with an AJA HDi/o. Obviously I'm on a 1080 ProsRes time line, which may not be what you're aiming for, but we've been blown away at how good it looks.

Mark Tyson
 
You may not notice the aliasing unless things move in the shot. We use a jib regularly and the camera motion shows a repeating pattern of breaks in the diagonal lines. These breaks are only a few pixels apart and as they dance on the moving diagnal lines they betray the need for quality down conversion.
 
Mark Crabtree said:
You may not notice the aliasing unless things move in the shot. We use a jib regularly and the camera motion shows a repeating pattern of breaks in the diagonal lines. These breaks are only a few pixels apart and as they dance on the moving diagnal lines they betray the need for quality down conversion.
Click to expand...

It is always necessary to use the correct scaling filters. Just like lens or camera filter choice, there's no accident to which scaling filter one chooses, and using the wrong one can produce undesirable results like Leo has been experiencing. Even if it's not blatantly apparent, there are subtleties to each type of image - soft, sharp, high contrast, etc... that necessitate correct filter choice.

I've produced and post'd plenty of jib shot, high contrast, red originated footage with no crawling edges - and correct scaling filter choice in Scratch (or Red Cine) was the difference maker.

cheers,

jt
 
I think we need Graeme Nattress to come up with another of his wonderful plugins here :biggrin: - we use a number of these already, esp. his standards conversion plugin for our PAL to NTSC work.

With the move to shooting HD for SD delivery this is a problem that is only really now becoming apparent and there does not appear to be a high quality, easy to use, affordable software option available.

If NOT addressed quickly this will affect Red camera sales.

Best wishes

Scott
 
hdc.jpg

HDC-100 is a high quality HD digital Input Down Converter for converting HD-SDI video to standard definition SD-SDI (2ch), Analog Component, Composite and (Y/C) S-Video. In addition HDC-100 is Motion adaptive 3D de-interlacing with motion adaptive interpolation and Input peaking filter for horizontal edge enhancement.
Click to expand...

Quite promising & affordable to me.

TV Logic HDC-100 Mini Down Converter
http://www.tvlogic.co.kr/eng/products/converters/con_04/con_04.php
 
Red Guy said:
Here is my take,
this is a PhotoJpeg but I also
did an uncompressed version as well.

www.cotfl.com/leo.mov

leo.jpg
Click to expand...

Thank you!

I'm heading out of town and won't be back in the studio until Monday, but this looks good playing as a QT on my MacBook. I'll know for sure when I drop it into a FCS timeline.

If it looks as good there as it does here, you have the key. I hope you will share your method!

Best regards,

Leo
 
Hi Leo,

could you post your final result with the proper anti-aliasing setting from redcine. Do you export in ProRez NTSC 10 bit from RC? Is the footage acceptable for you?
 
Sorry, Mat, I don't understand your question.

I've processed from RedCine in every conceivable way, in uncompressed, in ProRez, with a variety of filters, and numerous resolutions.

As I have said, the HD footage is beautiful; the SD down-converts are unacceptable.

I won't be posting any footage for at least a couple of days.

Best regards,

Leo
 
Leo Ticheli said:
Thank you!

I'm heading out of town and won't be back in the studio until Monday, but this looks good playing as a QT on my MacBook. I'll know for sure when I drop it into a FCS timeline.

If it looks as good there as it does here, you have the key. I hope you will share your method!

Best regards,

Leo
Click to expand...

I think the key is to not scale down to SD in REDCINE.
I exported a 1280x720 DPX sequence and took that into
After Effects.
I opened a 720x486 Comp in AE and dropped the DPX into that.
Slight CC.
I edit most of my 30 sec spots in AE anyway.
I know that AE handles the scaling way better than FCP.
I use FCP as a final add slates tags & such and dump
to tape from there.
 
Red Guy said:
I think the key is to not scale down to SD in REDCINE.
Click to expand...

That's not the case. As I've been saying in all my posts, scaling in RedCine is probably the best thing to do... as long as you choose the correct scaling filters.

AE doesn't allow for any setting of scaling filters - but all scalers use an algorithm (mathematical formula) of one sort or another, and choosing the best one for a particular job is part of the deal. AE uses something like bilinear, which is decent all around, but not ideal for all situations.

RC has many scaling algorithms, one for just about any situation. The one that is defaulted, Linear, is very fast, but really only suitable for scaling by multiples of 2 or previews.

It is necessary to change that setting if you're doing anything beyond that. I've mentioned, in multiple previous posts, that Lancsoz, Gaussian, and Mitchell all produce good results right out of RC, obviating the need to scale in other software.

regards,

john t.
 
I've recently done a job involving montages from high resolution DSLR stills that had, as expected, exactly this problem.

What is the problem with applying a guassian blur pre-resizing?

This does not blur the SD image or lessen the percieved quality of the final SD image. The SD image simply doesn't have the resolution to show the blurring the process just gets rid of/prevents the jaggies that cause the aliasing.

Is the issue the greater time involved with applying a blur? Please give details.

If ones post budget is sqeezed so much that one cannot use the high quality resizing hardware and software out there then this is by far the simplest solution and IMO often delivers the best (low-cost) results.

JohnF
 
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