Down converting HD with minimum motion artifacts

Jerry K wrote on 8/13/2011, 4:59 PM

Before I start I wanna thank everyone that replied to my last thread on this subject and tried explaining the pitfalls of down converting HD to sd for DVD delivery. Some of the explanations of why down converting degrades the video was very interesting and informative but the problem still needs to be addressed.

This time I'm looking for less of the technical reasons why down converting degrades mainconcept mpeg-2 sd video and more of any remedies you might have. I'm looking for people that might have answers to this problem and have found an easy ways to get there HD video onto a DVD with minimal motion artifacts and still have a good quality video.

I use Vegas pro 10e for render out my avchd 1080x1920 60i videos and deliver it on sd DVD. After experimenting with many different settings and have read all the threads on this subject I get the feeling there are no good answers but maybe some one on this forum might surprise us.

I have found the best setting for me in Vegas Pro is what "John Cline uses"

Just set the "Deinterlace Method" in the "Project Properties" to either "blend" or "interpolate." In this case, it doesn't matter which one, just don't leave it set to "None." (Which method you choose only really applies when converting interlaced to progressive, which is not what your doing. I always use interpolate.) Set rendering quality to "Best" which tells Vegas to use the higher quality Bicubic rescaling algorithm and you're "good to go."

The only difference between John and I, I use Sony sharpness filter set to "0". These settings give the best possible sd video that I could find using Vegas Pro. I have never used any other programs or plug-ins to down convert HD.

The biggest problem I have with my DVD videos is motion artifacts. Otherwise the picture looks good. The motion artifacts drive me crazy.

So without all the technical talk has any one on this forum come up with a solution or better way of down converting HD videos and eliminate most of the motion artifacts and still keep the video looking good???

I apologize ahead of time for beating this subject to death but I think a lot of us are looking for more answers on this subject.

Jerry K

Comments

musicvid10 wrote on 8/13/2011, 5:23 PM

You are rendering your mpeg-2 as 29.97 interlaced, right?

Also, setting the Quality slider in the custom render properties all the way to the right uses the best motion estimation available in Vegas, but it is really hard to notice a difference.

Can you render and upload a short clip that shows these motion artifacts? There shouldn't really be any if you haven't changed the frame rate.
Also, posting the exact render properties you used may shed some light.
;?)

Jerry K wrote on 8/13/2011, 9:44 PM

Here are my settings:

Project Properties:
HD 1080-60i (1920x1080, 29.970 fps)
Field order: upper
Frame rate: 29.970 (NTSC)
Pixel aspect ratio: 1.0000 (Square)
Pixel format: 8 bit
Render quality: Best
Motion blur type: Gaussian
Deinterlace method: interpolate
Adjust source window to better match project: checked
__________________________________________________________
Render settings:

Main concept MPEG-2, DVD Architect NTSC wide.
Custom settings: DVD, 720x480, 29.970, I-frame 15, B-frame 2,
Profile Main, Level Main, Field order Lower, Video quality high 31,
Insert sequence heading before every GOP-checked, Veriable bit rate
Max 9,500,00 --- Aver 6,000,000 --- Min. 225,000
Advanced settings never changed.

I believe the motion artifacts are just part of down sizing and are being amplified by using the Sony sharpen filter at "0"

Jerry K

PeterDuke wrote on 8/13/2011, 10:03 PM

Maybe your minimum bit rate ought to be say 4,000,000. I like the average to be about 8,000,000 if practicable, although I know musicvid prefers a more conservative figure for better compatibility. You could leave the field order at upper for your render.

What is your Gaussian blur set to?

Can you describe how these artefacts look?

musicvid10 wrote on 8/13/2011, 11:56 PM

Trying Peter Duke's bitrate settings is a good idea. If that does away with the artifacts, you can then back off a little until you find the sweet spot. But don't go below 2,000,000 on the minimum bitrate. I would still like to see an example of what you are seeing.

farss wrote on 8/14/2011, 12:39 AM

"I believe the motion artifacts are just part of down sizing and are being amplified by using the Sony sharpen filter at "0"

If you're going to apply any sharpening it is best done after downsizing.
I've never really figured out how to ensure it is done after resizing except by nesting the HD project in a SD project, applying the sharpening in the SD project and encoding from that.

As others have said though without seeing your problem I'm really only taking a stab in the dark, your problem could quite different to what I imagine it to be. Many things can rob the encoder of the bit budget and cause other problems e.g. noise.

Bob.

amendegw wrote on 8/14/2011, 2:46 AM

"What is your Gaussian blur set to?Several months ago I started the following thread: HD to SD Challenge I don't think we came to any hard-and-fast conclusions to this issue, but there's lots of good ideas there. Is the twitter/flicker observed in the example clip the type of motion artifacts you are referring to?

Next, regarding Gaussian Blur, I've had some pushback on this forum, but I've found that setting "Reduce Interlace Flicker" does less damage to the image than adding even the minimum, vertical only Gaussian Blur. YMMV

I'd love to take a look at a few seconds of your before-and-after clips. Are you familiar with Dropbox ?

...Jerry

Edit: If you want to venture into the world of non-Vegas tools, Nick Hope has done some really good work. Here's a starting point: Interlaced HD to DVD AGAIN - some test renders

farss wrote on 8/14/2011, 5:08 AM

Jerry,
He's not using Gaussian Blur, he has Motion Blur set to "Gaussian" in the project properties..

Unless he's using the Motion Blur envelope in the Video Buss Master it has no effect.

Bob.

TheHappyFriar wrote on 8/14/2011, 5:39 AM

When I do my HDV to DVD conversions/renders I normally use a custom bitrate mpeg-2 template, nothing more. Sometimes (depends on how fast I need things & what I'm doing) I'll render to a DV AVI first, then render that to a mpeg-2.

In theory, if doing downsizing was always horrible, you would have horrible viewing results when you take a 16:9 DVD (even one bought in stores) & play it letterbox. I've never experienced that.

Jerry K wrote on 8/14/2011, 6:06 AM

Thanks for all the good replies. I did sign up last week for the free dropbox but haven't had time to figure it out. I will be out of town unit the end of the week. When I get back I will try and post a clip.

Musicvid asked, what is your Gaussian blur set to?
I believe that's a Sony filter which I do not using. I tried it once and did not like it. If you are talking about the one in project properties that is set to Motion blur type: Gaussian.

Peter said, You could leave the field order at upper for your render. The default is lower for Main concept MPEG-2, DVD. I thought I read that if you set it to upper you could have a bad interlace problem.

As I stated I use the Sony sharpen filter at "0" when rendering out Main concept MPEG-2, DVD from my AVCHD timeline. I think this could be my problem being it amplifies the high frequencies and gives more line twitter/flicker but with out this sharpen filter the picture has no snap.

How many other people on this forum do or do not use the Sony sharpen filter when rendering out?

Jerry, thanks for the link to the HD to SD challenge. I did follow that for awhile but it was getting out of hand and just like you said there were no hard-and-fast conclusions.

Jerry K

amendegw wrote on 8/14/2011, 6:15 AM

"As I stated I use the Sony sharpen filter at "0" when rendering out Main concept MPEG-2, DVD from my AVCHD timeline. I think this could be my problem being it amplifies the high frequencies and gives more line twitter/flicker but with out this sharpen filter the picture has no snap"Jerry K,

Humor me on this... right click on your video event(s) and click Properties->Reduce Interlace Flicker. This has helped my renders, although others in this forum don't like this "solution". If it helps, great. If not, we'll need to try something else.

Good Luck!
...Jerry

Jerry K wrote on 8/14/2011, 7:27 AM

I have tried Reduce Interlace Flicker a few times in the past. I did not like it because it help the twitter/flicker but caused other problems. If I remember correctly it put a slight strobe effect on pans or movement.

It definitely helps when panning still photos in Vegas.

Jerry K

John_Cline wrote on 8/14/2011, 2:23 PM

Jerry, define "motion artifacts", what exactly are you seeing?

Jerry K wrote on 8/14/2011, 4:48 PM

Jerry, define "motion artifacts", what exactly are you seeing?

Anything with fine detail or sharp outlines like grass, doorways, eye glasses, silverware on the table at weddings.
If the camera moves there's a twitter/flicker effect.

I just viewed 5 minutes of a wedding I shot. I made 2 DVDs. The first
one with out Sony sharpness filter, the second one with Sony sharpness filter at "0"

The twitter/flicker was acceptable on the one with out the filter but the picture looks just okay. The second DVD with the filter
looked sharp but had to much twitter/flicker for my taste.

I viewed this test on my Sony 47" HDTV. When I have time I will view this test again on my 32" Samsung HDTV which shows allot more
of this annoying twitter/flicker around sharp outlines during panning.

Jerry K

dougs wrote on 8/14/2011, 6:55 PM

can i also ask,

What HD format is best to shoot for a project that is going to end up on DVD, My camera has a range of options but i have narrowed it down to 1440 x 1080/50i which i think is HDV or 720/50p,

Both formats seem to work well in vegas from my testing but is this a consideration also? i have an i7 with 24gb ram.

thanks for any input.

John_Cline wrote on 8/14/2011, 7:50 PM

Jerry, try the convolution filter settings that I posted toward the bottom of the following thread instead of the sharpening filter.

http://www.sonycreativesoftware.com/forums/ShowMessage.asp?ForumID=4&MessageID=725526

Jerry K wrote on 8/14/2011, 8:20 PM

I was searching around and found this older link http://www.dvinfo.net/forum/archive/index.php/t-116196.html
with people that are having the same problem I'm having with line twitter. After reading the link I did some experimenting and here's what I came up with to minimize line twitter and still have a good quality DVD

Rendering out your HD timeline to Main concept MPEG-2, DVD Architect wide using Sony Vegas normal settings. If you are not sure see my settings above.
Set Sony Gaussian blur filter to Horizontal range to 0.001 vertical range 0.000 that's correct No range. Now set Sony sharpen filter to medium .500 to heavy .750 or somewhere in between. That's it.

I only had an hour to try this and it looks promising. I will play around some more when I get back from my trip later in the week.

In the meantime maybe some one could try this and report back.

Jerry K

Jerry K wrote on 8/14/2011, 8:29 PM

John, I will try your convolution filter when I get back.

Thanks, Jerry K

PeterDuke wrote on 8/14/2011, 11:26 PM

"Peter said, You could leave the field order at upper for your render. The default is lower for Main concept MPEG-2, DVD. I thought I read that if you set it to upper you could have a bad interlace problem."

DVDs will accept both UFF and LFF. If you convert SD from one field order to the other with a deinterlace method set you will get some blurring. However, it may be that going from HD to SD the effect will be unnoticeable, but it seems best to me to not do any unnecessary conversions.

Since the files are flagged with the field order, you shouldn't get jerkiness whatever you do - that only occurs if the flag is wrong.

PeterDuke wrote on 8/14/2011, 11:44 PM

"What HD format is best to shoot for a project that is going to end up on DVD, My camera has a range of options but i have narrowed it down to 1440 x 1080/50i which i think is HDV or 720/50p, "

If you have an HDV camera you can probably shoot in SD format. From there it is a no brainer - no conversions to worry about and near optimum performance.

Out of the two you suggested, 720p would probably be better because 1080i would need to be deinterlaced during the conversion process, and so you would avoid this step.

dougs wrote on 8/15/2011, 1:14 AM

Thanks Peter for your reply, (apologies for jumping in on this thread should have probably started a new one.)

yes if my camera (a sony pmw350) shot in SD i would definitely use that but sony want $1,000.00 to enable that, so far i have got by without it.

I assume then If you use a progressive format then then the de interlace option in the project render properties is irrelevant.

What sort of process does vegas go through to generate fields from progressive material when encoding to Mpeg2 for dvd which requires interlaced (except for 24p of course.)

Thanks

dougal

farss wrote on 8/15/2011, 1:16 AM

"Rendering out your HD timeline to Main concept MPEG-2, DVD Architect wide using Sony Vegas normal settings. If you are not sure see my settings above.

I've used that trick for almost a decade to wrangle line twitter. Applying GB in the vertical direction can help the problem or it might be too much softening.Whetever approach you use the order in which you do things is critical. It must go Soften>Downsize>Sharpen.
If you get the order around the other way for example you will make the aliasing / line twitter problem worse and then you'll need so much softening to wrangle it you'll end up with mush.

One other tip, try reducing the "detail" or "sharpness" setting in your camera.
Also as you've hinted you're going to do, check your problem on several different displays. Some displays do horrible things and you can get yourself into a deep hole trying to "fix" the problems that some displays have.

Bob.

PeterDuke wrote on 8/15/2011, 2:07 AM

Yes you really should have started your own thread. If you have any more questions, I suggest you do.

"What sort of process does vegas go through to generate fields from progressive material when encoding to Mpeg2 for dvd which requires interlaced (except for 24p of course.)"

None of us are privy to the finer points of the internals of Vegas, but by experimentation some things can be gleaned. This is my guess of what happens:

To convert from 50p to 50i with say UFF, the even lines are dropped in the first frame and the odd lines in the second frame and the two are then interleaved to form a new frame, and so on, giving 25 frames per second instead of 50. Some vertical blurring (low pass filtering) should also be done first, to reduce vertical aliasing or shimmer that might show up in non-static frames.