Help a newbie with Still Images/Freeze Frame Problem?

ksuwildcat93 · Post by **ksuwildcat93** » Wed Jul 05, 2006 12:19 am

Hi!

This is my first post...so please be patient or give me directions if I am not asking my questions properly on the forum. I used the search function but couldn't find an answer for my exact question.

I am currently using MSP 6.5. I am thinking of upgrading, but that is another issue...

My question is what I can do to stop my still images and freeze frames from jumping/flickering/fluttering - what is the correct term? The images "wiggle" instead of remaining still. It is especially a problem when I have a picture with alpha channel overlayed on a video file, when I use moving paths, and most anytime I use a freeze frame.

I am already using the flicker reduction option under the field properties. It helps... but the problem is still very noticeable in some projects.

I doesn't seem to matter what picture format I use (jpeg, png, gif, etc) and it makes it worse if I choose an option other than frame based with flicker reduction.

Any thoughts??

Thanks!

Gorf · Post by **Gorf** » Wed Jul 05, 2006 9:22 am

Best thing to do is to use an image editing program to resize the images to the resolution you plan to use for your output medium. For example, if you're going to PAL DVD, use 720x576. NTSC DVD is 720x480.

Be sure to maintain the correct aspect ratio by "padding out" the image with black (or whatever) borders or alpha channel. For example, if you've taken an image with your digital camera in portrait orientation (so it's 1920x2560, say) pad it out with blank space left and right so that it's a 4:3 image (in this case, 3413x2560) then resize it with resampling to 720x480 or 720x576.

The reason you have to resample is that when you scale an image down, you are losing pixels. When you do this in MSP, it simply takes away the pixels, so you are losing colours that make up the image. Resampling averages the value of pixels that will disappear with the one that remains, in effect blurring them together.

The removal of pixels is one of the reasons you get flicker from stills.

ksuwildcat93 · Post by **ksuwildcat93** » Thu Jul 06, 2006 2:46 am

Your answer makes a lot of sense for the stills. I never considered that when I was resizing them inside the video editor. I will go back to my picture editor and take care of that before inserting them in MSP.

It doesn't quite follow for me with some of the titles I have used though. I often use a separate titler that exports the titles in proper size and ratio (720 x 480) with an alpha channel background, but still I have a flickering problem around the title itself. This means the whole picture must be moving, correct?

Same with the freeze frames on videos - the whole video jumps and wiggles. They are really horrendous sometimes.

Any thoughts on that?

Thanks for your help!!

Gorf · Post by **Gorf** » Thu Jul 06, 2006 1:14 pm

No, you'll get flicker even if the picture isn't moving. It's typically caused by thin and/or high contrast horizontal lines, where the scan pattern of the TV is showing one line first, then the other, a fiftieth or sixtieth of a second apart.

It's in these circumstances that you would use flicker reduction, but to be honest you're unlikely to completely remove flicker.

The scan pattern is the same reason you get the atrocious flicker when video is paused. Each 25th of a second or 30th of a second frame is not a whole picture, but two distinct images taken a 50th or 60th of a second apart. These images are interlaced together to make up a frame, a bit like those little plastic stickers you get with cereal that show different images depending on the angle you look at them. If you take the ridged plastic cover off them you'll see it's just an interlaced pic, like you'll see in the MSP preview window.

When you pause the video, you see the first field of a frame, then one Nth of a second later you see the next field, then one Nth of a second later, you see the first field again. Result: Flicker.

If you have a problem with flicker in the titles, it's likely that they are being rendered with the wrong field order or a different field order to the rest of your images. Can you give more info on the format you're using and how you're creating them. Does the flicker only happen over your stills?

ksuwildcat93 · Post by **ksuwildcat93** » Fri Jul 07, 2006 3:58 am

The freeze frame flicker is much worse than the still or title flicker. Your explanation makes sense. I sometimes capture the frame as a still shot and insert it after the video clip. This improves it to the level of the stills at least.

The titles have the least flicker of the 3 situations we have discussed, but it is still present if you look closely. (I am probably being too picky on this one). I am using Bluff Titler which saves them as TARGA with transparency at 720 * 480 pixels. I have played with all the field order options in MSP and find that using the frame based option with flicker reduction gives the best results. I am not sure if I totally answered your questions?

Thank you again for your help. At least I understand what is happening now and I can do a few things to make it better.

Gorf · Post by **Gorf** » Fri Jul 07, 2006 9:25 am

Are you saving the image from the preview window before using it? If so, that would explain the problem. You're introducing your own "VCR pause" effect.

To get around it, find your chosen frame, set the clip to "deinterlaced" in media source options. Move the preview indicator backward and forward a frame to update the image in the preview window (it doesn't do this automatically when you change media source options). Then save the image, then turn off deinterlacing.

The resulting image will not flicker on the timeline.

re: the titles - just blur them a tiny bit. Also, if you're saving the video as DV AVI but eventually plan to go to MPEG, try MPEG now, to see how bad it will be when you finish the project.

ksuwildcat93 · Post by **ksuwildcat93** » Sat Jul 08, 2006 3:43 am

That's it!!

Your suggestion for deinterlacing and saving the still image worked like a charm on the freeze frame flicker.

And, I went to my titler program and lookie there! Right in front of my face there is a blur option in the export window. That is NOT intuitive! Why would you choose to blur your title?

Upon investigation it is an antialiasing feature. Anyhow, it also helped on my titles.

I have been struggling with these issues for over a year through multiple projects. Thank you so much for all your help!!

walter.mittwoch · Post by **walter.mittwoch** » Sat Jul 08, 2006 5:27 am

Hello administrators !

I suggest to save this thread in the product tutorial section.
It's worth it.
Thanks gorf - It was good help for me also.

Walter

Gorf · Post by **Gorf** » Sat Jul 08, 2006 10:04 am

Thanks, guys - but I don't really deserve much of the credit. I've learned virtually everything I know from this board and the mug-sw list, so I'm really only passing on what other people have taught me.