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I have just rendered a movie using "2 pass variable" (at 8000Kb/s with audio at LCPM) and then burnt to a DVD and when played on my plasma flat screen noticed that some scenes (only a few) FLICKER.

When I checked the project timeline for the movie I noticed that EVERY scene which flickers has had the "playback speed" INCREASED so that the the 'action' is faster some at 150% and others at 200%.

Can one of the many learned readers advise what to do?

I have read that movies should always be rendered at a CONSTANT rate when space is not important. Could this fix my problem or is there something else?
I have also read somewhere here that rendering using 'frame based' rather than 'lower field first' can fix flickering however I was under the impression that 'lower field first' should ALWAYS be used when the output is intended to be burnt to DVD for output at a TV.

I am sure that I have changed the 'playback speed' of movie clips in the past without any flickering.

Oh yes, I am reasonably sure (but not 100% sure) that I applied the 'anti- flicker filter' when rendering.

Thanks

Please disregard this post - I accidentally created the same post twice when I attempted to edit the original post

I have also read somewhere here that rendering using 'frame based' rather than 'lower field first' can fix flickering however I was under the impression that 'lower field first' should ALWAYS be used when the output is intended to be burnt to DVD for output at a TV.

That's because older CRT TVs are interlaced, i.e. writing alternating lines of the picture, starting with either the upper or lower field first. LCD and Plasma TVs are not interlaced. If that is the only TV you will be viewing this DVD you could render it as Frame-based.

Hi John

I just did some tests on a short DV avi file, rendering it with VS11 on this laptop to various mpeg2 types, including CBR, VBR, two pass VBR, both lower field first and frame based, and with the quality slider at the default 70% and also at 100%.

In all cases, there was a noticeable degradation of the output picture quality when increasing the playback speed to 150% in the project.

When you check the output in Virtual Dub, you can see a sort of alternating instability as you step thru the frames - it's as if each other frame is slightly out of focus, and that might be causing your flickering effect.

jparnold wrote:................... I was under the impression that 'lower field first' should ALWAYS be used when the output is intended to be burnt to DVD for output at a TV.
..........

NO.

The field order is determined by the SOURCE of the material and not the OUTPUT.

If you filmed something with a DV Camcorder it would be in Lower field first and would play back on a TV set in Lower field.
If you recorded something with a TV card it would be in Upper Field First and would play back on the TV in Upper field.
If you create a slide show with Images from a digital camera or photographs that have been scanned you would use Frame Based.

Deleted.

Just an update even though my original post was a couple of weeks ago.
I did a test using a combination of 'lower frame first' and frame based of both the clip at it's normal speed and the clip at an increase of 150% playback speed and also at 200% playback speed.

At 150% it made no difference as to 'lower frame first' or 'frame based' they BOTH flickered - Steve was RIGHT.

At normal speed and 200% increase in playback speed there was NO evidence of flickering.

So it would seem that when INCREASING playback speed you should only do it at 200% (and maybe also 300%, 400% etc) eg doubling the frame rate etc.

I even tdid the test using MEDIASTUDIO with the SAME results.

Anyone have any ideas why the 'phenonoma' occurs?

Haven't time right now to test it but you are probably on the right track that it is a question of mathematics. Logically I would think that it may be related to the frame rate - 25 fps for PAL or 29.97 fps for NTSC.

It could be worth doing a few more experiments to see if the increase is dividable or a multiplication of something other than a factor of 2. Perhaps for PAL 20% might work because one 5th of 25 is 5 - a whole number.
For this experiment you can probably round up NTSC to a nice round 30 and work on that e.g. 50% 20% 10% 6% 5% 2%

Steve
I had already done some more experimenting but did not 'post' the results.
Firstly I found that using Mediastudio Pro I could 'see' the flickering in the output window while creating an output video file.
So I experimented using MS Pro so that I saved time having to create and burn a DVD using VS.
I tried 104%, 110%, 112%, 116%, 120%, 150%. Every one flickered. But using 200% and 300% I did not see any flickering.
I also tried SLOWING the playback using 60%, 75%, 887% and there was NO flickering.
So I have learnt that when requiring to INCREASE playback speed ONLY use 200%, 300%, 400% etc.
Why would I want to INCREASE speed? When I have planned a scene with my camera too slowly. Also when using the camera while walking (wish I had a real steadycam but if you hold the camera above your head with a wide angle lens it is fairly steady) and I use the first 2 seconds at normal speed and increase thye playback speed of remainder apart from the last 2 seconds like you sometimes see on TV shows.

Thanks John.
By the way - speeding up a video can be fun - here is one I did
Countdown Timer

Have XP and VS 11+
Could not open this file
Any ideas?

What couldn't you open the youtube demo or the download?
I run XP, downloaded the file and had no problem (using the instructions provided) installing the filter and using it.

Clicked on
http://forum.corel.com/EN/viewtopic.php?p=125673#125673
Unzipped a .vft file of 71kb
Tried to open it in VS 11+
unable to open Timecode.vft File format mismatch [16803:13]
Then
Data Execution Prevention-Windows closed this programme
Windows explorer needs to close ..................Ken

Kenneth,

A VFT file is not a video file, it is a Video Filter file. It should be placed/installed in the VFT_plug-in folder. For WinXP users that would be located at C:\Program Files\Ulead Systems\*Ulead VideoStudio 11*\vft_plug. For Vista users it would be the same.

NOTE: * * substitute the version you're using if not VS11

Thanks Ron,
The documentation states -
Copy this *.vft file to the VFT_Plug folder in the installation folder.
I had no difficulty with this as have an IT background but some may find it difficult to comprehend.