Rendered video is sharper during transition

[jparnold]

Is it normal for video to be sharper during the CIRCLE transition and then return to the 'normal' sharpness at completion of the transition.

I have just rendered a project which contains quite a few transitions including Crossfade, Side, Spin, Face and Circle. Every time I have used the Circle transition the image 'inside' the 'circle' appears sharper until the 'circle' fills the screen (ie the end of the transition) when the image appears 'normal'.

Has anyone else noticed this? I think that there is something wrong with CIRCLE transition as I have also noticed that it does not display correctly (preview window goes black) when you 'drag' the scrubber along the timeline.

Strange behaviour.

[lata]

Hi John

I have just tried the Circle transition with Video and image samples and have no problems.

There is no difference in quality during the transition and scrubbing the timeline is ok.

Maybe its related to the type of video file you are using.
Can you try using the libraries sample clips, that way we are all using the same types.

Have you applied any other effects/filters to your clips?

If you only notice the difference after rendering then try disabling Smart Render?

Finally have you manually updated Direct X to the latest version.

[jparnold]

Hi Trevor,

Thanks for your fast reply.


After reading your suggestions I created a very simple project of just 2 of the sample video clips (V14.wmv and V20,wmv) with a CIRCLE transition between them. When I dragged the scrubber along the timeline the transition displayed correctly but I have noticed in the past that once my project becomes larger and more complicated (more transitions, attributes etc etc) then it does not display correct using the scrubber. I know this probably sound absurd but that is what I have noticed. BUT I did notice a slight change the the displayed image of V14 as the scrubber passed the end of the transition AND when I rendered this was also evident.

Have a look at the following images taken from the rendered video and note the subtle differences around the area of the black and white vertical lines the first image is where the CIRCLE transition is nearly complete and the second image is after the transition is complete.

[erdna]

I don't think that the resolution is higher during transition. Because of the re-encoded transition part, there is a lower brightnes level in the "high res" parts. This lower brightness together with the artifacts introduced by re-encoding may look subjectively "sharper". I tresholded your samples and there you could see the difference, and the artifacts introduced by the re-encoding on sharp edges.

[jparnold]

Thanks for your input,
BUT
Regardless of what it actually is (sharpness or brightness level) the fact remains that when viewing a rendered movie which has a CIRCLE transition you can see an OBVIOUS change to the 'quality' of the image as the transition completes.
Maybe then I should have made the subject 'rendered video is DIFFERENT during transition.

And so the question remains - has anyone else noticed this?

In the meantime I will use P-in-P for the transition which doesn't give me the same effect that I want as it is a rectangular shape to start with.

There must be a bug in either the transition or how VSX4 treats it.

[erdna]

Everytime the video has to be fully decoded (decompressed an inverse DCT applied, down to the rgb or yuv level) it has to be re-encoded which introduces differences (generally detail losses and extra artifacts). This happpens during a transition. I think you will see the same "difference" in an undertitling part. In non electronic testpatterns those diferences are difficult to be detected.

[jparnold]

That could be the reason as I noticed that at another part in the (rendered) video which also has a CIRCLE transition that I did not notice any difference.
I have been using the CIRCLE transition often over the past years and had never noticed much difference during the actual transition until the first one used in my current project. Still it was so noticable (and annoying) that I substituted it for Picture-in-picture with the video clip in the overlay track gradually increasing in size to eventually fill the screen. Not quite as simple to use as a transition though.

[Kingston]

There is a slight difference when I change the option "Perform non-square pixel rendering" in the project properties and in the share properties. I won't influence you by telling you whether the option is on or off when I don't see any difference.

[jparnold]

I have "Perform non-square pixel rendering" set but when I unchecked it I saw NO difference.