Quality degrades after applying filters

rich963 · Post by **rich963** » Tue Apr 18, 2006 10:59 pm

Hi, I'm using a trial version of UVS9 and find that if I use color video filters, the quality of the resulting mpeg2 file is seriously degraded. (I am creating a project from existing mpegs to burn to DVD).

The picture goes jerky and the colour streaky / blotchy. It looks like the quality of a very poor mpg file, but I haven't changed the quality settings. Clips on which I don't use the video filters come out fine, but I do need to correct the colour on some.

Any suggestions please as to what I could do to stop this happening?

Thanks,
Richard.

Post by **Ken Berry** » Tue Apr 18, 2006 11:07 pm

Are you applying the filter to a DV/AVI file, and then rendering it to an mpeg-2? Or are you applying it direct to an mpeg-2? The latter is not recommended as you should be very limited in the extent to which you edit lossy mpeg files. Depending on their original quality, applying a filter and then rendering again (if that is what you are doing) could result in quality loss -- though normally, I'd have to confess, perhaps not as great as that which you describe.

DVDDoug · Post by **DVDDoug** » Tue Apr 18, 2006 11:39 pm

Ken is right. You cannot perform an MPEG decode/re-code cycle without some quality loss. Applying a filter requires that the video be decoded first. This is true of almost all editing, except that you can cut & splice without re-coding.

You might try a special-purpose MPEG editor. I use Womble ($100 - $140 after 30-day trial). I've never tried Womble's color filters, so I don't know exactly what it can do. It did solve a couple of my other MPEG related problems, and I noticed that it does smoother MPEG crossfades than VideoStudio. (The Womble programs are not a complete replacement for Video Studio... You probably need both programs if you decide to get Womble.)

rich963 · Post by **rich963** » Tue Apr 18, 2006 11:42 pm

Hi Ken, Thanks for your reply.

I'm using mpegs extracted from a home DVD. I tried capturing from DV but this also seemed to affect the quality (Sony DV problem?....)

I can use crossfades, etc and the rendered files come out fine. It's just when I use video filters that I get the quality degrade problem.

Richard.

Post by **lancecarr** » Tue Apr 18, 2006 11:48 pm

Hi Richard, My first cam was a Sony DVD cam and as such everything I was handling was in MPEG2.
MPEGs are highly compressed and, as a format, were never really intended for editing so generally speaking the more drastic the editing move you make the more unreliable the results can become.
I have applied a variety of filters (well attempted to at least!) to various clips and the results vary from exactly what one would have expected to total disaster.
Normal cutting, splicing, crossfading etc are usually fine but the application of a filter is totally different story. Applying a filter results in the entire clip being re-encoded with the properties of the filter added and what you end up with varies wildly.
To save time you might try loading the single clip you wish to apply the filter to then render it to see the results.
As an added note the "preview" window will give you a far more degraded version of the effect of the filter as the program is trying to display the MPEG WITH the filter on the fly. It is much better to use an RW disc to burn tests if the final display is to be on a TV or output to a test file on the computer and play it in WM Player if it is for distribution on computers or the net.