Video quality in Overlay Tracks

[Phil]

Hi, I'm using VSP x3 and enjoying it! Can you help me with track overlays??

I need to take 2 different clips and play them simultaneously, lets say clip 1 on the left side and clip 2 on the right side of the screen. For each clip, picture quality is perfect on normal playback on their own, however once burned to DVD the picture quality reduces a lot with the 2 clips playing - lines and smaller objects would not be as sharp. I like the way the clip can be moved about in the preview screen using the yellow squares but is this part of the problem i.e. playing a standard clip into half a screen? The DVD I produce would have 25ps, MPEG 8000kbps PAL.

I watched a tutorial where the same clip was played in 4 different rectangles simultaneously (looks great), but no advice given to maintain picture quality when going to DVD - Help!

[Black Lab]

While I can't say I've used 2 clips side by side, I have used a picture-in-picture before, with good results. I can't imagine having 2 clips reduced in size affects the quality "a lot". How is the quality of the rest of the DVD, aside from the side by side clips?

What are your output settings?

[Trevor Andrew]

Hi

Can you also give details of the original video file, in particular the frame order.
From the timeline right click an original clip and select properties, what are they?

If you start with Upper field then use the standard templates to convert create the dvd Video Studio may use Lowe Field. Changing the field order may reflect problems with lines.

When resizing the video try to keep the aspect ratio, that is keep the video in proportion.

[Phil]

Thanks - Original clips are either Full HD AVCHD or 1920x 1080 Upper Field First. I had the DVD settings to be Lower Field First. The quality of all other clips are great - it's just when I use 2 or 3 of these clips beside each other using the overlay tracks, the sharpness disappears. Aspect ratio is always 16:9 both on capture and DVD production.

Perhaps Picture in Picture is a solution, but I like the way overlay tracks allow me to freely shape the clips as I want them to be viewed.

[Ken Berry]

Is there *any* Lower Field First video in the project at all? If not, then you must definitely reset the output DVD settings to Upper Field First. A basic rule of video editing is that you should never mix field orders (i.e. Upper and Lower) in the one project, and if the original video started out as Upper Field First, you must maintain that throughout the whole project, including the output file. If not, as Trevor has indicated, various artifacts will likely show, particularly in fast moving panning shots or where there are strong vertical lines...

The only exception to the rule relates to Frame Based or Progressive (i.e. full p HD) video which can fit into either an Upper or Lower Field First project.

If you cannot avoid mixing UFF and LFF video in the one project, then you have to decide which occupies the larger part of the project or which has the least panning shots or vertical lines so as to minimise the distortion artifacts...

[Phil]

Ok - perhaps I've got some basics wrong in my Project Settings? I tried an HD clip - the same clip playing in one corner as a Picture in Picture and the same clip entered to the Overlay Track and set it beside the first, burned it on DVD with highest MPEG Kbps setting and the images still are not sharp, particulary when the camera zoomed in.

[Phil]

Following on from my last comment, and judging by the playback of the original clip using Windows Media Player, a sharp playback is achieved when the window is full screen. Reducing this window distorts lines and small objects on the picture quality - let's call it to thumnail size....so, is this what's really happening on DVD playback?? High bitrate clips trying to squeeze into a thumnail like aspect. If correct, how can this be overcome when building a project?

[Ken Berry]

You're almost there -- though the answer has probably already been given above. Quite apart from the question of the relative sizes of images in the smaller screen superimposed on the larger one, if you are using HD video, that will be sharp and crisp and quite high quality. But to achieve this effect, the frame size is much larger than a DVD -- the latter is a maximum of 720 x 480 pixels (NTSC) and 720 x 576 (PAL), whereas your HD is probably 1920 x 1080.

Moreover, the high quality of the HD also comes from the much higher bitrate the HD camcorders use -- at the least 16,000 kbps, and more likely 18,000 kbps or even 24,000 kbps for the latest camcorders. That's for AVCHD, and 1440 x 1080 (anamorphic) and 25,000 kbps for HDV.

On the other hand, DVDs can only have a maximum combined bitrate (video and audio) of 10,000 kbps. In reality, few stand-alone DVD players can play discs at more than 8000 kbps, so that tends to be the default bitrate for DVDs in many editing programs, such as VS.

Regardless of anything else, even if you start out with HD video but are burning a standard def DVD, the bitrate and frame size has to comply with what I outlined above. That means a fairly big hit in terms of end quality. To put it at its most basic: to compare original HD video to final DVD is like comparing apples and oranges. And the quality hit will only be compounded by squeezing at least some of the video into a smaller picture-in-picture and perhaps by displaying it on a small screen (although more often than not, the quality will often look better on a small screen since blowing it up to a large HDTV-size screen will only magnify any defects in quality... )

[Phil]

Thanks Ken - a solution then, if there is one? I've no problem with the HD being compared to Standard Definition....HD is very good. I can still get a very good quality standard DVD with a high bit rate setting - but the reduction in sharpness is noticeable RELATIVE to the DVD clips before and after it. Would reducing the "thumbnail" sized clips first to a lower bit rate before it's put into the project be a solution? e.g. 4000kbps. Then, when ready to render or burn, chose my overall setting to the 8000kbps. What do you think?

[Ken Berry]

I certainly wouldn't be reducing the inlaid clips to 4000 kbps. That is low quality, and later including them in another render, even if at 8000 kbps will probably make them worse. My own inclination would be to first render all your HD to DVD-compatible mpeg-2 at 8000 kbps regardless of whether it is for main track or overlay, and see how that goes.

[Phil]

Hmmm, seems I'm back to square 1

[Phil]

I've taken the same clip (used 4 in small rectangles to fill a 16:9 screen) and rendered them to a standard DVD burning AVCHD (1920x1080) files. Played this back on my Blu Ray player and the playback was very good and sharp! This was at a rate of 16,000kpbs. Unless someone can come up with a solution for Standard Definition, I'll have to keep this effect for HD only