# Sony Vegas Pro 8 Zoom and Keyframes



## #Bazzy# (Jan 26, 2009)

Hey I've just got Sony Vegas Pro 8, and am quite the novice. I know how to focus in on a specific part for videos and still pics.(Also, is there a way to do this without having the actual videos borders moving all over the place?) 
I was wondering if there is there a way to just gradually zoom in on the full picture. Like have it look like it's gradually coming towards you, like you can in simpler editing programmes such as Windows Movie Maker?

And also, can anyone please explain keyframes. What they are, their uses, and how to use them. In simple layman's terms?:tongue:

Is there away to insert a Picture in Picture effect?

Thank you very much in advanceray::smooch:


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## zuluclayman (Dec 16, 2005)

Keyframes are used in video editing to mark the point at which some effect or action is to start and then another to mark its end - interpolation can then allow the effect to gradually come into play and end at the second keyframe. A simple example is fade in - a keyframe will mark where the clip is to begin fading and a second keyframe will mark where the clip is to be at 100% opacity. In between the clip will gradually fade in. Your zoom, if not a preset effect in Vegas, could be achieved using keyframes - look on Youtube for tutorials on zooming in Vegas.
Have a look at these to help you out with the use of keyframes in Vegas - try the Youtube tutorials among others.
Picture in Picture (PiP) is relatively easy to achieve - you use multiple tracks and resize and move clips to suit - too long an explanation for here so again have a look at these
Don't be afraid to use the Help menu in Vegas - I don't use Vegas (I have Adobe premiere Elements) but did have a trial version and played with that making good use of the Help menu and Youtube tutorials - sometimes easier if you can see someone doing the actions.
Google can be a good friend too :grin:
Hope this has helped.


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## blah789 (Aug 25, 2008)

zulu's explanation of keyframes might be in the context of editing (I hadn't seen it before)

In the context of video compression, keyframes are frames that contain all the image information and don't need any additional information to construct it. They're the equivalent of I frames (intra frames) in MPEG encoding. In MPEG, the next level is P frames (predicted frames). They contain information about how much the image has changed since the previous frame. The idea is if you've got a video of a bouncing ball (with a non-moving camera), most of the video doesn't move, just the ball. The background doesn't change, and it would be redundant to store all the image information for the background. Instead store the information about which pixels did change - that takes a lot less space. Then you have B-frames, which are bidirectional frames. While P frames rely on previous frames to reconstruct the following frame, bidirectional interpolate information from both the previous and the next P and/or I frame(s) to construct the image. This takes even less space but is more computationally complex. In AVI files, you have keyframes (which are the equivalent of MPEG I-frames) and everything else (equivalent of P frames). There are no B-frames in the AVI specs, but there are "hacks" that can make use of them (packed bitstreams, for example in DivX and Xvid).
The interval between keyframes can be fixed or it can be variable. The more keyframes, the larger the video. The less keyframes, the harder it is to seek (because to get to a random P frame, you have to get to the I frame before it, then decode all the P frames before it to get to where you want), and also the more processor-intensive it is (the tradeoff is size vs. computational complexity). Smart codecs use variable keyframe intervals, and insert keyframes at scene changes (if you think about it, that's when the most abrupt changes in the image occur, so it's not worth computing all the change in the image (which could end up taking more space then simply inserting the full image); it's better to just put in a keyframe). Those scene change points may actually correlate with the keyframes described in zulu's explanation.
In ASF/WMV files keyframes are called indexes (at least that's how I saw it in Windows Media Encoder: there's a box called "index file"; if it's unchecked you pretty much can't seek the file at all)


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## #Bazzy# (Jan 26, 2009)

Thank you!


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