Choppy security video

Edin1 wrote on 10/18/2005, 12:25 PM
I loaded this video from a Swann DVR4Net video recorder. This recorder is a hard disk based unit that is used in security video.
The problems I'm having:
1. When playing the video back directly on the recorder, the video is slow and very choppy. Frames jump back and forth, one frame forward, one frame back, and then one frame ahead of the first frame. This makes it almost impossible to save on a VHS tape (to give to it to the police).
2. When saving the video digitally via ethernet, similar problem occurs, although I am able to adjust the saved framerate.

My guess is that the problem is in the framerate setting, which was 60fps. Since this recorder uses modified MJPEG codec, my guess is that it records the fields as frames, and then displays them like that on playback, but in a little messed up way.
I am also guessing that the solution to this problem would be to remove every second frame or so, in order to remove redundant frames, or the ones "jumping back". I will also have to stretch the video, so that the timecode imprinted onto video (thank God for that) matches real time.

Any suggestions for fixes, and/or how to apply the above mentioned solution in Vegas Studio 6?

Comments

Chienworks wrote on 10/18/2005, 12:43 PM
If you have the project frame rate set to match the video's frame rate exactly, you can use undersample set to 0.500 to skip every other frame. More precisely, the 1st frame will be shown for two frames, then the 3rd frame for two frames, 5th frame for two frames, etc. If instead you need to see the 2nd, 4th, 6th, etc. then bump the video to the right one frame.
Chienworks wrote on 10/18/2005, 12:46 PM
Oops, forgot i was in the "Studio" forum. The Studio version probably doesn't have undersample. You can accomplish the same thing by doubling the speed of the video, turning off resampling (i think Studio has this option) and rendering to a new file. If you want the alternate frames then trim one frame from the beginning before speeding it up. You can then load the new file and slow it back down to the original speed, or whatever speed you need.
Tim L wrote on 10/18/2005, 1:50 PM
Could this be an interlaced "field order" problem? ie choice between odd or even field first, or maybe referred to as upper or lower field first?

I can't offer specific advice (I'm not at a computer with VMS), but if you can find a setting for "field order" somewhere (maybe in file properties of the clip), and if you can change it to the opposite setting, then maybe it will work correctly.

Tim L