Security Video - 24h Mode

jopereira wrote on 11/25/2002, 3:18 AM
I do have to take a security video and convert it to a "Windows" format.
As most of you know, security videos run in time lapse mode. This mean that if I record in 24h mode (for instance) a frame is recorded in every 0,125s, instead of normal 0,04s (25 fps- PAL).
Reading that tape is 3hr mode (a security VCR have that mode, a home video will also do it) the video is accelerated about 8 times normal speed, but the reading is much more stable than reading in 24hrs mode (where the VCR is running in steps - less accurate).

My problem now is: I have a video that runs 8x normal speed and I want to make it run "normal". No problem, almost every NLE package will do it. Some will give me the option to make interppolated frames or not, making the video running in steps - this is the way I want it to be, since want it to feel like a security video.

How can I do it without ghost frames generated by making a frame from a field and the next frame with next field?
Should I previously convert it to progressive scan, and then use that video to slow down to normal speed?

Some ideas wanted...

TIA,

JP
Portugal

Comments

SonyDennis wrote on 11/25/2002, 6:45 AM
I used to work with one of these timelapse decks (I used it for CG animation), and I am familiar with the mode they work in.

Should be no problem. Set the media's "field order" property to "(none) progressive" so that Vegas doesn't deinterlace it. Create a velocity envelope on the event, and set it to 12%. Do not use resampling, as I don't think you want frame blending in the final rendered result. Render out the result.

You actually want 12.5%, but the Velocity envelope uses integer settings, so if rate is critical, to get 12.5%, set the event's 'rate' property to 0.5 and the velocity envelope to 25% (or, .25 and 50%, either way, they multiply to .125 or 12.5%).

///d@
SonyDennis wrote on 11/25/2002, 7:42 AM
Hold on, does that deck record 7.5 fields per second, or 3.75 full frames per second? If it's 7.5 fields per second, then the footage really is interlaced, so set field order to "lower first" and you'll get better results.
///d@
jopereira wrote on 11/25/2002, 9:40 AM
The video source is VHS converted to DV with my Digital8 camera.

JP
Portugal