Video Compression Batch Routine

[ddrueding]

I have 2 surveilence cameras, D-Link DCS-1000Ws, they work great.

I'm able to capture 640x480x24-bit@30fps only when there is motion in the frame. Perfect. It stores these in "MS-MPEG4 V3" format...about 1.2MB/min. One file per "incident".

Is there a way to process these into a more efficent format at the end of the day/week?

What format would offer the best compression?

What program would be best for performing this tasK?

TIA

 

[SteveC]

It should be pretty easy to do with VirtualDub and DubMan to automatically schedule it, but I'm not sure how much space you'll be able to save by recompressing them. 1.2MB/min is already pretty low for 640x480@30fps.

 

[sechs]

You can always save space by recompressing. You just lose a lot of data in the process.

How much of the picture is worth losing to save space?

 

[ddrueding]

Well, we'll be keeping a week's worth at this higher resolution, so we can lower the quality for keeping the video longer term. What type of quality could I expect for ~768KBps? I'd prefer to half the frame rate rather than lose frame quality.

I'll check out CirtualDub and DubMan, thanks for the tips

 

[sechs]

I've never worked with MPEG4, but, presumably, it's keyframed; so a framerate drop would involve a complete reencode of the video (as opposed to just pulling out the frames that you wish to drop).

Depending on what exactly you expect to show up in the video, decreases in resolution, framerate, colour depth, and bitrate may individually or in combination leave you with acceptable results. However, any reencode is going to leave you with less quality than the theoretical decrease in information would otherwise leave.

Your best bet is to take a sample video and manipulate it in various ways to see if you can hit the target size with acceptable quality.

 

[Mercutio]

You're complaining about 1.2MB/minute?!? How many incidents do you have?

 

[ddrueding]

You're complaining about 1.2MB/minute?!? How many incidents do you have?

The business is open 10 hours a day, plus anyone walking by too close to the windows/looking in will trigger it. I'm estimating the cameras running about 50% of the time (worst case) and I'd like 2 weeks worth of video to fit on a DVD.

60*12*14=10,080 minutes
The capacity of a current DVD is 4700MB (not going dual-layer just yet)
4700/10080=0.45MB/min :-?

This is a security camera, so the quality of individual frames is more important than the number of frames. Cutting it down to 320x240x16-bit@10fps would be acceptible, if I could fit it in a DVD.

 

[SteveC]

This is a security camera, so the quality of individual frames is more important than the number of frames. Cutting it down to 320x240x16-bit@10fps would be acceptible, if I could fit it in a DVD.

If you're happy with the individual frame quality you have now and just want to cut the frame rate, then you can load it into VirtualDub, and select "Frame Rate" from the Video menu. Then pick "Process every third frame (decimate by 3)." Hit OK, and pick "Direct Stream Copy" from the Video menu. Then save it to a file. That'll keep the current quality but cut it to 10FPS, so you'll only need about 1/3 the space you currently do now.