stevefpi 0 Posted January 31, 2011 Sorry for the stupid newbie question but this one is bugging me and I can't seem to google an answer that makes sense to me. You got two identical cameras on the DVR and you record for the exact same amount of time. Camera 1 is in a location where no one entered the room so nothing moved during the recording. The second camera is in a high traffic area so lots of motion. The filesize for the resulting AVI video from camera 1 is much smaller than that for camera 2. I can except the simple answer that camera 2 recorded more so the resulting filesize is bigger but I guess I want a more detailed explanation on why that is. Does that make sense? I'm sure I'm coming off as a huge idiot for asking this. I do have brain, I just can't seem to find a detailed explanation that my mind can accept. Any help for this mentally challenged individual? cheers Share this post Link to post Share on other sites
Soundy 1 Posted January 31, 2011 Assuming both cameras' DVR channels are set for constant (rather than motion-triggered) recording... Most forms of video compression used for DVRs, use a method whereby they store one complete image (known as an I-frame), then store a series of images containing only what has changed from the previous image (B-frames or P-frames, depending on the compression used), before storing one complete frame again. If you have no movement in the frame, then you'll get the one large frame of video, followed by several small frames, then another large frame, and several more small ones, etc. etc. On the whole, that makes for fairly compact video files. On the other hand, if there's lots of movement, then the B- or P-frames will be much larger, as more has changed from one to the next. String them all together, and they result in a much larger file. Of course, if the DVR is set to use motion-triggered recording, then camera 1 simply isn't recording ANYTHING when there's no movement going on - which results in FAR less space being used - while camera 2 is consistently recording whenever there's movement. Share this post Link to post Share on other sites
stevefpi 0 Posted January 31, 2011 Matt, Thank you. That makes perect sense and is exactly what I needed to know! Cheers Steve Share this post Link to post Share on other sites
