Steve's Digicams Forums

Steve's Digicams Forums (
-   Hybrid Still/Movie/MP3 Digicams (
-   -   Aiptek lies about framerates too (

adric22 Jul 26, 2007 1:22 PM

Well, we all know they lie about their megapixels, but I've now confirmed they lie about their framerates too. It shouldn't be any big surprise. I've suspected for a while, but wasn't sure of a good way to test it. Well, I thought of a way. A few days ago I put the aiptek on a tripod and took video of me pushing my daughter on a swing. There is constant clear motion in the scene. So I took that into video editing software and examined it frame by frame. What I found is that the file itself is actually stored as 1,000 frames per second. It is just that 99% of those frames are just repeats of the first. So there isn't a lot of processing needed to deal with it. (yet it may explain why it has problems playing on some PCs.) So I took several 1-second slices of video and examined them frame by frame. Guess what I found? In a 1-second period there are only 15 to 18 unique frames. It seems to be variable. Perhaps the encoder takes longer on some frames than others to encode. So they must give the 1,000 frames-per-second situation to allow for that frame to fall anywhere it needs to fall, whenever the encoder is done with it.

When I get home from work today, I'm going to re-do the experiment in the 320x240 mode and see if it makes any difference, maybe giving us more frames per second?

This was done with the IS-DV2, so I have no idea about other Aiptek products.. but they haven't exactly been honest with most of their advertising.

adric22 Jul 26, 2007 5:31 PM

As a follow-up to this... I performed the same test using the low res 320x240 mode. I counted an average of 24 frames per second in this mode. So it is better, as I suspected, but still nowhere near the 30 fps we are promised in the specifications.

fishycomics Jul 26, 2007 6:58 PM

24 isa good number for me I believe when i do my filming it is all pc but when it goes th the tube watch out some freezing occures ?

rgvcam Jul 26, 2007 9:18 PM

24 fps is very near the PAL TV framerate of 25fps so not too terrible for 320x240. The 15-18fps for VGA is basically the bare minimum to achieve the illusion of fluid motion.

I wonder if the framerate differs depending on scene complexity as well? ie if you film a woodland scene, would it have a lower framerate than a scene in a city with buildings as a background meaning less detail to cope with.

That would be a good test to do.

sgspirit Jul 26, 2007 11:46 PM

I'm under the impression that .asf is a variable framerate coding. The cameras only have so much bandwidth. So scenes with more detail, or more motion, contain more information and so either the amount of compression has to be increased, or the frame rate lowered, or both.

I've noticed a tendency for cameras that save videos in .asf to be rated as "up to 30fps", as opposed to .avi cameras, which generally just state 30fps.

I found 15fps to be intolerable. 30 is fine unless you're filming something like Formula 1.

fishycomics Jul 27, 2007 3:24 AM

Just remember this is not a imax vamcorde

th box states "UP TP" not :AT:

so yes Like RGV mentions I left that out pal is the primary of the camera not Ntsc?

All times are GMT -5. The time now is 6:39 PM.