IPS v FPS

[marty_88 0]

Can someone please tell me, the difference between IPS v FPS.

 

Comes up a lot and i just don't know, so any help is great

[kensplace 0]

Usually IPS means individual pictures per second, whereas FPS means frames per second.

 

A Frame is made up out of two pictures, the odd lines, and the even lines.

 

So 25fps is really 50 individual pictures, merged to make 25frames

[marty_88 0]

Thanks,

 

So FPS is better, so when there is 100IPS that is only 50FPS

[Daryl733 0]

Thanks,

 

So FPS is better, so when there is 100IPS that is only 50FPS

 

Not neccessary.

Different manufacturer have different way of specifying their equipments.

Some may call it IPS, FPS, etc.

There are also Frame Per Sec, Field Per Sec, Image Per Sec, etc.

 

If they stated Field Per sec, then is most likely as what kensplace said. Alternate Lines. i.e. first Field contain all odd lines, 2nd field contain all even lines, etc. But for Frame and Image, it's not that clear. Some may mean field, some may mean the whole picture.

 

But from what i seen, if it's compressed, it doesn't really matters sometimes. Especially when you are not recording in CIF.

 

Most DVR has only 1 encoding chip for 4 Channels. This is a 25 FPS (or 30 if it's NTSC) encoding chip. And they also have a multiplexer chip inbuilt.

For Full Resolution, they switch between the 4 channels and feed in the video to the encoding chip to encode into mpeg, mpeg4, mjpeg, or whatever codec. This mean that for all channels, it's feeding in 1234123412341234123412341 video sequentially. When you playback, it playback this feed, and with the encoded information, seperate the channel back into 4 different channels. Thus ur max FPS can only be 25/4.

When recording in CIF, what the multiplexer chip does is it feed a quad video feed into the encoding chip. Now all the video are only in CIF resolution, but the encoding chip will be encoding all at 25FPS, thus achieving full framerate recording.

 

From what most high compression ration codec does is they encode key frames or full frame only at interval, and then record the changes inbetween these key frame, thus achieving high compression. e.g. out of 25 images, only 1 image is save in full, and 24 images only save the moving differences. Mpegs (1,2,4), H.26x, wavelet, etc.

 

But considering the full resolution recording, where the multiplexer is feeding a sequential feed into the encoding chip, i.e. 12341234123412341234.... each frame recorded is actually very different from the previous frame. The basic logic of high compression is basically render ineffective. Every single frame is basically totally different from the previous frame. In this case, these compression function basically similar to Mjpeg, and not mpeg.

 

Of course, there are some dvr which have better programming, increasing the effectiveness of these compression, but basically most dvr, especially the entry level dvr, deal with multiplexing and encoding in these methods.

Edited August 16, 2007 by Guest

[scorpion 0]

Thank you Daryl733.

 

That was really informative!

 

Is there some more links that you can PM me on this?

 

Scorpion

[marty_88 0]

Cheers Daryl733,

 

Nice guide to compression and how it works.

 

Marty

[Daryl733 0]

Thank you Daryl733.

 

That was really informative!

 

Is there some more links that you can PM me on this?

 

Scorpion

 

Sorry.. nope.. dun have any links on that. That's based on my own understanding.