640x240 Resolution

[mateck8888 0]

I'm just curious if anyone knows what 640x240 resolution is all about. I have run into it on a DVR system, and can't quite understand it.

 

If the resolution is 640x240, would that not be a rather wide screen resolution? Yet everything is still in the 4:3 resolution.

 

Thanks,

Matt

[rory 0]

Its less pixels, so lower quality.

HOWEVER, when played back I think it is widescreen.

Only DVR I used that on before was the Iview.

 

QVGA = 320x240

CIF = 352 x 240

VGA = 640x480

2CIF = 704 x 240

D1 = 720x480

 

edit: whoops

Edited September 25, 2009 by Guest

[Soundy 1]

I've also seen DVRs (Video Insight) that give you 320x480 as an option. Whether playback shows properly (non-stretched/squished) depends on the codec and the playback software. VI footage recorded at those 320x480 or 640x240 will be distorted if played in WMP or VLC, but playback properly within VI, for example.

[rory 0]

Yeah seems some call 320x480 2 CIF as well, also called Half VGA.

[megapixel man 0]

640x240 is HVGA (Half VGA), 8:3 DAR (Display Aspect Ratio).

[megapixel man 0]

Its less pixels, so lower quality.

HOWEVER, when played back I think it is widescreen.

Only DVR I used that on before was the Iview.

It is considered 2 CIF.

 

QCIF = 160x120

CIF = 320x240

2 CIF = 640x240

4 CIF = 640x480

 

4 CIF also known as VGA.

 

 

VGA is 640x 480. 4CIF (NTSC 704x480), (PAL 704x576).

 

CIF (NTSC 352x240), (PAL 352x288)

2CIF (NTSC 704x240), (PAL 704x288)

4CIF (NTSC 704x480), (PAL 704x576)

 

Cheers

[rory 0]

 

VGA is 640x 480. 4CIF (NTSC 704x480), (PAL 704x576).

 

CIF (NTSC 352x240), (PAL 352x288)

2CIF (NTSC 704x240), (PAL 704x288)

4CIF (NTSC 704x480), (PAL 704x576)

 

Cheers

 

quite right, i had just googled that as memory not as good as it use to be

[mateck8888 0]

The actually machine I am seeing this on is an Intellex DVR system. Most Intellex I have seen I think are 4CIF, so I took a double take when I saw this one. When I play it back within the system, it looks 4:3. It's only about 2 years old, so I find it kind of strange that the manufacture was making some with only 50% quality, especially considering the cheap prices of hard drives now. But those big companies always have big price tags and minimal bang. (But super good support).

 

Thanks all for your input.

Matt

[survtech 0]

4CIF analog video is two interlaced fields so a full 640x480 frame is made up of two 640x240 fields. Essentially, 640x240 means the encoding skips every other field. It has the same horizontal resolution as 4CIF but only 1/2 of the vertical resolution. Being only odd (or even) fields, the resulting picture is free from "jaggies" on motion, though.

[mateck8888 0]

That's the best explanation I have seen so far. That makes sense. I guess that means it is actually "progressive" video, lacking an "A" and "B" field.

[hardwired 0]

I've had that setting available on a few DVR's, it can help with license recognition with non-progressive scan cameras. Some DVR's also have a "deinterlace" setting which copies just an odd or even field twice to make a 640x480 image without the "jaggies".