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is 4 cif at 7.5 as good as once cif at 30? What is D1?

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I was looking at a dvr and it said something about d1, not sure what d1 is, and it had one cif at 30 as specs and 4 cif at 7.5?

 

Is 4 cif at 7.5 enough to make out details of a face or identify an intruder in a yard?

Thanks for any help

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I was looking at a dvr and it said something about d1, not sure what d1 is, and it had one cif at 30 as specs and 4 cif at 7.5?

 

Is 4 cif at 7.5 enough to make out details of a face or identify an intruder in a yard?

Thanks for any help

 

From http://www.dvrsecurityforum.com/showthread.php?tid=30&pid=30:

 

What is resolution of D1/ CIF / QCIF?

 

D1

 

So-called "full resolution" for TV specs. Normally D1 can mean one of the following video resolutions:

* 704x576 (TV PAL)

* 704x480 (TV NTSC)

* 720x576 (DVD-Video PAL)

* 720x480 (DVD-Video NTSC)

 

 

4CIF (4 Common Intermediate Format)

 

* 704x576 in PAL

* 704x480 in NTSC

 

 

2CIF (2 Common Intermediate Format)

 

* 704x288 in PAL

* 704x240 in NTSC

 

 

DCIF (Double Common Intermediate Format)

 

Compared DCIF with CIF and 2CIF: under the same bit rate, the image quality and definition is greatly improved.

 

* 528x384 in PAL

* 528x320 in NTSC

 

 

CIF (Common Intermediate Format)

 

Back in history, this acronym's name comes from video conferencing tools in late 1980's and early 1990's. Nowadays the term CIF is used to mean specific video resolution:

* 352x288 in PAL

* 352x240 in NTSC

CIF is 1/4th of "full resolution" TV, also called as D1 and is best-known because VideoCD standard uses this resolution.

 

 

QCIF (Quarter Common Intermediate Format)

 

Old video resolution name. 1/4 of CIF video resolution. Standard sizes :

* 176x144 in PAL

* 176x120 in NTSC

 

So yes, D1/4IF will be substantially better than CIF for picking out facial details. Standard TV/DVD video is 30fps; 7.5fps will be a little "stuttery" but unless you need to catch fast-moving action, it should be plenty smooth and worth it to gain the extra resolution.

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