Internal Domes

[digitalwitness]

Hi James, it is 6.3M and I believe this to be relatively standard amoungst the Koreans (or at least close to it), there are chinese versions that go up to that but those DVRs are significantly more expensive than the Korean machines and generally reserved for Hyrbids or NVRs (megapixel).

Its not the only factor when it comes to picture quality but could be a significant factor in certain situations, like at low light with CCD noise, all the power is spent saving the differences due to noise rather than the target required.

[james.wilson]

well from my tests i wouldnt want to drop below 6 meg as a max. Its not a problem in high light levels. 2 meg is probably enough. But if you get any noise in the image or high motion then it isnt.

[digitalwitness]

In my experience the two different applications are not directly comparable, i.e. 2M on a Korean DVR versus 2M on the Chinese when comparing overall picture quality, this is simply more about been able to handle changes between subsequent images.

The apollo have the option of VBR or CBR (Variable or Constant Bit Rate), Koreans general just use VBR and the 6M setting as the reference bit rate, reducing the quality on the Korean DVR will also reduce the Bit Rate. Its quite easy to see the effects on an apollo by setting the Bit rate low but keeping the picture quality the same. Compare two cameras will similar movement (high movement preferably) one on VBR and the other on CBR both at a low bit rate and the effect will be evident. CBR is handy though for network transmission.

[Adi]

I'm afraid that its not quite that simple any more, D1 or HD1. There are so many different profiles for H.264 and ways of implementing it, as not to get too complicated, generally the Koreans have used Hardware compression where generally the Chinese have used DSP, both have their advantages/ disadvantages and limitations.

But to get to the chase in this regard, one main difference between the two methods of implementation is the sampling frequency of the compression, comparing similar level machines, the Koreans I have seen go over 6Mbps where the Chinese go to 2Mbps (can depend on the number of channels though as the 32Ch only goes to 1Mbps), this is at D1 best picture quality.

There are other factors to consider so I am not saying that there is 3 times the picture quality difference but where you may see the difference is when there is a large amount of movement or change in a picture, so the choice to use D1 or HD1 (which is more than acceptable to the human eye) will depend on the application and equipment used (including camera choice). Oh and watch out of interlace noise if using D1 with fast moving scenes.

it is on an apollo, cif is ****.

agree with last comment