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Sooki Choi

HD cameras' time delay comparing to Analog camera?

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Designing the HD cameras (over hundreds) for my customer.

We are worring about the time-delay (latency) made by HD camera itself

and computers' latency to decoding the images.

 

Bosch datasheet says minmun 100ms and maxium 250ms, some vendors do

not say.

 

1. the information of HD camera time dalay?

2. how to test the delay time?

 

I need your advices.

 

Thanks

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Question: why does it matter? What's going to happen in that time?

Customer walks away and buys a system that doesnt do that

 

then again ... that delay is like equivelant on the eyes to 22-27fps end result.

Doubt anyone will notice the difference at all.

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Designing the HD cameras (over hundreds) for my customer.

We are worring about the time-delay (latency) made by HD camera itself

and computers' latency to decoding the images.

 

Bosch datasheet says minmun 100ms and maxium 250ms, some vendors do

not say.

 

1. the information of HD camera time dalay?

2. how to test the delay time?

 

I

 

If you ask those kinda questions then you are not ready to sell and/or design IP based system

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Are we talking about HDcctv or HDip.

 

Are we measuring "one way" or "round trip" latency?

 

How about "minimal latency" - the minimum potential latency of every link in the network, added together?

 

Are we purely measuring or perceiving true latency, or the combined effect of network latency, queuing and processing delays?

 

Are the cameras being deployed where precision or immediate intervention is required?

 

What codec is being used to decode, and display the HD video?

 

On average we are talking about 5 microseconds per kilometer over a fiber connection. Generally that should not present a problem , but how about viewing an HD camera from the other side of the world, or from thousands of kilometers away? So what transmission media is involved in your case - cat5, fiber? and what distances are involved?

 

What operating system are you using? and is the PC dedicated to VSS, or multi-tasking? OS are not real time systems but work on queues and priority, the more executables that are being executed , the higher potential processing latency on the system - without even starting to transmit via a network?

 

I believe that the timing between hardware and commands on a windows PC is less than exact, so how significant can a delay of 24/1024 transitions be in a precision system --- if you need precision? Such as synchronizing POS text overlay to the recorders clock to get accurate time/text overlay for example.

 

Basically ----- there are many factors that might contribute to perceived latency on a HD camera and many of them do not originate with the fact that a camera is HD. Correct Codecs, real time low level OS, etc and numerous other configs can significantly impact upon the degree of total latency returned by a system.

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Hey Sooki,

 

Just do as I do when (possibly) presented with a question

there is no way you can answer on the spot.

 

Tell them you'll check into that and you'll get back within

the next day with an answer, then change the subject.

 

Or, in that (obvious) unnecessarily asked question by them,

tell them it's negligable and change the subject.

__________________________________________________

 

Was with a sales rep with a natl company (I was their sub)

and we were w/an IT guy in an equip room looking at the

fiber I was going to have to go over with the video and

controls. We were walking out and the IT guy looks at me

and say's "you're going to use FC connectors, right?" I said

"of course, what else would I use?".

__________________________________________________

 

A few minutes later, the sales guy say's "wow, you know what

those FC connectors are?" I said "hell no, never heard of them

before, but I'm not going to let IT guy know that".

__________________________________________________

 

 

Bunited2

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