Help with remote transmission speeds...please help...

[dvrsnoop 0]

desperate to find an answer. ive seen a few different dvr's over the net and they have different frame rates, i want to get a system but what upload speed(dvr in my shop) should i be looking at to get the best picture from home. secondly do different dvr manufacturers produce different speeds when uploading or does it come down to the speed only?

 

Please help.. so confused.

[cctv_down_under 0]

There is a difference in speeds per DVR, however, most will happily gobble up the bandwidth that is available to it.

 

Some DVR's will let you throttle bandwidth to adjust the size of the data that is sent, the most important thing to consider is exactly that... some compressions are larger in file size than others, so therefore you get faster speeds from these different compressions if their file sizes are smaller when compressed.

 

I cant speak for what speeds you would need because each country has different performance in internet speeds, depending on how much sharing of the line occurs, but you can work it out by saving one compressed frame and measuring the file size then multiply x 25 this will give you 25FPS file size then multiply by number of cameras and this will give you the upspead data stream that you need to achieve real time transmition, but unless your broadcasting a movie or something, you really can afford to drop a frame or two

 

That measuremnt is not entirely true in some cases, for example some forms of MPEG4 will only transmit the moving parts of the picture and overlay it on the previous frame. and some only transmit when motion occurs, but it will give you a worse case scenario answer

[Thomas 0]

And bandwith isn't the only issue. Latency is a major factor in frame rates. Bandwith is the amount of data you can send, latency is how long it takes to get there. The most bandwith possible is a cargo ship full of 400 gb hard drives. But the latency on that sucks. Now if your business has business class broadband, your limiting factor is more likely to be your home system.

 

Cable: Variable up and down depending on how many users are on the cable systems local network. If you are the only user for 50 miles great, densely populated urban area, less great. latency is a factor of the other users on the cable network.

 

DSL: Variable up and down based on distance from CO (telephone office). Unlike cable it tends to be more stable on it's speeds and more consistant in latency.

 

Satilite: Is unsuitable for any kind of DVR work as a general rule. Upload bandwith is slightly faster then dial up, but you have a painful latency. Keep in mind, that you have to send a signal up, then back down, then to the ISP, then onto the net. This takes a little bit of time.

 

Dial up: Poor upload, poor latancy.

 

T-1: Expensive but excellent bandwith, but the major kicker is the low latancy.

 

There are some other broadband options but things like an OCR-3 is overkill for most users. There is also a differance between consumer class and business class broadband. Business class users need things like low latency for VPN's.