Looking for what is the newest dahua NVR part numbers

the 4216 is too small, I would like to get the 4416, i will purchase it from Ali, thanks guys you were a big help
 
Shockwave199 said:
Back to topic- could you explain what the incoming bandwidth number means, the recording rate number means, and why they can be different from each other? And since the best a dahua nvr offers these days is 200mps incoming and recording rate, does that help an 8 channel unit full of 3mp cameras recording at 15fps, 4096? LOL- hope so!
Click to expand...
My question here still stands.
 
Bitrate of Video and Recording Bandwidth are not the same numbers; a higher bitrate uses more bandwidth because it contains more data but Video Bitrate is basically detail level; for example a BluRay disk is ~35MBit and contains alot more detail than my Dahua @ Max 8MBit.. Think of it as how wide the video channels are; the wider the channel the more detail can flow.. Variable Bitrates change the width dynamically to better suite the current demands while reducing traffic.. if the image is mostly static it can save alot of bandwidth by lowering the bitrate until there is alot of changes; at which point it ramps up the bitrate... its the same with MP3's, low bitrate songs sound flat with more artifacts while high bitrate songs sound nearly identical to the original source.

The 200Mbps incoming bandwidth is basically the maximum write speed the NVR is capable of recording; the Gigabit Ethernet is faster; the HDD's are faster.. the limitation here is how fast incoming streams can flow internally from the network to the storage.. the more Resolution/FPS/Bitrate you try to squeeze out the more bandwidth the stream uses..

Most small embedded computers have a maximum bus speed lower than networks/disks and this is the speed limit on Input/Output; for example my CuBox i4Pro w/Quad 1Ghz CPU's, 2GB RAM, eSata and Gbit ethernet has a maximum bus speed of 470Mbps.. thus it cannot saturate either eSata or Gbit ethernet capabilities.. but for its job it is plenty fast.
 
Last edited by a moderator:
Shockwave199 said:
My question here still stands.
Click to expand...

I have just started down this road and I am not an expert by any means, however if you were to look at an NVR internally it is a router, a PC which processes then video signals and a switch, or switch port which connects to the switch where cameras are connected. 100Mbit Ethernet does not give you 100Mbit throughput. It crashes at about 33Mbits/s. I believe that the 200Mbit value comes from a fact that the NVR now have Gigabit Ethernet ports. if the cameras still all have 100Mb ports i don't think you will get anywhere near the 200Mb. It is also possible that when they say the NVR can handle 200Mb input they are talking about memory used for the buffers on the input port to the processing portion of the NVR. the record rate is likely the write rate from these buffers and memory to the hard disk. What do you think..........am I even close?
 
nayr said:
Bitrate of Video and Recording Bandwidth are not the same numbers; a higher bitrate uses more bandwidth because it contains more data but Video Bitrate is basically detail level; for example a BluRay disk is ~35MBit and contains alot more detail than my Dahua @ Max 8MBit.. Think of it as how wide the video channels are; the wider the channel the more detail can flow.. Variable Bitrates change the width dynamically to better suite the current demands while reducing traffic.. if the image is mostly static it can save alot of bandwidth by lowering the bitrate until there is alot of changes; at which point it ramps up the bitrate... its the same with MP3's, low bitrate songs sound flat with more artifacts while high bitrate songs sound nearly identical to the original source.

The 200Mbps incoming bandwidth is basically the maximum write speed the NVR is capable of recording; the Gigabit Ethernet is faster; the HDD's are faster.. the limitation here is how fast incoming streams can flow internally from the network to the storage.. the more Resolution/FPS/Bitrate you try to squeeze out the more bandwidth the stream uses..

Most small embedded computers have a maximum bus speed lower than networks/disks and this is the speed limit on Input/Output; for example my CuBox i4Pro w/Quad 1Ghz CPU's, 2GB RAM, eSata and Gbit ethernet has a maximum bus speed of 300Mbps
Click to expand...

Even though the Gigait Ethernet is faster, there are no Gigabit cameras as far as I know, they are all 100Mb. the only way to converge these streams into a Gigabit signal is to go through a router which will have to process this signal.
 
200Mbps is > 100Mbps therefore a Gigabit port is needed on the NVR if you wish to have more than 100Mbps incoming bandwidth..

Individual security cameras do not come close to exceeding 100Mbit individually so there is absolutely no need for them to have Gigabit ports..

Every gigabit switch is capable of converging Gigabit and 100Mbit networks together.. technically the terms are:
10/100/1000Mbps Ethernet
10/100Mbps Ethernet
and 10Mbps Ethernet

HD cameras just barely exceed 10Mbps speeds, but 10x of them can surely exceed 100Mbps when combined @ the NVR port (which is internally limited @ 200Mbps on the 4xxx NVR)

You can find some old managed 24 port 10/100 PoE Switches with a pair of Gigabit uplink ports that would work great for large IPCam installs.
 
Last edited by a moderator:
That NVR4416 looks like a nice upgrade and still has the analog output that I want to send to some tv's over modulator.
AE seller has it for $350 as nayr stated
 
nayr said:
200Mbps is > 100Mbps therefore a Gigabit port is needed on the NVR if you wish to have more than 100Mbps incoming bandwidth..

Individual security cameras do not come close to exceeding 100Mbit individually so there is absolutely no need for them to have Gigabit ports..

Every gigabit switch is capable of converging Gigabit and 100Mbit networks together.. technically the terms are:
1000/100/10Mbps Ethernet
100/10Mbps Ethernet
and 10Mbps Ethernet

HD cameras just barely exceed 10Mbps speeds, but 10x of them can surely exceed 100Mbps when combined @ the NVR port (which is internally limited @ 200Mbps on the 4xxx NVR)
Click to expand...

the conversion between gig and 100MB Ethernet requires memory buffers and cpu cycles to disassemble and assemble the different packet structures. 100Mb Ethernet crashes at 33% or about 32.5Mbps once there is more data than that on the wire it will crash. The most any 100 Mb camera can send to a switch-port is about 32.6Mbps. If the switch is internal to the NVR, then the NVR cpu has to place the video packets off each switch port on its internal bus to the processor. There will be buffers memory and cpu cycles needed for that. if all the camera's are located on an external switch this will remove some processing required by the NVR and allow it to work more efficiently
 
It does not; you are confused somewhere.. packets are encapsulated exactly the same across all speeds ethernet; its just the throughput that changes.. switching is done in hardware on switches and packet encapsulation is offloaded to the network interfaces which does all the heavy lifting.

100Mbit ethernet does not crash at 33% I can reach full 12.5MB/s across any 100Mbit port on my network and a full 125MB/s across any 1000Mbit port.. Ethernet encapsulation is an overhead but ontop of specified throughput, not subtracted from it.. tcp protocol has overhead but thats being calculated in here with overall throughput.

I run a 40Gbps fiber channel encapsulated network at home for christs sake... but meh what do I know; I only work for THE networking company everyone knows because we can afford superbowl ads.

even the cheap broadcom network interface/swtich they put in these NVR's is the same stuff you get in off the shelf consumer switches just with a lil PoE added on.. completely capable of full wire speeds (200Mbps on the NVR in discussion) without any load on the host CPU and why they dont come in more than 16 ports (hint it stops being cheap)
 
Last edited by a moderator:
  • Like
Reactions: catseyenu and tokyojoe
I knew asking this question I'd get the answer...and still be scratching my head! I will re-read to try and absorb!
 
ah your confusing bits for bytes my friend.. 100Mbps = 100 Mega bits Per Second
8 bits = 1 Byte (lower b = bit / upper B = Byte, confused yet?)

1Mega Byte per second = 8 Mega Bits Per Second...
12.5 Mega Bytes Per second = 100 Mega Bits Per Second..

I will leave the rest for you to google and become enlightened; were working with a base-8 number system and it screws your base-10 brains up for a lil while :)
 
  • Like
Reactions: tokyojoe
hah its okay; reading and internet are like opposing forces for some weird reason; thus why the internet excels at porn ;)

anywase; my FTP server recording 4x Streams of all about 8Mbit Bitrate & 15FPS is using about 4MB/s of network traffic tops which = 32Mbps if I were to scale that up to 16x cameras thats 128Mbps and thats still < 200Mbps; plenty of headroom to run a few 30fps cameras and/or a few 5MP cameras if I get a need for em.

In theory if I upped all my cameras to 30fps my network traffic would double to 8MB/s (64Mbps); in which case i'd exceed the NVR's capabilities if I tried to run 16x cameras in this configuration (would require 256Mbps throughput).. The reality is no; the video compression and environment wont average out to double (especially if using VBR) but it could spike that high in theory. (a swarm of bugs causing all cameras to hit 100% bandwidth at same time and thus crashing your NVR LOL!)

Its probably best to stay clear of the upper limits and give your self a good overhead so you dont get dropped frames at the worst possible time.
 
Last edited by a moderator:
on another subject; anyone here plug a generic security cam joystick (Pelco-D or something) into there Dahua NVR yet? I presume it can control an IP PTZ with no Joystick IO's (RS485) directly on the camera.. I'll be really sad if it dont work over IP.
 
From a LEO stand point I would be happy to get the evidence on either USB or DVD. I have copied the video files from USB onto dvd at the office if they are able to be separated into multiple discs many times without problems. I think people understand and put great trust that law enforcement will not tamper with the media.

The sheriffs department and my department will usually have a usb drive assigned to each officer and if the business burns dvds we replace the dvd with a new blank one for the owner.
 
  • Like
Reactions: nayr
thanks for the insider info!

I was more concerned with defense bringing up the possibility of tampering, not that you guys would actually do such a thing.. lets say the NVR started glitching out right as some crime was occurring and it went from its normal 15FPS to 2-3fps.. If I were on the defense and saw this I would suspect some frames were purposely removed and call into question he authenticity of the video... thats where I'd call you onto the stand and question where the original copy of the video is and how it was obtained.. if the evidence can be presented, I saw the security system eject write protected disk, this exact one right here... tha'd be good right?

but then again im not a lawyer; so im just thinking outloud.
 
You must log in or register to reply here.
Top Bottom