VMS Software

Digital IP cameras have much more options that AHD-cameras don't offer. For example, mobile alerts, real-time video analytics, etc.
It can be useful if your office is closed and you need to know if someone is walking inside without premission. You can set the system to record events and send push notifications to your smartphone, along with recorded video footage.

Video Surveillance Cameras

Resolution: For a good quality video, you will need an IP camera that can capture at least in resolution - 720 p.
Resolution is one of the most important feature when you selecting am IP camera.

Frame rate: Video is simply a series of images glued together to create a motion picture. "Real time" is typically measured as 25 or 30 fps (frames per second). The higher the frame rate means the smoother the video.

Indoor/outdoor: Many security cameras are made specifically for the indoors.
If you plan to use cameras outdoor, make sure you buy models that are weatherproof.
Outside security cams might be weather resistant. Indoor and outdoor IP cameras can use a Wi-Fi to connect to your home network, allowing you to access them from anywhere. But more safe models that use wired Ethernet.

Audio: AHF cameras don't record audio at all, while IP Cameras do. Some IP Cameras enable 2-way audio communications.

Lighting: Unlike humans, the security surveillance cameras are able to see infrared light, enabling them to capture clear footage in dark conditions. The more infrared LEDs lets camera better be able to see at night.

Models: There are a number of different types of security surveillance cameras. Some of the most common ones are dome cameras, bullet cameras and pan tilt zoom cams, which offer remote control options to change the angle of vision.

Reuse your mobile phone as an IP Camera

Just install the app on your old smartphone and use it over Wi-Fi as an IP Camera.
App has built-in RTSP-server to stream the video and audio in your home network.
See more information from here.

P2P Cameras

Software is responsible for locating, and attaching to all the IP cameras on the network, providing a secure links to the cameras. Usually users need to view their IP cameras anywhere and anytime. However, RTSP is blocked by router or firewall. To view an IP camera remotely, there are new P2P technology. You don't need to have a static Public IP address or DDNS service and don't need to open certain ports on your router and configuring port forwarding to the IP camera. In peer-to-peer video delivery each player shares video without a cloud server.
P2P makes video streaming more scalable and you will have higher bandwidth and better quality. For P2P camera the server only connects IP camera device and remote computer. The video stream is transmitted directly through peer-to-peer connections, bypassing the cloud service.

Video Surveillance Storage

Storage capacity: The main question you have to ask yourself is how much disk space you will need. The answer depends on the number of cameras in your VMS, video resolution and how long you plan to keep archived videos.

The actual space taken up may differ due to frame rate and embedded audio.

You can set software to "overwrite" the old files once you reach the system's quotes.
But if you are not careful, the VMS might overwrite video that you still need.
If you're running a large video management system that has HD cameras, you will want to enlarge your storage capacity.

There are a number of tools that can help you to calculate how much disk space you will need based on the details of your system.

Cloud storage: Recorded video can be stored on the video surveillance cloud in addition to on your local archive. Online cloud storage solutions have come to replace traditional on-premise storage hardware.
It's important to ensure that uploading large video file won't take up all the available bandwidth and slow down your internet connection for other processes.
On the benefit side, storing files in the video surveillance cloud means that even if your hardware is is broken, you will still have access to your video archives.

Compression: Video compression is the process of encoding a video file in such a way that it consumes less storage than the original file and is easier to transmit over the internet. Compression reduces the size of video file by eliminating redundant information from the video streamed to your storage, thereby saving disk space.

The most common compression technologies used for HD video: MJPEG and H.264.
(you can still use MPEG4, but the quality tends to be lower than that counterparts)

Camera compatibility: Not every video recorder can work with any camera.
Some hardware are compatible with the IP cameras only from certain vendors. DVR can requires AHD or TVI analog cameras, while network video recorders use IP cameras.