DVRs & NVRs — Understanding the Difference
Purpose
This document explains what DVRs and NVRs are, how they differ, what to look for when specifying one, and how Hikvision's product ranges are structured. Understanding the recorder is fundamental to designing and installing any CCTV system.
What Is a DVR?
A DVR (Digital Video Recorder) records video from analogue and HD-TVI cameras connected via coaxial cable. Each camera runs a coax cable directly to a channel input on the DVR's rear panel.
The DVR:
- Receives the raw HD-TVI video signal from each camera
- Compresses and encodes the video digitally (H.265+)
- Writes the compressed video to an internal hard drive
- Provides live view on a connected monitor (HDMI or VGA)
- Serves live view and playback remotely via Hik-Connect or web browser
- On POC-capable models, supplies 12V DC power to cameras via the coax
DVRs are the right choice for: Standard residential CCTV, small commercial installs, POC camera systems, any job where coax cable is being installed or already exists.
What Is an NVR?
An NVR (Network Video Recorder) records video from IP cameras connected via a network. IP cameras connect to the NVR via Cat5/6 cable, either directly into the NVR's built-in PoE ports or via a separate PoE switch.
The NVR:
- Receives compressed video streams from IP cameras over the network
- Stores streams to an internal hard drive
- Provides live view via HDMI
- Serves remote access via Hik-Connect
- On models with built-in PoE ports, also powers cameras via Cat5/6
NVRs are the right choice for: Larger commercial installs, multi-building sites, systems with higher camera counts or resolutions, any job using IP cameras.
Side-by-Side Comparison
| DVR | NVR | |
|---|---|---|
| Camera type | HD-TVI / AHD / CVBS (analogue) | IP cameras |
| Cable to cameras | Coaxial (RG59/RG6) | Cat5e / Cat6 |
| Camera power | Separate PSU or POC | PoE via cable |
| Max resolution per channel | Up to 8MP (4K) | Up to 12MP and beyond |
| Complexity | Lower | Higher |
| Typical install size | 4–16 cameras | 4–64+ cameras |
| Cost per channel | Lower | Higher |
Key Specifications
Channel Count
The number of camera inputs. Common sizes: 4, 8, 16, 32 channels. Always specify enough channels for the current install plus headroom — you cannot expand a 4-channel DVR to 8 channels later.
Hard Drive Bays
DVRs and NVRs have one or more HDD bays. Most residential units have 1 bay. Commercial units may have 2–4 bays, allowing larger storage or RAID configurations.
Recording Resolution
The maximum resolution the DVR/NVR can record per channel simultaneously. On budget models, only some channels may support full resolution. For Wilsons' standard 5MP POC cameras, the DVR must support 5MP recording per channel.
H.265+ Compression
All current Hikvision recorders support H.265+ — the most efficient compression standard available.
- H.265 typically halves file size vs H.264 at equivalent quality
- H.265+ (Hikvision's enhanced version) compresses static areas more aggressively — intelligent scene analysis
- A system in H.265+ uses approximately 50–70% less storage than the same system in H.264
Always enable H.265+ on both the recorder and cameras. There is no reason not to.
Motion Detection 2.0 / AcuSense
This requires AI processing capability in the recorder. On Hikvision's range, AcuSense models include this. Look for "AcuSense" or /K in the model name.
Wilsons' standard DVR for all new installs should be an AcuSense model. It is a significant customer-facing benefit and should be on every quote.
POC Support (DVR only)
Not all DVRs include POC capability. Check the spec sheet before specifying POC cameras — the DVR must explicitly state POC support.
Hard Drive Selection
Consumer desktop hard drives are not suitable — CCTV systems write continuously, 24 hours a day. Consumer drives fail quickly under this load.
Always use surveillance-grade HDDs:
| Brand | Range |
|---|---|
| Western Digital | WD Purple |
| Seagate | SkyHawk |
Rough capacity guidelines (H.265+):
| Cameras | Motion recording | Continuous recording |
|---|---|---|
| 4 × 5MP | 1TB ≈ 2–3 weeks | 1TB ≈ 4–5 days |
| 8 × 5MP | 2TB ≈ 2–3 weeks | 2TB ≈ 4–5 days |
| 16 × 5MP | 4TB ≈ 2–3 weeks | 4TB ≈ 4–5 days |
Recommendation: For most residential installs, a 2TB or 4TB WD Purple gives comfortable retention on motion recording. For continuous-record commercial systems, size up or use the Hikvision storage calculator.
Recording Modes
Continuous — records every channel 24/7. Maximum storage use. Used on commercial sites needing complete evidence capture.
Motion-triggered — records only when motion is detected. Significantly reduces storage consumption. With Motion Detection 2.0, only human/vehicle triggers matter — far less false recording.
Schedule-based — different modes at different times. e.g. continuous during business hours, motion-only overnight.
Wilsons' standard: Motion-triggered recording with Motion Detection 2.0 enabled. Meaningful footage, efficient storage.
Hikvision Model Reference
DVR naming
| Code | Meaning |
|---|---|
| DS-7200 | DVR product family |
| HUHI | High resolution — up to 8MP |
| HQHI | Quad HD — up to 4MP |
| HGHI | Standard HD — 1080p |
| /K | AcuSense (Motion Detection 2.0) |
| -K2 | Two HDD bays |
Example: DS-7208HUHI-K2 = 8-channel, 8MP capable, 2 HDD bays, AcuSense.
For Wilsons' standard 5MP POC installs: DS-7200HUHI-K series (AcuSense, POC).
NVR naming
| Code | Meaning |
|---|---|
| DS-7600NI | NVR product family |
| /K | AcuSense |
| -P | Built-in PoE ports |
Example: DS-7608NI-K2/8P = 8-channel NVR, AcuSense, 2 HDD bays, 8 built-in PoE ports.
Common Mistakes
- Specifying a non-AcuSense DVR — customer misses out on Motion Detection 2.0
- Forgetting the hard drive — DVRs and NVRs ship without HDDs; always include in the quote
- Undersizing the HDD — 1TB fills up fast on continuous recording
- Mismatching DVR to cameras — non-POC DVR with POC cameras, or vice versa
- Not enabling H.265+ — system works but wastes storage; always enable at commission