HD SDI / HDcctv TutorialBy: John Honovich, Published on Aug 20, 2014
Want megapixel but don't want IP? That's the promise of HD SDI / HDcctv. In this tutorial, we examine what it is, how it differs from IP Megapixel and the key factors impacting its use including backwards compatibility, product availability, VMS integration and feature tradeoffs.
[Important: Contrast / compare to Analog HD offerings like HDCVI and HDTVI.]
Traditional analog CCTV cameras cannot deliver megapixel. Constrained by NTSC / PAL standards, traditional cameras are limited to standard definition (typically quantified at 640 x 480 or ~0.3 megapixel). To get megapixel, those cameras need to be replaced. To date, this has overwhelmingly been done by using megapixel IP cameras.
While Megapixel IP cameras encode video inside the camera, HD SDI cameras can transmit uncompressed digital video digitally. Equally importantly, HD SDI can directly connect to coaxial cable, like analog cameras but unlike IP which typically uses UTP cabling or additional adapters for coax.
HD SDI video feeds are encoded and recorded in DVRs or video servers / encoders just like analog cameras. However, you cannot directly connect them to a PC or NAS as you can with IP cameras.
HD SDI vs HDcctv
HDcctv is a trade group that is attempting to certify / legitimate HD-SDI for surveillance. The HDcctv 1.0 specification is simply HD-SDI with a claim of compliance / interoperability testing. In 2013/2014, the HDcctv Alliance, now sponsored by Dahua, is promoting / specifying a non HD-SDI alternative called HDCVI.
Advantages of HD SDI / HDcctv
The following are key advantages og HD SDI / HDcctv over Megapixel IP cameras:
- No network configuration needed: Unlike IP cameras, HD SDI requires no IP address, no network discovery, no firmware, etc.
- Simpler for low voltage techs: Because it is similar to installing analog camera, demands far less training and new skills for existing techs.
- Re-uses coaxial cable: Since most deployments have coaxial cable in place, this allows many to re-use their cable (presuming the cable is not degraded and is not too long).
- Better Quality Live Viewing: Since HD SDI video is transmitted uncompressed, if it is displayed directly on a monitor, the live view quality will be superior to an equal resolution MP IP camera.
- Lower Latency: Again, since HD SDI video is transmitted uncompressed, directly connected PTZs should have smooth control, potentially much smoother than IP alternatives.
Overall, HD SDI / HDcctv looks and feels like traditional surveillance systems, making this more comfortable for those with significant existing investments into analog.
Disadvantages of HD SDI / HDcctv
On the other hand, HD SDI / HDcctv have a number of key disadvantages compared to Megapixel IP cameras:
- Lower Resolution: Megapixel IP cameras are commonly available in 3MP, 5MP and 10MP+ models while HD SDI is only available in 1080p / 2MP. While 3MP+ IP camera options are rapidly expanding, HD SDI will remain at 2MP for years to come.
- Limited Product Availability: Despite being available for 5 years, HD SDI has only a fraction of the options available as does megapixel IP. Key limitations in camera form factors, PTZs, matrices and large scale DVRs (e.g., 16 camera units) are notable.
- Requires New Recorder: HD SDI is not backwards compatible with analog recorders, requiring a new recorder. Equally important, dedicated ports are needed for HD SDI and analog cameras stopping users from mixing the two or easily adding HD SDI in the future.
- Cost Higher: HD SDI camera and recorder costs are typically higher than megapixel IP + VMS, limiting the motivation to switch.
- Limited Brand Support: Very few big brands support HD SDI, even among incumbent CCTV providers (nothing from Pelco, Honeywell, Interlogix, Bosch, Panasonic, Sony, etc.)
- No edge storage: HD SDI cameras, by design, cannot support edge storage, one of the biggest emerging trends in the industry.
- No practical VMS integration: Video Management Software (like Milestone, Genetec, etc.) can only support HD SDI via encoders (that are very rare) or through support of 3rd party HD DVR recorders (also very rare).
HD SDI has never taken off.
However, other non-IP megapixel offerings are gaining momentum. Compare / contrast to Analog HD technologies.
[This is an August 2014 revision of a tutorial first published in 2012.]