Camera Edge Storage / Recording Tutorial 2015By John Honovich, Published Jun 29, 2015, 12:00am EDT
~70% of IP cameras allow storing video onboard, at the 'edge', typically through the use of SD cards.
The big question is whether and when it makes sense to use edge storage / recording inside the IP camera.
In this tutorial, we teach:
- Edge compared to centralized and edge site storage
- The 3 most common edge applications explained - server elimination, network load reduction and recording redundancy
- Camera support and limitations
- Third Party Compatability and ONVIF Profile G
- Storage Reliability
- Direct to NAS Alternative
- Stealing Storage
- The Business Case for Edge Storage
- Future of Edge Storage
Compared to Centralized and Edge Site Storage
Almost all surveillance systems today make use of centralized storage, whether it is a VMS server or an NVR or DVR recorder. Video is captured in a camera and transmitted to a 'central' location where multiple video feeds are recorded in the same PC, server or appliance.
Larger organizations, with many sites, typically have a recorder (or recorders depending on number of cameras) at each site. This can be considered a form of 'edge storage' but it is not camera based edge storage but recorders deployed at the edge.
By contrast, with edge storage, the video is captured, encoded and stored right inside the camera itself. Video does not need to be sent out of the camera unless someone wants to view live video or review recorded video. However, only IP cameras support edge storage; This is not possible in analog or HD SDI cameras that need to transmit their video to stand-alone recorders. IP cameras that record to their own local edge storage are essentially 'single channel NVRs" as they combine both video capture and recording in one.
While video can be recorded to many storage mediums, the most typical are SD cards:
- SD card slots are frequently built into cameras allowing storage to be plugged in.
- In the past, a few manufacturers (e.g. VideoIQ) built hard drives into the cameras but the significant increased size requirements made this unpopular.
- In the past, a few manufacturers allowed external hard drive to be connected directly to the camera.
Three potential applications are most likely for edge storage:
- VMS Server elimination - Instead of setting up a server or deploying an NVR, just record inside the camera using edge storage and connect to those cameras directly using a client. This has the most appeal in sites with a small number of cameras as VMS servers represent disproportionate cost and complexity here.
- Network Load reduction - For low bandwidth networks, like wireless, recording inside the camera radically reduces the demands on the network. Instead of streaming continuously or whenever there is motion, now video only is transmitted when someone wants to watch live or do an investigation.
- Recording Redundancy - Edge storage can be used as a back-up to recording centrally, ensuring that no video is lost even if the network connection goes down temporarily or the VMS / NVR is offline periodically. When the connection to the recorder is reestablished, the recorder can request video missed during the downtime to be sent from the camera to it (note: must verify VMS support for this feature and integration with specific cameras). Redundancy via edge storage is most often used in large scale, mission critical applications.
Increasingly, SD card support is commonplace for IP cameras, even on low-cost, low-end models at essentially no additional cost. 70% of IP cameras support onboard storage in the IPVM Camera Finder , almost all via SD cards.
There are three important limitations frequently encountered:
- Storage size
- Storage reliability
- Playback / Recording Compatibility
Storage Size Limitations
In 2015, the max storage size per card used in IP cameras ranges from 32GB to 128GB.
Some IP cameras, especially older ones, only support SDHC cards, limiting storage to 32GB. Newer cameras may support SDXC, which removes that limitation. However, regardless of the SD card version supported, make sure the manufacturer verifies the maximum storage size they support.
In practice, 64GB is becoming fairly common and, for example, is what Axis has 'standardized' on with its recent SanDisk OEMed SD cards.
64GB per camera is equivalent to a 1TB 16 channel recorder, which for today's HD video is not a lot of storage. Like any camera, how long it will record depends on resolution, frame rate, compression, motion vs continuous recording, activity levels, etc. That said, getting a month of recording will be very hard without sacrificing on one of those key parameters above.
In the past few years, concerns over edge storage reliability have become very significant. For example, see: Axis Edge Storage And Camera Companion Is Unstable and Axis Admits Edge Recording Problems, Offers Solution. Axis took the biggest hit, at least partially because they are a large company who marketed edge storage heavily. However, many reports of issues with other vendor's edge storage also were received.
One clear factor is the use of lower 'quality' SD cards, as SD cards range from flimsy booth giveaways to enterprise offerings. Most industry people recommend Class 10 SD cards, though we believe that is insufficient as 'Class' just measures throughput, only part of what is required for reliable storage. Recently, SanDisk, who has taken a lot of criticism for its cards in surveillance, released a 'surveillance optimized' version, though only in 64GB max and with less than 1.5 years effective warranty.
Bottom line: storage reliability is a concern and before you deploy edge storage, speak with your specific camera supplier on what they recommend and are willing to support / warranty.
Third Party Compatibility
The biggest barrier today is, unfortunately, the same as 3 or 5 years ago. Third party VMS support for edge storage remains weak. Even if you can record video inside a camera, it does not mean you can easily retrieve it. Many IP cameras support SD cards but only allow for rudimentary opening of individual video files. Some will provide VMS integration but only for their own VMS, not for third parties.
On the centralized side, users obviously expect to connect dozens of manufacturer's cameras to a VMS and record them all. However, with edge storage, most VMSes support no cameras and the few that do support 3rd party camera manufacturers, typically only record Axis. From what IPVM has seen, Genetec likely has the widest third party edge storage support but that is still a minority of all cameras.
Net / net: verify that your choice of recorders can fully integrate with your choice of edge storage.
ONVIF Profile G
A newer ONVIF Profile, G, aims to simplify support / retrieval of recorded video, in general. This has the potential to help third party systems connecting to VMSes / recorder as well as VMSes / recorder integrating with camera edge storage. On the plus side, official camera support for ONVIF Profile G is growing, with 163 listed as of June 2015. However, no VMSes are officially supporting ONVIF Profile G at this time, though Genetec unofficially supports it and Milestone is using a variant of it for their edge support.
Profile G is making progress but not at a very fast rate. The probability that it helps many today in 2015 is low but it does have potential to help reduce the third party compatibility barrier.
Edge Storage Alternative - Direct to NAS
One alternative, direct to NAS, should be considered for those who want to eliminate VMS servers but desire less expensive and/or greater amounts of storage. However, this will only work if one's chosen VMS supports direct to NAS recording, which is uncommon. See our Direct to Storage tutorial for the pros and cons of that.
Since cameras are widely distributed inside and outside of facilities, using edge storage means leaving the recorded video wherever the cameras are. Clearly, this makes it easier for an adversary to destroy video evidence. All they need to do is access the back of the camera and pull out the card. How much of a practical risk this is and whether users will accept it will vary based on the security concerns of the organization. We expect many high security facilities to view this as unacceptable while the rest of the market to be less concerned about this.
The Business Case for Edge Storage
The best business case for edge storage comes in larger, more complex systems that value redundancy. In those systems, often using expensive wireless or corporate IT networks, the incremental price of a ~$100 SD card per camera is not significant and the likelihood that the VMS being used supports edge recording is decent, though not certain.
A few years ago, using edge storage to eliminate centralized VMSes / recorders was intriguing but the case has mostly gotten worse. For those who really demand the lowest cost, HD analog has provided a simpler and lower cost alternative to deliver this. Edge only solutions like Axis Camera Companion, given the higher cost of Axis cameras and the ~$100 SD card cost per camera cannot come close on price, especially since HD analog DVRs are so inexpensive.
One niche, though, where edge storage replacing VMSes can work, is if only a few cameras (1, 2 or 3) is needed per site. In such scenarios, the cost and complexity of adding a recorder outweighs a few SD cards.
Future of Edge Storage / Recording
Edge storage is definitely a niche in 2015 (see IPVM edge storage usage statistics).
The key barriers are (1) third party compatibility, (2) reliability and (3) size. Though there has been some progress on each front over the past few years, it is not fast. Indeed, the outlook going forward looks to be at a similar pace. As such, proceed with caution when using edge storage.
NOTE: This is a substantially revised version of our 2012 edge storage / recording tutorial.
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