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CCTV Test: Edge Recording

by Benchmark

When edge-based storage first became commonplace in the security industry, many saw it as an approach solely designed to tackle issues regarding bandwidth management. However, it actually offers a significant benefit in surveillance system design, and delivers a better level of security too. Benchmark looks at a range of devices to test the potential of edge recording to add benefits for surveillance archiving needs.

Edge recording is commonplace in today’s surveillance marketplace. It enhances security, safeguarding against the loss of footage during infrastructure outages. It allows a more flexible approach to system design. It enables the creation of cost-effective solutions. It adds value to surveillance systems of all sizes and complexities. Given these benefits, it’s hard to understand why, when edge recording first became possible, that so many people objected to its use!

In many applications, the case for recording at the edge is very strong. Centralised recording has been, and some would argue still is, a cornerstone with regard to surveillance system design. This is not because it offers better functionality, is more secure or aids overall performance. It isn’t because customers demand it, or because it is ‘best practice’.

It is because historically surveillance technology was restrictive, and centralised recording was a necessity if systems were to be cost-effective!

When networked solutions appeared in the surveillance sector, centralised recording remained the dominant method. Many manufacturers simply replicated existing analogue systems, but with network connectivity. Force of habit also played a part! Manufacturers, installers, integrators, specifiers, consultants and even end users were used to centralised recording, and so the model was difficult to change.

Network-based solutions are well suited to distributed archiving. They offer the flexibility to distribute storage without fragmenting the system. Many manufacturers offer software or VMS solutions that manage edge recording sources as if the system was one unified entity.

A centralised approach can sometimes be detrimental to the system. Overall design becomes unnecessarily cumbersome, with many of the benefits of network infrastructure being ignored.

Management elements are required to address vulnerabilities which the centralised model introduces. A centralised approach can over-complicate the system, introduce unnecessary duplication, deliver less performance and cost more.

There will always be some applications where a centralised approach remains the best choice. However, edge recording offers significant benefits.

Edge recording is not limited to archiving at the camera or encoder. Video can be archived on numerous networked devices: NVRs, NAS or SAN storage devices, servers or appliances, memory cards in nodes, etc..

In many cases, the lack of a need for a centralised control room frees up personnel to manage the video system in a more effective way. With a centralised system, the topology can also create certain issues.

Systems are generally accessed as a singly entity. Distributed solutions can be accessed as a single entire system, or as individual subsystems. Management is flexible; you and the customer decide how to manage it.

Edge recording is often highlighted as an option to protect against network outages. However, other benefits also exist. The ability to mix and match devices based upon the requirements of specific parts of site can save budget. Some systems can operate without an NVR or servers.

Parts of a system can be segmented at certain times of the day. For example, business management teams could manage video during working hours with access to their own device, with the system switching to a VMS out of working hours for security purposes. Such an approach would still see video recorded, and in an emergency a security operator could easily access the edge video via the VMS.

In recent years storage costs have fallen. However, it is not only the low cost of storage, but also the variety of ways in which it is packaged, that makes edge recording an attractive proposition.

Importantly, edge recording isn’t about eliminating the server or the NVR! These devices can play an important role in edge recording. Devices can be deployed near a group of cameras and operate within that cluster. Overall control can then be taken via management software.

Edge recording enhances the capabilities and performance of systems, and delivers genuine cost savings. There will always be cases where centralised recording makes sense. However, by ignoring the possibilities of recording at the edge, installers and integrators could lose out on valuable contracts.


Edge storage management has been integrated as a part of the XProtect family of VMS products from Milestone Systems; many other VMS providers have also added support for this approach as its benefits become more obvious. Indeed, integration of edge recording with a VMS makes much sense in a wide range of applications for many reasons.

Milestone has recognised the many benefits that the technology provides. These include increased fault tolerance, conservation of bandwidth during times when the user might wish other traffic to be prioritised, and where recordings may be required at a higher quality than the infrastructure might allow if footage was continuously streamed. The functionality allows footage to be recorded on numerous edge devices, and it then can be retrieved by the VMS automatically or on demand.

If devices are connected to the system over a public network, an unstable network or one with high peak traffic, traditional recording servers could suffer from occasional dropped connections. Edge storage solves the issue as the camera will record to on-board or local storage. Once the connection is restored, recordings are transferred back to the server, ensuring continuity. This functionality can be enabled simply via a single tick box.

Failover recording servers are increasingly common, and add value as they can take over from standard recording servers if a failure occurs. Even so, short breaks in the recordings can occur in the time between the recording server failing and the failover server taking over. These gaps can be covered by edge storage. The system will automatically identify any period missing from footage on either the recording or the failover server and can retrieve the recordings automatically.

Edge storage can also be a cost-effective alternative to a failover recording server in smaller applications.

In some applications it might not be necessary for all video to be transmitted to the central recording server, such as where an event-based approach is taken. In such installations, edge storage can be used for initial on-site recording and then only later be retrieved when needed by the system or an operator. In order to achieve this, a simple action is initiated via the VMS client.

At times the bandwidth may also used for business purposes and the user might prefer the video does not increase load on the network. Edge storage could be used for recordings, with only alarm incidents sent over the network. The VMS could then be scheduled to retrieve other footage during specified periods, such as during non-working hours.

Edge storage management via a VMS is simple to implement, and underlines the importance of this approach.


Many feel that SD cards – the most commonly used cards for on-device edge storage – offer poor reliability. As with many things, when you buy memory, you get what you pay for. There are cheap memory cards that will probably fail in a few weeks if used a lot, but you can also buy cards that are reliable. The latter obviously cost slightly more.

As an example, Benchmark uses a number of high capacity SDXC cards. They have been used heavily over a few years, in a wide range of environments such as temperatures approaching 35°C with high humidity, down to well below freezing. They have been used for data, images and HD video. Once in a fit of clumsiness one was bent in half and forced flat again, To this day it retains a severe kink. Whilst such abuse is not recommended, the card in question still works perfectly.

MicroSD cards are smaller than the standard SD units, and are increasingly used due to their small form factor and economies of scale which have increased due to the use of the cards in smartphones and tablets. Currently MicroSDXC cards offer capacities of up to 128GB.

When considering cards, there are MicroSDHC, SDHC, MicroSDXC and SDXC cards generally supported by security devices.

SDHC and MicroSDHC cards offer storage capacities of up to 32GB. The SDXC cards currently have capacities of up 512GB, with MicroSDXC cards widely available with 128GB capacities.

When used with video surveillance, devices should support SDHC as a minimum, but preferably SDXC cards in either standard or Micro formats. It is worth realising that a MicroSDXC 128GB card offers the equivalent storage as a single channel on a 16 channel 2TB server or NVR, and an SDXC 512GB card is equivalent to a 16 channel 8TB device.

While capacity choice is straightforward, it is important to be aware of the card’s speed ratings. SD cards have a class rating which states minimum data transfer rates, and a UHS speed which identifies the minimum rates for writing video.

The speed class is displayed on the card, usually as a number inside a letter C. Classes are 2, 4, 6, 8 and 10; these relate to speed in MB/s. A class 6 card’s minimum transfer rate is therefore 6MB/s, while a class 10 card’s minimum transfer rate is 10MB/s. Maximum rates can be significantly higher, but of course this isn’t guaranteed. Class 10 cards are recommended for archiving video.

The UHS (ultra high speed) class is displayed by a number inside a letter U and is also displayed on the card. There are two UHS classes: 1 and 3. These indicated the guaranteed minimum write speed when recording video.

Class 1 is 10MB/s and Class 3 is 30MB/s. The latter has been developed in response to the growing need to record 4K UHD video.

Axis: Edge Recording

Axis Communications has offered edge recording as a standard feature on its cameras for many years. The company has moved to the smaller form factor microSD cards, and supports both microSDHC and microSDXC formats. Obviously, NAS devices can also be supported via the network connection.

What makes the Axis approach to edge recording somewhat different for smaller sites looking for a credible but cost-effective security solution is the Axis Companion software. The software is free, and allows a network of up to 16 cameras to be configured, via a laptop or other standard PC. The cameras record onto the edge-based SD cards, and if an event occurs the footage can be viewed and downloaded via the PC. When in operation, there is no need for the PC to be connected, and the system can operate without any server or NVR.

Using edge recording with Axis cameras is not limited to Companion-based systems. The recordings can be accessed via the camera, or can be used via a VMS which supports edge-based archiving. That said, using Companion can be beneficial if a larger or more complex system is required, but a temporary solution is desired by the end user until the installation is complete. Companion works with any Axis cameras, and so devices specified for a larger solution can be used during the set-up and configuration of a VMS or other recording system.

Memory cards are loaded using the microSD slot on the rear of the camera. Once the card is inserted, the recording parameters can be configured via the camera’s menus. Which menus are used depends upon the type of recording required. For event-based recording the Action Rules can be used. This allows a trigger to be set: it can be a motion event, an IVA trigger via an on-board camera application, an input or a device event. The trigger can also be scheduled. It is possible to add additional conditions, thus creating a double-knock type event if necessary.

Once the trigger is set, the action is selected to prompt recording and the destination for recording is set as the memory card. Other configurations include the video stream profile, pre- and post-event recording times, and whether recording should continue while the rule is active.

For continuous recording, it is simply a case of using the Recordings menus. The Continuous page simply requires a check box to be ticked to enable the feature, the storage medium to be set as SD Card, and a stream profile to be selected.

Replay is achieved by the other page in the Recordings menu section: List. Filters are applied with regard to start and finish times, events and storage media. When the filter is run a list of recordings appears, and these are simply selected for viewing.

Axis cameras offer flexibility with regard to edge recording, and work well when accessed via a compatible VMS. Quality was as configured, and recording replayed smoothly. We did see some skipped frames when reviewing footage at the highest resolutions, but nothing to cause concern. Most users wouldn’t spot this. If the video is retrieved via a VMS there are no issues at all.

Axis has delivered a good range of options for edge recording, and installers or integrators have a choice as to whether the video is accessed via a third party VMS or through Axis’ range of software. Add to this the Companion software, and it allows smaller sites with limited budgets to enjoy higher quality cameras as costs associated with recording hardware are eliminated.

Bosch Security: Dinion Range

The Dinion range cameras from Bosch support edge recording via the use of iSCSI devices or microSD memory cards. The cameras support local use of both microSDHC and microSDXC cards.
The connection of iSCSI devices is achieved via the network, while local archiving makes use of a slot on the rear of the camera.

Dinion cameras can support two recording tracks; one can be allocated to the iSCSI device and one to local archiving if ANR (Automatic Network Replenishment) is required. ANR ensures that if recording streams are interrupted, the footage can be captured locally until the network connection is re-established. For critical applications, this delivers a fail-safe solution. Both recording options can be password protected.

There is the possibility to create up to 10 recording profiles. These can be used for differing times of day, days of the week or for various shifts or site status changes. Each individual profile allows a video profile to be set for the streams. These include independent configuration of resolution, frame rate and bit rate. The video profiles are set in the encoder menus.

Recording profiles allow audio to be included or excluded, and metadata can also be added or ignored. The type of recording (standard or event-based) is also configurable. Pre- and post-alarm periods for recording can be adjusted to suit specific needs. Finally, the type of trigger to initiate alarm recordings can be selected, and includes inputs, analysis or virtual alarms.

There is an option to specify video retention times. These are set in days, and can be configured independently for each recording track. Finally, full schedules can be created for the different recording profiles.

A recording status page delivers updates and contains information about errors, media, buffer sizes and ANR progress.

The Dinion range gives a good degree of flexibility with regard to edge recording, and allows the functionality to enhance the level of protection on offer. The ANR feature is certainly a benefit.

Accessing edge recordings is simple. The playback options are reminiscent of an NVR and make use of a timeline. Playback controls include play/pause, jump forwards/back in one second increments, fast forward and fast rewind. There are also options to capture a snapshot or to manually control archiving.

Switching between recorded streams is achieved via a drop down menu. There is also a basic motion search function and an option to export video clips.

When working with edge recordings via a compatible VMS, accessing recordings from the camera is straightforward and footage is replayed as expected. Quality is as configured, and recording replays smoothly without any juddering or skipped frames.

It is quite clear that Bosch has given consideration to the inclusion of edge recording, and as such the functionality does inspire confidence that it will remain robust and reliable over time. Certainly, during the test period, it behaved as expected and was consistent.

Hikvision: Edge Recording

Hikvision supports edge recording on its cameras and like the other devices in this test makes use of the small form factor microSD cards. It supports both microSDXC and Micro SDHC formats. For the purpose of the test we used the Hikvision turret cameras. These feature the microSD slot on the side of the device. This is concealed beneath the mounting ring which makes it tamper-resistant unless the camera is removed from the mounting.

There are two ways to view recordings from the SD card: the first is through the web page of the camera or Hikvision’s own software can be used instead. The second way is via a compatible VMS and when testing using Milestone’s Xprotect package, this allowed full connectivity with footage on the edge recording card.

Initial configuration of the edge recording functionality is carried out via the camera’s Storage menu. This comprises of two main screens. The first is Schedule Settings and incorporates two tabs: Record Schedule and Capture. The Record Schedule page allows times for enabling recording to be set, with options for continuous, motion, motion/alarm and event. The stream to be recorded is also selected. The Capture screen allows the parameters for the video to be set, including format, resolution, quality and interval. It also allows configurations for event-triggered snapshots.

The Storage Management page includes two tabs: HDD Management and Net HDD. The first gives status information about the SD card, and also allows it to be formatted. There is also an option to allocate a certain percentage of the card’s capacity to video footage and/or snapshots. The Net HDD tab allows network-connected NAS devices to be linked.

If the edge recording is to be used for event-based recording, this will need to be set up in the Event menu. Once a motion detection, video tampering or smart IVA event has been configured, a schedule can be created and finally the linking and actions can be set. This is where edge recording can be specified as an action.

Within the camera’s web pages there is an option to display a Playback screen. This includes a timeline which highlights continuous, alarm-based and manual recordings using colour coding. Alternatively, a search can be made using date and time information. Once the appropriate video we selected, the Playback page makes use of typical video control buttons such as play/pause, stop, slow and fast forward and single frame jump.

There are also options to capture snapshots, clip the video, digitally zoom or download the clip. The Playback functionality works as expected, and video delivery is with no obvious signs of lag or dropped frames.

When accessed via the VMS, the edge recording footage was as expected in terms of resolution and quality, and both the manual and automated control of the video was as expected.

Whilst Hikvision’s edge recording features are arguably not as comprehensive as some of the others, they do work well and add benefits for users in terms of enhanced reliability and protection, plus cost-effective secondary recording for a wide range of applications.


Axis Communications

Axis Communications has attacked edge recording on two fronts. If you are using the company’s edge devices with a third party VMS that supports the management of edge recording, the feature will work seamlessly via the management software. If you are using AXIS Camera Station, the company’s own VMS, you can also control the recording functions. However, smaller applications can also benefit via the AXIS Companion software, which enables a 16 camera system to be created without an NVR or server. As such, the Axis approach is recommended.

Bosch Security

Bosch offers a very high degree of flexibility with regard to its edge recording configurations. By combining iSCSI connectivity and local storage on memory cards, it is possible to create a failover system using more cost-effective devices. There is a high level of control which will make life simpler for installers and integrators, and all the functionality works as expected., even when used with a third part VMS. As such, the Bosch approach is recommended.


Hikvision takes a somewhat simpler approach to edge recording, but this also means that set-up and configuration is very simple and quick to implement. It works well, including with a third party VMS, but can also be accessed via Hikvision’s own software of via the camera’s web pages. As such, it is recommended.

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