SD Card For Surveillance Tutorial

By: Brian Rhodes, Published on Mar 21, 2012

Axis's VMS elimination solution uses SD cards to store video on the camera. This makes SD card selection and specification a key part of a surveillance design. In this note, we examine SD cards, key criteria and descibe which types to best apply.

Here are the key elements reviewed:

  • Function
  • Format
  • Speed Class
  • Backward Compatibility
  • IP Camera Application
  • Pricing

Function

SD card memory is an 8 or 9 pin solid-state memory format, using flash memory chips packaged in narrow form factor. This memory format has gained wide acceptance since its introduction in the early 2000s for a variety of electronic media storage, including music, pictures, and video clips. It is commonly available, inexpensive, and widely distributed. The low cost of the memory format has made it an ubiquitious storage medium for many data recording devices. 

Format

A number of SD card formats exist, and they are not entirely interoperable. Care should be taken to ensure the proper media is used according to the type storage device supports.

  • SD cards - too small for widespread use in IP cameras.
  • SDHC cards - the most common format accepted by IP cameras
  • SDXC cards -  not yet commonly accepted by IP cameras

The storage capacity of these card formats vary:

  • With the older 'SD' format supporting a maximum size of 2 GB. This small capacity is not practical for use as onboard storage.
  • The 'SDHC' format is widely accepted by many IP camera manufacturers and supports a range of size denominations from 8 - 32 GBs. This format is limited to a design maximum of 32 GB and is cheap enough at 32 GB to be a good fit for edge storage use.
  • The newest 'SDXC' format is designed to support capacities from 64 GB to a theoretical maximum of 2 TB per card. This format is not yet widely adopted by IP camera manufacturers for onboard storage, but due to the larger capacities supported, we expect to see edge storage moving to this format.

An interesting theory surrounding the slow release of SDXC memory has been that "there is no real need for larger card". We consider the development of edge storage using SD format storage to increase demand for larger denominations and their eventual introduction into the market.

'MicroSD' cards are a smaller form factor of memory using the same storage technology. The full scope of micro SD, microSDHC, and microSDXC cards exist, and the same storage limits apply to this form factor. MicroSD card are available in the same denominations and with similar prices to SD formats. The microSDHC format is popular in smaller dome IP cameras like the Axis M50 series, Vivotek FD series, and Panasonic's WV series.

SD Speed Class

Get Notified of Video Surveillance Breaking News
Get Notified of Video Surveillance Breaking News

Speed class is a critical consideration when recording video to SD cards. The 'speed class' notes the data transfer rate supported by the card. Since SD card formats can be built using different types of memory, the speed class designates how fast the included memory chips will transfer data for storage. Common SD Speed Class marks are "2", "4", "6", and "10" and they refer to the speed in Mb/s (e.g., class 2 = 2MB/s, Class 4 = MB/s).

While Class 2 might be enough for many IP cameras, it is safer to use Class 4 or higher. For instance, Class 2 max speed is 2MB/s, equivalent to 16Mb/s. This should be enough for most HD cameras, however, VBR streams might spike and approach the max of this class. By contrast, Class 4 provides double the speed, up to 32 Mb/s, which should be safe for almost any H.264 camera stream/configuration.

Backward Compatibility

An SDXC card can be used in an SD or SDHC reader, but it first must be formated for use in the lower format. This results in losing the benefits of the higher format. An expensive SDXC card can be purcahsed and used in an SDHC device, but at the expense of losing the additional SDXC capacity.

IP Camera Application and Storage Capacity

A number of manufacturers are adding SD storage onboard cameras, including Mobotix MX Control Center, Axis Camera Companion, Genetec Trickle Storage, and Milestone Edge Recording. Sizing the storage properly based on both capacity aand speed class is a critical consideration.

Once a card is installed, it should be fortmatted by the device before use. Despite the transportability of the memory card, it should not be removed from the device to recover video, but video should be downloaded from the camera via the web interface.

The storage capacity of the card, in terms of days of storage, may be insufficient. Many manufacturers claim multi-week storage capabilities with larger capacity SD cards (e.g., Axis Edge Storage Whitepaper). However, these settings may be too low to reflect practical usage. For example, Axis claims 19 days of 720p video on a 32 GB card. However this presumes a 10 FPS framerate and only 20% motion detection. Also, if using Axis in its default VBR mode at night, bandwidth could spike far higher. Real life results will vary wildly depending upon how these variables impact recordings.

Recording each camera to its own SD card eliminates storage advantages of aggregating cameras on a single recorder. With an NVR or DVR, if some cameras required a lot of storage and others required little, the storage averages out between cameras (e.g., one camera required 50GB and a second only required 10GB, only 60GB would be needed for both). However, with SD recording, the capacity is limited to the capacity of the card. The end result is that some camera's SD card storage might be insufficient for its particular needs, resulting in fewer days of storage.

Warning on Max Storage

At the current time, most IP camera manufacturers support SDHC but not the SXDC format. SDHC limits card size to 32 GB per camera. The greatly impacts how useful SD storage is as a primary method of storage. This capacity may not be sufficient enough to record video for many applications - continuous recording or high motion scenes or high resolution, etc. This hard capacity limit will be expanded to 2 TB once SDXC formats are supported, which is an 'upcoming adoption' or roadmap release from many camera manufacturers. However, it is not possible to field upgrade cameras with SDHC to SDXC. As such, any camera that only supports SDHC is stuck with that 'forever'.

Pricing

Due to the capacities required to be useful for recording onboard video, an SD denomination of less than 16 GB will be marginally useful. While smaller denominations of storage can be purchased, the pricing is not significantly less to warrant purchasing less storage.

SD card pricing is very volatile, and the commodity nature of this memory results in steep discount specials and 'loss leader' pricing from many online vendors.

Conclusion

We expect to see this trend continue and eventually be a common feature. Understanding the camera and software's ability to use this storage is only half the equation. The other half of understanding the accompanying media will ensure the right product is specified.

Comments : PRO Members only. Login. or Join.

Related Reports

Proactive CCTV "Only Affordable Video Archiving Solution" Profile on Aug 12, 2019
Proactive CCTV is claiming to offer "the only affordable video archiving solution on the market", reducing the storage typically required for H.265...
Razberi Technologies Company Profile on Aug 06, 2019
Razberi says they have doubled their revenue in the first half of 2019, citing their proprietary camera hardening and cybersecurity capabilities...
Avigilon Blue VSaaS Tested on Aug 05, 2019
Avigilon says Blue is a "powerful integrator cloud service platform", easy to set up and configure, quickly scale business, by leveraging cloud...
History of Video Surveillance on Jul 19, 2019
The video surveillance market has changed significantly since 2000, going from VCRs to ab emerging AI cloud era.  The goal of this history is to...
New GDPR Guidelines for Video Surveillance Examined on Jul 18, 2019
The highest-level EU data protection authority has issued a new series of provisional video surveillance guidelines. While GDPR has been in...
Lens Focal Length Tutorial on Jul 10, 2019
3mm, 6mm, 2.8 - 9mm, 5 - 50mm, etc. Camera specifications often list lens lengths but what do they mean? These metrics are important in...
Directory of 60 Video Surveillance Startups on Jun 25, 2019
This directory provides a list of video surveillance startups to help you see and research what companies are new or not yet broadly known. 2019...
Startup Vaion Launching End-to-End AI Solution Backed with $20 Million Funding on Jun 17, 2019
An EU / USA video surveillance startup, Vaion, founded by ex-Cisco Senior Directors is launching an end-to-end VSaaS platform with $20 million in...
Directory of 30+ VSaaS / Cloud Video Surveillance Providers on Jun 07, 2019
This directory provides a list of VSaaS / cloud video surveillance providers to help you see and research what options are available. 2019 State...
Startup Rhombus Systems Says Twice the Features, Half the Price of Verkada on Jun 04, 2019
Closed cloud systems may be the fastest growing segment of video surveillance with Meraki and Verkada. Now another California company is joining...

Most Recent Industry Reports

TMA Apologizes to Amazon / Ring on Aug 23, 2019
Not only is Amazon / Ring making major incursions into the residential security market, the organization representing the biggest incumbents, The...
China Dahua Replaces Their Software With US Pepper on Aug 22, 2019
What does a US government banned company do to improve its security positioning in the US? Well, Dahua is unveiling a novel solution, partnering...
Security Integrators Outlook On Remaining Integrators In 2025 on Aug 22, 2019
The industry has changed substantially in the last decade, with the rise of IP cameras and the race to the bottom. Indeed, more changes may be...
First GDPR Facial Recognition Fine For Sweden School on Aug 22, 2019
A school in Sweden has been fined $20,000 for using facial recognition to keep attendance in what is Sweden's first GDPR fine. Notably, the fine is...
Anyvision Facial Recognition Tested on Aug 21, 2019
Anyvision is aiming for $1 billion in revenue by 2022, backed by $74 million in funding. But does their performance live up to the hype they have...
JCI Sues Wyze on Aug 21, 2019
The mega manufacturer / integrator JCI has sued the fast-growing $20 camera Seattle startup Wyze. Inside this note: Share the court...
Dahua 4K Camera Shootout on Aug 20, 2019
Dahua's new Pro Series 4K N85CL5Z claims to "deliver superior images in all lighting and environmental conditions", but how does this compare to...
ZK Teco Atlas Access Control Tested on Aug 20, 2019
Who needs access specialists? China-based ZKTeco claims its newest access panel 'makes it very easy for anyone to learn and install access control...
Uniview Beats Intel In Trademark Lawsuit on Aug 19, 2019
Uniview has won a long-running trademark lawsuit brought by Intel, with Beijing's highest court reversing an earlier Intel win, centered on...
Suprema Biometric Mass Leak Examined on Aug 19, 2019
While Suprema is rarely discussed even within the physical security market, the South Korean biometrics manufacturer made global news this past...

The world's leading video surveillance information source, IPVM provides the best reporting, testing and training for 10,000+ members globally. Dedicated to independent and objective information, we uniquely refuse any and all advertisements, sponsorship and consulting from manufacturers.

About | FAQ | Contact