Selecting the Right Bit Rate for CBR Cameras

Author: John Honovich, Published on Mar 12, 2012

Some of the most popular cameras on the market, like Panasonic and Sony, are especially tricky to configure the right bit rate. In our experience, because of these camera's use of Constant Bit Rate, most deployments significantly waste bandwidth in real world usage. This note explains the issues involved and how to overcome this problem.

Background

Many camera manufacturers only support Constant Bit Rate (CBR) streaming, generally done to ensure quality video level. With CBR, the camera will always stream at the same bandwidth level regardless of the scene or conditions. For HD cameras, Panasonic and Sony typically set their default CBR rates at either 2Mb/s or 4Mb/s (depending on model). Equally important, this bit rate assumes the use of maximum frame rate of 30fps.

[UPDATE: Panasonic has added VBR streaming with new firmware. They call it 'Best Effort'. If you do not find it in your camera's configuration menu, upgrade to the most recent firmware.]

Most users, however, will set significantly lower frame rates. The average frame rate in real world usage is between 6 - 10 fps - 60-80% less than the max frame rate. Bandwidth consumption scales rather linearly - as the frame rate drops, bit rate needed drops at a proportionate level (see our bandwidth vs frame rate results).

Problem and Solution

The practical problem is that many users will drop the frame rate but not the bit rate. As a result, you can have a camera set to 8fps at 2Mb/s. This is highly inefficient for almost every scene possible. The plus side is that your video quality should look good (assuming camera is in focus, etc.). However, a lot of bandwidth is being wasted. You could drop the bit rate to 1Mb/s or even 750Kb/s and get the same visual quality.

When people talk about HD video requiring 2Mb/s - 4Mb/s, this is premised on running full frame rate video and typically assumes a moderate amount of motion (people walking, cars driving through, etc.). However, if one is not using full frame rate video (like most people), 2Mb/s - 4Mb/s is almost certainly too high.

The 'Exact' Right Bit Rate

The one challenging element remaining with CBR is setting the 'exact' or the precise right bit rate. Returning to our HD camera at 8fps, 2Mb/s is definitely too high but it is hard to say whether 500Kb/s, 750Kb/s or 1Mb/s is right. As we demonstrated in the bandwidth vs image quality shootout, the 'best' level depends on the motion in the scene - a hallway might be fine with 500Kb/s but a parking lot might need 1Mb/s. 

Getting the exact right setting is fundamentally hard with CBR and is a big reason why we recommend VBR and VBR plus a cap as superior alternatives. CBR locks the bit rate yet bandwidth needs vary with the scene over time. Nonetheless, a number of the most respected cameras, like Panasonic and Sony, only use CBR. If you are going to use these cameras, it is imperative that you properly appreciate and optimize the use of CBR.

Comments : PRO Members only. Login. or Join.

Related Reports

Winter 2019 IP Networking Course on Dec 18, 2018
[Tomorrow, Thursday Dec. 20th is the last day to save $50] This is the only networking course designed specifically for video surveillance...
8MP / 4K Fixed Lens Camera Shootout - Dahua, Hikvision, TVT, Uniview on Dec 17, 2018
8MP / 4K fixed lens models are now common in lower cost lines, with nearly every Chinese brand and their OEMs now offering multiple options. To...
Ubiquiti $79 Flex IP Camera Tested on Dec 07, 2018
U.S. Manufacturer Ubiquiti has released a 1080p, integrated IR IP camera, selling it directly for $79, making this one of the least expensive IP...
Hanwha L Series Lowest-Cost Camera Tested on Dec 04, 2018
Hanwha has released their lowest-priced IP camera line ever, the L series, that competes on price with low cost competitors Dahua and...
Dahua Dual Imager Dome Camera Tested (HDBW4231FN-E2-M) on Nov 07, 2018
Dahua has introduced a dual-imager dome model, the HDBW4231FN-E2-M, with two independently positionable sensors including integrated IR, not found...
Building Occupancy Codes and Access Control Tutorial on Nov 01, 2018
A building or room's classification can greatly impact which building codes must be followed. In terms of access control, these 'occupancy codes'...
Camera Course January 2019 on Nov 01, 2018
This is the only independent surveillance camera course, based on in-depth product and technology testing. Lots of manufacturer training exists...
Cloud Video Storage Usage 2018 on Oct 31, 2018
Storing email and documents in the cloud have long been common, with on-site email or file servers increasingly eliminated. However, what about...
Video Quality / Compression Tutorial on Oct 17, 2018
While CODECs, like H.264, H.265, and MJPEG, get a lot of attention, a camera's 'quality' or compression setting has a big impact on overall...
Axis 4K vs. 5MP Camera Shootout (Q3518-LVE + Q3517-LVE) on Oct 04, 2018
Axis has released the 4K counterpart to their 5MP Q3517-LVE (see our test). Axis claims of both these cameras: Simply put, AXIS Q3518(17)-LVE...

Most Recent Industry Reports

Dahua USA Sales Team Cuts - 'Strategic Right Sizing' on Dec 18, 2018
Dahua USA finishes a tumultuous year in which it acquired the Flir SMB business, was subject to the US government ban, terminated and restructured...
This Brooklyn Storefont Sells Millions In Uniview And Hikvision on Dec 18, 2018
Looking at their Brooklyn headquarters for this "CCTV Manufacturer", it is not much: Inside, it is not better: However, this company is one...
ACRE-Acquired Open Options Access Company Profile on Dec 17, 2018
Who is the company ACRE is acquiring? In this note, we examine Open Options line for best customer fit, key features, pricing, and main...
Open Options Acquired By ACRE on Dec 17, 2018
ACRE is doing deals again. A year after they sold Mercury, they are buying another access control company - Open Options. In this note, we...
8MP / 4K Fixed Lens Camera Shootout - Dahua, Hikvision, TVT, Uniview on Dec 17, 2018
8MP / 4K fixed lens models are now common in lower cost lines, with nearly every Chinese brand and their OEMs now offering multiple options. To...
Network Cable Shootout - Belden, Commscope, Hikvision, Honeywell, NavePoint CCA, Windy City Wire on Dec 17, 2018
Every IP camera install needs UTP cabling. But how much of a difference is there between dirt cheap generic cables found online and the bigger,...
Hikvision Government Parent Holds Communist Party Congress on Dec 17, 2018
The Communist Party committee of Hikvision’s government parent, CETHIK, held a Party Congress earlier this month where senior executives, including...
Imperial Capital Security Investor Conference 2018 Review - ADT, Resideo, Alarm.com, Arlo, Eagle Eye, ACRE, More on Dec 14, 2018
Imperial Capital Security Investor Conference is an event matching industry executives with financiers that frequently leads to future funding...
Cisco Meraki New Cameras and AI Analytics on Dec 14, 2018
Meraki has released their second generation of video surveillance with 3 new cameras, AI-based video analytics, and 2 cloud-based storage...
Foolish Strategy: OEMing Facial Recognition on Dec 13, 2018
Almost as 'hot' as face recognition marketing right now is OEMing facial recognition. Last year, they were a who's who of company's with...

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