Law Enforcement Technology

NOV 2014

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TALKING POINTS www.officer.com November 2014 Law Enforcement Technology 41 Both the MPEG-2 and MPEG-4 standards are suites made up of differ- ent parts, with Part 1 traditionally deal- ing with file format, Part 2, video and Part 3, audio. MPEG adopted MPEG-2 (H.262) to meet the demands of broad- cast, emerging Internet and cable distri- bution, and the DVD format. As digital technology progressed, with it grew public demand for ever-higher qual- ity, making it necessary to find a way to pack information into a signal more efficiently. MPEG developed MPEG- 4 (now with 31 parts) to meet these demands, especially for Internet stream- ing, Blu-ray and the needs of portable smart devices. Today, MPEG-4 Part 10/ AVC, or H.264, is arguably the most popular format for video and audio. MPEG-4 benefits There are several reasons to move from MPEG-2 to MPEG-4 encod- ing. Foremost is that MPEG-4 allows for more efficient video and audio encoding, which reduces the data rates of HD and SD video. Reduced data rates, especially in microwave applications, allow for more robust coded orthogonal frequency division multiplexing (COFDM) parameters. These robust COFDM parameters in turn allow for an increased opera- tional range of radius—critical for our opening crime scenario. Departments have also embraced the increased resolution of HD video, installing HD cameras on their plat- forms. MPEG-4 allows an agency to transition from SD to HD video without negatively affecting perfor- mance in distance. It also makes pos- sible the use of narrow-band COFDM (NBCOFDM), covering bandwidths 1.25MHz and 2.5MHz, which is extremely beneficial for agencies that operate multiple aircraft within a single licensed channel. MPEG-4 also places a reduced bandwidth payload on video management networks, lead- ing to a 30-percent decrease in payload in some cases. Making the change So what resources are necessary to complete a backwardly compatible upgrade to MPEG-4 transmitters and receivers? Upgrading the "receive" side of a microwave link can be had through the addition of a cost-efficient MPEG-4 decoder. The decoder will take the asynchronous serial interface (ASI) output of any manufacturer's digital receiver and output HD/SD SDI, composite video, L/R audio and IP streaming. This decoder also comes standard with BCRYPT key-derivation function coding for passwords and AES128 and 256-bit decryption. The digital transmitter side, meanwhile, might simply require a printed circuit board (PCB) replace- ment that adds MPEG-4 HD/SD encoding ability while retaining existing MPEG-2 capability. Adding an MPEG-4 encoder that can inter- face with any manufacturer's digital radio is another cost-effective option. This encoder can take HD/SD SDI, composite video signals, while still providing BCRYPT and AES 128 and 256-bit encryption. Users can upgrade existing encoder or decoder sites by employing a simple instal- lation kit that includes a power and video cable. In many cases, these upgrades will take less than 30 minutes. Field example The Delaware State Police (DSP) successfully transitioned its existing MPEG-2 infrastructure to MPEG-4. W hen the time came for the agency to purchase new aircraft, it decided to update its transmitters to MPEG-4 based units. It already had an extensive receive system, a fairly new system that includes central receive sites, mobile command units and handheld receiv- ers. Instead of replacing the receivers outright, DSP installed an external decoder that bypassed the internal decoder to update the receive systems to handle both MPEG-4 and MPEG-2. This simple installation saved the agency close to $15,000 per site by upgrading the existing systems. A final word The best course of action for law enforcement, fire, rescue and security operations departments is to transi- tion to MPEG-4-based systems to take advantage of the technical power offered by the standard. With avail- able equipment upgrades that encom- pass both MPEG-4 and MPEG-2 capabilities, they can bring their agen- cies into the MPEG-4 family, while staying in touch with its installed MPEG-2 cousins, thereby maintain- ing interoperability. ■ Sean Drew is a Business Development Manager for Integrated Microwave Technologies LLC's (IMT) Law Enforcement Division and has worked in the microwave video and audio industries for over 15 years. While moving to MPEG- 4 brings operations effciently into the future, not everyone has made the change, requiring a system that can also look backward to include the older, industry-standard MPEG-2 equipment. The goal in the move to MPEG- 4-based equipment is to maintain interoperability between both systems.

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