Specifications

Security and surveillance
Digital video recorders (DVRs)
116 Maxim Industrial Solutions
the available network bandwidth
without efficient compression. DVR
system designs without H.264 often
rely on reduced-frame-rate or lower
resolution recording techniques that
degrade picture quality in order to
increase recording time and reduce
video bit rates. Older codec formats
(MPEG-4 and MJPEG) are often still
required for legacy support, but the
industry’s trend to adopt H.264 as
the primary codec in DVR is well
under way. Maxim’s family of H.264
processors supports MJPEG recording
and playback for backward compati-
bility with prior-generation equipment.
DVR system requirements
Security video applications are
moving to higher recording and
display resolutions. CIF resolution
recording (NTSC 360 x 240) was used
extensively in early generation DVRs
to produce digital video quality
comparable to the analog VCR that
it replaced. Low-resolution CIF was
also well suited to first-generation
codec technology (MJPEG/MPEG-4)
that cannot produce acceptable
compression ratios at higher resolu-
tions. The market requirement today
and moving forward is standard-
definition (D1 NTSC 720 x 480) or
“DVD-quality” video recording.
Standard definition (SD) represents
a fourfold performance increase
in system processing power per
channel as compared to CIF. State-
of-the-art H.264 codec technology is
used at D1 resolution and above to
ensure efficient compression ratios.
Maxim’s family of H.264 processors
allows programmable video resolu-
tions for recording at any level of
quality required.
Another trend in security and surveil-
lance video is the requirement for
full-frame-rate video recording
and storage. Full frame rate for an
analog CCTV camera is 30 frames-
per-second (fps) in NTSC and 25fps in
PAL. Real-time video recording repre-
sents a twofold to fourfold increase
in processing power required per
channel versus DVR designs that
record at reduced frame rates such as
7.5fps (25% in NTSC) or 15fps (50% in
NTSC). A powerful, scalable system
architecture is required to meet the
processing requirements of new
DVR designs.
Many video security systems today
are hybrid designs of analog CCTV
equipment and digital network
technologies that have built up over
time. Preexisting digital equipment
based on older codec technologies
(MJPEG/MPEG-4) creates the need
for transcoding between formats in
new equipment. For example, the
video from an existing IP camera
with MJPEG compression must be
re-encoded to H.264 in the DVR
for efficient storage and network
bandwidth usage. DVR designs today
must accommodate multiformat
digital video input (MJPEG/MPEG-4/
H.264) to preserve investments made
in earlier generation equipment.
Maxim’s family of H.264 processors
supports video decoding in MJPEG
and MPEG2, prior to re-encoding to
H.264, for recording and streaming.
www.maxim-ic.com/DVR