user21290: Are MPEG and  H.264  Lossless??
I need a brief explanation about lossy and lossles... And which compression technique is generally using in CCTV Surveillance applications of video??

user1950: OK, MPEG is the Motion Picture Experts Group, it's a group of people who decide stuff about moving picture standards. Some of these standards are well known, such as MPEG2 which includes the standards for video on DVDs and digital television. There are also lots of MPEG standards that no-one has ever heard of like MPEG-M and MPEG-21.
One standard you have probably used is MPEG4, the standard used widely to compress video for the web. The MPEG4 standard includes the compression-decompression standard MPEG-4 Part 10 (most commonly known as H.264, but also known as MPEG4 AVC). 
MPEG-2 is lossy. MPEG-4 files can be lossless, but more commonly they're lossy.H.264 is a far more efficient codec than MPEG-2, so the quality for a given bit-rate is much higher, and in many cases is visually lossless, i.e. you won't see the difference.
Surveillance may use either or neither of these standards, it totally depends on the equipment.

21290: <p>Are MPEG and  H.264  Lossless??
I need a brief explanation about lossy and lossles... And which compression technique is generally using in CCTV Surveillance applications of video??</p>
 1950: <p>OK, MPEG is the Motion Picture Experts Group, it's a group of people who decide stuff about moving picture standards. Some of these standards are well known, such as MPEG2 which includes the standards for video on DVDs and digital television. There are also lots of MPEG standards that no-one has ever heard of like MPEG-M and MPEG-21.</p>

<p>One standard you have probably used is MPEG4, the standard used widely to compress video for the web. The MPEG4 standard includes the compression-decompression standard MPEG-4 Part 10 (most commonly known as H.264, but also known as MPEG4 AVC). </p>

<p>MPEG-2 is lossy. MPEG-4 files can be lossless, but more commonly they're lossy.H.264 is a far more efficient codec than MPEG-2, so the quality for a given bit-rate is much higher, and in many cases is <em>visually lossless</em>, i.e. you won't see the difference.</p>

<p>Surveillance may use either or neither of these standards, it totally depends on the equipment.</p>
