[align=justify][align=justify]The Moving Picture Experts Group (MPEG) is a working group of experts that was formed by ISO and IEC to set standards for audio and video compression and transmission. It was established in 1988 and its first meeting was in May 1988 in Ottawa, Canada. As of late 2005, MPEG has grown to include approximately 350 members per meeting from various industries, universities, and research institutions. MPEG's official designation is ISO/IEC JTC1/SC29 WG11 - Coding of moving pictures and audio (ISO/IEC Joint Technical Committee 1, Subcommittee 29, Working Group 11).
MPEG algorithms compress data to form small bits that can be easily transmitted and then decompressed. MPEG achieves its high compression rate by storing only the changes from one frame to another, instead of each entire frame. The video information is then encoded using a technique called Discrete Cosine Transform (DCT). MPEG uses a type of lossy compression, since some data is removed. But the diminishment of data is generally imperceptible to the human eye.
MPEG1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively) without excessive quality loss, making video CDs, digital cable/satellite TV and digital audio broadcasting (DAB) possible.
MPEG2 is widely used as the format of digital television signals that are broadcast by terrestrial, cable, and direct broadcast satellite TV systems. It also specifies the format of movies and other programs that are distributed on DVD and similar discs. As such, TV stations, TV receivers, DVD players, and other equipment are often designed to this standard.
MPEG2 was the second of several standards developed by the Moving Pictures Expert Group (MPEG) and is an international standard. Parts 1 and 2 of MPEG2 were developed in a joint collaborative team with ITU-T, and they have a respective catalog number in the ITU-T Recommendation Series.
MPEG-4 is one of the latest (audio and video) compression method standardized by MPEG group, designed especially for low-bandwidth (less than 1.5MBit/sec bitrate) video/audio encoding purposes. Probably the best-known MPEG-4 video encoders are called DivX and XviD, which both are nowadays fully standard-compliant MPEG-4 encoders.
It should be noted that unlike MPEG-1 and MPEG-2, the MPEG-4's predecessors, MPEG-4 itself isn't just one unified encoding mechanism, but rather a group name for several flavors of video and audio encoding methods that share certain same characteristics. These "flavors" are often referred either as "profiles" or "layers" in MPEG-4 compression scheme and each new profile should be backwards compliant to the older, "lower" versions of MPEG-4 in terms of playback capability. MPEG-4 group has standardized several new layers - most important ones are h263+(which is used widely in mobile phones, named as 3GP) and h.264 (often also called as AVC).
MPEG-4 Overview
MPEG-4 enables different software and hardware developers to create multimedia objects possessing better abilities of adaptability and flexibility to improve the quality of such services and technologies as digital television, animation graphics, the World Wide Web and their extensions.
The MPEG-4 format provides end users with a wide range of interaction with various animated objects. Standardized Digital Rights Management signaling, otherwise known in the MPEG community as Intellectual Property Management and Protection (IPMP).
The MPEG-4 format can perform various functions, among which might be the following: Multiplexes and synchronizes data, associated with media objects, in such a way that they can be efficiently transported further via network channels.
Difference between Mpeg2 and Mpeg4 in DTH
MPEG-2 and MPEG- 4 are just two different compression standards developed at different points of time. Videos compressed using MPEG-4 at a given bit rate are of better quality than those compressed with MPEG-2. But if videos are compressed at a lower bit rate in MPEG-4 than in MPEG-2 there will not be any significant difference in quality. DTH signals are transmitted through a satellite to you STB. DTH operators rent transponders on a satellite to broadcast their signals. Each of the transponder on a satellite has a fixed bandwidth and the number of channels that a transponder can carry depends on the bit rate of channels that are transmitted. For E.g. if the bandwidth of a transponder is 50 Mbps, DTH operators can broadcast upto 25 channels with each of the channel encoded at 2 Mbps. DTH operators using MPEG-4 can use the transponder’s capacity more effectively as their compression technology is superior to MPEG-2. In other words, they can broadcast more channels using the same transponder than the DTH operators using MPEG-2. In the above given example, DTH operators using MPEG-4 can reduce their channel’s bit rate to 1.2 Mbps and broadcast nearly 40 channels. But as explained above, a video compressed at a bitrate of 1.2 Mbps using MPEG-4 is not superior to the one compressed at 2 Mbps using MPEG-2. So a DTH operator using MPEG- 4 can either follow the same bit rate as MPEG-2 operators and offer superior quality or reduce the bitrate and broadcast more number of channels at the same quality.
Conclusion: As the popularity of HD channels spreads in India, all DTH operators will be forced to switch to MPEG-4 as they need to use their transponders more efficiently.and also to provide more channels to the users this is the reason why tatasky is moving from MPEG2 TO MPEG4.
[/align][/align]MPEG algorithms compress data to form small bits that can be easily transmitted and then decompressed. MPEG achieves its high compression rate by storing only the changes from one frame to another, instead of each entire frame. The video information is then encoded using a technique called Discrete Cosine Transform (DCT). MPEG uses a type of lossy compression, since some data is removed. But the diminishment of data is generally imperceptible to the human eye.
MPEG1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively) without excessive quality loss, making video CDs, digital cable/satellite TV and digital audio broadcasting (DAB) possible.
MPEG2 is widely used as the format of digital television signals that are broadcast by terrestrial, cable, and direct broadcast satellite TV systems. It also specifies the format of movies and other programs that are distributed on DVD and similar discs. As such, TV stations, TV receivers, DVD players, and other equipment are often designed to this standard.
MPEG2 was the second of several standards developed by the Moving Pictures Expert Group (MPEG) and is an international standard. Parts 1 and 2 of MPEG2 were developed in a joint collaborative team with ITU-T, and they have a respective catalog number in the ITU-T Recommendation Series.
MPEG-4 is one of the latest (audio and video) compression method standardized by MPEG group, designed especially for low-bandwidth (less than 1.5MBit/sec bitrate) video/audio encoding purposes. Probably the best-known MPEG-4 video encoders are called DivX and XviD, which both are nowadays fully standard-compliant MPEG-4 encoders.
It should be noted that unlike MPEG-1 and MPEG-2, the MPEG-4's predecessors, MPEG-4 itself isn't just one unified encoding mechanism, but rather a group name for several flavors of video and audio encoding methods that share certain same characteristics. These "flavors" are often referred either as "profiles" or "layers" in MPEG-4 compression scheme and each new profile should be backwards compliant to the older, "lower" versions of MPEG-4 in terms of playback capability. MPEG-4 group has standardized several new layers - most important ones are h263+(which is used widely in mobile phones, named as 3GP) and h.264 (often also called as AVC).
MPEG-4 Overview
MPEG-4 enables different software and hardware developers to create multimedia objects possessing better abilities of adaptability and flexibility to improve the quality of such services and technologies as digital television, animation graphics, the World Wide Web and their extensions.
The MPEG-4 format provides end users with a wide range of interaction with various animated objects. Standardized Digital Rights Management signaling, otherwise known in the MPEG community as Intellectual Property Management and Protection (IPMP).
The MPEG-4 format can perform various functions, among which might be the following: Multiplexes and synchronizes data, associated with media objects, in such a way that they can be efficiently transported further via network channels.
Difference between Mpeg2 and Mpeg4 in DTH
MPEG-2 and MPEG- 4 are just two different compression standards developed at different points of time. Videos compressed using MPEG-4 at a given bit rate are of better quality than those compressed with MPEG-2. But if videos are compressed at a lower bit rate in MPEG-4 than in MPEG-2 there will not be any significant difference in quality. DTH signals are transmitted through a satellite to you STB. DTH operators rent transponders on a satellite to broadcast their signals. Each of the transponder on a satellite has a fixed bandwidth and the number of channels that a transponder can carry depends on the bit rate of channels that are transmitted. For E.g. if the bandwidth of a transponder is 50 Mbps, DTH operators can broadcast upto 25 channels with each of the channel encoded at 2 Mbps. DTH operators using MPEG-4 can use the transponder’s capacity more effectively as their compression technology is superior to MPEG-2. In other words, they can broadcast more channels using the same transponder than the DTH operators using MPEG-2. In the above given example, DTH operators using MPEG-4 can reduce their channel’s bit rate to 1.2 Mbps and broadcast nearly 40 channels. But as explained above, a video compressed at a bitrate of 1.2 Mbps using MPEG-4 is not superior to the one compressed at 2 Mbps using MPEG-2. So a DTH operator using MPEG- 4 can either follow the same bit rate as MPEG-2 operators and offer superior quality or reduce the bitrate and broadcast more number of channels at the same quality.
Conclusion: As the popularity of HD channels spreads in India, all DTH operators will be forced to switch to MPEG-4 as they need to use their transponders more efficiently.and also to provide more channels to the users this is the reason why tatasky is moving from MPEG2 TO MPEG4.
