22-08-2012, 04:06 PM
HDTV
[attachment=32433]
John Logie Baird, a Scottish inventor, demonstrated what many refer to as the first television broadcast on January 26, 1926. Baird’s grayscale image, presented to members of the Royal Institution in London had only about 30 lines of resolution.
The search for standards: the FCC & the NTSC
FCC Established by the Communications Act of 1934
Radio Manufacturers Association (RMA) recommended a standard for television using 441 horizontal scan lines and 30 frames per second with a 4:3 aspect ratio
The search for standards: the FCC & the NTSC
FCC urged the RMA to form the National Television System Committee (NTSC) in 1940
1941 - NTSC established its first set of standards, which kept the 4:3 aspect ratio but called for a higher resolution image with 525 scan lines refreshing at a rate of 30 interlaced frames, or 60 fields per second. (263 lines followed by 262)
The search for standards: the FCC & the NTSC
FCC allotted 6 MHz slices of bandwidth to TV stations.
Eventually covered a frequency range spanning from 54 MHz to 890 MHz on the broadcast spectrum
The search for standards: the FCC & the NTSC
1950s brought the addition of color (Home viewing was brought a step closer to cinema)
1953 - The NTSC standard had to be revised
The search for standards: the FCC & the NTSC
1953 - The NTSC standard had to be revised to adapt to color TV.
Engineers split the signal into two components: luma, which contained the brightness information, and chrominance, which contained the color information.
Field refresh rate of 60 Hz was slowed down by a factor of 1000/1001 to 59.94 Hz.
Broadcast television downshifted from 30 to 29.97 frames per second
Same old standard (The song remains the same)
Many improvements were made in cameras, production and broadcast gear, and in television receivers
Despite advances, the quality of analog broadcast was still limited to the NTSC standard of 60 fields and 525 horizontal scan lines
Stuck with more or less same standards created in 1941.
Same old standard (The song remains the same)
By the 1980s, manufacturers had been developing and using both analog and digital HD systems
It became clear that the replacement for analog would use digital television technology.
Needed a new set of standards to ensure compatibility.
ATSC
Formed in 1982
The Advanced Television Systems Committee is a not-for-profit organization whose purpose is to develop standards for the transition to DTV.
Its published broadcast standards are voluntary unless adopted and mandated by the FCC.
ATSC proposed DTV Standard (A/53) that specifies the protocol for high-definition broadcasting through a standard 6MHz channel
DTV
In December 1996, the FCC adopted standards proposed by the ATSC, mandating that broadcasters begin broadcasting digitally.
WRAL of Raleigh, North Carolina was the first station to broadcast in digital.
DTV
FCC’s current plan is to terminate analog broadcasting by February 2009 (though the deadline could be extended).
DTV, SDTV, & HDTV
NTSC standards defined one analog format
ATSC created a framework supporting multiple digital formats
There is considerable confusion among consumers regarding SDTV, DTV and HDTV.
Broadcaster do not have to broadcast in HD, just in DTV.
Technical Aspects
Codec is short for compressor-decompressor or coder-decoder, and refers to a manner in which data is compressed and uncompressed
Broadcast and production codecs differ
In order to squeeze the data into a form that can be reliably broadcast within a 6 MHz section of bandwidth, the HDTV signal must be compressed at about a 50:1 ratio.
Technical Aspects
Most DTV broadcasts (terrestrial, cable & satellite) use MPEG-2
MPEG-2’s compresses the video into groups of pictures (GOPs) not individual frames. Images are divided into macroblocks, which are areas of 16 x 16 pixels.
GOPs are created with three types of pictures: I, P, and B frames. I frames are intracoded frames. P are predicted frames and B are bidirectional frames.
Technical Aspects
In addition to audio & video, DTV contains metadata - auxiliary information related to the program or its content including audio dialog level info, closed captioning, format descriptor tags, and digital rights management (DRM) data.
[attachment=32433]
John Logie Baird, a Scottish inventor, demonstrated what many refer to as the first television broadcast on January 26, 1926. Baird’s grayscale image, presented to members of the Royal Institution in London had only about 30 lines of resolution.
The search for standards: the FCC & the NTSC
FCC Established by the Communications Act of 1934
Radio Manufacturers Association (RMA) recommended a standard for television using 441 horizontal scan lines and 30 frames per second with a 4:3 aspect ratio
The search for standards: the FCC & the NTSC
FCC urged the RMA to form the National Television System Committee (NTSC) in 1940
1941 - NTSC established its first set of standards, which kept the 4:3 aspect ratio but called for a higher resolution image with 525 scan lines refreshing at a rate of 30 interlaced frames, or 60 fields per second. (263 lines followed by 262)
The search for standards: the FCC & the NTSC
FCC allotted 6 MHz slices of bandwidth to TV stations.
Eventually covered a frequency range spanning from 54 MHz to 890 MHz on the broadcast spectrum
The search for standards: the FCC & the NTSC
1950s brought the addition of color (Home viewing was brought a step closer to cinema)
1953 - The NTSC standard had to be revised
The search for standards: the FCC & the NTSC
1953 - The NTSC standard had to be revised to adapt to color TV.
Engineers split the signal into two components: luma, which contained the brightness information, and chrominance, which contained the color information.
Field refresh rate of 60 Hz was slowed down by a factor of 1000/1001 to 59.94 Hz.
Broadcast television downshifted from 30 to 29.97 frames per second
Same old standard (The song remains the same)
Many improvements were made in cameras, production and broadcast gear, and in television receivers
Despite advances, the quality of analog broadcast was still limited to the NTSC standard of 60 fields and 525 horizontal scan lines
Stuck with more or less same standards created in 1941.
Same old standard (The song remains the same)
By the 1980s, manufacturers had been developing and using both analog and digital HD systems
It became clear that the replacement for analog would use digital television technology.
Needed a new set of standards to ensure compatibility.
ATSC
Formed in 1982
The Advanced Television Systems Committee is a not-for-profit organization whose purpose is to develop standards for the transition to DTV.
Its published broadcast standards are voluntary unless adopted and mandated by the FCC.
ATSC proposed DTV Standard (A/53) that specifies the protocol for high-definition broadcasting through a standard 6MHz channel
DTV
In December 1996, the FCC adopted standards proposed by the ATSC, mandating that broadcasters begin broadcasting digitally.
WRAL of Raleigh, North Carolina was the first station to broadcast in digital.
DTV
FCC’s current plan is to terminate analog broadcasting by February 2009 (though the deadline could be extended).
DTV, SDTV, & HDTV
NTSC standards defined one analog format
ATSC created a framework supporting multiple digital formats
There is considerable confusion among consumers regarding SDTV, DTV and HDTV.
Broadcaster do not have to broadcast in HD, just in DTV.
Technical Aspects
Codec is short for compressor-decompressor or coder-decoder, and refers to a manner in which data is compressed and uncompressed
Broadcast and production codecs differ
In order to squeeze the data into a form that can be reliably broadcast within a 6 MHz section of bandwidth, the HDTV signal must be compressed at about a 50:1 ratio.
Technical Aspects
Most DTV broadcasts (terrestrial, cable & satellite) use MPEG-2
MPEG-2’s compresses the video into groups of pictures (GOPs) not individual frames. Images are divided into macroblocks, which are areas of 16 x 16 pixels.
GOPs are created with three types of pictures: I, P, and B frames. I frames are intracoded frames. P are predicted frames and B are bidirectional frames.
Technical Aspects
In addition to audio & video, DTV contains metadata - auxiliary information related to the program or its content including audio dialog level info, closed captioning, format descriptor tags, and digital rights management (DRM) data.