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Thursday, 14 June 2007 |
 When you are buying a new flatscreen TV you hear buzzwords like HD-ready, or FullHD.
What is HDTV exactly? This article tries to explain it & will guide you into the future of TV...
Currently the the PAL/SECAM picture quality (TV standard mostly used in Europe) isn't sufficient anymore for big-screen TV’s, like modern Plasma's & LCD's.
That's why in the early 2000s a number of high-definition television standards were developed. Current HDTV standards are defined by the International Telecommunication Union (ITU-R BT.709) The highest standard is 1080 interlaced or progressive scan lines (1080i/1080p) next to the lower 720 progressive scan lines standard (720p) Both standards are using the 16:9 widescreen aspect ratio. All current HDTV broadcasting standards are encompassed within the DVB specification, together with either MPEG2, or MPEG4 audio/video compression.
HD-ready means that the TV has a panel which is capable of displaying at least 720 lines. FullHD is demanding a panel which can display at least 1080 lines. Currently not that many TV’s are supporting FullHD. FullHD delivers only a noticeable better picture quality at displays who are larger then 42 inch.
DVB is the digital standard for broadcasting video/audio, which uses MPEG-2, or MPEG-4 for compressing the audio/video. MPEG-2 is most commonly used as the compression codec for HDTV broadcasts. Although MPEG-2 supports up to 4:2:2 YCbCr chroma subsampling and 10-bit quantization, HD broadcasts use 4:2:0 and 8-bit quantization to save bandwidth. Some broadcasters also plan to use MPEG-4, such as the BBC which is trialing such a system via satellite broadcast, which will save considerable bandwidth compared to MPEG-2 systems. Some German broadcasters already use MPEG-4 AVC together with DVB-S2. Although MPEG-2 is more widely used at present, it seems likely that in the future all European HDTV channels may use MPEG-4.DVB is the digital standard for broadcasting video/audio, which uses MPEG-2, or MPEG-4 for compressing the audio/video. MPEG-2 is most commonly used as the compression codec for HDTV broadcasts. Although MPEG-2 supports up to 4:2:2 YCbCr chroma subsampling and 10-bit quantization, HD broadcasts use 4:2:0 and 8-bit quantization to save bandwidth. Some broadcasters also plan to use MPEG-4, such as the BBC which is trialing such a system via satellite broadcast, which will save considerable bandwidth compared to MPEG-2 systems. Some German broadcasters already use MPEG-4 AVC together with DVB-S2. Although MPEG-2 is more widely used at present, it seems likely that in the future all European HDTV channels may use MPEG-4.
There are 3 DVB standards - DVB-T: DVB Over the air with an antenna. Currently HDTV is not broadcasted in Europe over the air.
- DVB-S/DVB-S2: DVB-S was the 1st DVB standard used & the signal is spread by satellites. First European HDTV provider Euro1080 started with their HD broadcasts in 2004, with the DVB-S standard in 1080i, with MPEG2 compression. Currently they are migrating to DVB-S2. DVB-S2 uses less bandwith because the use of the more efficient MPEG4 audio/video compression.
- DVB-C: DVB-c is used for cable distribution. Currently many big European cable companies are starting with a few HD channels into their DVB-C packages.
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