Seven Oceans Video & Digital Media
provides full
High Definition Video Production
Seven Oceans Video & Digital Media
provides full
High Definition Video Production
· Digitizing – From any source in any format through HD-SDI, SD-SDI, component, composite or FireWire input. We can capture non-compressed HD video in full resolution as AVI or QuickTime file, or as single frames in DPX, Cineon, TGA, TIFF and BMP format in 8-bit or 10-bit depth.
· Editing – Beside other formats, our workhorse in live video editing is CineForm codex in full resolution of 1920 x 1080, in 8 and 10 bit depth, and 4:2:2 color sampling in various levels of compression of your choice. We can also convert to this lossless quality editing format directly during digitizing of HDV live video or tape recording. Our editing can handle simultaneously four live video streams of highest quality high definition video with graphic layer, titles, transitions and video corrections.
· Output – From FireWire output to HDV format through HD-SDI output to VCR of your choice, to external hard disk, or encoding into WM9 format to DVD. We will master HD-DVD and Blu-Ray burners as soon as they become available.
We continue to offer full line of filming and editing in standard definition formats from Betacam SP to DVCAM, DVPRO, MiniDV and other old analog formats. We provide tape and DVD dubbing and full range of DVD mastering, including interactive forms with live links to the Web. We handle stills and old 16mm and 8mm movies and their transfer to DVD or video tape. For more information please call our office at (401) 846-0001. Thank you
Sincerely
Richard Konkolski
Seven Oceans Video
Richard@SevenOceans.com
(401) 846 0001
Information on digital TV
Pre-existing TV system
was defined in 1946 by National Television System
Committee – NTSC. This analog system was updated for color in 1953 and for
stereo in 1984. All updates were backward compatible. To continue using an NTSC
TV after February 17, 2009 you will need a converter box. You will not need it
if you continue using a cable or satellite system with an NTSC output. In the
1980s, the ATSC (Advanced Television System Committee) was formed to move TV
forward.
New Telecommunications Act of 1996
passed by congress and signed by president requires
all TV stations to convert to digital modulation. There are 1700 TV stations in
the U.S. and by the end of 2005, 1550 of them had a digital channel on the air
and about 850 transmitted some high definition programs. The Consumer
Electronics Manufacturers Association estimates 30 percent of U.S. households
will have digital sets by 2006.
Main improvement from viewer point of view is:
The new digital standard is called ATSC (Advanced Television Standards Committee) and defines digital TV (DTV). Standard includes 18 formats with various resolutions from 640x480 pixel to 1920x1080 pixel. ATSC uses MPEG-2 compression standard with average 50-to-1 compression of data.
The Monitor Interface
All TV systems will be required to receive all of
these digital formats and display them properly, however while the receiver (or
converter box) will receive all 18 formats, only 4 formats will be used for the
display monitor. Most receivers will let you select the output format, which
must match the monitor’s input, and will convert the received format to it.
Presently there are only four defined interface formats: 480i, 480p, 720p, and
1080i, but there could be more in the future.
Most display monitors must draw each image interlaced to prevent flicker. It’s a rare TV set that can draw 1080 lines at 60 frames per second. That is why the receiver will, for example, convert an ATSC transmitted format 1080 30p (progressive format) into 1080 60i (an interlaced format more suitable for today’s display monitors).
Digital cable TV systems and DBS systems like DirecTV have worked out their own transmission standards that differ from ATSC and only their output conforms to ATSC. DirecTV and Dish Network have announced that their future systems will use MPEG-4.
• Interlaced scan: These TV images are created by displaying every other row of horizontal lines on the screen in one pass and then going back through and displaying the remaining lines in the pass. It happens so fast that your eye can't really tell it is happening. The changes to even (and odd) numbered lines (a field) are controlled by our electrical current of 60 Hz (hertz) and therefore we have 60 fields per second. When interlacing is employed, two fields create one frame and therefore we have 30 pictures frames (60 fields) per second. The advantage of interlacing is that, for a given bandwidth, it allows a higher resolution (more pixels) and reduces flicker. A bright white area of the screen will appear to flicker if that area is drawn only 30 times per second. Drawing 60 fields per second mostly prevents that. A disadvantage of interlacing is that it doesn’t show motion as smoothly with only 30 frames per second. Also data compression is not as efficient and when the TV set grows old, the two fields often become misaligned.
• Progressive scan: These systems light all the horizontal lines in the same pass, which can make the image seem "smoother" and more like film.
· Frame rate – number of frames (pictures) per second - describes how many times a complete picture is created on the screen every second. DTV frame rates usually end in "i" or "p" to indicate whether they are interlaced or progressive. 1080i and 480i are interlaced formats, while 720p and 480p are progressive formats. DTV frame rates range from 24p (24 frames per second, progressive) to 60p (60 frames per second, progressive).
The lowest quality digital format is about the same as the highest quality analog TV.
Many of these new standards have exactly the same aspect ratio and resolution, but their frame rates differentiate them from one another. When you hear someone mention a "1080i" HDTV set, they're talking about one that has a native resolution of 1920 x 1080 pixels and can display 60 fields per second interlaced.
A digital signal is of a better quality than an analog signal but it is not necessarily high definition. HDTV is only the highest of all the DTV standards. Whether you see a high-definition picture and hear the accompanying Dolby Digital® sound depends on two things. First, the station has to be broadcasting a high-definition signal. Second, you have to have the right equipment to receive and view it. For now the NTSC images sometimes look worse on a large high-def set than on a small standard TV.
Full horizontal resolution for HDTV is 1920 pixels. But many sets being sold today only have resolution to 1280 pixels, and it is often difficult to see the difference. Not the best, but 1280 is still considered hi-def.
If you are shopping for HDTV monitor, bear in the mind that the 480p is called by many Enhanced Definition TV (EDTV). An EDTV set can produce better quality than SDTV, but it's not an HDTV set. Most EDTV sets are flat-panel LCD or plasma sets. The 480i is Standard Definition TV (SDTV).
List of eighteen ATSC formats:
|
spec
|
Horizontal pixels |
Vertical pixels |
Aspect ratio |
Monitor interface |
Format name |
Frames per sec |
Fields per sec |
Transmitted interlaced |
|
ATSC |
1920 |
1080 |
16:9 |
1080i |
1080 60i |
30 |
60 |
yes |
|
1080 30p |
30 |
30 |
no |
|||||
|
1080 24p |
24 |
24 |
no |
|||||
|
1280 |
720 |
16:9 |
720p |
720 60p |
60 |
60 |
no |
|
|
720 30p |
30 |
30 |
no |
|||||
|
720 24p |
24 |
24 |
no |
|||||
|
704 |
480 |
16:9 |
480p |
480 60p |
60 |
60 |
no |
|
|
480i |
480 60i |
30 |
60 |
yes |
||||
|
480 30p |
30 |
30 |
no |
|||||
|
480 24p |
24 |
24 |
no |
|||||
|
704 |
480 |
4:3 |
480p |
480 60p |
60 |
60 |
no |
|
|
480i |
480 60i |
30 |
60 |
yes |
||||
|
480 30p |
30 |
30 |
no |
|||||
|
480 24p |
24 |
24 |
no |
|||||
|
640 640 |
480 |
4:3 |
480p |
480 60p |
60 |
60 |
no |
|
|
480i |
480 60i |
30 |
60 |
yes |
||||
|
480 30p |
30 |
30 |
no |
|||||
|
480 24p |
24 |
24 |
no |
High-definition television
(HDTV)
generally refers to 1080i or 720p images with 16:9 aspect
ratio, much more suitable to human vision. It is a
television signals with a higher resolution
than traditional formats allow, resulting in crystal clear, noise-free pictures
and CD quality sound. HDTV is broadcasted digitally, and therefore its
introduction sometimes coincides with the introduction of digital television (DTV).
Historically, the term high-definition television was used to refer to television standards developed in the 1930s to replace the early experimental systems. Most patents were expiring by the end of World War II leaving the market wide open. The world used analog PAL, NTSC, SECAM and other standards for over half a century.
The lowest 12 ATSC formats are very close in display to NTSC format and consumers may not pay attention to this spectrum. However the highest 6 formats forming high definition TV standard will pick up everybody’s interest. HDTV has at least twice the resolution of SDTV, allowing the display of much more detail.
HDTV at four times the
resolution of SDTV
Main Advantages of HDTV
Digital signal will deliver an excellent picture, putting a stop
to snowy or washed out images from a weak signal or effects from signal
interference.
What do I need to
receive HDTV?
HDTV
is mostly only available as an over-the-air broadcast signal. This requires the
use of an outdoor antenna and HDTV receiver that can decode the digital signals.
HDTV channels are typically different than your cable or over-the-air channel.
Digital Video Production Formats
NTSC analog video has 525 lines of resolution, but 35
lines are outside of viewing area. Few decades ago, video editing was based on
copying analog video signal from tape to tape. Shortly after computer’s video
display improved from EGA (320x240 pixels) to VGA (640x480), the video editing
slowly moved to computers – the Nonlinear Editing (NLE) was born. Expensive
digitizing cards were able to capture video in 640 x 480 pixels resolution and
store it on hard disks in motion-jpeg format for further editing.
A decade later almost nobody was using analog editing anymore and NLE took completely over with many various digital formats, from costly Digital Betacam to widely spread Mini DV format. Majority of standard definition digitizing is done in 720 x 480 resolutions with non-square pixel (0.9:1). However, when playing back, those resolutions are displayed by using a square pixel (1:1) which converts all video into 640 x 480 resolution. Even DVD Video works in that same way.
New ASTS specification sets formats for standard definition TV at resolution in 640x480 and 704x480 pixels and aspect ration of 4:3 and 16:9. This is very similar to the old analog NTSC format. Unfortunately new standard resolution formats when displayed on large flat LCD monitors may look worse then the old analog signal.
In general viewers would probably not notice any difference between old analog NTSC and new digital ASTS standard definition video on their TV sets. All the all excitement with new TV systems lays in high-definition formats with their high quality video, crisp high resolution and quality audio. TV future is in high definition TV and many video producers already film in high-definition formats, even if they are not able to edit in that format yet. They already think about future use.
High Definition
Kodak once declared that 35 mm slide is equal to 2200
lines of video resolution. The true high definition video is getting close to
film quality and actually HD video is easily converted directly to film.
Non-compressed HD video with bit depth of 8,10 or 12 bits and color sampling of 4:4:4 have data rate up to 2000Mbits/s, which only the latest high end computers with very fast hard disk raids and fastest video cards can handle. One hour of non-compress HD video would occupy about 600 GB of hard disk space. It would be very costly and impractical way to handle videos. In reality, only few studios capture this high end video from cameras directly to their computers – mostly for creating short top quality high-definition commercial spots.
Some studios can film in high definition and direct HD video to mixer and then pass it through a compressor to a TV transmitter. Only high end professional cameras and decks are equipped with a connection that is capable to handle HD video stream. This Serial Digital Video Interface (SDI) is used to connect video production equipment to transfer HD video at 1.485 Gbps or SD video at 270, 360, or 540 Mbps.
1920 x 1080 – True HD (for comparison only)
Bit depth – 8, 10, 12
Color sampling – 4:4:4
Compression – None
Data rate - 1000-2000Mbits/s
Audio – 12 channels of audio
You can't find a single "HDTV" standard out there. Instead, ATSC contains 18 different TV standards with different resolutions, aspect ratios, and scan types. Some of these standards are truly HDTV; most aren't. In real life, all HD video producers are using different HD formats with various production hardware by recording video to a tape, optical disk or hard disk in various compressions, various pixel sizes and different frame rates – resulting of course in various qualities.
In the real world, you deal with four following standards, two high definition and two standard definition, when you watch TV content on your HDTV.
The two primary High Definition TV standards are:
High Definition Production Formats
Following are specifications of major HD production formats in order by video quality defined by video resolution:
1920 x 1080
HDTV image recording with 1080 vertical lines by 1920
horizontal pixels wide (16:9 aspect ratio and 60i, 30p and 24p frame rate)
Best quality format is probably HDCAM SR from Sony with color sampling 4:4:4 and 440 Mbits data rate with 12 audio channels followed by D5-HD from Panasonic with color sampling 4:2:2 and 235 Mbits data rate with 8 audio channels
Bit depth – 10
Color sampling – 4:4:4 / 4:2:2
Compression – DPCM / DCT / Mpeg 4 SP
Data rate - 440Mbits/s (4.2:1 / 2.7:1 compression)
Audio – 12 channels, 24 bit 48Hz sampling
HDCAM SR meets the production demand for higher bandwidth image capture. The RGB
images can be stored real time in a cost effective and time efficient manner. It
can record full HD images at an exceptionally high picture quality using 1080 x
1920 active pixels. The entire range of both interlaced and progressive frame
rates are available, ranging from 24/25P progressive imaging, to 50/60i for
high-end HDTV production applications.
Some HDCAM SR VTRs (SR camcorders are not available) can also use a 2x mode with
an even higher bitrate of 880 Mbit/s, allowing for a single 4:4:4 stream at a
lower compression or two 4:2:2 video streams simultaneously. The 440 Mbit/s mode
is called as SQ, and 880 Mbit/s mode is called as
HQ.
Bit depth – 8, 10
Color sampling – 4:2:2
Compression – DCT / CCIR601 uncompressed data stream
Data rate - 235Mbits/s (8 bit mode 4:1, 10 bit mode 5:1 compression)
Audio – 8 editable 16 bit audio cannels
High end and high bit rate studio deck modeled after D5 format. D5-HD is a
studio production format; there are no camcorders and works in the high
definition domain at 1080i, 720p and 1080p24. DCT processor compresses the
1.5Gbps of the CCIR601 uncompressed data stream down to the 235Mbps recordable
on tape. It records a true 1920 pixels by 1080i image.
1440 x 1080
HDTV image recording with 1080 vertical lines by 1440 horizontal
pixels wide (16:9 aspect ratio and 60i, 30p and 24p frame rate)
Probably the best is HDCAM format from Sony with 140 Mbits/s data rate followed by XDCAM HD – variant of XDCAM – with up to 35 Mbits/s data rate. This recording resolution is dominated by HDV format - recording and playback of high-definition video on a DV cassette tape – introduced by JVC, quickly followed by Sony and Canon.
Bit depth – 8
Color sampling – 3:1:1
Compression – DCT
Data rate - 140Mbits/s (7:1 compression)
Audio – up to 8 audio channels
It uses Betacam-like cassettes and is backward compatible with Betacam, DVCAM,
or other formats. It works in 1080i native domains and with optional board the
output can be converted to 720p and 1080p24. Optional board can output 1.5 Gbps
and 270Mbps by SDI
Bit depth – 8
Color sampling – 4:2:0
Compression – MPEG-2 (VBR)
Data rate - 18, 25, 35Mbits/s (22.4:1 / 16:1 compression)
Audio – 4 uncompressed audio channels.
XDCAM HD is a variant of XDCAM, it is a format between HDCAM and HDV. The 18Mbps
allows for a recording time of two hours, and the other two (25 and 35Mbits)
allow for 90 and 60 minutes. XDCAM HD has four uncompressed audio channels.
The XDCAM records onto capacious Blu-ray discs and
the XDCAM HD will record to the smaller 8 cm discs with about 15GB of room for
the storing the MPEG-2 1080i signal.
Most HDV cameras record one I-frame followed by 14 predicted (B or P) frames. This forms the 15-frame group of pictures (GOP)
The HDV format includes two sub-formats:
There are four specifications that define HD1:
HD1 is recorded to DV tape exactly as is DV. Each DV track has three segments.
The 19.4Mbps is composed of:
A Closed 6-frame
GOP (IBBPBB) is employed in Region 60 products.
An acceptable data rate for 720p30 video with a 15-frame GOP is only 7.8Mbps.
The JVC camcorders use a data rate of 17.2Mbps—more than double the 7.8Mbps.
Doubling of the data rate compensates for the short GOP.
Interestingly, HDV is more robust than DV and so less subject to dropout damage.
That is because with Region 60 HD1, a 6-frame GOP requires 60-tracks. Moreover,
in addition to the error correction scheme, the IBP frames are interleaved in
small blocks over all tracks so a drop-out cannot damage a complete I, B, or P
frame.
Future HDV camcorders may offer 720p60. Doubling the frames-per-second (720p30
to 720p60) will put a much greater load on an MPEG-2 encoder. Because 720p HDV
encoding has a limit of 19Mbps: either a longer (e.g., 25 or 30 frames) GOP will
need to be used or the encoding will have to be twice as efficient—else there
are likely to be more MPEG-2 artifacts.
There are four specifications that define HD2:
The 25Mbps is composed of three types of data:
The ATSC standard defines the number of horizontal pixels to be 1920 square pixels while the Sony records only 1440 pixels but each pixel is rectangular with 1.33:1 pixel aspect ratio. The anamorphic nature of its 1440 pixel line makes it a valid ATSC HD format.
In order to
write 25Mbps to DV tape, HD2 is not recorded exactly as is DV. HD2 is more
robust than DV and so less subject to dropout damage. That is because with
Region 60 HD2, a 15-frame GOP requires 60-tracks. Moreover, in addition to the
error correction scheme, the IBP frames are interleaved in small blocks over all
tracks so a drop-out cannot damage a complete I, B, or P frame.
HDV 1080i has 1.7X more pixels than 720p HDV, yet the data rate is only 1.3X
greater. One can expect that 1080i HDV will be more prone to MPEG-2 artifacts
than is 720p30 HDV. With its longer GOP it will also handle motion not as well.
Audio
Both HD1 and HD2 support two audio channels of audio
signals that are digitized with a 48 kHz at 16-bit quantization and compressed
to 384kbps by MPEG-1 Audio Layer 2 encoding.
|
Media |
Same as DV format (DV and/or Mini DV Tapes) |
|
|
Video |
||
|
Video Signal |
720/60p, 720/30p |
1080/60i, 1080/50i |
|
Number of pixels |
1280 X 720 |
1440 X 1080 |
|
Aspect Ratio |
16:9 |
|
|
Compression |
MPEG2 Video (profile & level: MP@H-14) - long-GOP MPEG2 for video, with a 6-frame GOP for 720p and a 15-frame GOP for 1080i, Data rate -25Mbits/s (22.4:1 compression) |
|
|
Sampling Frequency |
74.25MHz |
55.7MHz |
|
Sampling Format |
4 : 2 : 0 |
|
|
Quantization |
8 bits (both luminance and chrominance) |
|
|
Bit rate after Compression |
Approximately 19Mbps |
Approximately 25Mbps |
|
Audio |
||
|
Compression |
MPEG1 Audio Layer II |
|
|
Sampling Frequency |
48kHz |
|
|
Quantization |
16 bits |
|
|
Bit rate after Compression |
384kbps |
|
|
Audio Mode |
Stereo (2 channels), 4:1 compression |
|
|
System |
||
|
Data Format |
MPEG2 Systems |
|
|
Stream Type |
Transport Stream |
Packetized Elementary Stream |
|
Stream Interface |
IEEE1394 (MPEG2-TS) |
|
1280 x 1080
HDTV image recording with 1080 vertical lines by 1280
horizontal pixels wide (16:9 aspect ratio and 60i, 30p and 24p frame rate)
Major player at this resolution is JVC with its D9-HD line. It has 100 Mbits/s data rate and 4:2:2 color sampling.
1280 x 1080 – D9-HD (JVC)
Bit depth – 8
Color sampling – 4:2:2
Compression – DCT
Data rate - 100Mbits/s (6.7:1 compression)
Audio – 8 editable 16 bit audio cannels
The D9-HD format offered by JVC is modeled after its D-9 (Digital S) recording system. It is switchable between
Cost effective quality recording format with recording time on camcorders and studio deck of 62 minutes.
1280 x 720
Major player at this resolution is Panasonic with its DVCPRO-HD
line. It has 100 Mbits/s data rate and 4:2:2 color sampling
1280 x 720 – DVCPRO-HD (Panasonic)
Bit depth – 8
Color sampling – 4:2:2
Compression – DCT
Data rate -100Mbits/s (variable up 7:1 compression)
Audio – 8 channels digital audio, 16 bit at 48 Khz sampling
The DVCPRO-HD is built on the DVCPRO format called D-7 and is backward compatible. Camcorders operate in the 1080i domain. The studio recorder is a little different with an optional build-in universal format converter allowing playback of all DV formats (mini DV, DVCAM, DVCPRO, 25, 50 megabit, progressive) with output in 1080i or 720p. It is compatible with metadata and ancillary (closed captioning) data recording. You can feed in 1920 x 1080, but it records and plays back only 1280 x 720
DVCPRO versus HDV
· 1080i and 720p require about the same bandwidth when showing live action: A 1080i image has twice as many pixels, while 720p shows twice as many frames per second.
· While showing films at 24 frames per second, 720p requires about half the bandwidth of 1080i.
· A common opinion is that 720p is better for sporting events, while 1080i looks better for documentaries, dramas, and most things that come 24 frames per second.
· Many images are stills or have little motion, and will look better in 1080i. Flicker is rarely a distraction, and it is peculiar to CRTs.
· The problem with 1080i is that when motion is complex and sustained
Unfortunately the networks are picking one format for all their shows. ABC, ESPN, and FOX have chosen 720p. All other networks are using 1080i. Maybe some day they will choose the format according to the content.
Technical details
MPEG-2 is most commonly used as the compression codec for
digital HDTV broadcasts. Although MPEG-2 supports up to 4:2:2 YUV 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.
It seems likely that all European HDTV may use MPEG-4, including Ireland.
HDTV is capable of "theater-quality" audio because it uses the Dolby Digital (AC-3) format to support "5.1" surround sound.
The pixel aspect ratio of native HD signals is 1.0, or 1 pixel length = 1 pixel width. New HD compression and recording formats such as HDV use rectangular pixels for more efficient compression and to open HDTV acquisition for the consumer market.
Within television studios and other production and distribution facilities, the SMPTE 292M interconnect standard HD-SDI (a nominally 1.5 Gb/s, 75-ohm serial digital interface) is used to route uncompressed HDTV signals. The native bitrate of HDTV formats is highly excessive for over-the-air broadcast and consumer distribution media, hence the widespread use of compression in consumer applications.
DBS Quality
Today’s DBS systems (DirecTV, Dish Network, and Voom)
carry too many channels and have a bandwidth problem. These companies have
resorted to some filtering to reduce the bandwidth per program. This allows
them to carry more channels, but it gives the images a slightly blurry look.
They call it “noise filtering”, but in effect they have reduced the resolution
to below 640x480. Exactly what this resolution is has not been stated -
550x400? On a small size TV this problem is not very noticeable. But the larger
the set is, the more offensive it becomes. This filtering has been applied only
to standard-definition channels. The satellite HDTV channels are uncompromised.
Bandwidth
The term “bandwidth” means “channel size” and
generally refers to high-bandwidth capacity. Broadband has a multi-channel
capacity that is equal or greater to 45 Mbps for US and 34 Mbps for Europe. The
bandwidth for NTSC is always 6 MHz, the same as for new ATSC. Without data
compression, the bandwidth for 1080i would be 300 MHz. With MPEG-2 data
compression the bandwidth varies according to how fast the image changes. For
480i the bandwidth rarely goes above 1 MHz. For 1080i and 720p the bandwidth
rarely goes above 3 MHz and therefore it is possible to put six 480i programs or
two 1080i programs in a 6 MHz channel. A sub-channel showing a static image
like a weather map or bulletin board requires almost no bandwidth despite being
at high resolution.
Format considerations for
broadcasting
The optimum format for a broadcast depends on the type of media used for the
recording and the characteristics of the content. The field and frame rate as
well as resolution should match the source. A very high resolution source may
require more bandwidth than is available in order to be transmitted.
Photographic film typically destined for the theater has a high resolution and is recorded at 24 frames per second. The optimum format for video transfer is either 720p24 or 1080p24, all depending on the available bandwidth and the amount of detail and movement in the picture. The film must be converted to 25 frames per second by speeding it up by 4% for countries using PAL format. In countries using the NTSC standard, (60 fps) a technique called 3:2 pulldown is used to achieve the correct film rate.
Older recordings on Betacam SP are often in the 480i60 or 576i50 form. Video tapes may be up converted to a higher resolution format (720i), but removing the interlace to match the 720p format may distort the picture or require filtering which reduces the resolution of the final output.
Non-cinematic HDTV video recordings are recorded in either 720p or 1080i format. The format depends on the broadcast company if destined for television broadcast. The 720p is more appropriate for fast action as it uses progressive fields and is used more with internet distribution of HD video, as all computer monitors are progressive. The 720p video also has lower storage and decoding requirements than 1080i or 1080p, and few people possess displays capable of displaying the 1920x1080 resolution. An LCD capable of native 1080i resolution costs close to a thousand dollars.
In North America, Fox, ABC, and ESPN currently broadcast 720p content. NBC, Universal HD, CBS, HBO-HD, INHD, HDNet and TNT currently broadcast 1080i content.
ATSC standard for data stream broadcasting is 19.3 Mb/s, the HD transmitting trend is anywhere from 12 to 17Mb/s. The signal is mostly decoded back to baseband (1.5Gb/s) at the station for master control functions like inserting commercials or local bugs, then re-encoded for local HD broadcast.
Broadcasters
H.264 as a standard has already been selected and adopted by the
biggest broadcasters in the U.S. A handful of very minor broadcasters are
considering VC-1 codex which is better adapted for the IPTV world than H.264. HD
DVD has also announced support for VC-1. There is an uncertainty on the levies
Microsoft may want to impose once the algorithm is adopted. Other codecs are in
contention such as H.264/AVC (MPEG-4 Part 10) and the VP6/VP7 codecs from On2
Technologies.
Recording, compression,
and prerecorded media
HDTV can be recorded to D-VHS
(Data-VHS), an HDTV-capable digital video recorder or to a computer equipped
with an HDTV capture card. In the U.S., the only current archival option is
D-VHS (JVC, Panasonic).
D-VHS digitally records a 28.2-Mbit stream (6.7:1 compression) onto a classic VHS tape, using a FireWire (IEEE 1394) digital transport to carry a compressed MPEG-2 Transport Stream from the tuning device to the recorder. D-VHS is the digital version of VHS. Designed for recording and playing back pre-recorded MPEG-2 data streams like one transmitted via a satellites or one transmitted by DTV broadcasters and recorded on oxide VHS-like cassette, which can hold about 45 Gb of data (9 x DVD) – about 3.5 hour HDTV movie with full quality. D-VHS machines are not production recorders.
Future media
HD programming may be recorded on optical
disc using Blu-ray Disc or HD DVD. Blu-ray technology is currently
available only in Japan with a Japanese satellite/terrestrial tuner, but is
expected to be released in other world markets on May 23, 2006. Blu-ray uses a
blue-laser optical disc with an MPEG-2 or MPEG-4 codec. Sony will include
a Blu-ray player and it is expected to have a big impact on the HDTV market.
Similarly, Microsoft's Xbox 360 doesn't ship with an HD DVD-compatible
player as standard at present (nor Blu-Ray).
Microsoft
Microsoft introduced their Windows
Media 9 Series codec with the ability to compress a high-definition
bitstream into the same space as a conventional NTSC bitstream (approximately 5
to 9 megabits per second for 720p and higher). Microsoft is marketing its
high-definition Windows Media 9 Series codec as WMV HD.
Online HD
H.264 has made significant progress
towards becoming a widespread video format on the internet thanks to Apple
Computer's QuickTime software supporting the format as of version 7.
VP6
VP6 have been chosen by China
for use in the Enhanced Versatile Disc (EVD) format initiative. The
choice of standards becomes more important for everyone as China starts to
dominate manufacturing of TV and DVD units.
HD DVD and Blu-ray
Format war is under way between the
DVD Forum's HD DVD (formerly "Advanced Optical Disc"), since they failed
to agree on standards for high-definition 12-cm discs. HD DVD and Blu-ray
selected the same three video codecs to be mandatory in their designs: MPEG-2
Part 2, VC-1, and H.264/AVC. Some DVD players will output enhanced
or high-definition signals from standard-definition DVDs. These players,
however, are not considered to be true HD DVD players DVD manufacturers such as
Philips are licensing the DivX codec in order to play 720p/1080i
content recorded on standard consumer DVD-R discs.
HD cameras
The standard for consumer/prosumer HDTV acquisition is
High-Definition Video (HDV). It records MPEG-2 TS compressed HDTV
video on standard DV media (regular DV or MiniDV cassette tape)
and transfers it using FireWire. At this time all consumer/prosumer HD
camcorders only record at a maximum resolution of 1080x1440. The image is then
stretched from a 4:3 aspect ratio to a 16:9 aspect ratio. This means that even
consumer or prosumer camcorders that claim 1080i resolution do not include the
full horizontal resolution of 1920 pixels per line.
Broadcast-level HD camcorders and other cameras often record to hard drives via a raw input/output or to tape or flash cards in formats that support higher bitrates than standard DV cassettes such a DVCPRO HD. Recording at 100 Mbits/s, it uses a better color compression method to give better color representation than a standard MiniDV or other DV25 cassette and less compression artifacts.
The terrestrial HDTV
transmission systems
There are three following HDTV
transmitting systems in the world:
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Systems
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USA |
Europe |
ISDB-T Japan |
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Video |
Main Profile syntax of ISO/IEC 13818-2 (MPEG-2 – Video) |
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Audio |
ATSC Standard A/52 (Dolby AC-3) |
ISO/IEC 13818-2 (MPEG-2 – Layer II Audio) and Dolby AC-3 |
ISO/IEC 13818-7 (MPEG-2 – AAC Audio) |
HD-MAC
The European Commission established a European standard for uncompressed digital
HDTV in a 1986 directive (MAC). However, it never became popular among
broadcasters. The HD-MAC standard was abandoned in 1993, and since then all EU
and EBU efforts have focused on the DVB system (Digital Video Broadcasting),
which allows both SDTV and HDTV. HD-MAC (the high-definition variant of MAC) was
left for transcontinental satellite links and could be used only by cable and
satellite providers, where there is a wider bandwidth available.
Is there a HDTV distribution format?
There currently is not a consumer format for mass
distribution of HDTV content. That must initially be accomplished over the air.
HDTV is changing the way we view television. In addition to broadcast television
this new technology provides stunning picture quality for many other
applications.
Currently there are many different HDTV production formats. You can choose from 1080-i, 1080-24P, 1080-30P, 720P, 480P to name a few. Each has its own advantages and disadvantages.
HD - True
1920x540x60 = 62,208,000 pixels/sec - 6 x DVD quality
1280x720x60 = 55,296,000 pixels/sec-
5.33 x DVD quality
HDV
1440x540x60 = 46,656,000 pixels/sec – 4.5 x DVD quality
HD - Lite
1280x540x60 = 41,472,000 pixels/sec – 4 x DVD quality
Standard Definition DVD
· 720x480i:
720x240x60 = 10,368,000 pixels/sec
Movies by
Internet
Six major movie studios have signed up with
MovieLink
to provide movies for sale by download. Warner, Universal, Sony, Paramount, 20th
Century Fox, and MGM will offer older titles as well as first-run movies. Sony,
MGM, and Lion’s Gate will also sell movies through
CinemaNow.
The two services have different requirements and restrictions, and you won’t be able to burn your downloads to a DVD and play it on a regular DVD player. You will be able to watch them on a PC or notebook only.
And online delivery of HDTV versions eliminates the conflict between Blu-ray and HD DVD.
Richard Konkolski
© 2006 - Seven Oceans Video
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Please, for more information call Seven Oceans Video & Digital Media at (401) 846 0001 or email your request to Richard@SevenOceans.com
© Seven Oceans Video - Richard Konkolski
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