Saturday, December 15, 2007

HD Primer

The ins and outs of entry and mid-level HD camcorders

Never before has the video industry seen such an explosion of formats as we're experiencing today, and along with the plethora of formats comes confusion about what HD is and what it isn't. Rarely does a day go by that we don't hear the phrase "True HD" or "Full HD" in the context of comparing camcorders and/or formats.

If the camcorder displays 1280 x 720, or 1920 x 1080 on OUTPUT, it is indeed a "High Definition" camcorder. Truly!
Hopefully this simple statement clarifies HD. I believe the confusion stems from marketing campaigns in the early days of low-cost HD camcorders and discussions of imager sizes and recorded image sizes.

Although some manufacturers, evangelists, or editors might suggest that the sensor/imager of a camcorder determines whether a camera is an HD camcorder or not, the imager/sensor size isn't directly related to whether a picture is HD or not. DSP may be employed to create an HD output from the camcorder. In theory, a camcorder manufacturer might take a Standard Definition imager and use DSP (Digital Signal Processing) to upsample the SD image output from the imager, and store the image on tape, hard drive DVD, or memory card as an HD image. Of course, recording a VHS signal to HDCAM might make it HD, but the picture quality obviously comes into question.

HD camcorders range in price from $800.00 to $800,000.00; this article is predominantly focused on the lower and mid-level camcorders.

Various camcorders offer different sizes of imagers. The HDV format for example, is always a 1280 x 720 or 1920 x 1080 display, but various sized imagers may be employed to reach the display size. For example, the Canon XLH1 camcorder uses a 1920 x 1080 imager to generate a 1440 x 1080 recorded image. The JVC GY-HD200U High Definition 3-CCD MiniDV Professional Camcorder (Body Only)

uses a 1280 x 720 imager to create a 1280 x 720 recorded image. The Sony Z1 uses a 960 x 1080 imager to deliver a 1440 x 1080 recorded image. The Panasonic HVX200 offers the smallest imager of any HD camcorder at 960 x 540, slightly smaller (vertically) than a PAL SD imager, recorded to a 960 x 720 frame size (in 1280 x 720 modes). All of these camcorders upsample or downsample the recorded image, excepting JVC's HDV camcorders and Sony XDCAM EX. Their format is a full-raster format (meaning imager matches recorded frame size). SONY PDW-510 XDCAM CAMCORDER (DVCAM)
HD offers a 1440 x 1080 recorded image derived from a 1920 x 1080 imager, while SONY PDW-510 XDCAM CAMCORDER (DVCAM)
EX offers a 1920 x 1080 recorded and displayed image.

Imagers range in size from 1/4" to 2/3", depending on the camcorder model. The Sony HVR V1U features 1/4" imager set on the diagonal, providing a sample equal to 1440 x 1080, but using unique (and oft-debated) technology, the image is sampled at 1920 x 1080. SONY PDW-510 XDCAM CAMCORDER (DVCAM)
HD features a 1/2 imager, while Varicam and HDCAM products offer a 2/3 imager. The larger imagers are not only more light sensitive, but they also allow for shallow depth of field and a smoother image in most shooting situations.

Smaller imagers packed with many more pixels than their SD counterparts are prone to being low-light challenged. More pixels in the same space comes at the cost of sensitivity, although new imagers and DSP are making tremendous strides in low-light situations.

SxS card
HD images are stored on a variety of storage formats. The Sony HVR Z7U stores HDV tape simultaneously, while the SONY PDW-510 XDCAM CAMCORDER (DVCAM)
EX stores media on the new SxS (pronounced "S by S") cards that read incredibly fast. AVCHD is stored on memory sticks, DVD, HDD, and SDHD cards. XDCAM is stored on Sony Professional Discs, which uses Samsung BD-P1000 High Definition Blu-Ray DVD Player

technology to store HD media on optical storage. Panasonic uses the P2 card system, which is a PCMCIA card format. Grass Valley Infinitycam stores on Iomega REV discs, while RED and SI record to hard drive units. Higher end camcorders may record to tape, or use dual-channel SDI output to large hard drive arrays.

When dealing with the various flavors of MPEG (MPEG 2/AVCHD), the primary consideration is the bitrate at which the video file/frames are encoded. Ranging from 11Mbps to 50Mbps and differing ratios of compression, it can easily become confusing. Don't confuse compression with color sampling.

AVCHD varies the bitrate from 11Mbps to 16Mbps, depending on the manufacturer and model of the camera. HDV offers two bitrates that are constant bitrates (CBR). 720p offers a bitrate of 19Mbps, while 1080i/p is encoded at 25Mbps. SONY PDW-510 XDCAM CAMCORDER (DVCAM)
offers a variable bitrate (VBR) of 35Mbps and 50Mbps (depending on the model). SONY PDW-510 XDCAM CAMCORDER (DVCAM)
EX offers a VBR of 35 Mbps or a CBR of 25Mbps. MPEG is the same format as delivered over satellite and cable, DVD, Samsung BD-P1000 High Definition Blu-Ray DVD Player

, or Toshiba HD-A2 Single Disc High Definition DVD Player

. It's possible with some camcorders to shoot to disc or card and play back the footage immediately on a BD system.

HDV compresses media at a rate of approximately 20:1, while AVCHD compresses at nearly double the HDV ratio. HDV may be used for broadcast in many applications, whereas currently, AVCHD is predominantly a consumer format, and likely will be for some time to come. The benefit of higher compression is that it allows for storage of high resolution media on small or slow format devices such as memory stick, DVD, or hard drive. The drawback to higher compression is that color and detail may be compromised, particularly in scenes containing complex color and complex MAC MOTION P818 Series Softskin Recliner

. An AVCHD camcorder may manage broad latitude images (lots of dark black and bright whites) while holding static, and may manage low latitude images with some MAC MOTION P818 Series Softskin Recliner

, but combining wide latitude with high MAC MOTION P818 Series Softskin Recliner

is very challenging for highly compressed formats. HDV also suffers in some circumstances of high MAC MOTION P818 Series Softskin Recliner

and extreme chroma/color.

Surface-conduction Electron emitter Display (SED)

SED TVWe all know that SED sets are planned, but what the heck are they and how do they work? Better yet, how will they compete with current HDTV television technologies like DLP, LCoS, LCD and Plasma? Here's a quick overview of what you need to know.

First things first: we'll get the SED acronym out of the way to make sure we're all speaking the same language. SED isn't "Super Extraordinary Definition"; in fact, it isn't a resolution definition at all. SED is a type of display technology and it stands for "Surface-conduction Electron emitter Display". While it sounds like something out of "Star Trek", it's actually a technology that Canon helped to develop in 1986.

SED is probably the closest concept to the Cathode Ray Tube (CRT) that is predominant today. However, it also provides the flat-panel benefits we gain from Liquid Crystal Display (LCD) and Plasma Display Panel (PDP) technology as well. Consider SED to be the best of both worlds: bright, high-quality images with less bulk. Let's see how it works to better understand this.

How a CRT worksSimilar to a CRT, the display is created with electrons that collide with a phosphor-coated screen. CRTs use a single electron gun to emit the particles that create the display. The one electron gun essentially draws the screen by passing all of the electrons to the screen. Since the electron gun has to cover the entire screen, the set tends to be deep, although some slimmer sets are coming to market. Additionally, since the electron gun is constantly sending particles to the entire screen, it tends to be a heavy consumer of power.

How an SED worksSED technology applies the electron-phosphorus concept, but radically changes one key element: the electron mechanism. Instead of a single electron gun, SED sets have one electron emitter for each pixel. This brings two key CRT advantages to the flat panel world. Less power is needed because the electrons don't need to travel as far. Since the electrons are close to the display surface, the set is much slimmer than a CRT set, as well. If that doesn't get you as excited as a charged electron, then just wait, there's more!

Here's the key reason that SEDs are likely to gain a stranglehold over other flat-panel technologies in the long run: brightness and contrast. Currently, there isn't a flat-panel or microdisplay technology that can compete with CRTs for either brightness or contrast. The real beauty of SED technology is that it has the same brightness and contrast qualities of a CRT because the same electron-phosphor display approach is used; it simply does so more efficiently and in less space!

There are plenty of additional technical details on SED technology, but at least this provides the basics. The real question is: now that you know what SED is, how likely are you to consider an SED purchase in your not-so-distant future?

PureVideo HD

NVIDIA PureVideo

Essential for the Ultimate HD Movie Experience
Blu-ray and HD DVD movies are bringing a new level of movie-viewing experience, with high-definition image quality far surpassing standard-definition DVDs. To deliver the ultimate HD movie experience when playing Blu-ray and HD-DVD, NVIDIA developed PureVideo™ HD technology, available with NVIDIA® GeForce® Series 7 and 8 GPUs.

PureVideo HD technology is the combination of a dedicated video processing core on the NVIDIA GPU and software in the NVIDIA ForceWare ® drivers that delivers superb video quality with minimal CPU use and low power consumption when playing Blu-ray or HD DVD discs on a PC.

It is the essential ingredient for the ultimate high definition movie and video experience on a PC.

Revolutionary New Video Processing Architecture
NVIDIA GeForce 8400, 8500, and 8600 GPUs for Desktop and GeForce 8400M, 8600M and 8700M for Notebooks, incorporate a revolutionary new video processing architecture, making them the world’s first GPU video processors to offload 100% of Blu-ray and HD DVD H.264 video decoding from the CPU. This added processing power gives PureVideo HD technology the ability to support more complex features as they are added to Blu-ray and HD DVD movies, including “picture-in-picture” movies, interactive games and menus, and higher bit-rate / higher quality movie pictures.

Low CPU Utilization and Power Consumption
PureVideo HD technology on the GPU takes on the processing-intensive video decoding task, freeing the CPU and 3D engine to run other applications while playing a high-definition movie. Lower CPU utilization can result in reduced power consumption, heat and noise, and longer battery life.

Superb Picture Quality
NVIDIA PureVideo HD technology delivers outstanding picture clarity, ultra-smooth video, vivid color, and precise image scaling for video and HD DVD and Blu-ray movies. PureVideo HD accelerates and enhances high-definition movies delivering life-like images that have up to six times the detail of standard DVD movies at resolutions up to 1080p - the highest HD resolution available.

The Core of a Complete Blu-ray/HD DVD Solution
PureVideo HD technology is a core ingredient for playing visually stunning movies on a PC. Leading PC manufacturers, including DELL, HP, Toshiba and Acer, have adopted NVIDIA GeForce GPUs with PureVideo HD technology to power their PCs with Blu-ray and HD DVD drives.

High-Definition Video - HD in filmmaking

Film as a medium has inherent limitations, such as difficulty of viewing footage whilst recording, and suffers other problems, caused by poor film development/processing, or poor monitoring systems. Given that there is increasing use of computer-generated or computer-altered imagery in movies, and that editing picture sequences is often done digitally, some directors have shot their movies using the HD format via high-end digital video cameras. Whilst the quality of HD video is very high compared to SD video, and offers improved signal/noise ratios against comparable sensitivity film, film remains able to resolve more image detail than current HD video formats. In addition some film has a wider dynamic range (ability to resolve extremes of dark and light areas in a scene) than even the best HD cameras. Thus the most persuasive arguments for the use of HD are currently cost savings on film stock and the ease of transfer to editing systems for special effects. Notable directors who have used HD to a large degree thus far are: George Lucas, Michael Mann, and Robert Rodriguez.

Many television shows with science fiction themes and special effects such as Star Trek: Enterprise, Stargate SG-1, Stargate Atlantis and the re-imagined Battlestar Galactica have also begun to use digital cameras.

Movies that have been shot on HD digital video include:

HDV Film released through UFO Gajab din bhaige

High-Definition Video - Format considerations

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 should match the source, as should the resolution. On the other hand, a very high resolution may require more bandwidth than is available. The lossy compression that is used in all digital HDTV systems will then cause the picture to be distorted.

Photographic film destined for the theater typically has a high resolution and is photographed at 24 frame/s. Depending on the available bandwidth and the amount of detail and movement in the picture, the optimum format for video transfer is thus either 720p24 or 1080p24. When shown on television in countries using PAL, film must be converted to 25 frames per second either by speeding it up by 4% or using pulldown techniques. In countries using the NTSC standard, (60 fields per second) a technique called 3:2 pulldown is used. One film frame is held for three video fields, (1/20 of a second) and then the next is held for two video fields (1/30 of a second) and then the process repeats, thus achieving the correct film rate with two film frames shown in 1/12 of a second. (See also: Telecine) (Note: This is slightly more complicated because film is photographed at exactly 24.00 frames per second while NTSC digital video at 24p is recorded at 23.976 frames per second since color NTSC video is actually recorded at 59.97 fields per second (not 60.00) which is a difference of 1000/1001 from black and white NTSC video. Therefore, telecine from film to NTSC video also requires a slow down of the projection rate for both the picture and the audio by 0.1%.)

Older (pre-HDTV) recordings on video tape such as Betacam SP are often either in the form 480i60 or 576i50. These may be upconverted to a higher resolution format (1080i), but removing the interlace to match the common 720p format may distort the picture or require filtering which actually reduces the resolution of the final output. (See also: Deinterlacing)

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, however in other scenarios the format choice will vary depending on a variety of factors. In general, 720p is more appropriate for fast action as it uses progressive fields, as opposed to 1080i which uses interlaced fields and thus can have a degradation of image quality with fast motion. In addition, 720p is used more often with internet distribution of HD video, as all computer monitors are progressive, and most graphics cards do a sub-optimal job of de-interlacing video in real time. 720p Video also has lower storage and decoding requirements than 1080i or 1080p, and few people possess displays capable of displaying the 1920x1080 resolution without scaling. 720p appears at full resolution on a common 1280x1024 LCD, which can be found for under US$160 as of June 2007. An LCD capable of native 1080p resolution still costs over five hundred US dollars.

In North America, Fox, ABC, and ESPN (ABC and ESPN are both owned by Disney) currently broadcast 720p content. PBS, NBC, Universal HD (both owned by General Electric), CBS, UPN, Showtime, INHD, HDNet and Time-Warner-owned HBO-HD, the WB and TNT currently broadcast 1080i content.

In the United Kingdom, BBC HD and Sky HD broadcast in 1080i. It is worth noting, however, that the two main HD providers, Virgin Media and Sky, provide set-top boxes which are capable of upscaling the video to 1080p.

High-Definition Multimedia Interface (HDMI)


HDMI defines the protocol and electrical specifications for the signaling, as well as the pin-out, electrical and mechanical requirements of the cable and connectors.


The HDMI Specification has expanded to include three connectors, each intended for different markets.

The standard Type A HDMI connector has 19 pins, with bandwidth to support all SDTV, EDTV and HDTV modes and more. The plug outside dimensions are 13.9 mm wide by 4.45 mm high. Type A is electrically compatible with single-link DVI-D.

A higher resolution version called Type B is defined in HDMI 1.0. Type B has 29 pins (21.2 mm wide), allowing it to carry an expanded video channel for use with very high-resolution future displays, such as WQSXGA (3200x2048). Type B is electrically compatible with dual-link DVI-D, but is not in general use.

The Type C mini-connector is intended for portable devices. It is smaller than Type A (10.42 mm by 2.42 mm) but has the same 19-pin configuration.


The HDMI cable can be used to carry video, audio, and/or device-controlling signals (CEC). Adaptor cables, from Type A to Type C, are also available.

TMDS channel

The Transition Minimized Differential Signaling (TMDS) channel:

  • Carries video, audio, and auxiliary data via one of three modes called the Video Data Period, the Data Island Period, and the Control Period. During the Video Data Period, the pixels of an active video line are transmitted. During the Data Island period (which occurs during the horizontal and vertical blanking intervals), audio and auxiliary data are transmitted within a series of packets. The Control Period occurs between Video and Data Island periods.
  • Signaling method: Formerly according to DVI 1.0 spec. Single-link (Type A HDMI) or dual-link (Type B HDMI).
  • Video pixel rate: 25 MHz to 340 MHz (Type A, as of 1.3) or to 680 MHz (Type B). Video formats with rates below 25 MHz (e.g. 13.5 MHz for 480i/NTSC) transmitted using a pixel-repetition scheme. From 24 to 48 bits per pixel can be transferred, regardless of rate. Supports 1080p at rates up to 120 Hz and WQSXGA.[3]
  • Pixel encodings: RGB 4:4:4, YCbCr 4:4:4 (8–16 bits per component); YCbCr 4:2:2 (12 bits per component)
  • Audio sample rates: 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, 192 kHz.
  • Audio channels: up to 8.
  • Audio streams: any IEC61937-compliant stream, including high bitrate (lossless) streams (Dolby TrueHD, DTS-HD Master Audio).

Consumer Electronics Control channel

The Consumer Electronics Control (CEC) channel is optional to implement, but wiring is mandatory. The channel:

  • Uses the industry standard AV Link protocol.
  • Used for remote control functions.
  • One-wire bidirectional serial bus.
  • Defined in HDMI Specification 1.0, updated in HDMI 1.2a, and again in 1.3a (added timer and audio commands).

This feature is used in two ways:

  • To allow the user to command and control multiple CEC-enabled boxes with one remote control, and
  • To allow individual CEC-enabled boxes to command and control each other, without user intervention.

An example of the latter is to allow the DVD player, when the drawer closes with a disk, to command the TV and the intervening A/V Receiver (all with CEC) to power-up, select the appropriate HDMI ports, and auto-negotiate the proper video mode and audio mode. No remote control command is needed. Similarly, this type of equipment can be programmed to return to sleep mode when the movie ends, perhaps by checking the real-time clock. For example, if it is later than 11:00 p.m., and the user does not specifically command the systems with the remote control, then the systems all turn off at the command from the DVD player.

Alternative names for CEC are Anynet (Samsung), Aquos Link (Sharp), BRAVIA Theatre Sync (Sony), Regza Link (Toshiba), RIHD (Onkyo), Simplink (LG) and Viera Link/EZ-Sync (Panasonic/JVC).

Content restriction

  • According to High-bandwidth Digital Content Protection (HDCP) Specification 1.2.
  • Beginning with HDMI CTS 1.3a, any system which implements HDCP must do so in a fully-compliant manner. HDCP compliance is itself part of the requirements for HDMI compliance.[4][5]
  • The HDMI repeater bit, technically the HDCP repeater bit, controls the authentication and switching/distribution of an HDMI signal.

Blu-ray Disc - Disc structure

Laser and optics

Like its rival format HD DVD, Blu-ray uses a "blue" (technically violet) laser operating at a wavelength of 405 nm to read and write data. Conventional DVDs and CDs use red and near infrared lasers at 650 nm and 780 nm respectively.

The blue-violet laser's shorter wavelength makes it possible to store more information on a 12 cm CD/DVD sized disc. The minimum "spot size" on which a laser can be focused is limited by diffraction, and depends on the wavelength of the light and the numerical aperture of the lens used to focus it. By decreasing the wavelength, increasing the numerical aperture from 0.60 to 0.85 and making the cover layer thinner to avoid unwanted optical effects, the laser beam can be focused to a smaller spot. This allows more information to be stored in the same area. In addition to the optical improvements, Blu-ray Discs feature improvements in data encoding that further increase the capacity. (See Compact disc for information on optical discs' physical structure.)

Hard-coating technology

Since the Blu-ray data layer is closer to the surface of the disk, compared to the DVD standard, it was at first more vulnerable to scratches. The first discs were housed in cartridges for protection. Advances in polymer technology eventually made the caddies unnecessary.

TDK was the first company to develop a working scratch protection coating for Blu-ray discs. It was named Durabis. In addition, both Sony and Panasonic's replication methods include proprietary hard-coat technologies. Sony's rewritable media are sprayed with a scratch-resistant and antistatic coating. Verbatim recordable and rewritable Blu-ray Disc discs use their own proprietary hard-coat technology called ScratchGuard.

HD DVD - Technical specifications

The current specifications for HD DVD-ROM and HD DVD-RW are version 1.0. The specification for HD DVD-R is currently at 0.9; the HD DVD-RAM specification is not yet finalized.

Disc structure

HD DVD-ROM has a single-layer capacity of 15 GB, a dual-layer capacity of 30 GB, and a 51 GB triple-layer disc (which uses slightly bigger 17 GB layers), approved in November 2007 by the DVD Forum[2]. Toshiba has declined to say whether the 51GB, triple-layer disc is compatible with existing drives and players. Specification 2.0 Part 1 (Physical Specification) for triple layer HD DVD has been approved in November 2007.[41]

HD DVD-R and HD DVD-RW has a single-layer capacity of 15 GB, a dual-layer capacity of 30 GB. The HD DVD-RAM has a single-layer capacity of 20 GB.[42] Like the original DVD format, the data layer of an HD DVD disc is 0.6 mm below the surface physically protecting the data layer from damage. The numerical aperture of the optical pick-up head is 0.65, compared with 0.6 for DVD. All HD DVD players are backward compatible with DVD and CD.

Physical size Single layer capacity Dual layer capacity Triple layer capacity
12 cm, single sided 15 GB 30 GB 51 GB (17 GB per layer instead of 15 GB)
12 cm, double sided 30 GB 60 GB 39 GB (HD DVD/DVD Twin-Format - HD-34 Double-Layer/DVD 5 Single-Layer)
8 cm, single sided 4.7 GB 9.4 GB
8 cm, double sided 9.4 GB 18.8 GB

File systems

As with previous optical disc formats, HD DVD supports several file systems, such as ISO 9660 and Universal Disk Format (UDF). Currently, all HD DVD titles use UDF version 2.5 as the file system.


HD DVD discs support encoding in up to 24-bit/192 kHz for two channels, or up to eight channels of up to 24-bit/96 kHz encoding.[43] For reference, even new big-budget Hollywood films are mastered in only 24-bit/48 kHz, with 16-bit/48 kHz being common for ordinary films.[citation needed]

All HD DVD players are required to decode linear (uncompressed) PCM, Dolby Digital AC-3, Dolby Digital EX, DTS, Dolby Digital Plus and Dolby TrueHD.[44] A secondary soundtrack, if present, can be stored in any of the aforementioned formats, or in one of the HD DVD optional codecs: DTS-HD High Resolution Audio and DTS-HD Master Audio.

For the highest-fidelity audio experience, HD DVD offers content-producers the choice of linear PCM, Dolby TrueHD and DTS-HD Master Audio. Due to the high-bandwidth requirements of linear-PCM, lossless audio on HD DVD movies has thus far been delivered in the lossless format Dolby TrueHD.


The HD DVD format supports a wide variety of resolutions, from low-resolution CIF and SDTV, all video resolutions supported by the DVD-Video standard, and up to HDTV formats such as 720p, 1080i and 1080p.[43] HD DVD supports video encoded in MPEG2 which is what is used in DVDs as well as the new formats VC-1 and AVC which are more efficient. All movie titles released so far have had the feature encoded in 1080p, with most supplements in 480i or 480p. Almost all titles are encoded with VC-1, and most of the remaining titles encoded with AVC.