Information about Hdv

HDV is also an abbreviation for Hepatitis D

HDV is an inexpensive high-definition video recording format which uses MPEG2 compression to fit high-definition content onto the same DV or MiniDV tapes originally developed for standard definition recording. The compression used results in some quality compromises compared to higher bandwidth HD recording formats, but has still proved useful for many purposes including several popular TV shows. (However, most TV shows shot in HD are recorded using higher-end formats.)

History

The HDV format was developed by JVC and Sony. The format was initially supported by three other companies: Canon Inc., Sharp Corporation, and Sony Corporation. These four companies make up the HDV consortium and are all manufacturers of HDV hardware. They announced their HDV partnership in September, 2003. Sharp has not manufactured an HDV camcorder at this time. They have since been joined by other companies, notably Avid, Canopus, Ulead, Sony Media Software, and Apple, Inc. 2007 Constructive Lab developed a solution allowing HDV to be securely transmitted over low bandwidth Intranets and Internet.

JVC was the first to release an HDV camcorder, the GR-HD1. With the GR-HD1, the user could select standard DV (480i), or HDV (720p30, 480p60) mode. Sony was next to launch an HDV camcorder. Introduced in September 2004, the Sony HDR-FX1 recorded in HDV 1080i format. Depending on the TV standard in the released market, the unit would support either 50 Hz or 60 Hz recording (but not both.) The Sony HVR-Z1U, the equivalent U.S. professional model, supports both and adds XLR audio plus 44 additional features, most notably a dual clock that could support either 50 Hz or 60 Hz formats, allowing for both PAL and NTSC on a single camcorder. In 2005, Sony released the consumer-oriented HDV Camcorder, the HDR-HC1. A professional version of the HDR-HC1, the Sony HVR-A1E, was released in September 2005. In 2006, Sony released the HDR-FX7, HDR-FX7E, HVR-V1U, and the HVR-V1E, marking the world's first full 1080p camcorders in a small format, with both 24p and 30p (only 25p on the HVR-V1E) features on the camcorder (except for the HDR-FX7 and HDR-FX7E).

JVC has developed its own extension of the HDV format called ProHD which shoots natively at 720p24.

In September 2005, Canon entered the HDV market with the Canon XL H1, a professional, modular HDV camera system, and in July of 2006, Canon announced their XH A1 and XH G1 models which are similar to the XL H1 but in a smaller form factor and a fixed-mount lens. In 2006, Sony appended the HDR-HC1 with the less-expensive HDR-HC3. The HDR-HC3 features a slightly improved CMOS chip, but omits some features (such as external mic-in) of its predecessor.

Canon then introduced the Canon HV10 which is a compact consumer priced 2.76 Megapixel CMOS chip HDV camera system. In April 2007 Canon released an updated compact consumer camera model Canon HV20 which, in addition to its predecessor's features, has a 24p Progressive + film mode where the CMOS sensor captures 24 frames per second progressive but using telecine is taped in 60i to remain compatible with consumer level editing suites.

The Sony HDR-HC3 was later replaced by the HDR-HC5 which uses the same CMOS chip as the HC3, but with different hardware not too dissimilar to that of the HC3 with the exception of xvYCC recording. The Sony HDR-HC7 was introduced with a higher pixel count CMOS sensor and the re-introduction of the microphone input. Like the HC5, the HC7 can also record xvYCC.

In August 2007, Sony introduced a shoulder-mount HDV camcorder called the HVR-HD1000U, which uses the same CMOS sensor as the HC7, and is basically a more professional version of the HC7. It has a lens similar in size to that of the HVR-Z1U or HVR-V1U.^[1]

Overview

HDV was designed to offer existing video production environments a cost-conscious upgrade path from standard-definition (SD) to high-definition (HD) video. As such, HDV shares the same DV25 cassette-media and tape-transport as DV. Recording times for HDV are identical to DV -- a 60 minute MiniDV cassette can store 60 minutes of either DV or HDV footage. As of yet, no HDV cameras can record HDV at LP speed, so the maximum record time on one tape is 80 minutes, as opposed to 120 with an 80 minute tape at LP. Although wanted by the consumer market, it isn't likely that there will be an HDV camcorder that records HDV in LP mode because of the even higher risk of video drop outs on the thinner 80 minute tapes!

HDV recorders are offered to both the consumer and entry-level video production market. Consumer models are sold to the mass consumer market, competing with other camcorder product used for home, travel and vacation video. HDV video can be edited on a modern desktop/laptop PC, and burned and distributed on home-video DVDs. Prosumer models are designed for individuals and organizations specifically interested in video production, and are generally sold to amateur vidoegraphers, local production and marketing agencies, etc. HDV video can also be imported into a professional environment, although the quality of the product limits this use to news and other non-studio applications.

HDV compression

HDV compression is based on MPEG-2 video, a intraframe (spatial compression) and interframe (temporal compression) compressor. The older DV codec was strictly an intraframe (spatial) compression scheme (similar to M-JPEG.) The more complex MPEG-2 technology allows HDV to achieve its higher spatial resolution at the target bitrates of 19.7 Mbit/s (720p) and 25 Mbit/s (1080i), but compression-quality is highly dependent on the scene.

In the older DV codec, each frame of video is recorded as a self-contained unit, with no references/dependence on past or future frames. A compressed DV sequence consists of a series of compressed pictures, each given a uniform amount of space on the videotape. In contrast, the HDV codec, using MPEG-2 video semantics, divides a motion video-sequence into a handful 'I' (key) frames and many delta-frames. The key-frames are stored as self-contained units (and are the only randomly accessible points in the sequence), while the delta-frames consist of predictions and error-corrections based on the surrounding key-frames. In HDV 1080i, one in every 12 (25 FPS) or 15 (30 FPS) frames is an I frame. In HDV 1080p, one in every 12 (25 FPS) or 15 (24 or 30 FPS) frames is an I frame. In HDV 720p, one in every 6 (24, 25, or 30 FPS) or 12 (50 or 60 FPS) frames is an I frame. Frames vary in size depending on their prior and future neighbors. A portion of the codec manages bit allocation, to ensure the entire sequence does not exceed the maximum allowed datarate.

MPEG-2 video enables HDV to achieve a much higher compression ratio than DV, but at the cost of motion-induced artifacts in scenes of complex motion. The artifacts are a limitation of the compression technology and bitrate allocated to the video bitstream. Scenes with little motion are easier for HDV to compress than scenes with rapid movement, strobing lights, or other complex activity. For example, a scene of a moving riverbed may exhibit regions of picture breakup, depending on the amount of movement in the water. A static scene of a mountain countryside, by comparison, will exhibit none of these visual problems.

For audio, HDV uses lossy compression (MPEG-1 Layer 2) to reduce the audio bitrate to 384 kbit/s. DV audio uses uncompressed 16-bit PCM at 1536 kbit/s. As a result, HDV audio is technically inferior, although MPEG-1 at 384 kbit/s is regarded as 'perceptually lossless.' For the typical recording scenario with an on-camera microphone, HDV audio is not a limiting factor.

HDV has a lower tolerance for drop-outs because of its long-GOP compression. This is an unavoidable characteristic of interframe compression. Since interframe compression introduces dependency between frames, a dropout impacts many frames. Many HDV users purchase either "master" quality Mini-DV or specially formulated HDV tapes, and limit the re-use of tapes to a set number of hours.

It is important to view HDV's limitations in the proper context. For the DV codec to approach the spatial quality of HDV, it would require more than four times the storage space, which would greatly increase the cost of recording equipment and blank media. As such, consumers, amateur videographers, and low-budget TV programming shoot on HDV for budget reasons.

Canon has started to ship consumer camcorders that are capable of 24 progressive frames per second. That is, 24 progressive 1080 frames are captured per second, each of which is stored as two coded fields in a 1080i bitstream. This allows decoders to display the progressive frames as full resolution 1080p frames at 24 frames per second or to use "2:3 pull-down" display to show it on a 60-field per second interlaced display.

Currently the BBC considers HDV marginal for broadcast purposes but accepts it in limited amounts for some programs with prior consent. Their preferred choice of format for recording HD is currently HDCAM. They also accept HDV cameras for use in producing widescreen SD footage, with some caveats about how to approach doing so. (For example see Alan Roberts' Z1E/FX1E analysis.)

HDV has been used in the primetime television series "JAG" shot many scenes using HDV equipment, over extreme latitudes of sunlight over ocean water, with dark and light content in the subject matter.

The Sony XDCAM HD format is very similar to HDV.

Resolution and aspect ratio

In HDV, the video frame is defined to have an aspect ratio of 16:9. Permitted resolutions are 720p and 1080i.

HDV 720p uses a resolution of 1280x720 square pixels. HDV 1080i uses a resolution of 1440×1080 pixels, but is still displayed with an aspect ratio of 16:9 (like SD widescreen formats, it uses a pixel aspect ratio of 1.33 instead of 1.0). This means it has lower horizontal resolution than true 1080 HD formats (1920x1080), but the same applies also to most other widely used HD formats including XDCAM HD, DVCPRO HD and HDCAM, all of which have the same or lower resolution as HDV.



Despite this, the perceived detail of HDV is much higher than that of PAL or NTSC DV formats. 1440 pixels is still twice the horizontal resolution of SD formats. In total, each HDV frame has 1,555,200 pixels, which is 4.5 times the resolution of NTSC DV (345,600 pixels) and 3.75 times that of PAL DV (414,720 pixels).

The numbers above refer to the luminance (brightness) information only; chrominance (color) information is subsampled ( for HDV) to reduce the amount of data, as happens with DV and DVD, although NTSC DV uses a different sampling pattern (). In other words, in all these formats, the chrominance resolution is one quarter of the luminance resolution. Most professional video formats use a sampling pattern, and some high-end formats support , which is to say full chroma sampling.

Notes regarding specific camcorder models

Many HDV cameras support progressive scan (which they denote by "P"). They achieve this by doubling the horizontal scan rate to scan the interlaced sensor twice in one cycle. This lets them use a less expensive sensor at the expense of some interlacing artifacts. There will be fewer artifacts than 50i/60i, but it will not be as smooth as true 25P/30P. Also, various practical tests have shown that resolution in 24P/25P/30P progressive modes is lower than when 1080i interlaced is selected. The exception to this are the Sony HVR-V1 camcorders which scan progressively and store the resultant data using either (in 24p mode) or PsF (in 25p and 30p modes) techniques, so there's no resolution loss.

Editing HDV

As a consequence of the fact that HDV uses the interframe MPEG-2 GOP (group of pictures) structure instead of a solely intraframe compression system, native editing of HDV footage differs technically from the native editing of DV footage. In DV, frame-accruate splicing does not disturb the surrounding video because each frame of the video is stored as a self-contained unit. In HDV, splicing always introduces distortion at the splice points, due to the interdependencies between groups of video frames. Any editing of the video, whether it be a complex transition or a simple scene-change, requires a decompression and recompression of the entire HDV frame group. All modern professional non-linear editing software handles HDV by recompressing only in scenes where absolutely necessary, rather than needlessly recompressing the entire video. This limits degradation to the points of edit.

Editing HDV's native MPEG-2 transport stream files also forces the computer system to work much harder to perform even simple tasks of cutting and splicing as frames that don't actually exist as independent cells have to be re-built by the NLE system on-the-fly.

If HDV footage is converted (known as 'Transcoding') to a good intermediate format for editing, these considerations will not necessarily apply, and gradual degradation from generation to generation of edit may be avoided while substantial system performance gains are made. The lossy Apple Intermediate Codec (which runs out of QuickTime) is an efficient, easily usable codec for editing HDV in systems such as Final Cut Pro but lacks the transcoding and generational quality of some third-party HDV Intermediate codecs and offers no realtime performance assistance. CineForm's 'ConnectHD', 'AspectHD' and 'ProspectHD' intermediate codecs and encoding utilities not only maintain higher quality but also function within the rendering engine of some software editing systems (such as Premiere Pro) to boost real-time performance without hardware assistance. CineForm products currently work with Sony Vegas, Premiere Pro, and Corel's Ulead MediaStudio Pro 8 and Ulead Videostudio 11 Plus editing systems. Lumiere HD offers a similar functionality for Mac based editing systems (namely Final Cut Pro) but without any real-time assistance. BitJazz's SheerVideo offers lossless real-time codecs that speed editing with zero generational loss, although Final Cut Pro does not yet support third-party codecs for real-time effects.

There are many advantages to editing HDV using a Lossless Intermediate rather than the native MPEG-2 file however the trade off for transcoding to a HDV Lossless Intermediate is that the file size is substantially increased and so large hard drive arrays are required for storage of footage. Avid Xpress Pro can edit using native HDV, and Avid also claims to have the advantage of being able to work with mixed formats in the timeline, without the need to transcode any material, since different formats are coped with seamlessly for viewing and output, with automatic conversion as required. It must be noted though that when DV material, for example, is included in an HDV project, a problem arises because it must be de-interlaced prior to scaling to the HDV format, and then re-interlaced. De-interlacing is generally regarded as a very difficult process to do well. This problem will arise of course in all editing software, regardless of whether a lossless intermediate format is used.

Interlaced Video Issues

For HDV cameras recording in interlaced formats there may be playback issues on some digital TVs and computers. Interlaced video has been criticized by many, but has been a useful compromise for decades due to its ability to display motion smoothly while reducing recording and transmission bandwidth.

HDV 1080i footage viewed on some plasma screens with interlaced display technology (e.g. ALiS) retains both sharpness and smooth motion while having less motion blur than typical movies. Hand-held material shot in progressive-scan mode can look jittery and confusing on such interlaced displays, probably due to an improper attempt to interlace what has been recorded progressively. Interlaced digital displays are not very common, however: recent sales trends increasingly favor progressive display technology such as LCD flat panels. Such displays use deinterlacing conversion processing for proper display of interlaced material.

Personal computers can also have problems playing interlaced video material, and the Windows Media Player may produce vertical ripples that appear to depend on the size of the output image and other factors. Good deinterlacing can help solve this problem if the deinterlacing option is turned on, but deinterlacing high resolution video in real time requires appropriate video processing hardware.

One solution for preparing HDV source material for internet delivery is to encode it to a format like WMV-HD with deinterlacing during the encoding process. Some software can do this better than others, and the encoding time can be quite long depending on the output resolution and other factors. HDV source material yields excellent web video when properly encoded to WMV-HD or H.264 at bit rates of approximately 5-8 Mbit/sec, as demonstrated on many HD demo sites.

Alternatives

Since the introduction of HDV, other options have been developed to record high-definition video at modest prices compared to previous high-end solutions, as described below.

- Panasonic introduced the AG-HVX200 camcorder, which records in DVCPRO HD format at bit rates up to four times that of HDV on DVCPRO P2 cards or external hard-drive based recorders. This allows the HVX200 to offer better color depth and avoid inter-frame compression issues compared to HDV, but requires a significant investment in recording media and a careful archiving plan for master footage. (Since keeping footage on the P2 cards or hard drive recorders isn't economically practical.)

- Panasonic also partnered with Sony to develop the AVCHD format, which uses H.264 encoding to compress high-definition video at bit rates similar to HDV with potentially higher quality. Some think AVCHD will eventually replace HDV for similar purposes, but for now HDV remains popular due to its cost-effectiveness and convenience.

- In late 2007 Sony plans to introduce the 'XDCAM EX' video camera recording in the XDCAM HD format on a new solid-state media format calles 'SxS'. This camera will use MPEG2 compression like HDV but with a higher bit rate recording option, and offer a tapeless workflow like the Panasonic HVX200 with longer recording times and potentially lower cost for the memory cards. It will also have the largest imaging sensor of any HD camera under $10,000 and hence likely offer better low-light performance, an issue with all other HD cameras in this price range.

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With those requiring the highest HD video format available, there are some more advanced (and costly) options for those consumers. It has been disputed that HDV is not true HD, it delivers near quality as true high-definition video.

Editing software support

See also Non-linear video editing

For Mac OS X:

• VLC Media Player, Free and opensource. Displays 24p without trying to interlace it like other decoders.
• Avid's Xpress Pro HD, Supports a wide range of HDV formats/standards, but no support for true 24p HDV.
• iMovie HD Universal binary, as of latest version (6.0.3), it does not support 24p HDV.
• Final Cut Express and Final Cut Pro 6 Latest version of FCP 6.0 does support direct HDV 24p, and 720/25p which is used in PAL countries (i.e. needed when working with a JVC Pro HD camera in 720/25p mode)
• Lumiere HD Lumière HD (beta) for Final Cut Pro 5. First available software to edit HDV on a Mac with QuickTime based Non Linear Editing systems. This is the only Mac based application (other than FCP) which allows for back to tape in HDV encoding (Including JVC's 24p ProHD). No universal binary is currently available, and is reportedly unstable under Rosetta on Intel Macintoshes.
• MPEG Streamclip 1.8 for Mac is a Universal Binary and supports automatic 3:2 pulldown (Converts 24p to 29.97), this program can only perform basic edits such as cutting, copying, pasting and trimming, but is available free of charge, and has excellent tools for exporting, demuxing and converting video, for example from HDV format (usually with the .m2t extension) to MPEG-2 (.mp2) format. MPEG Streamclip can handle most MPEG container formats (including ts, ps, vob, dat, mpg, and mp2) which adds to its usefulness.
• HDVxDV's http://www.hdvxdv.com/ Now Universal Binary. This program loads in HDV (Including JVC's 24p ProHD) and transcodes to whichever format the user wishes to cut in. Timecode support is inaccurate. Does not allow for back to tape in HDV.

For Microsoft Windows:

• VLC Media Player, can display 24p properly, does not try to interlace like other decoders.
• NewTek SpeedEDIT, Supports all SD, HD and HDV resolutions/frame rates up to 2k film. Does not need an intermediate codec for real time editing. First software editor with real time full resolution/framerate 1394 HDV preview through camera or deck while editing. Can mix formats, resolutions and framerates in a single timeline. Well integrated timeline and storyboard interface.
• Avid's Xpress Pro HD,
• Avid's Liquid
• Adobe's Premiere Pro
• Adobe's Premiere Elements (from version 3.0 onward)
• Canopus' Edius
• Pinnacle Studio 11 Plus or Ultimte
• VirtualDub called VirtualDub-MPEG2
• Sony Media Software's Sony Vegas.
• Sony Media Software's Sony Vegas Movie Studio Platinum Edition.
• CineForm Aspect HD + Connect HD
• Avid Adrenaline HD + Xpress HD + Avid DS/Nitris
• Ulead MediaStudio pro 7, 8 and VideoStudio 9 and 10 Plus
• CyberLink PowerDirector
• MPEG Streamclip 1.0 for Windows, which has the same features as its Mac counterpart.
• MPEG Video Wizard DVD.
• Serif MoviePlus 5

Under Linux:

• Cinelerra - free software, allows and composition
• Kdenlive is a non linear video editor, free software, based on the MLT video framework which relies on the FFMPEG project, thus providing support for various HD standards, including HDV.

Specifications

Media	DV or MiniDV Tape
Video signal	720/60p, 720/30p, 720/50p, 720/25p, 720/24p, 1080/60i, 1080/50i, 1080/25p, 1080/30p, 1080/24p
Video sampling frequency for luminance	74.25 MHz (720p), 55.6875 MHz (1080i)
Video Chroma subsampling
Video sample quantization	8 bits (both luma and chrominance)
Video Compression	MPEG2 Video (profile & level: MP@H-14)
Video compressed bitstream rate	Approximately 25 Mbit/s for 1080i / 19.7 Mbit/s for 720p
Audio sampling frequency	48 kHz
Audio quantization	16 bits
Audio compression	MPEG-1 Audio Layer II
Audio compressed bitstream rate	384 kbit/s (192 kbit/s per channel)
Audio mode	Stereo (2 channels); optional 4-channel MPEG-2 Audio Layer II at 96 kbit/s per channel mode
MPEG Stream type	Transport Stream Packetized Elementary Stream
Stream interface	IEEE 1394a Apple FireWire 400 or Sony i.LINK (MPEG-2 TS)
File extension	.m2t (Generally)

See also

• ProHD - a variant on HDV
• Digital cinematography
• Filmizing

References

External links

• How DV Works at Videomaker.com
• Latest HDV camcorder reviews, news, and product information at DigitalCamcorderNews.com
• HDV Format Legal Information site
• HDV Video production at *FilmDailies.com - a filmmaker's blog
• Sony HDV Info
• HDV Cafe Hi Def Video Resources
• German Forum with HDV focus
• HDV information: HDV FAQ

•  • [ e] Industrial & home video media
Magnetic tape	Analog VERA (1952) • 2 inch Quadruplex videotape (1956) • 1 inch type A videotape (1965) • 1/4 inch Akai (1967) • U-matic (1969) • Cartrivision (1972) • Video Cassette Recording (aka VCR) (1972) • V-Cord (1974) • VX (aka "The Great Time Machine") (1974) • Betamax (1975) • IVC 2 inch Helical scan (1975) - 1 inch type B videotape (1976) • 1 inch type C videotape (1976) • VHS (1976) • VK (1977) • SVR (1979) • Video 2000 (1980) • CVC (1980) • VHS-C (1982) • M (1982) • Betacam (1982) • Video8 (1985) • MII (1986) • S-VHS (1987) • Hi8 (1989) • S-VHS-C (1987) • W-VHS (1994) Digital D1 (1986) • D2 (1988) • D3 (1991) • D5 (1994) • Digital-S (D9) (199?) • Digital Betacam (1993) • DV (1995) • DVCPRO (1995) • DVCAM (1996) • HDCAM (1997) • DVCPRO50 (1998) • D-VHS (1998) • Digital8 (1999) • DVCPRO HD (2000) • D6 HDTV VTR (2000) • MicroMV (2001) • HDV (2003)• HDCAM SR (2003)
Optical disc	Analog Laserdisc (1978) • Laserfilm (1984) Digital CD Video • VCD (1993) • MovieCD (1995?) • DVD-Video (1995) • MiniDVD • CVD (1998) • SVCD (1998) • FMD (2000) • EVD (2003) • FVD (2005) • UMD (2005) • VMD (2006) • HD DVD (2006) • Blu-ray Disc (BD) (2006) • DMD (2006?) • AVCHD (2006) • Tapestry Media (2007) • Total Hi Def (2008) • HVD (TBA) • PH-DVD (TBA) • SVOD (TBA) • Protein-coated disc (TBA)
Grooved Videodiscs	Analog Baird Television Record aka Phonovision (1927) • TeD (1974) • Capacitance Electronic Disc aka CED (1981) • VHD (1983)