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HDV is an entry-level format for high definition video recording. HDV uses DV tape providing a cost-effective HD production solution, compared to previously developed HD formats.

[edit] Overview

The HDV format was developed by JVC and Sony to offer an affordable upgrade path from standard-definition DV video to high-definition recording. The format was initially supported by Canon and Sharp, and in September 2003 the four companies formed the HDV consortium.

Most HDV camcorders use MiniDV/DVC cassettes that are also known as "S-size" tapes. Some shoulder-mounted camcorders are also capable of recording onto larger DV cassettes known as "L-size" tapes. The recording time is the same as DV Standard Play. Unlike DV, HDV does not support Long Play speed.

Two major versions of HDV are HDV 720p and HDV 1080i. The former is used by JVC and is informally known as HDV1. The latter is preferred by Sony and Canon and is often referred to as HDV2.^[1] The HDV 1080i defines optional progressive recording modes, and in recent publications is often called HDV 1080 or 1080-line HDV as progressive 1080-line recording becomes commonplace.^[2][3]

[edit] HDV 720p

 

JVC ProHD camcorder

HDV 720p closely matches broadcast 720p video standard in terms of scanning type, frame rate, frame size, aspect ratio and data rate. Presently, JVC is the only manufacturer of HDV 720p camcorders. JVC was the first to release an HDV camcorder, the handheld GR-HD1. Later JVC shifted its HDV development to shoulder-mounted cameras.

JVC did not leave the market of consumer high definition camcorders, but instead switched to tapeless recording technologies. For example, its Everio GZ-HD7 camcorder, introduced in January 2007, can record MPEG-2 video to either built-in hard disk drive or to a Secure Digital memory card. JVC chose to use 1080i format instead of 720p on its consumer camcorders, with data rates, frame rate and frame size matching or exceeding parameters of HDV 1080i video.^[4] This format is informally known as TOD.

A common misconception is that JVC developed a proprietary extension to HDV called ProHD, featuring film-like 24-fps progressive recording mode and LPCM audio, for professional use. JVC states that ProHD is not a separate format, but "an approach for delivering affordable HD products," and stresses that 24-fps progressive recording and LPCM record/playback has always been part of the HDV format specification.^[5]

[edit] HDV 1080i

 

Canon XL-H1

HDV 1080i is an interlaced video standard. Interlaced video has been a useful compromise for decades due to its ability to display motion smoothly while reducing recording and transmission bandwidth. Interlaced video is still being used in acquisition and broadcast, but interlaced display devices are being phased out.

Modern flat-panel television sets that utilize plasma and LCD technology are inherently progressive. All modern computer monitors use progressive scanning as well. Interlaced video must be converted to progressive before it is displayed on a progressive-scan device. The process of converting interlaced video into progressive is known as deinterlacing. Progressive-scan television sets employ built-in deinterlacing circuits to cope with interlaced broadcast signal, but computers rarely have this capability. As such, native interlaced video must be deinterlaced if it is intended for viewing on a computer.

Some HDV 1080i camcorders are capable of recording progressive video within an interlaced stream, provided that the frame rate does not exceed half of the field rate. The first HDV 1080i camcorder to implement such Progressive Scanning was the Sony HVR-V1.^[6] To preserve compatibility with interlaced equipment the HVR-V1 records and outputs video in interlaced form. 25-fps and 30-fps progressive video is recorded on tape using progressive segmented frame technique, while 24-fps recording employs 2-3 pulldown. The camcorder offers two variations of 24-fps recording: "24" and "24A", the latter is also known as "24pSCNA". With the 24P mode the camera ensures that there are no cadence breaks for a whole tape, this mode works better for watching video directly from the camera and for adding "film look" to interlaced video. In the 24A/24pSCNA mode the camera starts every clip on an A frame and with timecode set to an even second margin.^[7][8]

Prior to the HVR-V1, Sony was offering Cineframe, essentially an interlaced-to-progressive converter, to simulate film-like motion. The conversion process involved blending and discarding fields, so vertical resolution of the resulting video suffered. Because the camera was still shooting in interlaced mode, slower frame rate did not improve light sensitivity. In addition, motion, produced in the 24-fps variant of Cineframe was too uneven for professional use.^[9] The same or better film look effect could be achieved by converting regular interlaced video into progressive format using computer software.^[10]

In 2007 Canon commoditized progressive scanning, releasing the HV20 camcorder. The version for 50Hz market featured PF25 mode with PsF-like recording, while the version for 60Hz market had PF24 mode, which utilized 2-3 pulldown scheme. The HV30, released in 2008, implemented additional PsF-like PF30 mode for 60 Hz markets. Output is performed via component, HDMI and FireWire in interlaced form.^[11]

To achieve full vertical resolution without introducing interlace artifacts the progressive scan video must be properly deinterlaced. 25P and 30P video must be deinterlaced with "weave" or "no deinterlacing" algorithm, which means joining two fields of each frame together into one progressive frame. 24P video must go through film-mode deinterlacing also known as inverse telecine, which throws out judder frames and restores original 24-fps progressive video.

[edit] HDV 1080p

There is no separate standard for HDV 1080p recording. Instead, the HDV 1080i specification defines optional progressive recording modes, which are getting popular as the users become more interested in shooting digital movies and creating content for the Web. All HDV camcorders that can record in 1080p format can also record native 1080i video.

HDV camcorders, capable of 1080-line progressive video, record it at rates of 24 fps (actually 23.98 fps) and 30 fps (actually 29.97 fps) for 60 Hz markets, and at 25 fps rate for 50 Hz markets. Video is output as true progressive video via an i.LINK/Firewire port. Output through other ports is performed in interlaced mode to preserve compatibility with existing interlaced equipment.^[12][13]

The first 1080-line HDV camcorder to offer recording in native progressive format was the Canon XL H1, introduced in 2006. It was followed by the the XH-G1 and XH-A1. The camcorders generate and record progressive video from interlaced CCD sensors, which precluded Canon from calling these modes truly progressive. Instead, Canon reused the term Frame mode and a shorthand suffix "F" instead of commonly accepted "P" from its standard definition model lineup.^[14] The camcorders can be made 50Hz/60Hz switchable for additional fee.^[15]

In 2008 Sony announced HVR-S270, HVR-Z7 and HVR-Z5 models, capable of recording in what Sony have called Native Progressive Recording mode. The new Sony camcorders use true progressive sensors, which allowed Sony to claim superiority over Canon models by saying that Native Progressive Recording has been called 24F/25F/30F in some camcorders, while actually using interlace CCD imagers.^[2]

In January 2009 Canon announced the HV40 as a replacement for the HV30 consumer camcorder. Aside of minor cosmetic changes, the 60 Hz model sports 24-fps native progressive recording and uses the same progressive-scan CMOS sensor as the models it replaces.^[16]

Sony designed a "Progressive" logo for the camcorders that are capable of native progressive recording. Canon has no special logo to identify cameras that can record in frame modes.

Aside of aforementioned camcorders, other products that are capable of reading and recording in native progressive format are the Sony HVR-M15AU, HVR25AU,^[17] HVR-M15AE, HVR25AE^[18] and HVR-M35 HDV videocassette recorders, and the Canon HV20/HV30 camcorders when used in deck mode.

[edit] HDV compression

HDV is based on MPEG-2 video, which compresses data both within each frame (intraframe/spatial compression) and between frames (interframe/temporal compression). This is the same type of compression used for DVD video and many network TV broadcasts, and allows HDV to achieve high spatial resolution at low data rates compared to other HD recording formats. HDV 1080i uses a recording data rate of 25 Mbit/s (3.125 MB/s) while HDV 720p records at 19.7 Mbit/s (2.46 MB/s). In either case the data rate is constant because the recording media — tape — is transported with constant speed.

Using MPEG-2 video enables HDV to achieve a higher compression ratio than recording formats without interframe compression, but constant data rate limits the video quality in scenes with lots of detail, rapid movement or other complex activity like flashing lights. Such scenes may exhibit visible artifacts such as blockiness or blurring, depending on the amount of movement and on the algorithm employed in the encoder. On contrary, when using a tapeless recording standard such as XDCAM or AVCHD it is possible to increase or decrease the data rate depending on complexity of a scene, thereby preserving quality of a busy scene while saving recording space on a low-detail scene.

Interframe compression also means that a recording dropout in HDV can affect several frames of video rather than just one, since the compression introduces dependency between frames. Hence it is best to use high-quality tapes for HDV recording such as "master quality" Mini-DV or specially formulated HDV tapes, and limit the re-use of tapes. Some users have gotten good results with HDV using generic Mini-DV tapes, but this is not generally recommended.

For audio, HDV uses MPEG-1 Layer 2 compression to reduce the audio bitrate to 384 kbit/s, compared to 1536 kbit/s for DV video and 1411 kbit/s for audio CDs. This makes HDV audio less desirable for situations where sound quality is critical, but MPEG-1 audio at 384 kbit/s is considered 'perceptually lossless.' For general video recording with an on-camera microphone, HDV audio is not a significant limiting factor.

It is important to view HDV's compression limitations in the proper context. Other HD codecs using lower compression ratios need more bandwidth and storage capacity for a given amount of video, requiring significantly more complex and expensive recording solutions. For example, the Panasonic DVCPRO P2 cameras use memory cards which can cost over $50 per minute of recording capacity, compared to a few dollars per hour for Mini-DV tapes. This cost differential has helped make HDV a popular HD recording format for consumers, independent videographers and low-budget TV programs. Another cost-efficient HD recording option became available in October 2008 with a release of the Panasonic HMC150 camera, which records onto readily available SDHC memory cards using the AVCHD encoding.

[edit] Use of HDV in broadcast television

HDV is accepted with varying restrictions for broadcast TV use. It has been used for shows like "Deadliest Catch" and "Mythbusters", and was used in the TV series "JAG" for scenes where larger HD cameras would have been impractical. The BBC currently considers HDV a "non-broadcast domestic HD format," but accepts HDV footage for up to 25% of HD programming content with advance approval.^[19]

The preferred delivery formats for Discovery HD Theater are HD-D5 and HDCAM. HDV source content is accepted if it is limited to 15% of a whole program and is shot with a 1080-line camera. Producers wishing to use HDV are required to submit an approved postproduction path outlining their handling of the footage in the editing process.^[3] However, the main Discovery Channel's HD simulcast have less or no guidelines and accepts a mix of XDCAM HD, HDV and AVCHD for the length of a program.

[edit] Editing HDV

HDV footage can be effectively edited by most modern non-linear editors on fast personal computers. Performance may be reduced compared to other video formats due to both the high resolution and interframe compression, both of which require computers to work harder when calculating editing effects. Performance can be improved by converting HDV to alternative "intermediate" codecs prior to editing, including Cineform Aspect HD, Edius HQ and Apple ProRes 422. There are many advantages to editing HDV using an intermediate codec rather than the native MPEG2 file, however the trade-off is that the file size is substantially increased.

[edit] Products

[edit] JVC

JVC was the first to release an HDV camcorder, the GR-HD1. The GR-HD1 allowed to choose from a selection of resolutions: standard DV (480i), HDV 720p30, or HDV 480p60. Curiously, the HDV modes used the old 601 color space standard, rather than the newer 709 standard intended for high-definition video. The GR-HD1's imager used a single 1/3" CCD sensor instead of a 3CCD setup, another unusual choice discouraging professional use. Due to this, along with other limitations, the GR-HD1 was not popular in either the consumer or semi-professional market. JVC later shifted their HDV development to shoulder-mounted cameras.

[edit] Sony

 

Sony HDR-FX1

Sony specializes in 1080i HDV equipment and makes products for both 60 Hz and 50 Hz markets. Traditionally, Sony uses suffix "E" to identify 50 Hz models, and suffix "U" or no suffix at all to identify 60 Hz models. Models listed below are specified without suffixes.

In September 2004 Sony released the first HDV 1080i camcorder, the HDR-FX1. Its professional version, the HVR-Z1, came with XLR audio inputs and 44 additional features. Most notably, the HVR-Z1 was switchable between 50 Hz and 60 Hz scanning to cater for the different scanning rates used in different markets.

In the middle of 2005 Sony released its first consumer HDV model, the HDR-HC1, which had a single CMOS sensor, electronic stabilization system and was capable of recording in DV and HDV 1080i modes. Its professional version, the HVR-A1, added a second accessory shoe in place of the flash, XLR audio inputs, additional recording options, larger eyecup and larger lens hood.

In 2006 Sony replaced the HDR-HC1 with the smaller and cheaper HDR-HC3, which featured an incrementally improved CMOS chip, but omitted some features of its predecessor. The HDR-HC3 was replaced by the HDR-HC5 which used the same CMOS chip as the HDR-HC3, and added an option of recording in xvYCC color space. The replacement model, the HDR-HC7 came with a higher pixel count CMOS sensor and with a microphone input. Like the HDR-HC5, the HDR-HC7 could also record xvYCC. In 2008 the HDR-HC7 was replaced with the HDR-HC9.

In 2006, Sony added two new models to its upscale HDV lineup: the consumer HDR-FX7 and its professional cousin, the HVR-V1. The progressive-scan CMOS sensors of these models resolved full 1920x1080 resolution. 1080p capability of the HVR-V1 allowed the operator the choice of shooting interlaced or progressive video, which was converted to interlaced for recording on tape.

In August 2007, Sony introduced the shoulder-mounted version of the HDR-HC9, the HVR-HD1000. It has a lens similar in size to that of the HVR-Z1 or HVR-V1.^[20]

In November 2007, Sony announced the HVR-Z7 handheld camcorder and the HVR-S270 shoulder-mounted camera. Both use the same three 1/3" ClearVid CMOS sensors and attain light sensitivity similar to that of the SD DSR-PD170 while offering HDV recording in native interlaced, progressive scan and native progressive modes. The Z7 has 2 XLR audio inputs and HDMI output while the S270 has 4 XLR inputs and features HD-SDI output.^[21]

In 2008 the HVR-FX1 was replaced with the HVR-FX1000, and the HVR-Z1 was replaced with the HVR-Z5. Aside of multitude of improvements, the FX1000 can record progressive scan video like the HVR-V1, while the HVR-Z5 offers native progressive recording mode.^[22]

In November 2008 Sony restarted production of the HDR-FX7 camcorder, which was discontinued a year earlier. Offered for almost half the original price, the HDR-FX7 bridges the gap between the HDR-HC9 and the FX1000.

[edit] Canon

Canon entered the HDV market in September 2005, with the Canon XL H1, a professional-oriented modular camera system with interchangeable lenses, HD-SDI output, and three 1440x1080 1/3" CCDs. In July 2006, Canon announced their XH A1 and XH G1 models, which use the same sensor as the XL-H1 but in a smaller form factor with a (non-changeable) fixed lens. Canon then introduced the consumer oriented Canon HV10, a compact unit with a single 2.76 Megapixel CMOS sensor. In April 2007 Canon released the updated Canon HV20 which adds a 24p Progressive + film mode where the imager captures 24 progressive frames per second, but records to 1080/60i HDV using a built-in 3:2 pulldown (telecine) process, to remain compatible with consumer level editing suites. The current consumer model (HV30), has a black body instead of the HV20's grey one, and added a 30P mode to simplify video-uploads to online sites (such as YouTube and Vimeo.)

[edit] Sharp

Sharp is the only member of the HDV Consortium that has not produced an HDV camcorder or a videocassette recorder. The closest Sharp has ever got in supporting HDV standard is the AQUOS DV-ACV52 digital video player. The player supports HDV video, though it does not have a tape transport. Instead, it allows playback and dubbing of DV/HDV video from a camcorder connected to the player via a FireWire connector.

[edit] Alternatives

The main alternatives to HDV for moderately-priced HD recording are currently as follows:

• The AVCHD format uses the newer H.264 codec to achieve quality approaching that of HDV at lower bit rates, but with more processing power required for effective editing. AVCHD also expands recording options to include solid-state flash memory, hard drives and 8cm DVDs, which are not supported in the HDV spec.

• Panasonic has a variation of AVCHD called AVCCAM, with a bit rate nearly equal to that of HDV and hence potentially fewer artifacts.

• The Sony 'XDCAM EX' format uses similar compression technology to HDV but at a higher data rate (up to 35 Mbit/s), and with more flexible recording options using a new memory card format. The "SxS" memory cards (co-developed by Sony and SanDisk) supports a tapeless workflow.

• The DVCPRO HD format from Panasonic offers recording bandwidth of up to 100 Mbit/s (4X that of HDV2), intra-frame recording and a 4:2:2 color depth to minimize some of the compression issues associated with HDV, using solid state DVCPRO P2 cards which are significantly more expensive than HDV tape.

• Some digital photo cameras now offer functional HD video recording modes. The most notable as of this writing is the Canon EOS 5D Mark II, which can record 1920x1080 video in H.264 format at 38.6 Mbit/s from a full-frame 35mm sensor with interchangeable lenses. Many videographers are wondering if/when Canon might put similar technology in a proper video camera, which would be a dramatic improvement over current video cameras in the same price range.

[edit] Specifications

The table below lists three HDV formats: HDV 720p, HDV 1080i and HDV 1080p, this is done for convenience only. HDV 1080p is not officially defined as a separate standard, but is included instead into HDV 1080i specification as optional format. All HDV camcorders that are capable of 1080p recording can also record native 1080i video.