Definitions

HDV

HDV

HDV is a High-definition_video format that uses MPEG2 compression to record HD content onto tapes originally designed for standard definition DV recording.

There are two main variations of HDV: HDV1 records 1280x720 square pixels using a video data rate of 19 Mbit/s, while HDV2 records 1440x1080 anamorphic (non-square) pixels at 25 Mbit/s. Both formats produce a widescreen (16:9) image at playback for use on modern HDTVs, and both use MPEG1 layer II audio with a data rate of 384 kbit/s. Other minor variations exist (e.g. "p" and "f" modes) as described below.

HDV content can be captured and edited in most modern NLEs on personal computers, and is widely used by both consumers and professional videographers.

History

The HDV format was developed by JVC and Sony Corporation, and initially supported by both Canon Inc. and Sharp Corporation. In September 2003, the four companies announced the formation of the HDV consortium. Since the announcement, industry support has grown to include others: Apple, Avid, Canopus (now part of Grass Valley), Sony Media Software, and Ulead. Of the original four, Sharp is the only founding member that has not yet manufactured any HDV equipment.

JVC released the first HDV camcorder, the GR-HD1. The GR-HD1 allowed the user 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, 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.

Sony released the second HDV camcorder in September 2004, the Sony HDR-FX1. It's imager used three 1/3" CCDs, recording video in HDV 1080i. Despite the imager's sub-sampled resolution (960x1080), the FX-HD1 was a solid performer, attracting widespread interest among freelance videographers and independent The subsequent Sony HVR-Z1U, which inherited the FX1's imager-section and recording-unit, added XLR audio inputs and 44 additional features. Most notably, the Z1U was multi-standard; the camera was equipped with a dual-clock allowing the operator to switch the camera between PAL or NTSC operation. Both the FX1 and Z1U had a lasting impact on the video industry, because they made HD-video production an affordable reality. The FX1 and Z1U were also Sony's final HDV camcameras to use a CCD imager; later models switched to a CMOS imager.

In mid 2005, Sony released its first consumer-oriented model, the HDR-HC1. The Sony HVR-A1E, the same model with XLR audio-inputs, was released in September 2005. Sony later replaced (in 2006) the HC1 with the less-expensive HDR-HC3, which featured an incrementally improved CMOS chip, but omitted some features of its predecessor (such as external mic-in.) 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 2006, Sony refreshed the FX1/Z1 product line with 4 new models: HDR-FX7, HDR-FX7E, HVR-V1U, and the HVR-V1E. These models featured CMOS imagers instead of CCD, and the sensors now resolved a full 1920x1080 resolution (vs 960x1080 of the older CCD.) 1080p capability allowed the operator the choice of recording in 50i/60i, or 25p/30p.

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. At CES 2008, Sony revealed the HDR-HC9 which replaces the HC7. It is basically the same camera with a sleeker all black color scheme and some added manual features that were previously only available on prosumer camcorders. In November 2007, Sony announced the HVR-Z7 camcorder and the HVR-S270 shoulder-mount camera. Both use the same three 1/3" ClearVid CMOS sensors and attain low light sensitivity similar to that of the SD DSR-PD170 while offering HDV recording in 50/60i, 25/30P, and 24P. The Z7 has 2 XLR audio inputs and HDMI output while the S270 has 4 XLR inputs and features HD-SDI output.

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.)

In 2007 Constructive Lab developed a solution allowing HDV to be securely transmitted over low bandwidth networks.

The 720p and 1080i flavors of HDV are often abbreviated as HDV1 and HDV2, respectively. This abbreviation is not mentioned in HDV consortium documents and is hence unofficial, but the labels are de-facto standards.

Overview

HDV was designed to offer a cost-conscious upgrade path from standard-definition (SD) to high-definition (HD) video. As such, HDV uses the same DVC cassette as MiniDV. Recording time for HDV is identical to MiniDV SP. 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 is not likely that there will be an HDV camcorder that records HDV in LP mode because of the higher risk of video drop-outs at faster transport speeds.

HDV cameras are offered in both consumer and professional designs. Consumer models are sold to the mass consumer market, competing with other camcorders used for home, travel and vacation video. Professional models have better lenses and other advanced features for those doing paid video production, and are used for a wide variety of projects including some popular TV shows (e.g. "Deadliest Catch"). HDV can be captured and edited in most modern NLEs on personal computers, then output to either Blu-ray or computer delivery formats.

Two major versions of HDV are HDV 720p and HDV 1080i. The former is used by JVC, the latter is preferred by Sony and Canon.

HDV 720p

This version of HDV is supported by JVC, who was the first to release an HDV camcorder, the GR-HD1. The camcorder did not gain widespread acceptance, and JVC later shifted their HDV development from consumer to shoulder-mounted cameras. HDV 720p uses frame size of 1280x720 square pixels with 16:9 frame aspect ratio, closely matching 720p broadcast video standard.

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. This format is informally known as TOD.

ProHD

A common misconception is that JVC developed a proprietary extension to HDV, featuring a 24-fps progressive recording mode, 25-fps, 30-fps, 50-fps, 60-fps 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. and read from JVC in http://www.jvc-victor.co.jp/english/pro/prohd/index.html

HDV 1080i

HDV 1080i does not record full 1920×1080-pixels video, but instead sub-samples horizontal resolution to 1440 pixels. Similar subsampling is used in other popular HD formats including XDCAM HD, DVCPRO HD and HDCAM. It had been used in broadcast HDTV encoders as well to reduce compression artifacts.

HDV 1080i is an interlaced video standard, but there are techniques for storing progressive video with frame frequency up to a half of the field frequency within interlaced stream. This means that 50 Hz camcorders are capable of recording 25-fps progressive video, while 60 Hz camcorders are capable of 30-fps progressive video. 60 Hz camcorders intended for digital cinematography also offer recording of 24-fps progressive video.

To record 50-fps or 60-fps progressive video one has to use a 720p camcorder.

Cineframe

Cineframe was a synthetic method of achieving film-like motion, offered on early Sony HDV 1080i models. It was nothing more than an interlaced-to-progressive converter, applied to interlaced stream coming from interlaced sensors. The resulting video was then recorded to tape in interlaced format.

The conversion process involved discarding fields, so vertical resolution of the resulting video suffered. Because the camera still was 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.

The same or better film look effect can be achieved by converting regular interlaced video into progressive format using computer software.

Sony eliminated this shooting mode in its later camcorder models, replacing it with "P" mode that provides true progressive image acquisition.

"F" modes

Canon, as a member of HDV consortium, added three new recording modes to the 1080i HDV specification: 24F and 30F for 60Hz systems and 25F for 50Hz systems. In these modes interlaced video from the camera is converted to progressive and recorded to tape in the fashion similar to Progressive segmented Frame.

"F" recording modes are implemented in several Canon camcorders like the XH-A1 or XH-G1. These cameras have interlaced imaging sensors and produce progressive video by doubling the horizontal scan rate to scan the sensors twice in one cycle. In theory, the resulting video should be less detailed compared to video coming from a true progressive sensor, but the comparison between the HG-A1 and the HV20 did not reveal a clear winner.

From a user's perspective, the "F" modes can be considered genuinely progressive, as camera outputs true progressive video over FireWire. Tapes, recorded in an "F" mode can be only played on camcorders and decks that explicitly support it.

"P" modes

The first HDV 1080i camcorder to implement "P" modes was the Sony HVR-V1, which was introduced in September 2006.

The "P" modes, or simply progressive recording modes, have borrowed proven television techniques for broadcasting progressive video with interlaced transport.

25P and 30P modes are recorded on tape in PsF-like fashion. 24P and 24A modes uses technique known as 2 pulldown .28technically.2C 2:3 pulldown.29. The 24P mode ensures that there are no cadence breakups for a whole tape, while the 24A mode starts every clip on an A frame.

To preserve compatibility with interlaced equipment, video is recorded and outputted as interlaced and can be processed in interlaced form if needed. Unlike "F" modes, tapes recorded in "P" modes are compatible with all HDV 1080i equipment.

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

"PF" modes

These modes, first used by Canon in the HV20 camcorder, are similar to Sony's "P" modes. PsF-like recording is used for PF25, while 2-3 pulldown is used for PF24. The HV30 implements PsF-like PF30 mode for 60 Hz markets. Output is performed via component, HDMI and FireWire in interlaced form.

Despite the similarities between "PF" and "P" recording modes, it is apparent that their implementation is slightly different. In particular, Sony Vegas Movie Studio Platinum 9.0 is capable of correctly identifying and decoding 24p HDV video from Sony camcorders, but does not support PF24 HDV video. Sony stated that "PF" video does not include flags necessary for performing automated film-mode deinterlacing.

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.

Canon has started to ship HDV camcorders which 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.

HDV has some similarities to the more professional XDCAM-HD format, but the latter uses higher data rates for both video and audio signals.

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 will be available soon with the anticipated release of the Panasonic HMC150 camera, which records onto readily available SDHC memory cards using the AVCHD encoding standard.

Use of HDV in broadcast television

HDV is accepted with some restrictions for broadcast TV use, so check with specific broadcasters for their current HD source requirements. HDV has been prominently used for several shows including "Deadliest Catch" and "Mythbusters", and was used in the primetime TV series "JAG" for some scenes where larger HD cameras would have been impractical.

The preferred delivery format for Discovery HD Theater is HD-D5 or HDCAM. HDV source content is accepted if it is limited to 15% of a whole program and is shot with a 1080-line (HDV2) camera. Producers wishing to use HDV are required to submit an approved postproduction path outlining their handling of the footage in the editing process. 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.

Editing HDV

HDV footage can be effectively edited by most modern NLEs 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. 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.

Interlaced Video Issues

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 and are not well suited for representing interlaced material. All modern personal computers use progressive scanning as well. Interlaced video must be converted to progressive if it is intended to be watched on a progressive display.

The process of converting interlaced video into progressive is known as deinterlacing. Depending on the way original video was acquired and recorded (native interlaced, PsF or 3 pulldown) and on the deinterlacing method applied, different visible artifacts may be introduced.

In particular, "line doubling" causes loss of vertical resolution. "Blend" is notorious for ghosting. "Bob" preserves temporal resolution of native interlaced video, but loses spatial resolution. "Weave", also known as "no deinterlacing", works fine for PsF material, preserving both spatial and temporal resolution, but produces combing artifacts when applied to native interlaced video. Also, when video is scaled down, individual scanning lines are combined together, and combing may look like ghosting. Neither of the above methods works for video recorded with 2-3 pulldown, which requires film mode deinterlacing also known as inverse telecine.

Interlaced video can be deinterlaced in post-production and delivered as progressive, or it can be deinterlaced by a display device. All modern flat-panel televisions have a built-in deinterlacing engine and can cope with interlaced video. The efficiency of deinterlacing varies from one TV manufacturer to another, and depends on the complexity of viewed material.

Deinterlacing before delivery is practically a requirement when target device is a computer screen. While some new media players and decoders are capable of processing interlaced video in realtime, progressive video is the preferred format for watching on a computer.

One can completely avoid the hurdles of deinterlacing altogether by using a 720p camera instead of an 1080i camera. Unfortunately, only JVC makes 720p HDV camcorders at present time, and all of these are expensive ProHD shoulder-mount models. Also, the frame size of 720p video is smaller in comparison to 1080i. This may not be a real technical deficiency, but often becomes a marketing stumbling block as consumers tend to believe that a bigger number is always better.

Alternatives

In both the professional and consumer markets, HDV faces competition from a variety of other formats:

  • For the commercial and semi-professional market, the Panasonic AG-HVX200 camera records video in DVCPRO HD format, a intraframe-only codec running at 100 Mbit/s (4X the rate of HDV2.) This allows the HVX200 to offer better color depth and avoid inter-frame compression issues compared to HDV, but at a significantly higher price. The HVX200 is a tapeless device, recording to Panasonic's proprietary DVCPRO P2 cards, or external hard-drive storage over firewire/1394.
  • In late 2007, Sony introduced the 'XDCAM EX' CineAlta professional HD camera. The camera is equipped with three full-resolution (1920x1080) 1/2" CMOS sensors, and an XDCAM (MPEG2 at up to 35 Mbit/s) video-codec, and a dual auto/manual focusing system, and a camera-mounted 720p LCD display. The new "SxS" memory card format (co-developed by Sony and SanDisk) supports a tapeless workflow.
  • In the consumer market, tapeless-camcorders based on the AVCHD format record to optical-disc or solid-state storage (flash memory or hard-drive.) AVCHD utilizes a considerably more advanced video-codec, H.264, allowing AVCHD to achieve better video-quality than HDV, or to achieve longer recording times at comparable quality. AVCHD is expected to eventually replace HDV in the consumer-market, although both formats will coexist for many years.

Editing software support

See also Non-linear video editing

For Microsoft Windows:

For Mac OS X:

  • Adobe Premiere Pro
  • Adobe Premiere Elements (from version 3.0 onward)
  • Avid Media Composer, Supports a wide range of HDV formats/standards, but no support for true 24p HDV.
  • Final Cut Express and Final Cut Studio Latest version of Final Cut 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)
  • HDVxDV Now Universal Binary. This program loads in HDV (Including JVC's 24p ProHD) and transcodes to whichever format the user wishes to edit. Timecode support is inaccurate. Does not allow for back to tape in HDV.
  • iMovie As of iMovie HD. It does not support 24p HDV.
  • Lumiere HD (Now Discontinued) for Final Cut Pro 5. First available software to edit HDV on a Mac with QuickTime based Non Linear Editing systems. Like Final Cut Pro and Premiere Pro, it allowed 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 Macs.
  • 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.
  • Ulead MediaStudio pro 7, 8 and VideoStudio 9,10,11,12

Under Linux:

Specifications

Format HDV 720p HDV 1080i
Media DV or MiniDV Tape
Video
Video signal 720/60p, 720/30p, 720/50p, 720/25p (720/24p) 1080/60i, 1080/50i (1080/30p, 1080/25p, 1080/24p)
Frame size in pixels 1280 x 720 1440 x 1080
Frame aspect ratio 16x9
Video Compression MPEG2 Video (profile & level: MP@HL) MPEG2 Video (profile & level: MP@H-14)
Sampling frequency for luminance 74.25 MHz 55.6875 MHz
Chroma sampling format |- Quantization 8 bits (both luminance and chrominance)
Compressed video bitstream rate ~19.7 Mbit/s ~25 Mbit/s
Audio
Compression MPEG-1 Audio Layer II, PCM MPEG-1 Audio Layer II
Sampling frequency 48 kHz
Quantization 16 bits
Compressed audio 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
System
Stream type MPEG-2 transport stream
Stream interface IEEE 1394a Apple FireWire 400 or Sony i.LINK (MPEG-2 TS)
File extension .m2t (generally)

See also

References

External links


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