DV
Encyclopedia
DV is a format for the digital recording
and playing back of digital video
. The DV codec
was launched in 1995 with joint efforts of leading producers of video camcorder
s.
The original DV specification, known as Blue Book, was standardized within the IEC
61834 family of standards. These standards define common features such as physical videocassettes, recording modulation method, magnetization, and basic system data in part 1. Part 2 describes the specifics of 525-60
and 625-50
systems. The IEC standards are copyrighted publications available for purchase from IEC or ANSI
.
(DCT) to compress video on a frame-by-frame basis. Audio is stored uncompressed.
Closely following ITU-R Rec. 601 standard, DV video employs interlaced video scanning with the luminance sampling frequency of 13.5 MHz. This results in 480 scanlines per complete frame for the 60 Hz system, and 576 scanlines per complete frame for the 50 Hz system. In both systems the active area contains 720 pixels per scanline, with 704 pixels used for content and 16 pixels on the sides left for digital blanking. The same frame size is used for 4:3 and 16:9 frame aspect ratios, resulting in different pixel aspect ratio
s for fullscreen and widescreen video.
Prior to the DCT compression stage, chroma subsampling
is applied to the source video in order to reduce the amount of data to be compressed. Baseline DV uses 4:1:1 subsampling in its 60 Hz variant and 4:2:0 subsampling in 50 Hz variant. Low chroma resolution of DV (compared to higher-end digital video formats) is a reason this format is sometimes avoided in chroma key
ing applications, though advances in chroma keying techniques and software made producing quality keys from DV material possible.
Audio can be stored in either of two forms: 16-bit Linear PCM stereo
at 48 kHz sampling rate
(768 kbit/s per channel, 1.5 Mbit/s stereo), or four nonlinear 12-bit PCM channels at 32 kHz sampling rate (384 kbit/s per channel, 1.5 MBit/s for four channels). In addition, the DV specification also supports 16-bit audio at 44.1 kHz (706 kbit/s per channel, 1.4 Mbit/s stereo), the same sampling rate used for CD audio. In practice, the 48 kHz stereo mode is used almost exclusively.
s in raw form or wrapped in such file formats as Audio Video Interleave
(AVI), QuickTime and Material Exchange Format (MXF). One video frame is formed from either 10 or 12 such sequences, depending on scanning rate, which results in a data rate of about 25 Mbit/s for video, and an additional 1.5 Mbit/s for audio. This results in a compression rate of 5 to 1. When written to tape, each sequence corresponds to one complete track.
Baseline DV employs unlocked audio. This means that the sound may be +/- ⅓ frame out of sync with the video. However, this is the maximum drift of the audio/video synchronization; it is not compounded throughout the recording.
Post-production
capabilities, color rendition and raster size for use with professional video camera
s.
All DV variants except for DVCPRO Progressive are recorded to tape within interlaced video stream. Film-like frame rates are possible by using pulldown. DVCPRO HD supports native progressive format when recorded to P2 memory cards.
(ENG).
Unlike baseline DV, DVCPRO uses locked audio and 4:1:1 chroma subsampling for both 50 Hz and 60 Hz variants to reduce generation loss. Audio is available only in the 16-bit/48 kHz variant.
When recorded to tape, DVCPRO uses wider track pitch - 18 μm vs. 10 μm of baseline DV, which reduces the chances of dropout errors when video is recorded to tape. Two extra longitudinal tracks provide audio cue and for timecode control. Tape is transported 80% faster compared to baseline DV, resulting in shorter recording time. Long Play mode is not available.
Like DVCPRO, DVCAM uses locked audio, which prevents audio synchronization drift that may happen on DV If several generations of copies are made.
When recorded to tape, DVCAM uses 15 μm track pitch, which is 50% wider compared to baseline. Accordingly, tape is transported 50% faster (2.8cm/s) compared to DV (1.8cm/s), which reduces recording time by one third compared to DV. Because of the wider track and track pitch, DVCAM has the ability to do a frame accurate insert tape edit, while DV may vary by a few frames on each edit compared to the preview.
(ENG) and digital cinema
, and is often described as two DV-codecs working in parallel.
The DVCPRO50 doubles the coded video data rate to 50 Mbit/s, cutting recording time in half compared to base DVCPRO. Chroma resolution is improved by using 4:2:2 chroma sampling.
DVCPRO50 is used in many productions where high definition video is not required. For example, BBC used DVCPRO50 to record high-budget TV series, such as Space Race
(2005) and Ancient Rome: The Rise and Fall of an Empire
(2006).
A similar format, D-9
, offered by JVC, uses videocassettes with the same form-factor as VHS
.
Comparable Sony formats include Digital Betacam, launched in 1993, and MPEG IMX, launched in 2001.
The format offered six modes for recording and playback: 16:9 progressive (50 Mbit/s), 4:3 progressive (50 Mbit/s), 16:9 interlaced (50 Mbit/s), 4:3 interlaced (50 Mbit/s), 16:9 interlaced (25 Mbit/s), 4:3 interlaced (25 Mbit/s).
The format has been superseded with DVCPRO HD.
format that can be thought of as four DV codecs that work in parallel. Video data rate depends on frame rate and can be as low as 40 Mbit/s for 24 frame/s mode and as high as 100 Mbit/s for 50/60 frame/s modes. Like DVCPRO50, DVCPRO HD employs 4:2:2 color sampling.
DVCPRO HD uses smaller raster size than broadcast high definition television: 960x720 pixels for 720p, 1280x1080 for 1080/59.94i and 1440x1080 for 1080/50i. Similar horizontal downsampling is used in many other HD formats. To maintain compatibility with HDSDI, DVCPRO100 equipment upsamples video during playback.
Variable framerates (from 4 to 60 frame/s) are available on VariCam camcorders. DVCPRO HD equipment is backward compatible
with older DV/DVCPRO formats.
When recorded to tape, DVCPRO HD uses the same 18 μm track pitch as other DVCPRO flavors. A long play variant, DVCPRO HD-LP, doubles the recording density by using 9 μm track pitch.
DVCPRO HD is codified as SMPTE 370M; the DVCPRO HD tape format is SMPTE 371M, and the MXF
Op-Atom format used for DVCPRO HD on P2 cards is SMPTE 390M.
While technically DVCPRO HD is a direct descendant of DV, it is used almost exclusively by professionals. Tape-based DVCPRO HD cameras exist only in shoulder mount variant.
A similar format, Digital-S
(D-9 HD), is offered by JVC and uses videocassettes with the same form-factor as VHS
.
The main competitor to DVCPRO HD is HDCAM
, offered by Sony. It uses a similar compression scheme but at higher bitrate.
Progressive video can be recorded with interlaced delivery in mind, in which case high-frequency information between fields is blended to suppress interline twitter. If the goal is progressive-scan distribution like Web videos, progressive-scan DVD-video
or filmout
, then no filtering is applied. Video recorded with 2-2 pulldown and no vertical filtering is conceptually identical to progressive segmented frame
.
Consumer-grade DV camcorders capable of progressive recording usually offer only 2-2 pulldown scheme because of its simplicity. Such a video can be edited as either interlaced or progressive and does not require additional processing aside of treating every pair of fields as one complete frame. Canon and Panasonic call this format Frame Mode, while Sony calls it Progressive Scan recording. 24 frame/s recording is available only on professional DV camcorders and requires pulldown removal if editing at native frame rate is required.
DVCPRO HD supports native progressive recording at 50 or 60 frame/s in 720p mode. To record video acquired at 24, 25 or 30 frame/s frame repeating is used. Frame repeating is similar to field repeating used in interlaced video, and is also called pulldown sometimes.
DV was originally designed for recording onto magnetic tape
. Tape is enclosed into cassettes of four different sizes: small, medium, large and extra-large. All DV cassettes use tape that is ¼ inch (6.35 mm) wide.
Small cassettes, also known as S-size or MiniDV cassettes, had been intended for amateur use, but have become accepted in professional productions as well. MiniDV cassettes are used for recording baseline DV, DVCAM as well as HDV
.
Medium or M-size cassettes are used in professional Panasonic equipment and are often called DVCPRO tapes. Panasonic video recorders that accept medium cassette can play back from and record to medium cassette in different flavors of DVCPRO format; they will also play small cassettes containing DV or DVCAM recording, via an adapter.
Large or L-size cassettes are accepted by most standalone DV tape recorders and are used in many shoulder-mount camcorders. The L-size cassette can be used in both Sony and Panasonic equipment; nevertheless, they are often called DVCAM tapes. Older Sony decks would not play large cassettes with DVCPRO recordings, but newer models can.
Extra-large cassettes or XL-size have been designed for use in Panasonic equipment and are sometimes called DVCPRO XL. These cassettes are not widespread, only two models of standalone Panasonic tape recorders can accept them.
Technically, any DV cassette can record any variant of DV video. Nevertheless, manufacturers often label cassettes with DV, DVCAM, DVCPRO, DVCPRO50 or DVCPRO HD and indicate recording time with regards to the label posted. Cassettes labeled as DV indicate recording time of baseline DV; another number can indicate recording time of Long Play DV. Cassettes labeled as DVCPRO have a yellow tape-door and indicate recording time when DVCPRO25 is used; with DVCPRO50 the recording time is half, with DVCPRO HD it is a quarter. Cassettes labeled as DVCPRO50 have a blue tape-door and indicate recording time when DVCPRO50 is used. Cassettes labeled as DVCPRO HD have a red tape-door and indicate recording time when DVCPRO HD-LP format is used; a second number may be used for DVCPRO HD recording, which will be half as long.
Panasonic stipulated use of a particular magnetic tape formulation — Metal Particle (MP) — as an inherent part of its DVCPRO family of formats. Regular DV tape uses Metal Evaporate (ME) formulation, which was pioneered for use in Hi8 camcorders. Early Hi8 ME tape was plagued with excessive dropouts, which forced many shooters to switch to more expensive MP tape. After the technology improved, the dropout rate was greatly reduced, nevertheless Panasonic deemed ME formulation not robust enough for professional use. Tape-based Panasonic camcorders do not use small DV cassettes, effectively preventing use of ME tape.
DV cassettes can come with a memory-in-cassette (MIC) low capacity EEPROM memory chip. Using the I²C
protocol, cameras and recording decks can record any data desired onto this chip like contents list, times and dates of recordings, camera settings or video thumbnails, taken each time the record button on the camcorder is pressed. MIC functionality is optional and is not widely used in consumer equipment. Most tapes available to consumers do not include the MIC chip. Almost every recorder and camcorder includes the hardware to read and write to the MIC, but the firmware does not always have the code to actually perform the task.
video recording, DV video can be recorded on optical disc
s, solid state flash memory
cards and hard disk drives and used as computer file
s. In particular:
Video is stored either as native DIF bitstream or wrapped into an audio/video container such as AVI
, QuickTime and MXF.
(FireWire, i.LINK) ports for digital video transfer. When video is captured onto a computer it is stored in a container file, which can be either raw DV stream, AVI, WMV or Quicktime. Whichever container is used, the video itself is not re-encoded and represents a complete digital copy of what has been recorded onto tape. If needed, the video can be recorded back to tape to obtain full and lossless copy of the original footage.
Some camcorders also feature a USB 2.0 port for computer connection. This port is usually used for transferring still images, but not for video transfer. Camcorders that offer video transfer over USB usually do not deliver full DV quality - usually it is 320x240 video (except for the Sony DCR-PC1000 camcorder and some Panasonic camcorders providing transfer of a full-quality DV stream via USB).
High end cameras and VTRs may have additional professional outputs such as SDI
, SDTI or analog component video
. All DV variants have a time code
, but some older or consumer computer applications fail to take advantage of it.
and citizen journalism
.
The high quality of DV images, especially when compared to Video8 and Hi8 which were vulnerable to an unacceptable amount of video dropouts and "hits", prompted the acceptance by mainstream broadcasters of material shot on DV. The low costs of DV equipment and their ease of use put such cameras in the hands of a new breed of videojournalists
. Programs such as TLC's Trauma: Life in the E.R.
and ABC News's Hopkins: 24/7 were shot on DV.
Professional television reporters such as Anderson Cooper
and Katie Couric
seem to shoot some of their stories themselves.
DVCPRO HD has become the preferred high definition standard of the BBC Factual. This format will be replaced with AVC-intra when it becomes viable.
container files. The DV meta-information is preserved in both file types.
Most Windows
video software only supports DV packed into AVI containers, as they use Microsoft
's avifile.dll, which only supports reading avi files. A few notable exceptions exist:
The perpetuation of this controversy, based solely on hearsay, is misleading to end users. Sony
has done a significant amount of internal testing to simulate head clogs as a result of mixing tape lubricants, and has been unable to recreate the problem. Sony recommends using cleaning cassettes once every 50 hours of recording or playback. For those who are still skeptical, Sony recommends cleaning video heads with a cleaning cassette before trying another brand of tape.
. This allowed recording 40 minutes of DV video onto one-hour Video8/Hi8 cassette. Digital8 did not get as widespread acceptance as MiniDV and Sony discontinued Digital8 camcorders in 2007.
In 2003 a consortium of four companies - JVC
, Sony, Canon
and Sharp
- announced HDV
, a format for recording and playback of high-definition video
on a DV cassette tape. Initially marketed in the consumer video market, HDV quickly caught on with many professional users due to its low cost, portability and image quality acceptable for many professional productions. Most HDV camcorders are backwards compatible
with DV, meaning that they can play and record DV content. Many Sony HDV camcorders can play and record in DVCAM format.
Digital recording
In digital recording, digital audio and digital video is directly recorded to a storage device as a stream of discrete numbers, representing the changes in air pressure for audio and chroma and luminance values for video through time, thus making an abstract template for the original sound or...
and playing back of digital video
Digital video
Digital video is a type of digital recording system that works by using a digital rather than an analog video signal.The terms camera, video camera, and camcorder are used interchangeably in this article.- History :...
. The DV codec
Codec
A codec is a device or computer program capable of encoding or decoding a digital data stream or signal. The word codec is a portmanteau of "compressor-decompressor" or, more commonly, "coder-decoder"...
was launched in 1995 with joint efforts of leading producers of video camcorder
Camcorder
A camcorder is an electronic device that combines a video camera and a video recorder into one unit. Equipment manufacturers do not seem to have strict guidelines for the term usage...
s.
The original DV specification, known as Blue Book, was standardized within the IEC
International Electrotechnical Commission
The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...
61834 family of standards. These standards define common features such as physical videocassettes, recording modulation method, magnetization, and basic system data in part 1. Part 2 describes the specifics of 525-60
480i
480i is the shorthand name for a video mode, namely the US NTSC television system or digital television systems with the same characteristics. The i, which is sometimes uppercase, stands for interlaced, the 480 for a vertical frame resolution of 480 lines containing picture information; while NTSC...
and 625-50
576i
576i is a standard-definition video mode used in PAL and SECAM countries. In digital applications it is usually referred to as "576i", in analogue contexts it is often quoted as "625 lines"...
systems. The IEC standards are copyrighted publications available for purchase from IEC or ANSI
Ansi
Ansi is a village in Kaarma Parish, Saare County, on the island of Saaremaa, Estonia....
.
DV Compression
DV is an intraframe video compression scheme, which uses the discrete cosine transformDiscrete cosine transform
A discrete cosine transform expresses a sequence of finitely many data points in terms of a sum of cosine functions oscillating at different frequencies. DCTs are important to numerous applications in science and engineering, from lossy compression of audio and images A discrete cosine transform...
(DCT) to compress video on a frame-by-frame basis. Audio is stored uncompressed.
Closely following ITU-R Rec. 601 standard, DV video employs interlaced video scanning with the luminance sampling frequency of 13.5 MHz. This results in 480 scanlines per complete frame for the 60 Hz system, and 576 scanlines per complete frame for the 50 Hz system. In both systems the active area contains 720 pixels per scanline, with 704 pixels used for content and 16 pixels on the sides left for digital blanking. The same frame size is used for 4:3 and 16:9 frame aspect ratios, resulting in different pixel aspect ratio
Pixel aspect ratio
Pixel aspect ratio is a mathematical ratio that describes how the width of a pixel in a digital image compares to the height of that pixel....
s for fullscreen and widescreen video.
Prior to the DCT compression stage, chroma subsampling
Chroma subsampling
Chroma subsampling is the practice of encoding images by implementing less resolution for chroma information than for luma information, taking advantage of the human visual system's lower acuity for color differences than for luminance....
is applied to the source video in order to reduce the amount of data to be compressed. Baseline DV uses 4:1:1 subsampling in its 60 Hz variant and 4:2:0 subsampling in 50 Hz variant. Low chroma resolution of DV (compared to higher-end digital video formats) is a reason this format is sometimes avoided in chroma key
Chroma key
Chroma key compositing is a technique for compositing two images together. A color range in the top layer is made transparent, revealing another image behind. The chroma keying technique is commonly used in video production and post-production...
ing applications, though advances in chroma keying techniques and software made producing quality keys from DV material possible.
Audio can be stored in either of two forms: 16-bit Linear PCM stereo
Stereophonic sound
The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...
at 48 kHz sampling rate
Sampling rate
The sampling rate, sample rate, or sampling frequency defines the number of samples per unit of time taken from a continuous signal to make a discrete signal. For time-domain signals, the unit for sampling rate is hertz , sometimes noted as Sa/s...
(768 kbit/s per channel, 1.5 Mbit/s stereo), or four nonlinear 12-bit PCM channels at 32 kHz sampling rate (384 kbit/s per channel, 1.5 MBit/s for four channels). In addition, the DV specification also supports 16-bit audio at 44.1 kHz (706 kbit/s per channel, 1.4 Mbit/s stereo), the same sampling rate used for CD audio. In practice, the 48 kHz stereo mode is used almost exclusively.
Digital Interface Format
The audio, video, and metadata are packaged into 80-byte Digital Interface Format (DIF) blocks which are multiplexed into a 150-block sequence. DIF blocks are the basic units of DV streams and can be stored as computer fileComputer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
s in raw form or wrapped in such file formats as Audio Video Interleave
Audio Video Interleave
Audio Video Interleave , known by its acronym AVI, is a multimedia container format introduced by Microsoft in November 1992 as part of its Video for Windows technology. AVI files can contain both audio and video data in a file container that allows synchronous audio-with-video playback...
(AVI), QuickTime and Material Exchange Format (MXF). One video frame is formed from either 10 or 12 such sequences, depending on scanning rate, which results in a data rate of about 25 Mbit/s for video, and an additional 1.5 Mbit/s for audio. This results in a compression rate of 5 to 1. When written to tape, each sequence corresponds to one complete track.
Baseline DV employs unlocked audio. This means that the sound may be +/- ⅓ frame out of sync with the video. However, this is the maximum drift of the audio/video synchronization; it is not compounded throughout the recording.
Variants
Sony and Panasonic have created their proprietary versions of DV, which use the same compression scheme, but improve on robustness, linear editingLinear video editing
Linear video editing is a video editing post-production process of selecting, arranging and modifying images and sound in a predetermined, ordered sequence. Regardless whether captured by a video camera, tapeless camcorder, recorded in a television studio on a video tape recorder the content must...
Post-production
Post-production
Post-production is part of filmmaking and the video production process. It occurs in the making of motion pictures, television programs, radio programs, advertising, audio recordings, photography, and digital art...
capabilities, color rendition and raster size for use with professional video camera
Professional video camera
A professional video camera is a high-end device for creating electronic moving images...
s.
All DV variants except for DVCPRO Progressive are recorded to tape within interlaced video stream. Film-like frame rates are possible by using pulldown. DVCPRO HD supports native progressive format when recorded to P2 memory cards.
DVCPRO
DVCPRO, also known as DVCPRO25, is a variation of DV developed by Panasonic and introduced in 1995 for use in electronic news gatheringElectronic news gathering
ENG is a broadcasting industry acronym which stands for electronic news gathering. It can mean anything from a lone broadcast journalist reporter taking a single professional video camera out to shoot a story, to an entire television crew taking a production truck or satellite truck on location...
(ENG).
Unlike baseline DV, DVCPRO uses locked audio and 4:1:1 chroma subsampling for both 50 Hz and 60 Hz variants to reduce generation loss. Audio is available only in the 16-bit/48 kHz variant.
When recorded to tape, DVCPRO uses wider track pitch - 18 μm vs. 10 μm of baseline DV, which reduces the chances of dropout errors when video is recorded to tape. Two extra longitudinal tracks provide audio cue and for timecode control. Tape is transported 80% faster compared to baseline DV, resulting in shorter recording time. Long Play mode is not available.
DVCAM
In 1996 Sony responded with its own professional version of DV called DVCAM.Like DVCPRO, DVCAM uses locked audio, which prevents audio synchronization drift that may happen on DV If several generations of copies are made.
When recorded to tape, DVCAM uses 15 μm track pitch, which is 50% wider compared to baseline. Accordingly, tape is transported 50% faster (2.8cm/s) compared to DV (1.8cm/s), which reduces recording time by one third compared to DV. Because of the wider track and track pitch, DVCAM has the ability to do a frame accurate insert tape edit, while DV may vary by a few frames on each edit compared to the preview.
DVCPRO50
DVCPRO50 was introduced by Panasonic in 1997 for high-value electronic news gatheringElectronic news gathering
ENG is a broadcasting industry acronym which stands for electronic news gathering. It can mean anything from a lone broadcast journalist reporter taking a single professional video camera out to shoot a story, to an entire television crew taking a production truck or satellite truck on location...
(ENG) and digital cinema
Digital cinema
Digital cinema refers to the use of digital technology to distribute and project motion pictures. A movie can be distributed via hard drives, optical disks or satellite and projected using a digital projector instead of a conventional film projector...
, and is often described as two DV-codecs working in parallel.
The DVCPRO50 doubles the coded video data rate to 50 Mbit/s, cutting recording time in half compared to base DVCPRO. Chroma resolution is improved by using 4:2:2 chroma sampling.
DVCPRO50 is used in many productions where high definition video is not required. For example, BBC used DVCPRO50 to record high-budget TV series, such as Space Race
Space Race (TV series)
Space Race is a BBC docudrama series first shown in Britain on BBC2 between September and October 2005, chronicling the major events and characters in the American/Soviet space race up to the first landing of a man on the moon. It focuses on Sergei Korolev, the Soviet chief rocket designer, and...
(2005) and Ancient Rome: The Rise and Fall of an Empire
Ancient Rome: The Rise and Fall of an Empire
Ancient Rome: The Rise and Fall of an Empire is a 2006 BBC One docudrama series, with each episode looking at a different key turning point in the history of the Roman Empire.-Production:...
(2006).
A similar format, D-9
Digital-S
D-9 or Digital S as it was originally known, is a professional digital video videocassette format created by JVC in 1995. It is a direct competitor to Digital Betacam. Its name was changed to D-9 in 1999 by the SMPTE...
, offered by JVC, uses videocassettes with the same form-factor as VHS
VHS
The Video Home System is a consumer-level analog recording videocassette standard developed by Victor Company of Japan ....
.
Comparable Sony formats include Digital Betacam, launched in 1993, and MPEG IMX, launched in 2001.
DVCPRO Progressive
DVCPRO Progressive was introduced by Panasonic for news gathering, sports journalism and digital cinema. It offered 480 or 576 lines of progressive scan recording with 4:2:0 chroma subsampling and four 16-bit 48 kHz PCM audio channels. Like HDV-SD, it was meant as an intermediate format during the transition time from standard definition to high definition video.The format offered six modes for recording and playback: 16:9 progressive (50 Mbit/s), 4:3 progressive (50 Mbit/s), 16:9 interlaced (50 Mbit/s), 4:3 interlaced (50 Mbit/s), 16:9 interlaced (25 Mbit/s), 4:3 interlaced (25 Mbit/s).
The format has been superseded with DVCPRO HD.
DVCPRO HD
DVCPRO HD, also known as DVCPRO100 is a high-definition videoHigh-definition video
High-definition video or HD video refers to any video system of higher resolution than standard-definition video, and most commonly involves display resolutions of 1,280×720 pixels or 1,920×1,080 pixels...
format that can be thought of as four DV codecs that work in parallel. Video data rate depends on frame rate and can be as low as 40 Mbit/s for 24 frame/s mode and as high as 100 Mbit/s for 50/60 frame/s modes. Like DVCPRO50, DVCPRO HD employs 4:2:2 color sampling.
DVCPRO HD uses smaller raster size than broadcast high definition television: 960x720 pixels for 720p, 1280x1080 for 1080/59.94i and 1440x1080 for 1080/50i. Similar horizontal downsampling is used in many other HD formats. To maintain compatibility with HDSDI, DVCPRO100 equipment upsamples video during playback.
Variable framerates (from 4 to 60 frame/s) are available on VariCam camcorders. DVCPRO HD equipment is backward compatible
Backward compatibility
In the context of telecommunications and computing, a device or technology is said to be backward or downward compatible if it can work with input generated by an older device...
with older DV/DVCPRO formats.
When recorded to tape, DVCPRO HD uses the same 18 μm track pitch as other DVCPRO flavors. A long play variant, DVCPRO HD-LP, doubles the recording density by using 9 μm track pitch.
DVCPRO HD is codified as SMPTE 370M; the DVCPRO HD tape format is SMPTE 371M, and the MXF
MXF
Material eXchange Format is a container format for professional digital video and audio media defined by a set of SMPTE standards.- A brief summary of MXF :...
Op-Atom format used for DVCPRO HD on P2 cards is SMPTE 390M.
While technically DVCPRO HD is a direct descendant of DV, it is used almost exclusively by professionals. Tape-based DVCPRO HD cameras exist only in shoulder mount variant.
A similar format, Digital-S
Digital-S
D-9 or Digital S as it was originally known, is a professional digital video videocassette format created by JVC in 1995. It is a direct competitor to Digital Betacam. Its name was changed to D-9 in 1999 by the SMPTE...
(D-9 HD), is offered by JVC and uses videocassettes with the same form-factor as VHS
VHS
The Video Home System is a consumer-level analog recording videocassette standard developed by Victor Company of Japan ....
.
The main competitor to DVCPRO HD is HDCAM
HDCAM
HDCAM, introduced in 1997, is an High-definition video digital recording videocassette version of Digital Betacam, using an 8-bit DCT compressed 3:1:1 recording, in 1080i-compatible downsampled resolution of 1440×1080, and adding 24p and 23.976 PsF modes to later models...
, offered by Sony. It uses a similar compression scheme but at higher bitrate.
Progressive recording
Tape-based DV variants, except for DVCPRO Progressive, do not support native progressive recording, therefore progressively acquired video is recorded within interlaced video stream using pulldown. The same technique is used in television industry to broadcast movies. Progressive-scan DV camcorders for 60 Hz market record 24-frame/s video using 2-3 pulldown and 30-frame/s video using 2-2 pulldown. Progressive-scan DV camcorders for 50 Hz market record 25-frame/s video using 2-2 pulldown.Progressive video can be recorded with interlaced delivery in mind, in which case high-frequency information between fields is blended to suppress interline twitter. If the goal is progressive-scan distribution like Web videos, progressive-scan DVD-video
DVD-Video
DVD-Video is a consumer video format used to store digital video on DVD discs, and is currently the dominant consumer video format in Asia, North America, Europe, and Australia. Discs using the DVD-Video specification require a DVD drive and a MPEG-2 decoder...
or filmout
Film-out
Film-out is the process in the computer graphics, video production and filmmaking disciplines of transferring images or animation from videotape or digital files to a traditional film print...
, then no filtering is applied. Video recorded with 2-2 pulldown and no vertical filtering is conceptually identical to progressive segmented frame
Progressive segmented frame
Progressive segmented Frame is a scheme designed to acquire, store, modify, and distribute progressive-scan video using interlaced equipment and media....
.
Consumer-grade DV camcorders capable of progressive recording usually offer only 2-2 pulldown scheme because of its simplicity. Such a video can be edited as either interlaced or progressive and does not require additional processing aside of treating every pair of fields as one complete frame. Canon and Panasonic call this format Frame Mode, while Sony calls it Progressive Scan recording. 24 frame/s recording is available only on professional DV camcorders and requires pulldown removal if editing at native frame rate is required.
DVCPRO HD supports native progressive recording at 50 or 60 frame/s in 720p mode. To record video acquired at 24, 25 or 30 frame/s frame repeating is used. Frame repeating is similar to field repeating used in interlaced video, and is also called pulldown sometimes.
Magnetic tape
Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
. Tape is enclosed into cassettes of four different sizes: small, medium, large and extra-large. All DV cassettes use tape that is ¼ inch (6.35 mm) wide.
Small cassettes, also known as S-size or MiniDV cassettes, had been intended for amateur use, but have become accepted in professional productions as well. MiniDV cassettes are used for recording baseline DV, DVCAM as well as HDV
HDV
HDV is a format for recording of high-definition video on DV cassette tape. The format was originally developed by JVC and supported by Sony, Canon and Sharp...
.
Medium or M-size cassettes are used in professional Panasonic equipment and are often called DVCPRO tapes. Panasonic video recorders that accept medium cassette can play back from and record to medium cassette in different flavors of DVCPRO format; they will also play small cassettes containing DV or DVCAM recording, via an adapter.
Large or L-size cassettes are accepted by most standalone DV tape recorders and are used in many shoulder-mount camcorders. The L-size cassette can be used in both Sony and Panasonic equipment; nevertheless, they are often called DVCAM tapes. Older Sony decks would not play large cassettes with DVCPRO recordings, but newer models can.
Extra-large cassettes or XL-size have been designed for use in Panasonic equipment and are sometimes called DVCPRO XL. These cassettes are not widespread, only two models of standalone Panasonic tape recorders can accept them.
Technically, any DV cassette can record any variant of DV video. Nevertheless, manufacturers often label cassettes with DV, DVCAM, DVCPRO, DVCPRO50 or DVCPRO HD and indicate recording time with regards to the label posted. Cassettes labeled as DV indicate recording time of baseline DV; another number can indicate recording time of Long Play DV. Cassettes labeled as DVCPRO have a yellow tape-door and indicate recording time when DVCPRO25 is used; with DVCPRO50 the recording time is half, with DVCPRO HD it is a quarter. Cassettes labeled as DVCPRO50 have a blue tape-door and indicate recording time when DVCPRO50 is used. Cassettes labeled as DVCPRO HD have a red tape-door and indicate recording time when DVCPRO HD-LP format is used; a second number may be used for DVCPRO HD recording, which will be half as long.
Panasonic stipulated use of a particular magnetic tape formulation — Metal Particle (MP) — as an inherent part of its DVCPRO family of formats. Regular DV tape uses Metal Evaporate (ME) formulation, which was pioneered for use in Hi8 camcorders. Early Hi8 ME tape was plagued with excessive dropouts, which forced many shooters to switch to more expensive MP tape. After the technology improved, the dropout rate was greatly reduced, nevertheless Panasonic deemed ME formulation not robust enough for professional use. Tape-based Panasonic camcorders do not use small DV cassettes, effectively preventing use of ME tape.
DV cassettes can come with a memory-in-cassette (MIC) low capacity EEPROM memory chip. Using the I²C
I²C
I²C is a multi-master serial single-ended computer bus invented by Philips that is used to attach low-speed peripherals to a motherboard, embedded system, cellphone, or other electronic device. Since the mid 1990s, several competitors I²C ("i-squared cee" or "i-two cee"; Inter-Integrated Circuit;...
protocol, cameras and recording decks can record any data desired onto this chip like contents list, times and dates of recordings, camera settings or video thumbnails, taken each time the record button on the camcorder is pressed. MIC functionality is optional and is not widely used in consumer equipment. Most tapes available to consumers do not include the MIC chip. Almost every recorder and camcorder includes the hardware to read and write to the MIC, but the firmware does not always have the code to actually perform the task.
File-based media
With proliferation of tapeless camcorderTapeless Camcorder
A tapeless camcorder is a camcorder that does not use video tape for the digital recording of video productions as 20th century ones did. Tapeless camcorders record video as digital computer files onto random access data storage devices such as optical discs, hard disk drives and solid-state flash...
video recording, DV video can be recorded on optical disc
Optical disc
In computing and optical disc recording technologies, an optical disc is a flat, usually circular disc which encodes binary data in the form of pits and lands on a special material on one of its flat surfaces...
s, solid state flash memory
Flash memory
Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...
cards and hard disk drives and used as computer file
Computer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
s. In particular:
- Sony XDCAMXDCAMXDCAM is a a series of products for digital recording using random access solid-state memory media, introduced by Sony in 2003. Four different product lines — the XDCAM SD, XDCAM HD, XDCAM EX and XDCAM HD422 — differ in types of encoder used, frame size, container type and in...
family of cameras can record DV onto either Professional Disc or SxSSxSSxS is a flash memory standard compliant to the Sony and Sandisk-created ExpressCard standard. According to Sandisk and Sony, the cards have transfer rates of 800 Mbit/s and burst transfer rate of up to 2.5 Gbit/s...
memory cards. - Panasonic DVCPRO HD and AVC-Intra camcorders can record DV (as well as DVCPRO) onto P2P2 (storage media)P2 is a professional digital recording solid-state memory storage media format introduced by Panasonic in 2004, and especially tailored to electronic news-gathering applications. It features tapeless recording of DV, DVCPRO, DVCPRO25, DVCPRO50, DVCPRO-HD, or AVC-Intra streams on a solid-state...
cards. - Some Panasonic AVCHDAVCHDAVCHD is a file-based format for the digital recording and playback of high-definition video....
camcorders (AG-HMC80, AG-AC130, AG-AC160) record DV video onto Secure DigitalSecure DigitalSecure Digital is a non-volatile memory card format developed by the SD Card Association for use in portable devices. The SD technology is used by more than 400 brands across dozens of product categories and more than 8,000 models, and is considered the de-facto industry standard.Secure Digital...
memory cards. - JVC GY-HM750 records DV video onto either Secure Digital or SxS memory cards.
- Most DV and HDVHDVHDV is a format for recording of high-definition video on DV cassette tape. The format was originally developed by JVC and supported by Sony, Canon and Sharp...
camcorders can feed live DV stream over IEEE 1394 interfaceIEEE 1394 interfaceThe IEEE 1394 interface is a serial bus interface standard for high-speed communications and isochronous real-time data transfer, frequently used by personal computers, as well as in digital audio, digital video, automotive, and aeronautics applications. The interface is also known by the brand...
to an external file-based direct to disk recordingDirect to Disk RecordingDirect-to-disk recording refers to methods by which analog signals and digital signals such as digital audio and digital video are digitally recorded to optical disc recording technologies such as DVDs, and CD optical discs...
device.
Video is stored either as native DIF bitstream or wrapped into an audio/video container such as AVI
Audio Video Interleave
Audio Video Interleave , known by its acronym AVI, is a multimedia container format introduced by Microsoft in November 1992 as part of its Video for Windows technology. AVI files can contain both audio and video data in a file container that allows synchronous audio-with-video playback...
, QuickTime and MXF.
- DV-DIF is the raw form of DV video. The files usually have extensions *.dv or *.dif.
- DV-AVI is Microsoft's implementation of DV video file, which is wrapped into an AVI container. Two variants of wrapping are available: with Type 1 the multiplexed audio and video is saved into the video section of a single AVI file, with Type 2 video and audio are saved as separate streams in an AVI file (one video stream and one to four audio streams). This container is used primarily on Windows-based computers, though Sony offers two tapeless recorders, the HDD-based HVR-DR60 and the CompactFlash-based HVR-MRC1K, for use with DV/HDV camcorders that can record in DV-AVI format either making a file-based copy of the tape or bypassing tape recording altogether. Panasonic AVCHD camcorders uses Type 2 DV-AVI for recording DV video onto Secure Digital memory card.
- QuicktimeQuickTimeQuickTime is an extensible proprietary multimedia framework developed by Apple Inc., capable of handling various formats of digital video, picture, sound, panoramic images, and interactivity. The classic version of QuickTime is available for Windows XP and later, as well as Mac OS X Leopard and...
-DV is DV video wrapped into Quicktime container. This container is used primarily on Apple computers. - MXFMXFMaterial eXchange Format is a container format for professional digital video and audio media defined by a set of SMPTE standards.- A brief summary of MXF :...
-DV wraps DV video into MXF container, which is presently used on P2-based camcorders (Panasonic) and on XDCAM/XDCAM EX camcorders (Sony).
Connectivity
Nearly all DV camcorders and decks have IEEE 1394IEEE 1394 interface
The IEEE 1394 interface is a serial bus interface standard for high-speed communications and isochronous real-time data transfer, frequently used by personal computers, as well as in digital audio, digital video, automotive, and aeronautics applications. The interface is also known by the brand...
(FireWire, i.LINK) ports for digital video transfer. When video is captured onto a computer it is stored in a container file, which can be either raw DV stream, AVI, WMV or Quicktime. Whichever container is used, the video itself is not re-encoded and represents a complete digital copy of what has been recorded onto tape. If needed, the video can be recorded back to tape to obtain full and lossless copy of the original footage.
Some camcorders also feature a USB 2.0 port for computer connection. This port is usually used for transferring still images, but not for video transfer. Camcorders that offer video transfer over USB usually do not deliver full DV quality - usually it is 320x240 video (except for the Sony DCR-PC1000 camcorder and some Panasonic camcorders providing transfer of a full-quality DV stream via USB).
High end cameras and VTRs may have additional professional outputs such as SDI
Serial Digital Interface
Serial digital interface is a family of video interfaces standardized by SMPTE. For example, ITU-R BT.656 and SMPTE 259M define digital video interfaces used for broadcast-grade video...
, SDTI or analog component video
Component video
Component video is a video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video information that is transmitted or stored as three separate signals...
. All DV variants have a time code
Time code
A timecode is a sequence of numeric codes generated at regular intervals by a timing system.- Video and film timecode :...
, but some older or consumer computer applications fail to take advantage of it.
Usage
DV enabled filmmakers to produce movies inexpensively, and became strongly associated with independent filmIndependent film
An independent film, or indie film, is a professional film production resulting in a feature film that is produced mostly or completely outside of the major film studio system. In addition to being produced and distributed by independent entertainment companies, independent films are also produced...
and citizen journalism
Citizen journalism
Citizen journalism is the concept of members of the public "playing an active role in the process of collecting, reporting, analyzing and disseminating news and information," according to the seminal 2003 report We Media: How Audiences are Shaping the Future of News and Information...
.
The high quality of DV images, especially when compared to Video8 and Hi8 which were vulnerable to an unacceptable amount of video dropouts and "hits", prompted the acceptance by mainstream broadcasters of material shot on DV. The low costs of DV equipment and their ease of use put such cameras in the hands of a new breed of videojournalists
Video journalism
Video journalism or videojournalism is a form of broadcast journalism, where the production of video content in which the journalist shoots, edits and often presents his or her own material....
. Programs such as TLC's Trauma: Life in the E.R.
Trauma: Life in the E.R.
Trauma: Life in the E.R. is a medical-based television reality show that formerly ran on TLC from 1997 to 2002 and reruns are currently airing on Discovery Fit & Health...
and ABC News's Hopkins: 24/7 were shot on DV.
Professional television reporters such as Anderson Cooper
Anderson Cooper
Anderson Hays Cooper is an American journalist, author, and television personality. He is the primary anchor of the CNN news show Anderson Cooper 360°. The program is normally broadcast live from a New York City studio; however, Cooper often broadcasts live on location for breaking news stories...
and Katie Couric
Katie Couric
Katherine Anne "Katie" Couric is an American journalist and author. She serves as Special Correspondent for ABC News, contributing to ABC World News, Nightline, 20/20, Good Morning America, This Week and primetime news specials...
seem to shoot some of their stories themselves.
DVCPRO HD has become the preferred high definition standard of the BBC Factual. This format will be replaced with AVC-intra when it becomes viable.
Application software support
Most DV players, editors and encoders only support the basic DV format, but not its professional versions. DV Audio/Video data can be stored as raw DV data stream file (data is written to a file as the data is received over FireWire, file extensions are .dv and .dif) or the DV data can be packed into AVIAudio Video Interleave
Audio Video Interleave , known by its acronym AVI, is a multimedia container format introduced by Microsoft in November 1992 as part of its Video for Windows technology. AVI files can contain both audio and video data in a file container that allows synchronous audio-with-video playback...
container files. The DV meta-information is preserved in both file types.
Most Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
video software only supports DV packed into AVI containers, as they use Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
's avifile.dll, which only supports reading avi files. A few notable exceptions exist:
- Apple Inc.'s iMovieIMovieiMovie is a proprietary video editing software application which allows Mac, iPod Touch 4th generation, iPhone 4, iPhone 4S, and iPad 2 users to edit their own home movies. It was originally released by Apple in 1999 as a Mac OS 8 application bundled with the first FireWire-enabled consumer Apple...
: iMovie allows importing from HDV cameras since iMovie HD, which import in full quality, and DV cameras since iMovie 1, which decodes to half of the original quality. - Apple Inc.'s Final Cut ProFinal Cut ProFinal Cut Pro is a non-linear video editing software developed by Macromedia Inc. and then Apple Inc. The most recent version, Final Cut Pro X, runs on Mac personal computers powered by Mac OS X version 10.6.7 or later and using Intel processors...
: Final Cut Pro allows importing from DV and HDV cameras. It supports rewinding, fast-forwarding, pausing, stopping and playing from the computer. - Apple Inc.'s QuickTimeQuickTimeQuickTime is an extensible proprietary multimedia framework developed by Apple Inc., capable of handling various formats of digital video, picture, sound, panoramic images, and interactivity. The classic version of QuickTime is available for Windows XP and later, as well as Mac OS X Leopard and...
Player: QuickTime by default only decodes DV to half of the resolution to preserve processing power for editing capabilities. However, in the "Pro" version the setting "High Quality" under "Show Movie Properties" enables full resolution playback. - DVMP Basic & DVMP Pro: full decoding quality. Plays AVI (inc DVCPRO25 and DVCAM) and.dv files. Also displays the DV meta-information (e.g. timecode, date/time, f-stop, shutter speed, gain, white balance etc.)
- The VLC media playerVLC media playerVLC media player is a free and open source media player and multimedia framework written by the VideoLAN project.VLC is a portable multimedia player, encoder, and streamer supporting many audio and video codecs and file formats as well as DVDs, VCDs, and various streaming protocols. It is able to...
(Free softwareFree softwareFree software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
): full decoding quality - MPlayerMPlayerMPlayer is a free and open source media player. The program is available for all major operating systems, including Linux and other Unix-like systems, Microsoft Windows and Mac OS X. Versions for OS/2, Syllable, AmigaOS and MorphOS are also available. The Windows version works, with some minor...
(also with GUI under Windows and Mac OS X): full decoding quality - muvee TechnologiesMuvee Technologies' is a Singapore-based software company that produces automated video editing software and services for the Windows and Android operating systems....
autoProducer 4.0: Allows editing using FireWire IEEE 1394 - Quasar DV codec (libdv) - open source DV codec for Linux
- DVswitch - open source linear editor for DV streams, with live streaming capabilities
- DV Streamer - Shareware to use a DV drive as a backup tape driveTape driveA tape drive is a data storage device that reads and performs digital recording, writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability.A tape drive provides...
for PCs
Mixing tapes from different manufacturers
There is controversy over whether or not using tapes from different manufacturers can lead to dropouts. A research undertaken by Sony claimed that there was no hard evidence of the above statement. The only evidence claimed was that using ME tapes in equipment designed for MP tapes can cause tape damage and hence dropouts.The perpetuation of this controversy, based solely on hearsay, is misleading to end users. Sony
has done a significant amount of internal testing to simulate head clogs as a result of mixing tape lubricants, and has been unable to recreate the problem. Sony recommends using cleaning cassettes once every 50 hours of recording or playback. For those who are still skeptical, Sony recommends cleaning video heads with a cleaning cassette before trying another brand of tape.
Related video formats
In 1999 Sony retrofitted its 8-mm camcorders with DV encoding scheme, creating Digital8Digital8
Digital8 is a consumer digital recording videocassette for camcorders based on the 8 mm video format developed by Sony, and introduced in 1999.The Digital8 format is a combination of the older Hi8 tape transport with the DV codec...
. This allowed recording 40 minutes of DV video onto one-hour Video8/Hi8 cassette. Digital8 did not get as widespread acceptance as MiniDV and Sony discontinued Digital8 camcorders in 2007.
In 2003 a consortium of four companies - JVC
JVC
, usually referred to as JVC, is a Japanese international consumer and professional electronics corporation based in Yokohama, Japan which was founded in 1927...
, Sony, Canon
Canon Inc.
is a Japanese multinational corporation that specialises in the manufacture of imaging and optical products, including cameras, camcorders, photocopiers, steppers and computer printers. Its headquarters are located in Ōta, Tokyo, Japan.-Origins:...
and Sharp
Sharp Corporation
is a Japanese multinational corporation that designs and manufactures electronic products. Headquartered in Abeno-ku, Osaka, Japan, Sharp employs more than 55,580 people worldwide as of June 2011. The company was founded in September 1912 and takes its name from one of its founder's first...
- announced HDV
HDV
HDV is a format for recording of high-definition video on DV cassette tape. The format was originally developed by JVC and supported by Sony, Canon and Sharp...
, a format for recording and playback of high-definition video
High-definition video
High-definition video or HD video refers to any video system of higher resolution than standard-definition video, and most commonly involves display resolutions of 1,280×720 pixels or 1,920×1,080 pixels...
on a DV cassette tape. Initially marketed in the consumer video market, HDV quickly caught on with many professional users due to its low cost, portability and image quality acceptable for many professional productions. Most HDV camcorders are backwards compatible
Backward compatibility
In the context of telecommunications and computing, a device or technology is said to be backward or downward compatible if it can work with input generated by an older device...
with DV, meaning that they can play and record DV content. Many Sony HDV camcorders can play and record in DVCAM format.
External links
- Adam Wilt's DV page with in-depth technical information
- Technical Documentation on the storage of DV data in AVIAudio Video InterleaveAudio Video Interleave , known by its acronym AVI, is a multimedia container format introduced by Microsoft in November 1992 as part of its Video for Windows technology. AVI files can contain both audio and video data in a file container that allows synchronous audio-with-video playback...
files: http://abcavi.kibi.ru/docs/dv_data_avi.htm