XDCAM
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XDCAM is a tapeless professional video system introduced by Sony in 2003. The first two generations, XDCAM and XDCAM HD, use the Professional Disc as recording media. This disc is similar to Blu-ray Disc and holds either 23 GB of data (PFD23, single-sided) or 50 GB (PFD50, double-sided). The third generation, XDCAM EX, uses solid-state SxS cards instead. In September 2008, JVC announced its alliance with Sony to support the XDCAM EX format.
The XDCAM range includes cameras and decks which act as drop-in replacements for traditional VTRs allowing XDCAM discs to be used within a traditional tape-based workflow. These decks can also serve as random access computer drives for easy import of the video data files into non-linear editing (NLE) systems via IEEE 1394 and Ethernet.
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[edit] Compression methods
The XDCAM format uses multiple compression methods and container formats. Most standard definition XDCAM camcorders can switch from IMX to DVCAM with the flick of a switch, although both DVCAM-only and IMX-only models are available.
[edit] IMX (MPEG IMX)
IMX allows recording in standard definition, using MPEG-2 encoding at data rate of 30, 40 or 50 Megabits per second.
MPEG IMX does not use temporal compression, which makes it suitable as an editing format. At 50 Mbit/s it offers visual quality that is comparable to Digital Betacam[1], and is used for many TV productions, primarily ENG, where the practicality of a non-linear format outweighs Digital Beta's superior colour resolution (10-bit vs. IMX's 8-bit) and lower compression ratio. It is also a popular choice for Reality Television[2]
[edit] DVCAM (DV25)
DVCAM uses standard DV encoding, which runs at 25 Mbit/s, and is compatible with most DV editing systems.
[edit] XDCAM HD (XDCAM HD420, MPEG HD420)
XDCAM HD supports multiple quality-modes. The HQ-mode records at up to 35 Mbit/s (HQ mode), using variable bitrate (VBR) MPEG-2 long-GOP compression. The optional 18 Mbit/s (VBR) and 25 Mbit/s (CBR) modes offer increased recording-time, at the expense of motion-video quality.
[edit] XDCAM EX
Sony introduced XDCAM EX with the PMW-EX1 camera in November 2007. It offers a similar recording profile to XDCAM HD, but records on SxS memory cards. The codec is employed at either 25 Mbit/s CBR for SP mode (1440x1080), or 35 Mbit/s VBR for HQ mode (1920x1080). The recorded video is carried in an MP4 file wrapper, versus XDCAM's MXF file wrappers [3]. These differences meant that existing implementations of XDCAM HD codecs in editing applications were not functional with XDCAM EX when the product launched.
The PMW-EX1 camcorder employs three 1/2-inch "Exmor" CMOS sensors with over 2 million pixels, the camera was exhibited at the NAB (National Association of Broadcasters) 2007 show. It uses an 4:2:0 MPEG-2 Long-GOP codec when recording to SxS solid-state memory cards, but is 4:2:2 internally and a full 4:2:2 signal is present on the HD-SDI out connection. It is branded as a member of Sony's CineAlta family of production equipment. The EX1 offers variable framerate modes, from 1 to 60fps (1 to 30fps in 1080p)[4].
The PMW-EX1 made its debut in November 2007 with a street price of just under (US$) 6500.
In April 2008, Sony added a new interchangeable-lens camcorder, the PMW-EX3, to its XDCAM EX lineup. The internal components of the EX3 are identical to that of the EX1, but the EX3 is of shoulder mount design, implemented in a fashion much like the Canon XL series. The EX3 retails with a street price of around (US$) 8300.
In September 2008, JVC debuted a dockable SxS recording unit, the KA-MR100G. The MR100 docks with JVC Pro HD cameras (GY-HD200 and later models) between the battery mount and the camera. The MR100 records in XDCAM EX format through a 68 pin multi connector with the attached camera. The KA-MR100G has a MSRP of (US$) 3000. The KA-MR100G has been implemented in a retail camera package with the JVC GY-HM700 providing a complete solid state recording option for JVC users.
Sony unveiled, on October 21st 2009, two new members of XDCAM EX. The shoulder mount PMW-350 employs 3 chip of 2/3 inch CMOS image sensor and interchangeable lens mount. The second camera announced was an updated and modified version of PMW-EX1 which was named PMW-EX1R.
[edit] XDCAM HD422 (MPEG HD422)
Third generation XDCAM uses the 4:2:2 profile of the MPEG-2 codec, which has double the chroma-resolution of the previous generations. To accommodate the chroma-detail, the maximum video-bitrate has been increased to 50 Mbit/s.
In the second half of 2008, Sony released the PDW-700 camcorder and the PDW-HD1500 half-size deck. Also, Sony has expanded full XDCAM HD422 support to the PDW-U1 drive, through a free firmware-upgrade.
Despite its recent introduction, Sony's HD422 format has already been adopted into major video-productions.. Two primetime reality TV shows, CBS's Survivor and Fox's Cops[5], began on-location shooting of the 2008 fall-seasons using the aforementioned Sony equipment.
[edit] Proxy streams
The low resolution proxy is recorded in MPEG-4 at 1.5 Mbit/s (CIF resolution) with 64 kbit/s (8 kHz A-law, ISDN Quality) for each audio channel.
[edit] Recording media
[edit] Professional Disc (XDCAM and XDCAM HD)
The Professional Disc was chosen by Sony as its medium for professional non-linear video acquisition for a number of reasons, outlined in their white-paper Why Sony Adopted Professional Disc.
Essentially the Professional Disc format was deemed to be a suitable, cost effective and easy step forward. The discs are reliable and robust, suitable for field work (something which has previously been a problem with many disc-based systems). Additionally, the cost of media is comparable to existing professional formats.
[edit] SxS solid-state (XDCAM EX)
In 2008 Sony introduced a new recording media to their XDCAM range – SxS (pronounced "S-by-S"). It is a solid-state memory card implemented as an ExpressCard module. The first camera to use this media was the Sony PMW-EX1.
[edit] The Future of XDCAM
Sony has published an article at Sony Technology website [6] where Sony outlines the future of XDCAM. Among three goals of XDCAM, higher transfer speed and larger storage capacity seem reasonable, meanwhile Sony also indicates that a new generation of video compression algorithm will be developed for next generation of XDCAM. According to the development cycle of current XDCAM, the next generation of XDCAM (phase 4) should be available in around 2010.
[edit] References
- ^ Sony MPEG IMX Overview
- ^ HDTV Magazine
- ^ XDCAM System FAQs
- ^ PMW-EX1 Brochure
- ^ [http://news.sel.sony.com/en/press_room/b2b/broadcast_production/content_create_edit/release/34964.html Sony Tops 31,000 In Deliveries Of XDCAM Optical Disc Technology ]
- ^ "Technology - Broadcasting: Professional Disk" (in Jananese). http://www.sony.co.jp/SonyInfo/technology/technology/theme/xdcam_01.html. Retrieved 2009-03-17.
- Sony's official XDCAM web page
- Brochure for the Sony PMW-EX1
- Preliminary Brochure of Sony XDCAM HD422
- JVC Solid State Press Release
- JVC KA-MR100G Press Release
[edit] External links
- Sony's XDCAM introduction press release
- XDCAM pro user group
- XDCAM user group
- XDCAM EX training DVD
- XDCAM HD Training DVD
- XDcam EX Professional Training Camera Courses
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