XDCAM
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XDCAM is 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[citation needed], and is still suitable 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[citation needed].
[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 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[1], 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 with 64 kbit/s for each audio channel. The CIF resolution is used for the proxy recordings.
[edit] Recording media
[edit] Professional Disc (XDCAM and XDCAM HD)
- See also: Professional Disc
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)
A second XDCAM implementation has been developed by Sony called XDCAM EX. Implemented in the PMW-EX1 camera, it offers a similar recording profile to XDCAM HD, but records on SxS memory cards. The codec is employed at either 25 Mbit/s for SP mode (1440x1080), or 35 Mbit/s for HQ mode (1920x1080). The recorded media is carried in an MP4 file wrapper, versus XDCAM's MXF file wrappers[citation needed]. These differences mean that existing implementations of XDCAM HD codecs in editing applications are not functional with XDCAM EX[citation needed]. However, the EX1's SP mode does retain compatibility as it matches that of HDV (1440x1080 @ 25 Mbit/s CBR). The 35Mbit "HQ" implementation is Variable bitrate.
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 MPEG-2 long-GOP codec when recording to SxS solid-state memory cards, and a 4:2:2 color ratio can be achieved by using a HD-SDI out connection[citation needed]. It is branded as a member of Sony's CineAlta family of production equipment. The EX1 offers variable framerate modes[citation needed], from 1 to 60fps (1 to 30fps in 1080p).
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.
[edit] The Future of XDCAM
Sony has published an article at Sony Technology website[citation needed], 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
- official information about XDCAM technology and the future
- Sony's official XDCAM web page
- Brochure for the Sony PMW-EX1
- Preliminary Brochure of Sony XDCAM HD422
[edit] External links
- Sony's XDCAM introduction press release
- XDCAM pro user group
- XDCAM EX training DVD
- XDCAM HD Training DVD
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