XDCAM: Difference between revisions
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Revision as of 02:54, 12 December 2010
XDCAM is a a series of products for video recording using nonlinear 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 recording media.
None of the later products have made earlier product lines obsolete. Sony maintains that different formats within XDCAM family have been designed to meet different applications and budget constraints.[1]
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.
In September 2008, JVC announced its alliance with Sony to support the XDCAM EX format.
In August 2009, Convergent Design began shipping the nanoFlash Portable Recorder, which uses the Sony XDCAM HD422 codec.
Compression methods
The XDCAM format uses multiple compression methods and container formats.
Video is recorded with DV, MPEG-2 or MPEG-4 compression schemes. DV is used for standard definition video, MPEG-2 is used both for standard and high definition video, while MPEG-4 is used for proxy video.
Audio is recorded in uncompressed PCM form for all formats except proxy video, which uses A-Law compression.
Equipment that uses Professional Disc as recording media employs MXF container to store audio/video streams. Camcorders that record onto solid-state memory cards, use MP4 container for high definition audio/video, and DV-AVI container for DV video. JVC camcorders that use XDCAM EX recording format, are also capable of recording into QuickTime container besides using MP4 container.
Recording formats
MPEG IMX allows recording in standard definition, using MPEG-2 encoding at data rate of 30, 40 or 50 Megabits per second. Unlike most other MPEG-2 implementations, IMX uses intraframe compression with each frame having the same exact size in bytes to simplify recording onto videotape. Sony claims that at 50 Mbit/s it offers visual quality that is comparable to Digital Betacam[2] MPEG IMX is not supported in the XDCAM EX product line.
DVCAM uses standard DV encoding, which runs at 25 Mbit/s, and is compatible with most editing systems. Some camcorders that allow DVCAM recording, can record progressive-scan video.
MPEG HD is used in all product lines except for XDCAM SD. This format supports multiple frame sizes, frame rates, scanning types and quality modes. Depending on product line or a particular model, not all modes of this format may be available.
MPEG HD422 doubles the chroma-resolution compared to the previous generations of high definition XDCAM formats. To accommodate the improved chroma detail, video bitrate has been increased to 50 Mbit/s.
Proxy AV is used to record low resolution proxy videos. This format employs MPEG-4 video encoding at 1.5 Mbit/s (CIF resolution) with 64 kbit/s (8 kHz A-law, ISDN Quality) for each audio channel.
| Format name | Container | Video coding | Bit depth | Color sampling | Frame size | Frame rate and scanning type | Video bit rate, Mbit/s | Audio coding |
|---|---|---|---|---|---|---|---|---|
| DVCAM | MXF, DV-AVI |
DV | 8 | 4:2:0 | 720x576 | 25i, 25p | 25 (CBR) | PCM 4 ch/16 bit/48 kHz |
| 4:1:1 | 720x480 | 29.97i, 29.97p | ||||||
| MPEG IMX | MXF | MPEG-2 422P@ML | 8 | 4:2:2 | 720x576 | 25i, 25p | 30 (CBR), 40 (CBR), 50(CBR) | PCM 8 ch/16 bit/48 kHz, or 4 ch/24 bit/48 kHz |
| 720x480 | 29.97i, 29.97p, 23.98p | |||||||
| MPEG HD | MXF, MP4, MOV[1] |
MPEG-2 MP@HL | 8 | 4:2:0 | 1920x1080 | 29.97i, 25i, 29.97p, 25p, 23.98p | 35 (VBR) | PCM 4 ch/16 bit/48 kHz |
| 1440x1080 | 29.97i, 29.97p, 23.98p (pulldown), 25p | 18 (VBR), 25 (CBR), 35 (VBR) | ||||||
| 1280x720 | 59.94p, 29.97p, 23.98p, 50p, 25p | 25 (CBR), 35 (VBR), 19 (CBR)[2] | ||||||
| MPEG HD422 | MXF | MPEG-2 422P@HL | 8 | 4:2:2 | 1920x1080 | 29.97i, 25i, 29.97p, 25p, 23.98p | 50 (CBR) | PCM 8 ch/16 bit/48 kHz, or 4 ch/24 bit/48 kHz |
| 1280x720 | 59.94p, 50p, 23.98p (pulldown) | |||||||
| Proxy AV | ? | MPEG-4 | 8 | ? | CIF (50i - 352x288) | ? | 1.5 | A-Law 4 ch/8 bit/8 kHz |
^ 1 MOV (QuickTime) container is offered on JVC camcorders
^ 2 720p @ 19 Mbit/s is offered by JVC and is equivalent to HDV 720p
Recording media
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. This disc is similar to Blu-ray Disc and holds either 23 GB of data (PFD23, single-layer, rewritable), 50 GB (PFD50, dual-layer, rewritable) or 128 GB (PFD128QLW, quad-layer, write-once).
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.
SxS
In 2008 Sony introduced a new recording medium to their XDCAM range – SxS Pro (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.
In December 2009, Sony introduced the more affordable SxS-1. This unit is designed to have the same performance as the SxS Pro card however its life expectancy is shorter at an estimated 5 years of life when used every day to its full capacity.
Memory Stick
In 2010 Sony announced an adapter to use Memory Stick cards in XDCAM EX camcorders.
Secure Digital
In 2009 JVC released the HM100 and the HM700 camcorders, which record MPEG-2 video in Quicktime container (MOV) or in XDCAM EX container (MP4) directly on Secure Digital memory cards.
It is possible to use Secure Digital memory cards in Sony XDCAM EX camcorders as well via an adapter, though this solution is not officially supported by Sony.
The Future of XDCAM
Sony has published an article at Sony Technology website[3] 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.
References
- ^ "XDCAM HD Systems: for a new era of file-based HD production". Sony. Retrieved October 25, 2010.
- ^ Sony MPEG IMX Overview
- ^ "Technology - Broadcasting: Professional Disk" (in Japanese). Retrieved 2009-03-17.
{{cite web}}: CS1 maint: unrecognized language (link)
- 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