DVD recorder
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A DVD recorder (also known as a DVDR, mainly outside of the UK and Ireland), is an optical disc recorder that records video onto blank writeable DVD media. Such devices are available as either installable drives for computers or as standalone components for use in studios or home theatre systems.
As of March 1, 2007 all new tuner-equipped television devices manufactured or imported in the United States must include digital tuners. The US Federal Communications Commission has interpreted this rule broadly so as to include apparatus such as computer video capture cards, videotape recorders and standalone DVD recorders. NTSC DVD recorders are therefore undergoing a transformation, either adding a digital ATSC tuner or removing over-the-air television tuner capability entirely.[1]
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[edit] Technical information
Originally, DVD recorders supported one of three standards: DVD-RAM, DVD-RW (using DVD-VR), and DVD+RW (using DVD+VR), none of which are directly compatible. As a general rule, however, most current drives support both the + and - standards, while few support the DVD-RAM standard, which is not directly compatible with standard DVD readers.
Recording speed is generally denoted in values of X (similar to CD-ROM usage), where 1X in DVD usage is equal to 1.321 MB/s, roughly equivalent to a 9X CD-ROM. In practice, this is largely confined to computer-based DVD recorders, since standalone units generally record in real time, that is, 1X speed.
DVD recorders use a laser (usually 650 nm red) to read and write DVDs. The reading laser is usually not stronger than 5 mW, while the writing laser is considerably more powerful. The faster the writing speed is rated, the stronger the laser is. DVD burner lasers often peak at about 100-400 mW in continuous wave (some are pulsed). Some laser hobbyists have discovered ways to extract the laser diode from DVD burners.
[edit] Computer-based DVD drives
DVD recorder drives have become standard equipment in many, though not all, computer systems currently on the market, after being initially popularized by the Pioneer/Apple SuperDrive; aftermarket drives as of early 2007 can cost as little as $23 [1]. DVD recorder drives can be used in conjunction with DVD authoring software to create DVDs near or equal to commercial quality, and are also widely used for data backup and exchange. As a general rule, computer-based DVD recorders can also handle CD-R and CD-RW media; in fact, a number of standalone DVD recorders actually use drives designed for computers.
Most internal drives are designed with parallel ATA interfaces, with serial ATA becoming more readily available. External drives almost always use USB 2.0 or IEEE 1394, with eSATA becoming an option as well.
DVD recorder drives are required[by whom?]to respect DVD region codes when reading a disc, but do not impose a region code on written discs unless the code has specifically been written into the disc's content.
DVD duplication systems are generally built out of stacks of these drives, connected through a computer-based backplane.
[edit] Standalone DVD recorders
When the standalone DVD recorder first appeared on the Japanese consumer market in 1999, these early units were very expensive, costing between $2500 and $4000 USD. However, as of early 2007, DVD recorders from notable brands are selling for US$200 or €150 and less, with even lower "street prices". Early units supported only DVD-RAM and DVD-R discs, but the more recent units can record to all major formats DVD-R, DVD-RW, DVD+R, DVD+RW, and DVD+R DL. Some models now include hard disk-based digital video recorders (DVRs) to improve ease of use. Standalone DVD recorders generally have basic DVD authoring software built in; however, the appearance of the finished DVD is very basic and usually completely under the control of the unit.
Some believed that DVD recorders would supersede the VCR as the standard television-recording device; however, with the rise of DVR's and competing media formats like Blu-ray, the DVD recorder's future seems limited.
DVD recorders have several technical advantages over VCRs, including:
- Superior video and audio quality
- Easy-to-handle smaller form-factor disc media, and more durable than magnetic tape.
- Random access to video chapters without rewinding or fast-forwarding
- Onscreen multilingual subtitles and labeling not available on VCRs
- Reduced playback wear and tear
- High-quality digital copying, with little or no generation loss
- Improved editing, at least on rewritable media
- Playlisting
- No risk of accidentally recording over existing content or unexpectedly running out of space during recording
- Easy to find recordings due to chapter menus
- Not as reliable with DVD rewritables as DVDR's due to disks being more difficult to read and write on and unformattable and unwritable disks are likely to happens some of the time.
However, an inconvenience exists in which DVDs recorded with DVD recorders must be finalized to view in other DVD players. (This disadvantage does not apply to DVD-RAM or DVD+RW discs, which require no finalization due to their 'random access' nature.) Also, the implementation of MPEG-2 compression used on most standalone DVD recorders is required to compress the picture data in real time, producing results that may not be up to the standard of professionally rendered DVD video, which can take days to compress.
The United States is converting its over-the-air television broadcasts to digital "ATSC" in June 2009, however this will have very limited impact in ending the need for DVD recorders to perform realtime MPEG-2 encoding or transcoding. The only setup where ATSC could conceivably eliminate MPEG-2 encoding/transcoding in a DVD recorder would be where an antenna is hooked directly into a DVD recorder that has an integrated ATSC tuner. Even then however, the DVD recorder will have to transcode the ATSC MPEG-2 into DVD-Video-legal MPEG-2 if the ATSC MPEG-2 stream isn't already DVD-Video-compatible. This would require transcoding for all high-definition broadcasts and some if not all standard-definition broadcasts. The same general situation applies to digital cable service; only DVD recorders with integrated digital cable ("QAM") tuners can possibly avoid transcoding, and then only if the digital cable system is already sending a DVD-Video-compatible MPEG-2 stream, which again requires transcoding of all HD content and some if not all SD content. All other setups (digital cable box's analog outputs to DVD recorder, satellite box's analog outputs to DVD recorder, DVD recorder tuning and recording analog cable channels which are still permitted after 2/2009, etc.) usually always involve an analog step with MPEG-2 encoding being necessary inside the DVD recorder.
A number of manufacturers have combined DVD recorders with hard disk-based digital video recorders, allowing for simple recording to large fixed disks, and the ability to spool these recordings off the DVD at a later date.
[edit] ATSC standalone DVD recorders
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As a result of the North American digital switchover, tuner-equipped devices manufactured or imported into the United States are now required by the US Federal Communications Commission to include digital tuners.
This has caused most new VHS recorders to be implemented as DVD/VCR combo units, or to be manufactured without tuners. The US requirement of ATSC compatibility forces inclusion of MPEG-2 decoding hardware, which is already part of all DVD players but which otherwise would not have been needed in an analog-only VCR.
An ATSC-capable DVD unit can also serve as a more-powerful alternative to digital television adapters, which allow DTV reception with older NTSC analog televisions. The DVD recorders offer additional capabilities, such as automated VCR-style timeshifting of programming and a variety of output formats, that are deliberately not included in the most common mass-market US ATSC converters.
Unlike the more common digital television adapter boxes, DVD recorder units are able to tune both analog and digital signals - an advantage when receiving low-power television and foreign signals. Some, however, do suffer from many of the same design limitations as the less costly converter boxes, including poorly-designed signal strength meters, incomplete display of broadcast program information, incompatibility with antenna rotators or CEA-909 smart antennas and inability to add digital channels without wiping out all existing channels and rescanning the entire band. A DVD recording of an over-the-air HDTV broadcast is at DVD resolution, which is inferior to the original broadcast with 720p or 1080i resolution. Some units also provide limited USB or flash memory interface capability, often only supporting viewing of digital camera still photos or playback of MP3's with no ability to write video to these media. Do not rely on or trust dvd rewriteable disks on especially a SAMSUNG based stadalone dvd recorder due to dvd-vr formatting, recording and resetting to zero material on disk after failed autoformatting. Normal DVD single use disks are more reliable than before. Even if everything is done right or a ok; there known information in the computer world that dvd burners including Blu-ray Disc cannot consistently burn disks more than 20 full uses or constant heavy usage for one year before problems arise and the same is in all probability true for dvd recorders at present.[citation needed]
[edit] MiniDVD recorders
8 cm miniDVDs are widely used on some digital camcorders, primarily those meant for a consumer market ("point and shoot"); such discs are usually playable on a full-sized DVD player, but may not record on a full-sized DVD recorder system. Though popular for their convenience (in the manner of VHS-C), DVD camcorders are not considered suitable for more than casual use due to the much higher level of compression used compared to MiniDV and the difficulty of editing MPEG-2 video.
[edit] See also
- Digital video
- Digital video recorder (DVR)
- DVD
- Optical disc recorder
- Videocassette recorder (VCR, video recorder)
- Video scaler "Upconverting"
[edit] References
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