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What is DVD?
DVD was not really supposed to be an acronym. But people have begun to refer to them as Digital Versatile Discs. DVD is the successor to audio CD, CD-ROM, VHS tape and laser disc. DVD is the next generation of five-inch digital optical disc technology. It is a revolution in digital media.
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What is the capacity of a DVD and how does it compare to a CD, a CD-ROM or a computer floppy disc?
A single layer DVD (DVD 5) has a capacity of 4.7 gigabytes with double sided DVD having approximately twice as much. A 4.7 GB DVD will store as much music as seven CDs (9 hours of music). It has seven times the capacity of a CD-ROM and is the equivalent of 3,400 floppy discs.
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What is the capacity of a double-layer DVD?
DVD can use two layers, separated by half the width of a human hair. The laser can read the first layer of pits, then pass through a semi-transparent coating to play back the second layer. The dual layer design boosts the storage capacity to 8.5 gigabytes (DVD 9) for single sided media or 17 gigabytes (DVD 18) for two sides. Stated another way, a two sided double layer DVD has the potential to store:
- all three Godfather movies
- all the original Beatles albums plus those of John Lennon
- a stack of novels taller than the Empire State Building
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How long will DVD movies play before I have to turn the disc over?
At an average bit rate of 4.5mbs, a single sided DVD disc has the playback capability of 133 minutes of the highest quality audio and video images. That's nearly 92% of all Hollywood titles ever made!
In fact, a dual layer DVD disc can provide up to 4 hours of the highest quality audio and video... on a single side of the disc!
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Will DVD discs wear out?
No. With proper care and handling (just like audio CDs), the picture quality of the DVD disc is consistent from the first play to the thousandth play.
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What is an Aspect Ratio?
Aspect ratio refers to the ratio of width to height of a television set. Traditional television sets have a 4:3 aspect ratio. Widescreen television sets have a 16:9 aspect ratio. Traditional television sets are almost square in appearance; widescreen displays are more rectangular.
DVD has the unique capability to display movies in 3 different ways: Widescreen, which provides a special "anamorphic video" signal that, when processed by a widescreen television set, fills the entire screen and delivers optimum picture quality . There is a Pan and Scan version that fills the screen of traditional 4:3 television sets with an entire picture, much like watching network movies, and then there is a special letterbox mode that provides horizontal bands at the top and bottom to, in essence, create a widescreen picture in a traditional television set.
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Will it play Audio Compact Discs?
Yes. Many DVD-ROM devices are able to play Compact Discs, CD-ROM's, DVD movies and DVD-ROM software.
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Does a DVD store data in a similar manner to a CD?
DVDs store data in a manner similar to CDs: microscopic data-storing pits are embedded in a disc during production and, when played, a laser beam reflects light from the surface, detecting pitted areas and converting the information to an electrical signal. CDs and CD-ROMs use an infrared laser to read pits on a disc, while DVD uses a laser that emits light in the shorter red wavelength. This "thinner" beam can read smaller pits, which means more data can be packed on a disc. Additionally, while today's optical discs use a single layer of encoded information, DVD can use up to four layers. Storage potential also increases due to the fact that each disc can be double sided as a result of a bonding process that seals two 0.6mm discs back to back.
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Can I take advantage of the special features on the discs?
Yes. All DVD players are equipped to provide simple access to all DVD features including: multiple aspect ratios, multiple languages, multiple subtitles, multiple camera angles, parental control, and multi-story lines.
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What are the computer implications of DVD?
For multimedia computers, DVD capacity means an end to grainy, jerky snippets of video, replacing them with smooth, real-time MPEG-2 compressed video and discrete multi-channel surround sound. Software created for DVD-ROM drives will offer new levels of interactivity through increased data capacity and speed. Many multimedia developers will no longer be frustrated by the limited capacity of CD-ROMs with the advent of DVD-ROM.
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What is MPEG-2 and how does it differ from MPEG-1?
MPEG-2 is a more powerful and faster compression scheme than MPEG-1. MPEG-2 conserves storage space by scanning successive frames and pixels within a frame for repetitious information. Only information that changes from pixel to pixel or frame to frame is re-encoded digitally. Static scenes, such as two people talking against an unmoving blue sky, require far less memory than fast moving action scenes. MPEG-2 encoding takes advantage of the fact that some scenes/passages are more difficult than others to compress (variable bit rate or VBR) and require more data while other scenes/passages are less difficult and less data is necessary.
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What is the difference between the DVD video player, the DVD-ROM drive and the DVD-audio player?
A DVD video player is a component device designed to play video titles such as movies, music videos and instructional videos. It offers high quality video and audio with limited interactive capabilities. A DVD-ROM drive connects to your computer and offers similar capabilities to the DVD video player with additional complex features programmed to run on the computer itself. A DVD audio player is yet to be defined but will offer higher quality audio than today's Compact Disc.
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What is video encoding and how does video compression technology work?
In order to fit all the information necessary to reproduce broadcast quality video on a single disc, it is necessary to be clever about how much, and what type, of data is stored on the disc. MPEG-2 is a type of video compression system that takes a digital video signal and discards certain types of information in the signal and records the left over information, all the while retaining enough information about the discarded data to reconstruct the original signal when the compressed signal is decoded. Since a special decoder is required to view the video signal, the process of creating that compressed signal is often referred to as encoding.
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What is audio encoding?
Like video encoding, audio signals can also be compressed so that they take up much less space than they would normally. However, while the philosophy is the same as video encoding, much of the process is specific to audio and requires specialized hardware and software and is often done in a completely separate environment from the video encoding.
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What is authoring?
DVD offers certain functionality such as skipping to various places on the disc via elaborate menus, selecting the desired soundtrack or subtitles, playing back the director's cut or the edited version, or looking at out takes and trailers for the movie. In the authoring process, all the various audio and video elements, still pictures, menus and subtitles must be assembled along with navigation commands to create the finished disc image that ends up on the actual DVD itself. Depending on the complexity of the title, this process can take from hours to days, even weeks to complete and test.
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Just how good is the DVD picture?
Based upon pixel resolution, color resolution, color detail, black level reproduction and a virtual lack of color noise, the DVD picture is nearly 3 times better than conventional VHS.
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Is DVD better than Laserdisc?
Yes, DVD is component video, Laserdisc is composite video. The DVD picture is characterized by more color detail, and color resolution and contains significantly less NTSC picture artifacts than Laserdisc. It is generally accepted that a Laserdisc is capable of producing 400-425 horizontal lines of resolution. A DVD disc produces in the range of 480-500 horizontal lines of resolution. A single sided 5" dual layer DVD disc can store up to 4 hours of the highest quality audio and video images. A 12" Laserdisc can only store 60 minutes on a single side. And DVD movies will play on your computer equipped with a DVD-ROM device. DVD is the realization of true cross-platform multimedia.
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How does the audio quality compare to a laser disc or a VHS cassette?
DVD has Dolby Digital AC-3 encoding to enhance audio quality. The listener of DVD will be able to enjoy six discrete, digitally separated channels for lifelike surround sound. One DVD disc movie might come with audio tracks in up to eight different languages or with 32 different sets of subtitles.
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What is Dolby Digital AC-3 encoding?
Dolby Digital AC-3 is a technology developed by Dolby Laboratories that allows us to store much more CD-quality audio in much less space than traditional CD-audio. Dolby Digital also allows us to present soundtracks in the home that offer a complete surround sound experience, just like at the movie theatre, with left, centre, and right channels, stereo surround channels and a subwoofer. For the viewers without the most advanced surround systems in their homes, Dolby Digital offers the same soundtracks optimized for mono, stereo or Dolby Pro Logic reproduction.
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What is the difference between DVD and Video CD, CD-I, CD-XA and enhanced CD?
DVD is the most sophisticated, highest quality audio and video format today. It offers quality far surpassing Video CD (MPEG-1 technology) on a very similar physical format, higher quality and interactivity than CD-I, greater data storage and speed than CD-ROM and more flexibility than CD-XA or enhanced CD. DVD sets a new standard for consumer media.
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Is DVD better than DSS?
Yes. DVD is mastered as CCIR601 4:2:2 digital component video and utilizes 100% MPEG-2 data reduction. DSS, on the other hand, is 4:1:1 digital component video and features scalable compression schemes that vary from MPEG-1 to MPEG-2. In fact, the digital component video signal of DVD has the capability to rival the best studio masters.
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What are "regional codes," "country codes," or "zone locks"?
Motion picture studios want to control the home release of movies in different countries because theater releases aren't simultaneous (a movie may come out on video in the U.S. when it's just hitting screens in Europe). Also, studios sell distribution rights to different foreign distributors and would like to guarantee an exclusive market. Therefore they have required that the DVD standard include codes that can be used to prevent playback of certain discs in certain geographical regions. Each player is given a code for the region in which it's sold. The player will refuse to play discs that are not allowed in that region. This means that discs bought in one country may not play on players bought in another country.
Regional codes are entirely optional for the maker of a disc. Discs without codes will play on any player in any country. It's not an encryption system, it's just one byte of information on the disc that the player checks. Some studios originally announced that only their new releases will have regional codes, but so far almost all releases play in only one region. Region codes are a permanent part of the disc, they won't "unlock" after a period of time.
There are 8 regions (also called "locales"). Players and discs are identified by the region number superimposed on a world globe. If a disc plays in more than one region it will have more than one number on the globe.
1: Canada, U.S., U.S. Territories
2: Japan, Europe, South Africa, Middle East (including Egypt)
3: Southeast Asia, East Asia (including Hong Kong)
4: Australia, New Zealand, Pacific Islands, Central America, Mexico, South America, Caribbean
5: Former Soviet Union, Indian Subcontinent, Africa (also North Korea, Mongolia)
6: China
7: Reserved
8: Special international venues (airplanes, cruise ships, etc.)
Some players can be modified to play discs regardless of their regional codes. This usually voids the warranty. Some discs, such as those from Buena Vista/Touchstone/Miramax, MGM/Universal, and Polygram contain program code that checks for the proper region. These "smart discs" won't play on code-free players that have their region set to 0, but they can be played on code-switchable players that allow you to change the region using the remote control. They may also not work on "auto-switching" players that recognize and match the disc region.
Regional codes also apply to DVD-ROM systems, but are allowed for use only with DVD-Video discs, not DVD-ROM discs containing computer software. Computer playback systems check for regional codes before playing movies from a DVD-Video. Newer "RPC2" DVD-ROM drives let you change the region code several times. Once a drive has reached the limit (usually 5 changes) it can't be changed again unless the vendor or manufacturer resets it.
Information and software for circumventing DVD-ROM region restrictions are available from various Internet sites. Regional codes do not apply to DVD-Audio.
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What are the copy protection issues?
There are four forms of copy protection used by DVD:
1) Analog CPS (Macrovision)
Videotape (analog) copying is prevented with a Macrovision 7.0 or similar circuit in every player. The general term is APS (Analog Protection System). Computer video cards with composite or s-video (Y/C) output must also use APS. Macrovision adds a rapidly modulated colorburst signal ("Colorstripe") along with pulses in the vertical blanking signal ("AGC") to the composite video and s-video outputs. This confuses the synchronization and automatic-recording-level circuitry in 95% of consumer VCRs. Unfortunately, it can degrade the picture, especially with old or nonstandard equipment. Macrovision may show up as stripes of color, distortion, rolling, black & white picture, and dark/light cycling. Macrovision creates severe problems for most line doublers. Macrovision is not present on analog component video output of early players, but is required on newer players (AGC only, since there is no burst in a component signal). The discs contain "trigger bits" in the header of each sector telling the player whether or not to enable Macrovision AGC, with the optional addition of 2-line or 4-line Colorstripe. This allows fine control over which sections are copy protected. The producer of the disc decides what amount of copy protection to enable and then pays Macrovision royalties accordingly (a few cents per disc). Just as with videotapes, some DVDs are Macrovision-protected and some aren't.
2) CGMS
Each disc also contains information specifying if the contents can be copied. This is a "serial" copy generation management system (SCMS) designed to prevent copies or copies of copies. The CGMS information is embedded in the outgoing video signal. For CGMS to work, the equipment making the copy must recognize and respect the CGMS. The analog standard (CGMS/A) encodes the data on NTSC line 21 (in the XDS service). The digital standard (CGMS/D) is not yet finalized, but will apply to digital connections.
3) Content Scrambling System (CSS)
Because of the potential for perfect digital copies, paranoid movie studios forced a deeper copy protection requirement into the DVD-Video standard. Content Scrambling System (CSS) is a form of data encryption to discourage reading media files directly from the disc. Most players have a decryption circuit that decodes the data before displaying it. No unscrambled digital output is allowed until work in progress for secure digital connections is finished. On the computer side, DVD-ROM drives and video display/decoder hardware or software exchange encryption keys so that the video is decrypted just before being displayed by the encoder. This means that many DVD-ROM drives and video display boards have extra hardware (and cost) for movie copy protection. All DVD-ROM drives are required to support regional management in conjunction with CSS. Some drives may allow the user to reset the region a limited number of times; other drives will self-program after a certain number of movies have been played. Makers of equipment used to display DVD-Video (drives, chips, display boards, etc.) must license CSS. There is no charge for a CSS license, but it's currently a lengthy process, so it's recommended that interested parties apply as soon as possible. Near the end of May 1997, CSS licenses were finally granted for software decoding.
4) Digital Copy Protection System (DCPS)
In order to provide for digital connections between components without allowing perfect digital copies, five digital copy protection systems have been proposed to CEMA. The frontrunner is DTCP (digital transmission content protection), which focuses on IEEE 1394/FireWire but can be applied to other protocols. The draft proposal (called 5C, for the five companies that developed it) was made by Intel, Sony, Hitachi, Matsushita, and Toshiba in February 1998. In December 1998, Sony announced the development of a DTCP chip planned for release in spring 1999. Under DTCP, devices that are digitally connected, such as a DVD player and a digital TV or a digital VCR, exchange keys and authentication certificates to establish a secure channel. The DVD player encrypts the encoded audio/video signal as it sends it to the receiving device, which must decrypt it. This keeps other connected but unauthenticated devices from stealing the signal. No encryption is needed for content that is not copy protected. Security can be "renewed" by new content (such as new discs or new broadcasts) and new devices that carry updated keys and revocation lists (to identify unauthorized or compromised devices). A competing proposal, XCA (extended conditional access), from Zenith and Thomson, is similar to DTCP but can work with one-way digital interfaces (such as the EIA-762 RF remodulator standard) and uses smart cards for renewable security. Other proposals have been made by MRJ Technology, NDS, and Philips. In all five proposals, content is marked with CGMS-style flags of "copy freely", "copy once," "don't copy," and sometimes "no more copies". Digital devices that do nothing more than reproduce audio and video will be able to receive all data (as long as they can authenticate that they are playback- only devices). Digital recording devices are only able to receive data that is marked as copyable, and they must change the flag to "don't copy" or "no more copies" if the source is marked "copy once." Digital CPS is designed for the next generation of digital TVs, digital receivers, and digital video recorders. It will require new DVD players with digital connectors (such as those on DV equipment). These new products won't appear before mid 1999. Since the encryption is done by the player, no changes are needed to the existing disc format.
Movie studios and consumer electronics companies want to make it illegal to defeat DVD copy protection, and have promoted legislation in the U.S. and other countries. The result is the World Intellectual Property Organization (WIPO) Copyright Treaty and the WIPO Performances and Phonograms Treaty (December 1996) and the compliant U.S. Digital Millennium Copyright Act. (DMCA), passed into law in October 1998. A co-chair of the legal group of the copy protection committee stated, "in the video context, the contemplated legislation should also provide some specific assurances that certain reasonable and customary home recording practices will be permitted, in addition to providing penalties for circumvention." It's not at all clear how this might be "permitted" by a player or by studios that set the "don't copy" flag on all their discs.
DVD-ROM drives and computers, including DVD-ROM upgrade kits, are required to support Macrovision, CGMS, and CSS. PC video cards with TV outputs that don't support Macrovision will not work with encrypted movies. Computers with IEEE 1394/FireWire connections must support the final DCPS standard in order to work with other DCPS devices. Every DVD-ROM drive must include CSS circuitry to establish a secure connection to the decoder hardware or software in the compute, although CSS can only be used on DVD-Video content. Of course, since a DVD-ROM can hold any form of computer data, other encryption schemes can be implemented.
The first three forms of copy protection are optional for the producer of a disc. Movie decryption is also optional for hardware and software playback manufacturers: a player or computer without decryption capability will only be able to play unencrypted movies. DCPS is performed by the DVD player, not by the disc developer.
These copy protection schemes are designed only to guard against casual copying (which the studios claim causes billions of dollars in lost revenue). The goal is to "keep the honest people honest." Even the people who developed the copy protection standards admit that they won't stop well-equipped pirates. There are inexpensive devices that defeat analog copy protection, although only a few work with the new Macrovision Colorstripe feature. These devices go under names such as Video Clarifier, Image Stabilizer, and CopyMaster.
The Data-Hiding Sub-Group (DHSG) of the industry's Copy Protection Technical Working Group (CPTWG) is evaluating watermarking proposals. The original seven watermarking proposals that were merged into three: IBM/NEC, Hitachi/Pioneer/Sony, and Macrovision/Digimarc/Philips. On February 17, 1999, the first two groups combined to form the "Galaxy Group" and merged their technologies into a single proposal. Watermarking, which will be added to DVD at some point, permanently marks each digital video frame with noise that is supposedly visually undetectable. Watermark signatures can be recognized by video playback and recording equipment to prevent copying, even when the video is transmitted via digital or analog connections or is subjected to video processing. New players and other equipment will be required to support watermarking, but the DVD Forum intends to make watermarked discs compatible with existing players. There are reports that the watermarking technique used by Divx causes visible "raindrop" or "gunshot" patterns. The problem seems to have been solved with newer discs.
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What about DVD-Audio or Music DVD?
When DVD was released in 1996 there was no DVD-Audio format, although the audio capabilities of DVD-Video far surpassed CD. The DVD Forum sought additional input from the music industry before defining the DVD-Audio format. A draft standard was released by the DVD Forum's Working Group 4 (WG4) in January 1998, and version 0.9 was released in July. The final DVD-Audio 1.0 specification was approved in February 1999 and released in March. DVD-Audio products are available now. DVD-Audio is a separate format from DVD-Video. DVD-Audio discs can be designed to work in DVD-Video players, but its possible to make a DVD-Audio disc that won't play at all in a DVD-Video player, since the DVD-Audio specification includes new formats and features, with content stored in a separate "DVD-Audio zone" on the disc (the AUDIO_TS directory) that DVD-Video players never look at. New DVD-Audio players are needed, or new "universal players" that can play both DVD-Video and DVD-Audio discs.
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WHAT SHOULD I LOOK FOR WHEN APPROVING MY DISCFACE PROOFS?
Overall:
* Be sure all type and fonts are correct.
* Check for typos and misspelled words.
* Make sure that all the artwork is positioned in the template, as you wish it to be printed.
Discface proofs:
* Please note that everything in black on each "plate" will print as the ink color indicated above each plate and everything in white on each "plate" will knock out to whatever is underneath that plate.
* If your discface involves a background flood of white, make sure that this is indicated on your proof.
* If your discface involves a gradient, it is important to note that gradients are probably the most unpredictable aspect of silk-screen printing. When gradients are silk-screened, it can produce significant tonal jumps, creating bad transition areas instead of the gradual tone shifts that can be seen on your monitor.
* Be sure the center hole is the correct size.
* Keep in mind that our standard center hole size on disc faces is 26 mm in diameter. We can print to a smaller size diameter upon request, although it will add to your turn-time. Please consult with your CSR if you're interested.
* When viewing the discface proof, be sure to consider whether some of the disc elements (like the clear region, the stacking ring, and the highly reflective matrix hub) will have any undesirable effects on the final discface artwork.
* If you are uncertain about any of the above details on your proof, please be sure to point this out to your CSR prior to approval of the proof.
CMYK silk-screen discface proofs:
* If you have opted to do a CMYK silk-screen image on your discface, it is important to note that silk-screen printing will not yield the same results as offset printing. Items that are offset printed, such as jewel case inserts, traycards, and cardboard packaging, are printed at 150 - 175 lpi. Our standard line screen for silk-screening discface artwork is 110 lpi. If you are printing an image on the CD face that needs to match up with the same or similar image on your print-work / packaging you might want to consider having your discface printed offset rather than silk-screened. (Note: For CD orders, offset discface printing will be more expensive.)
* Be sure the center hole is the correct size.
* Keep in mind that our standard center hole size on disc faces is 26 mm in diameter. We can print to a smaller size diameter upon request, although it will add to your turn-time. Please consult with your CSR if you're interested.
* When viewing the disc proof, be sure to consider whether some of the disc elements (like the clear region, the stacking ring, and the highly reflective matrix hub) will have any undesirable effects on the final discface artwork.
* If you are uncertain about any of the above details on your proof, please be sure to point this out to your CSR prior to approval of the proof.
CMYK offset discface proofs:
* If your disc face involves a background flood of white, make sure that this is indicated on your proof.
* Be sure the center hole is the correct size.
* Keep in mind that our standard center hole size on disc faces is 26 mm in diameter. We can print to a smaller size diameter upon request, although it will add to your turn-time. Please consult with your CSR if you're interested.
* When viewing the disc proof, be sure to consider whether some of the disc elements (like the clear region, the stacking ring, and the highly reflective matrix hub) will have any undesirable effects on the final discface artwork.
* If you are uncertain about any of the above details on your proof, please be sure to point this out to your CSR prior to approval of the proof.
For PDF/jpeg proofs:
Overprint objects might not display properly on a PDF proof. Please double-check your files.
It is often helpful, when viewing the PDF in Acrobat Professional to select the "Overprint Preview" (or "Separation Preview" in Acrobat 6.0) viewing option to double check this detail.
Because PDF proofs (as well as jpeg proofs) are viewable only on a computer monitor, and no 2 monitors preview colors the same, colors in these proofs may vary from the final printed product due to the difference in color modes between what you see on your monitor and the ink on paper. By approving a PDF or jpeg proof, you are agreeing to accept color variances on press.
If color variance is an issue, you may choose to get a higher end proof (if available) and/or to do a sample run (both options will incur additional costs, however).
For Epson proofs:
Note, Epson proofs are not high end / 100 % color accurate proofs, though the colors on this type of proof are close to what will appear on your print job. By approving an Epson proof, you are agreeing to accept some amount of color variances on press.
If color variance is a concern, you may choose to get a higher end proof (if available) and/or to do a sample run (both options will incur additional costs, however).
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