小弟无聊自己翻译过了.....(翻译完才发现对岸有人翻译过了 囧) 翻的很烂请见谅 原文网址 请自己对照文图 http://www.cdfreaks.com/reviews/Why-DVDRW-is-superior-to-DVD-RW.html ---------------------------- Article Why DVD+R(W) is superior to DVD-R(W) Date June 2003 Author Michael Spath Since the war between DVD+R(W) and DVD-R(W) started, several comparisons of the two formats have been published, but none of those I read did contain really accurate technical information. Instead, journalists relied on public press releases and white papers provided by vendors to write their articles, resulting in the end into superficial explanations and sometimes contradictory conclusions. 自从DVD+R(W)跟DVD-R(W)阵营开始大战，许多厂商发布了这两种格式的资讯，但我并没有 从其中真正的了解到实际的技术细节。然而，记者依靠厂商发布的这些资讯来写新闻，导 致了肤浅与矛盾的结论。 The main problem here is that getting DVD+R(W) and DVD-R(W) standards require money and NDAs, so that little detailed technical information about these formats can be found on the Internet. This is very unfortunate, as it prevents both journalists and techies from all over the world to independently review, compare and choose the best format by themselves. 主要的问题是在於取得DVD+R(W) 与DVD-R(W) 标准内容需要金钱与签署不公开协定(NDAs) ，所以能在网际网路上找到的格式细节内容少之又少。这是令人遗憾的事，使的记者与资 讯使用者无法自主而独立的比较与选择最适合他们的格式。 Because they cannot access the technical details (or simply due to laziness), some people prefer to carefully conclude that there's no real technical difference between the two formats, and that if you forget all the marketing propaganda + and - are equally good. To me this is an evidence that such people have not understood (or more probably not even read) the format specifications. 正因为她们无法取得技术的细节，一些人仔细推断後倾向认为这两种格式并没有实际的差 异，不在意行销宣传的话+与-是同样的好。对我而言，这意味这人们并不了解，或没有仔 细分辨这两种格式的差异。 After having studied the two formats I found that there are several fundamental differences between them, and I concluded that + is superior to -. The goal of this paper is to present the technical details from the specifications that led me to this conclusion, so that anyone with basic engineering knowledge can make his own opinion. This article is by no mean exhaustive, and some exclusive + and - features (e.g. CAV writing or copyright management) are not tackled here because I considered them less significant. Note that this article is pretty technical, so some understanding of optical storage technologies is required. 在研读这两种格式後，我发现这两者有几个基本上的差异，而且我推断认为+比-好。这份 报告的技术细节是由我所下的结论，所以只要任何人有基本的资讯工程背景，可以自己下 判定。这份文件并不保证彻底无疑，+R 与-R 的专属功能 (例如定角写入或版权管理) 也 没有做比较，因为我认为那些部分并不重要。由於这份文件十分的技术性，所以读者需要 了解一些光学储存装置的技术。 Pre-pits versus ADIP 预刻反射坑对上ADIP To help its recording, a blank disc usually gives 3 kind of information to the drive : tracking (so that the pits are correctly written along a track), addresses (so that the drive can write at the good location) and speed (so that the disc is spinned at the correct velocity). With CD-R(W), tracking and speed information are carried by the wobble, while addresses are contained in the ATIP data (Absolute Time In Pregroove, a frequency modulation of the wobble). 为了帮助烧录，空白光碟通常会提供三种资讯给烧录机：轨道(使反射坑可以正确的沿着 轨道写入)，位址(使烧录机可以写入正确的位置)与速度(使碟片旋转正确的速率)。在 CD-R(W)，当位址包含了ATIP资料(将绝对时间放在预沟槽里，这是一个摆动的调变频率) ，轨道与速度的资讯由摆动提供。 DVD-R(W) format uses a slow wobble (140,6kHz) for tracking and speed, and the addressing (and additional) information is carried by the land pre-pits (pre-recorded pits between grooves). On the groove signal, pre-pits give amplitude spikes. DVD-R(W) 格式在轨道与速度上使用低摆动频率(140.6kHz)，位址(与其他)资讯则由陷落 预置反射坑(LPP，land pre-pits)，在沟槽间预录的反射坑提取。在沟槽上的讯号，预刻 反射坑产生扩大的波尖峰。 DVD+R(W) format uses a much faster wobble (817,4kHz), and the addressing (and additional) information is carried by a phase modulation of this wobble called ADIP (ADdress In Pre-groove). DVD+R(W)使用较快速的摆动频率(817,4kHz)，这种由摆动的相位调变来提取位址(与其他) 资讯的方式则叫做ADIP (位址直接放置在预沟槽里)。 　 As taught by signal theory, the phase modulation method has a better noise immunity than the pre-pits method, and therefore ADIPs are generally more robust than LPPs against all external disturbances (electrical noise, disc tilting, focusing problems, etc). Apart from the usual sources of noise in a drive, a particularly annoying example of this problem occur when you are burning data on a DVD-R(W) and try to read the pre-pits information at the same time : because the light emitted by the burning laser is interfering with the reading beam, correct pre-pits detection is much more difficult to achieve, which can jeopardize linking precision. 有如讯号学所教的，相调变方式对於杂讯的免除能力优於预刻反射坑方式，因此ADIPs方 式比起LPPs方式通常更加能对抗外来的干扰(电子杂讯，碟片倾斜，对焦失准等)。要从装 置中将有用的资料跟杂讯分开，举一个恼人的实际例子，就是当你烧录资料DVD-R(W)以及 同时试着读取 预刻反射坑资讯会发生：因为雷射烧录光线的射出与读取光束相抵触，使 的预刻反射坑的正确侦测变的更加困难，也影响到精密度。 But the pre-pit technology is not only a weakness against noise, it also becomes a limiting problem as the speed of the disc increases, because at high speeds pre-pits are more difficult to detect than phase inversions. Indeed, on the wobble signal the pre-pit information only exist where the pre-pit is located in time, while the information of phase inversion is spread over the complete inverted period of wobble (or more, actually as long as the phase is not inverted again). According to the specifications, the minimum length of a DVD-R(W) pre-pit is 1T (1/26.16E6 s), while a DVD+R(W) wobble period lasts 32T, which makes it much easier to detect. 而且预刻反射坑技术不只抵抗杂讯的能力较差，还会造成碟片增加速度的阻碍，因为高速 时比倒相式技术更难侦测。当然，在摆动讯号上，预刻反射坑资讯只存於 预刻反射坑所 在的位置，而相倒置则会展开至完成摆动的期间。(或更多，因为事实上相位并没有倒置 回来)。DVD-R(W)规范上最小的预刻反射坑长度为1T( 等於2616000分之1秒)，而DVD+R(W) 的持续摆动期间为32T，所以後者较容易被侦测。 Another bad side effect of this pre-pits method is that DVD-R(W) mastering is made more difficult than with DVD+R(W), since a higher precision is required to cut both the grooves and the pre-pits between them. Special dual-beam recorders are usually required for - stamper mastering, although some manufacturers now also use single beam cutting. 预刻反射坑的另外不良影响，就是使DVD-R(W)的後制比DVD+R(W)更加的困难，因为切割沟 槽与预刻反射坑时需要更高的精密度。通常会需要使用特殊的双光束烧录器来进行後制打 印 ；尽管现在一些厂商现在只使用单光束切割。 Not only are the pre-pits more error prone than phase modulation, but data they carry are also less protected. In one ECC block pre-pits carry 192 bits of information (one pre-pit block). Out of these 192 bits, 48 are not protected by any error correction mechanism, 24 bits are protected by 24 bits of parity (A parity), and the last 56 bits are also protected by 24 bits of parity (B parity). All in all, this strange heterogeneous structure finally gives a pretty weak protection to the information bits carried by pre-pits. 预刻反射坑不只比相调变倾向於有更多的错误，被携带的资料也缺於保护。在一个ECC Block(错误侦修区块)中，预刻反射坑含有资讯的192位元(一个预刻反射坑区块)。超过 192位元的部份，48位元并未受到任何错误修正演算法，24位元由24位元的同位法(A同位 法)保护，以及最後56位元由24位元同位法(B 同位法)保护。总而言之，混种的保护结构 使的预刻反射坑对於资讯的保护是糟糕而贫弱的。 On the other hand the corresponding DVD+R(W) structure is 4 times smaller : one ADIP word is 52 bits large, consisting of 1 sync bit, 31 data bits and 20 parity bits (which protect all data bits). One ECC block contains 4 ADIP words, so 204 bits of information in total. Also each ADIP word contains the full ECC block address, while 4 times this size are needed in the - technology to extract this address : this gives significant speedups when seeking uses this method. 另一方面，DVD+R(W)的对应结构小了四倍：一个ADIP 字元组是52位元大小，一个同步位 元组成，31个资料位元与20个同位检查位元(保护所有的资料位元)。一个ECC Block包含4 个ADIP字元组，所以资讯总共是204位元。每个ADIP字元也包含完整的ECC Block位址，当 展开後存在着需要的四倍长度，因此这个方法显着的提升了速度。 Defect management and recording quality 瑕疵管理与烧录品质 Another major advantage of DVD+RW format over DVD-RW (although no drive support it yet) is hardware defect management provided by the DVD+MRW standard (Mt Rainier for DVD+RW). On a DVD+MRW disc, when an error occur during a read or write access to an ECC block, this block is flagged as bad and the drive will not use it any more. Instead, when writing to the disc, data which should have been stored in this bad block are relocated elsewhere ; likewise, when the drive is asked to read these data again, it will fetch them from the new location. These operations are completely transparent for any software (whatever operating system, driver or burning application is used), and while the initiator is requesting consecutive sectors the drive will actually read data from various locations : this new abstraction layer is called Logical to Physical address translation. 另一个DVD+RW 优於DVD-RW (仅管撰写本文时还没有对应的烧录机) 的地方是硬体瑕疵管 理是由DVD+MRW标准 (Mt Rainier 於DVD+RW)。当在DVD+MRW上读写一个ECC区块而发生错 误时，这区块会被标示为损毁，而不再使用它。也就是当资料写入碟片损坏区时，会被重 新分配至别的地方，而读取时则会由被分配到的地方来读取。这些动作对於所有的软体( 乃至作业系统，驱动程式或烧录软体) 都是完全隐形的，实际上当需要读取连续的扇区资 料时，装置将从各分散的地方读取资料：这个新的概念层次叫做 "逻辑对实体位置转译" 。 As a side note, popular belief is that defect management is only useful when burning new discs (where data which are being written can also be read back, checked and moved to another location if needed), but that it is helpless on discs which get damaged after they have been burned. This is wrong, because when an ECC block is partially damaged and requires several retries to be read (or for instance give too many PI/PO errors), these data can proactively be moved to another clean location on the disc before media wear-out makes them unreadable. Of course, if an ECC block is damaged beyond error correction capabilities, data are definitely lost ; however, only very serious damages can make such a thing happen, as PI/PO correction can handle burst errors larger than 6 mm. 有如一个边注，一般的看法是，只有在烧录新的碟片的时候(或资料搬移，再烧录时)有使 用瑕疵管理。不过这对於碟片在烧录完成後才造成的损坏无可奈何。这是不正确的，因为 有部份ECC区块损坏而需要许多的重试读(或得到太多PI/PO)时，那些资料可以在媒体老化 而导无法读取前，前瞻性的搬移到碟片上其他乾净的区域。当然，如果ECC区块已经损毁 超过可以修正的能力，资料就肯定会流失了。不管怎样，那是非常严重的损毁才有可能发 生，像PI/PO可以修正满达6公厘的错误。 As with formatting, DVD+RW standard enables background verifications, i.e. the disc is checked for defects when the drive is idle. Of course, at any time the user can still read or write to the disc, or eject it from the drive ; background verification would then resume later from where it was stopped. Combining these features together gives a very powerful system which can continuously try to improve the longevity of discs : while the user performs its usual operations, the drive can check in the background the complete surface of the disc and move data from damaged locations to clean areas. Such advanced use of defect management are already described in the DVD+MRW specification, for instance with the Self Monitoring Analysis and Reporting Technology (SMART, a technology inspired from hard discs). Finally, it is important to mention that DVD+MRW provides full read-only compatibility for players which don't understand MRW. DVD+RW的标准将启用背景验证功能，好比光碟机在碟片闲置时检查瑕疵。当然，任何时候 使用者还是能够读写或退出碟片；背景验证将会在稍後继续进行。将这些功能集合起在一 起，成为一个使碟片寿命不断延长的强力系统。使用者只要一如往常的使用碟片，光碟机 会在背景自动将资料从发生损坏的区域移往乾净的区域。这类的先进瑕疵管理已被 DVD+MRW规范列入，并产生自我监测分析技术的建议(Self Monitoring Analysis and Reporting Technology S.M.A.R.T，来自硬碟的技术)。最後，必须要表扬的是DVD+MRW完 全提供唯读相容，甚至播放器不需要知道MRW。 Although DVD-R(W) also support some defect management (Persistent-DM and DRT-DM), it is mainly software based and actions must always be initiated by a specific program. Furthermore, since DVD-RW format lacks the needed structures, address translation has to be performed also by software, and translation tables have to be stored on the user area of the disc according to a higher level specification (for instance in the sparing tables of UDF 2.0). This makes DVD-RW not well suited for simple file storage or image burning, as it requires a complete file system to benefit from defect management. Note also that although DVD-RW cannot use +MRW technology (due to technical differences), DVD+RW can very well use UDF 2.0. 尽管DVD-R(W)也支援一些瑕疵管理(Persistent-DM 与 DRT-DM)，但这主要是以软体为主 ，必须使用特殊的程式去起始。而且由於DVD-RW格式缺少需要的结构，位置转译是由软体 完成，而且转译表必须与储存於使用者资料区，对应到较高阶的规范(好比UDF 2.0的节约 表)。这使的DVD-RW不适於单纯的档案储存或影像烧录，而需要档案系统去帮助瑕疵管理 。然而尽管DVD-RW无法使用+MRW技术(技术不同)，DVD+RW却可以完好的使用UDF 2.0。 Also a DVD+R(W) disc allows a drive to achieve better writing quality (independently of media quality), because it gives more information to a drive than a DVD-R(W). Indeed, just like with CD-R(W), the best writing settings for a given disc are found at startup during the OPC (Optimum Power Control) algorithm, which use data contained in the pre-pits blocks/ADIP words. And regarding OPC, a DVD+R(W) gives not only more information (e.g. power dependency on wavelength) but also more precise ones (e.g. startup laser power). Moreover, all these information are available for 4 different speed ranges (primary and upper speeds, normal and 4x+ mode), while - format only provides one set of data. This is very important because optimal writing settings are very sensitive to burning speeds. Also the OPC test area of DVD+ is 32768 sectors in total, compared to 7088 sectors for DVD-. DVD+R(W)碟片也允许烧录机达到较好的写入品质(媒体的独立品质)，因为烧录机从它获得 比DVD-R(W)更多的资讯。好比CD-R(W)，给碟片的最佳的写入设定可以在一开始的OPC(最 佳化工率控制)进行时找出来， 在那些预刻反射坑区块/ADIP字元使用已设置妥当的资料 。以及就OPC而论，DVD+R(W) 不但给予更多的资讯(如在波长上的功率依靠度)，也更加明 确(如起始雷射功率)。此外，这些资讯对於四种不同的速度范围(基本，快速，一般，与 4X+模式)都是全部有用的，而-R(W)格式只提共一部份资料。这很重要，因为光学写入的 设定很对於烧录速度是很敏感的。DVD+ 的OPC测试区有32768个扇区，也胜过DVD-的7088 个扇区。 Linking 链结 When for any reason writing on the disc has been stopped and is resumed, new data have to be linked with the old ones. Linking is a very important and tricky task, which can cause various problems both at physical and logical level. First, a short overview of the linking methods used by the two formats is required. 不管什麽原因，当写入碟片时需要停止与继续时，新的资料必须与旧的做链结。链结是一 个非常重要而且难处理的工作，容易在物理与逻辑层面造成许多问题。首先，我们需要总 览这两种格式链结的方法。 With DVD-R(W), 3 different linking methods can be used : 2K linking, 32K linking, and loss-less linking. In all cases recording has to stop 16 bytes after the first sync of the first sector of an ECC block, and new data are recorded starting between the 15th and the 17th byte of this same frame. The precision of the linking is therefore 2 bytes and the space waste either 2KB, 32KB or nothing (note that loss-less linking method does not work with DVD-R for Authoring). With DVD+R(W), linking is performed in the last 8 channel bits (4 data bits) of an ECC block. Linking precision is therefore 4 times higher and loss-less linking is the only method allowed by the standard, which guarantees no space waste. DVD-R(W) 有三种不同的链结方式可以使用：2K链结，32K链结，以及无损(loss-less) 链 结。不论是哪一种，一个ECC区块的第一扇个区之後有16位元组是停止位元组，而新资料 的写入则於同一页框(frame)里面的第15与第17位元组之间开始。DVD-R(W) 链结精密度需 要2资料位元组长，以及浪费空间2千位元组，或32千位元组，或不浪费 (但无损链结并无 法使用於DVD-R for Authoring )。DVD+R(W) 的链结则是使用一个ECC区块最後八个通道 位元(4个资料位元)，链结的精密度是DVD-R(W) 的四倍高，而且无损链结是唯一可以使用 的标准，以确保没有浪费的空间。 　 Even when loss-less linking methods are used, the pits are not perfectly contiguous on the disc, and therefore some PI/PO errors will always occur : to minimize this effect, the location of the linking region is very important. With -RW, the linking region is in user data, and therefore useful bytes will always be corrupted there. Also since the linking occurs after the first sync, the second sync frame (and possibly the third one) will also be lost, since the sync words will not be correctly spaced in the ECC block. With +RW, the linking region is in the last byte of PI correction, which leaves user data bytes untouched. Also the linking position guarantees that all syncs in the next ECC block will be corrected spaced, which gives at least one sync frame less to correct for the player compared to -RW. Note that with +RW, corrections due to the linking region and corrections due to the sync shift are split between two ECC blocks, while they must all be performed by a single ECC block with -RW. 即使使用无损链结，反射坑也无法在碟片上完美的连贯，因此总会造成一些PI/PO错误： 为了使这个影响降至最低，链结区域的位置是非常重要的。-RW的链结区域在使用者资料 区，因此有用的资料总是在这边损坏。也因此在第一个同步发生链结之後，第二个同步页 框(甚至第三个)也会造成遗失，之後同步指示在一个ECC区块里就无法被正确的间隔。+RW 的链结区域则是位在PI修正区的最後一个位元组，与资料区无关，也因此确保了下一个 ECC区块的同步间隔是正确的 ，至少比起-RW，+RW比较不需要校正同步页框。值得注意的 是，+RW修正链结区与同步位移是由两个ECC区块所处理，而-RW是由一个ECC区块完成。 Linking can also cause various troubles at physical level, and when looking directly at the HF signal read by the PUH, the linking region looks like the following: 链结也能导致许多物理层面的问题，直接由拾取头(Pick-Up Head ，PUH)读取的高频(HF) 讯号，链结区看来像是这样： The slicing level is the digital threshold which separates zeroes from ones, and therefore it must always be centred in the HF signal for good reading quality : when the slicing level deviates too much from its perfect position, the run-lengths (3T to 14T) are wrongly recognized, which causes decoding errors. But as explained previously linking is not perfectly accurate, and therefore a gap will always exist between the two recorded sessions, and the longer the gap, the further the slicing level can drift. Furthermore, between the two linked regions the slicing level can also differ, because of various physical parameters which could have changed between the two recording sessions (laser power, media properties, recording speed, etc) : when this jump is too high, again errors appear. So the smaller the gap and the jump, the better quality and compatibility we get : -RW allows a 32T large linking gap and does not care about this slicing level jump, while +RW allows a 8T large linking gap and a maximum limit for this jump under any condition. This makes +RW loss-less linking also more powerful at physical level. 这个切割水平(slicing level)是用来辨识数位0到1的门槛，因此必须位於HF讯号的中央 ，才能获得良好的读取品质：当这个切割水平偏离理想的位置太多， 约有一段长度(3T 到14T) 会被错误的辨识，这将导致解码错误。但如之前所说，链结不是精准完美的，因 此在两个烧录区间，总是会存在间隙，越长的间隙，导致越严重的切割水平漂移。再者， 切割水平可能在两个链结区不相同，因为在两个烧录区间，许多物理参数会变化(雷射功 率，媒体特性，烧录速度等)：当跳动太高，错误又再发生。所以较小的间隙与跳动，可 以让我们获得较好的品质与相容性：-RW 允许32T 大小的链结而不在乎切割水平的跳动， 而+RW 仅允许8T大小的链结，并在任何条件下有最大的链结跳动限制。这也使的+RW 的无 损链结在物理层面更有利。 Multiple recording sessions and compatibility 多重烧录与相容性 If you want to partially record a DVD-R(W) disc and use it immediately, but also want to be able to record more data later, border zones are used, which are meant to make this partially recorded disc compatible with standard DVD-ROM players. So every -R(W) recording session has to start with a border-in area (except the first one, which starts with the lead-in) and stop with a border-out area. 假如你要部份地烧录DVD-R(W)碟片而且立即使用它，而稍後还要再烧入更多的资料，那就 要使用分界区(border zones)使烧录好的碟片能相容於标准的DVD-ROM播放器。所以每个 -R(W)烧录区段皆始於一个入界(border-in)区(第一个区段则是例外，始於导入)，并止於 一个出界(border-out)区。 However, the size of these border zones is quite amazing : 32 to 96 MB for the first zone, then 6 to 18 MB for the next ones. This means that a disc containing 3 recorded sessions can require up to 132 MB (more than 2% of the complete storage capacity) just for separating these regions. Furthermore, the border-out and border-in areas have to be linked together, using one of the 3 methods (and the possible associated problems) explained previously. Note also that for some unknown reason a border-out is needed before the lead-out, while the first border-in is replaced by the lead-in. 然而令人相当吃惊的是：第一个分界区的大小为32到96百万位元组，接下来的每一个则为 6到18百万位元组。这意味着一片碟片若包含三个烧录区段，则光是为了区分这些区域， 就可花费超过132百万位元组(超过2%的储存空间)。此外，入界区与出界区使用之前说过 的三种方式的其中之一(与相关可能的问题)链结在一起。还要注意的是，由於不知道的原 因，当第一个界入区是由导入(lead-in)区置换时，必须在导出区(lead-out)前放置一个 出界区。 On the other hand, when multiple recording sessions are used on a DVD+R(W) disc, Intro and Closure zones are used (the counterpart of border-in and border-out), but they are always 2 MB large : therefore, with + format, a 3 sessions disc always uses only 4 MB to delimit the regions (the lead-out replaces the last Closure zone). Also a nice feature of multi-sessions implementation on DVD+R(W) is that one can use a session to reserve space, i.e. sectors which are left unrecorded (this blank area is called Reserved Fragment). Thus, additional data can be recorded in next sessions while the first one will only be written later : this can be useful for instance when a precise location on the disc has to contain file system tables, which can only be filled after all the files have been written to the disc. 另一方面，使用DVD+R(W)碟片来烧录多区段，则使用进入(Intro)区与结束(Closure)区( 有如入界与出界区)，不过他们是固定的2百万位元组大：因此，使用+格式烧录三个区段 ，只花费4百万位元组去界定区域(最後使用导出取代结束区)。还有一个在DVD+R(W)上实 现的好功能，就是可以使用一整个区段做为预留空间，也就是使扇区处於未烧录状态(这 个空白区块叫做已保留片段(Reserved Fragment))。这样新增的资料就可以跳过并烧录於 下一个区段，而这个空白区块可以稍後再写入：举一个实用的例子，当档案系统分配表需 要严谨的摆放在碟片上特定的区域时，可以在所有档案都写入碟片之後再写满它。 Compatibility is a very sensitive topic when comparing the two technologies, but independently of media, recorders and players quality, some logical causes of incompatibility can be noted. Indeed, both recordable formats use values in the lead-in structures which were forbidden or reserved in the first DVD-ROM specification (e.g. disc structure, recording density, etc) and which can cause compatibility failures on some old or particularly picky players. 在比较两种技术时，相容性是很重要的一个议题，但是媒体的独立性，烧录器与播放器的 品质，常见一些不相容的可能原因。当然，这两种烧录格式在导入结构中使用的数值资料 是初代DVD-ROM规范(如碟片结构，烧录密度等)所预留或禁止的，也因此在一些旧型或过 於严谨的播放器会导致不相容的状况。 A famous example of such logical incompatibility is the "Book Type" field, which indicates the type of the disc. The first DVD-ROM specification only allowed 0 (i.e. read-only) to be written there, but later each recordable format defined its own value to identify itself ; unfortunately it turned out that some players simply refuse to read a disc with a non-zero value. To handle this problem, the latest DVD+R standard specifically authorizes to write a zero Book Type for compatibility reasons, and nowadays many drive manufacturers have made this bit programmable. But this cannot be done for DVD-R(W), as the Book Type (with several other information in the lead-in) are pre-embossed (i.e. pre-recorded) on blank media. Note however that although it reduces compatibility, this pre-recorded Book Type also improves copy-protection security, as it enables any player to easily identify a DVD-R(W) disc. 用来辨识碟片种类的 "书入类别(Book Type)" 辨识栏位，有着一个常见的逻辑性不相容 问题。初版的DVD-ROM规范只允许将此设置为0(唯读)，但较晚出的每一种可烧录格式都定 义了他们自己的值作为辨识。不幸的是，一些DVD播放器遇到此区为非0值时，就直接拒绝 读取了。为了解决这个问题，最新的DVD+R规范允许在此栏位写入0值使其能相容，而且现 在很多烧录器厂商已经让使用者可以自由选择是否启用这个功能。这无法在DVD-R(W)上面 实践，因为书入类别(以及很多其他在导入的资讯)是已经在空白碟片上预先刻录好(在预 录置时)的。不过虽然因此减少了相容性，预录置的书入类别却也增加了拷贝保护的安全 性，因为它使的播放器能轻易的辨识是否为DVD-R(W)碟片。 An additional compatibility risk exist with DVD-(W) in the user data area and is introduced by the 2K/32K linking methods. Indeed, the linking sectors used with these methods must use a special data type to be differentiated from normal data sectors, and this value was not allowed in the original DVD-ROM specification. There's no known study about the impact of this field on compatibility, but sector headers are a vital part of the decoding process, and therefore it is always safer to keep them fully compliant with the strictest DVD-ROM standard. DVD-R(W)在使用者资料区还多了一个相容性的风险，就是采用2K/32K链结方式。当然，扇 区链结一定是使用一种特别资料型态，而不同於一般资料扇区的链结，且不被最原始的 DVD-ROM规格所允许。在这个部份对相容性的影响不得而知，然而扇区标头是解码过程极 为重要的一部份，所以严格的完全与DVD-ROM标准相容总是比较安全的。 Conclusion 结论 During my study of rewritable DVD formats it seemed very clear to me that DVD-R(W) standard was not as well designed as DVD+R(W) (or even DVD-RAM). And although some serious efforts have been put in the latest revisions of the - format to fix some of the original problems (at the cost of a much increased complexity), it still remains technically inferior to +, due to some intrinsic weaknesses (e.g. pre-pits). This is not very surprising, as Sony and Philips have a much longer experience at defining standards than Pioneer (and several key patents), and they also had the advantage to publish their standards after their competitors. 当我在研习DVD复写格式时，对我而言很清楚的DVD-R(W)格式不如DVD+R(W)(甚或DVD-RAM) 。 尽管在最後谨慎的再校定-R(W)的资料，以修正一些文章原来的问题(也使的文章更复 杂)，但最後还是在技术本质上输给了+R(W)格式(如预刻反射坑)。这不令人非常意外，新 力索尼与飞利浦在订定标准上，比起先锋有着更多的经验(与一些关键专利)，他们晚於对 手公布标准也取得一些优势。 Although the arguments presented in this document might look like technical details to most readers, disc format is what defines the limits of what drives can do with a given medium, both in terms of performances and features. Therefore, the technical advantages of the DVD+R(W) format will with time turn into faster, more powerful and more reliable drives for end users. This is already the case today, and the gap will continue to increase as DVD+R(W) drives will exploit more and more of the advantages of the + format. However, as history showed, the best ideas are not guaranteed to win on technology markets, and only time will tell which format becomes the new standard. 尽管对大多数的读者而言，这些在文章中的争论的呈现看起来像是技术细节，碟片格式限 制了烧录机在性能与功能中，所能达到的平衡点。因此，DVD+R(W)的格式的益处将为使用 者在未来带来更快速，更有力与更可靠的装置。这在今日已成事实，DVD+R(W) 烧录机的 优势差距将会扩大并拓展越来越多+格式的优点。然而不管如何，历史表明了最好的理念 不保证能赢得技术市场，只有时间能告诉我们何种格式能成为新的标准。 Acknowledgements (答谢) I would like to thank the engineers from Pioneer Japan and Philips Netherlands who reviewed early versions of this article for their most useful corrections and comments (note that this only means that these people kindly contributed to the technical correctness of the article, not that they - or their company - agree with my conclusions of this article). Also many thanks to J.W. Aldershoff for having suggested and organized these reviews, and for hosting this article. 我要感谢日本先锋与荷兰飞利浦的工程师预览了本文的早期版本，以及提供了宝贵的修正 与建议(仅表示这些工程师好心的替本篇文章提供技术修正，不代表他们或他们的公司同 意我在本篇文章的论点)。也很感谢J.W. Aldershoff 给予本篇文章建议与批评，以及为 本文所做的努力。 Disclaimer (不保证) This article is meant to be a list of technical arguments showing some of the advantages of the + format over the - format, and it reflects only my personal opinion, and not the one of CD Freaks. It is not a detailed comparison of the two formats, and it does not take into account specificities of drives, media or third party software : only the format differences are compared here, as described in the DVD-R 2.0, DVD-RW 1.1, DVD+R 1.1 and DVD+RW 1.1 standards. Corrections are welcome by email, but questions and contradictory opinions should be posted to our forum, so that everyone can benefit from an open discussion. 本文意旨在於列出+R与-R技术争论与优势，这只是我个人的观点，不代表CD Freaks。这 不是一个详尽的比较，也未比较装置，媒体或第三方软体；仅就两种格式的差异，於 DVD-R 2.0，DVD-RW 1.1，DVD+R 1.1 与DVD+RW 1.1 等标准之下做比较。欢迎将来信告知 错误，而问题与看法则请於论坛上发表，让每一个人都能在开放的论坛获得利益。 Michael Spath - [email protected] 译者注：感谢前辈Michael Spath先生所提供给世人的资讯，本文权利於Michael Spath先 生所有。本文章不代表本人立场，本人亦不保证原文之正确性，与翻译正确性。引用本翻 译务必注明译者。 -------------------------------- 有错或建议请置於推文修正就好 因为我懒的管了 (逃走) --

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