Talk:DVD/Archive 1

message: Question: is it possible to play DVDs from all regions with players that use DeCSS? I tried to find information on this, but found nothing that convinced me. And I don't any DVDs to try it. Guaka 13:31, 21 Sep 2003 (UTC)
thread_title:  Does DeCSS allow DVD from anywhere to be played? 

message: If you burn data to DVD for archival purposes, for how long can you expect it to be readable (assuming it is stored optimally)?  Is DVD the best long-term home data archival solution?  - DropDeadGorgias (talk) 21:50, Jul 7, 2004 (UTC)
* Nobody knows! DVD is such a new format that the only way to estimate how long a DVD will last is to artificially age it with air and UV exposure and whatnot. Manufacturers claim they have a shelf-life of something like 100 years. Do a google search for "DVD rot", however, and you'll get a lot of recent stories about new DVDs that are already unusable due to various factors unrelated to consumer abuse. It would be good to have an article on this subject, since it's of great concern to many people. From what I've gathered, it's fairly evident that DVD (or recordable CD, or anything else like it) is not well-suited to long-term archival unless you take care to check the integrity of your archives periodically, and make fresh copies every few years. And keep your discs out of sunlight and moisture, and preferably in a vacuum :-) -- Wapcaplet 22:36, 7 Jul 2004 (UTC)
thread_title:  Longevity 

message: I think that DVD-ROM, and probably DVD-R too, should be fusioned with DVD. xDCDx 12:30, 24 Aug 2004 (UTC)
thread_title:  [[DVD-ROM]] and [[DVD-R]] 

message: We've got to do something about this issue of DVD standing for digital video/versatile disc. The matter is explained in detail a few paragraphs into the article, but some editors keep adding the original expansion to the intro paragraph (, , ). I don't think the acronym expansion should be mentioned at all in the intro paragraph, because it's a relatively lengthy issue to explain fully, but apparently some editors disagree (or aren't bothering to read far enough to see that it's already mentioned). How should we handle this? -- Wapcaplet 05:30, 10 Jan 2005 (UTC)
replies: text: I hope this works.  If it messes anything up I apologise in advance, but I've never edited here before...  I just thought I'd ask, and forgive me if this is obvious, if anyone's checked the patent filed for the DVD?  I would've thought the invention would have to have been called something there and that that would be the more 'official' name for it?  I've done some brief searches but can't find a specific patent for the disc itself - just wondered if anyone with a bit more know-how might do better?  (For what it's worth I prefer Digital Video Disc since 'versatile' in this context sounds awkward and pretentious to me - but I'm sure there's an answer out there...) -- Adaru 17:14, 24 September 2005 (UTC)
replies: text: There isn't just one single patent for DVD (there are hundreds), so this doesn't help much, but you're on the right track. If you look up the U.S. trademark registration for DVD (originally filed in 1996 by Warner, then assigned to the DVD Forum) it's for the logo mark, not an acronym. This is further evidence that it's just three letters, not an acronym. --JimTheFrog 07:50, 13 March 2006 (UTC)

text: Acronyms are almost always expanded upon in the first sentence of encyclopedia articles.  Many people come to the page looking for a quick definition of what it means and to bury it a few paragraphs down is making the page less useful.  --Cyde 22:05, 21 November 2005 (UTC)
thread_title:  DVD as acronym/initialism 

message: First sentence of article defines DVD as a format. Second sentence talks of it as a physical object i.e. a disc. Nurg 04:01, 17 Jan 2005 (UTC)
thread_title: Definition - is DVD a format or a disc?

message: I think the paragraph about copy protection/region codes should go into a separate article, like DVD (Region Codes). I am also not quite happy when there is talk about the DVD format. There is no such thing as a DVD Format. The disc format is that of the CD, and the logical format on the disc is UDF, an extension of ISO9660.
While we are at it, we might split off the longer discussion of the different dvd formats (video, audio,..) too...
--Eptalon 20:55, 22 Mar 2005 (UTC)
replies: text: "The disc format is that of the CD"? Care to explain that cryptic remark? Mirror Vax 15:19, 22 Apr 2005 (UTC)
thread_title: Splitting the DVD article?

message: DVD-Audio has been split into a separate article.  Should DVD-Video also be split?  Please share your opinions on this issue.  To comment upon the DVD-Audio split, please use the above section.
— Lifeisunfair 11:55, 10 May 2005 (UTC)
replies: text: Seems like an excellent idea to me! --217.122.69.145 18:58, 26 Jun 2005 (UTC)

text: Yes it should.  After following a link to DVD-Video, it wastes time having to scroll down the article looking for the parts relating to DVD-Video.  Townmouse 13:09, 10 July 2005 (UTC)
replies: text: Suddenly i'm wondering if there's any provision for using named anchors. —Brian Patrie 12:52, 9 October 2005 (UTC)
thread_title:  DVD-Video: Split? 

message: In 3: DVD-Video, It is stated that RGB video is not component.  This is false.
I am aware that the luma-chroma and luma-chroma-chroma systems are very often refered to, in varying degrees, as "component".  It can be (and is) hotly debated, whether this is appropriate.
RGB, however, is very definately component.  It is the oldest currently used system to be called such.  (The Component video article, which is referenced in this same section) also acknowledges RGB as a type of component video.
—Brian Patrie 10:21, 26 September 2005 (UTC)
thread_title:  RGB is component video 

message: Can someone tell me why DVDs typically come in much larger plastic cases than CDs? They're the same size... Coffee 09:45, 4 October 2005 (UTC)
replies: text: This is just speculation, but I expect it's partly to be roughly compatible with existing VHS shelving units :-) According to the DVD FAQ, the popular black plastic version is an Amaray "keep case." I, for one, am glad DVDs don't come in standard CD cases--they're too prone to breakage, especially of the hinges or the disc-holder hub... -- Wapcaplet 21:12, 4 October 2005 (UTC)
replies: text: Durability might well have been a consideration, as videos are often handled by the small children of parents who enjoy letting the teevee babysit.  Mind you, they could have still been small.  I tend to agree that VHSoidness is most likely the reason for the size. —Brian Patrie 12:42, 9 October 2005 (UTC)
thread_title:  DVD cases 

message: The international DVDs section makes no sense to me. It appears to just be a list of children's channels. What is the purpose of this section? 2603:8080:1E40:2B2A:297E:6D8E:7287:44A5 (talk) 08:43, 5 December 2020 (UTC)
replies: text: Me neither – it became even more obscure with the added ... channels. I've just removed it. Possibly a mixup with DVB? --Zac67 (talk) 11:52, 7 December 2020 (UTC)
thread_title: International DVDs

message: This article states "Each DVD sector contains 2,418 bytes of data, 2,048 bytes of which are user data.",* but what is the source on that 2418 number? "2,048 bytes of which are user data" seems true - http://index-of.co.uk/Guides/CD%20And%20DVD%20Forensics.pdf. index-of.co.uk/Guides/CD%20And%20DVD%20Forensics.pdf (in http://index-of.co.uk/Guides/) states:
: "DVD sectors are composed of data frames on the physical disc. Information other than the 2,048 bytes of user data is not accessible. A DVD data frame contains 4 bytes of ID, 2 bytes of ID Error Correction Code (ECC), 6 bytes of copyright management information, 2,048 bytes of user data, and 4 bytes of Error Detection Code (EDC). Sixteen such data frames are assembled into a single 32K ECC block. It is not possible to access DVD data frames (also called ECC blocks) with consumer DVD drives."
:* That's 2064 (4 + 2 + 6 + 2,048 + 4)
https://www.powerdatarecovery.com/cd-dvd-resources/sectors.html states (bold mine):
: "Sector 2064 bytes of data is arranged into 12 rows × 172 column array structure, and then a row of 16 data sectors are combined with Reed-Solomon error correction coding, then work out the OCP and the ICP, constitutes a 208 × 182 array error correction block (ECC BLOCK). After encoding, each sector has got an increase of 302 bytes. The newly formed sector is called recording sector. A recording sector is 2366 bytes. Physical sector is to separate the recording sector into two and a half from the middle, each half-frame is added a 26 byte sync code. After the process of 8-16 modulation then a physical sector with sync frame is formed. The concocted physical sector has 4836 bytes which equals to the 2418 bytes before concocting. The data on the physical sector shall form channel data line after line, then recorded onto the DVD discs, it is the real sector on the disc."
Numbers:
* 2418 (26 + 2366 + 26) <--- recording sector plus two 26 byte sync code things
* 1032 (2064/2) <--- half of a data frame
* 2366 (2064+302) <--- recording sector, which is sector+ECC
* 2392 (2366 + 26)
* 946.4 bytes (2366/2.5) <--- 0.4 bytes = 3.2 bits = doesn't work
* 4128 (2064 x 2)
What is "8-16 modulation"? See https://www.powerdatarecovery.com/cd-dvd-resources/8-16-modulation.html:
: "DVD has the same principle in reading and writing in data with CD. The pit and land on the disc is to store information. The pit and land are all read as 0. The length of pit and land shall determine the number of 0. The joint of pit and land is read as 1. If the binary numbers works as channel code without concocting, the laser heads will have difficult in reading and writing in data. When coming up with "10101010" the read-write frequency is high, and the bandwidth of the laser circuit shall be wider, while coming up with "00000000", the read-write frequency is very low and the laser beam shall lose the track rail information. Therefore, CD uses EFM, which is 8-14 modulation technology and 3 bits of segregation code to from a 17 bit channel code. DVD is the 8-16 the use of advanced modulation techniques, without separation code, you can not meet up to have more than 10 continuous 0, at least two consecutive 0 requirements. The formation of the channel code is 16 bit to save one digit compared with CD."
I still don't know what 8-16 modulation is.
I'm confused; is a DVD sector 2064 bytes or 2418 bytes or 4836 bytes? Is there such a thing as a physical DVD sector? Or is it all just logical DVD sectors? What is OCP and ICP? Maybe the text (which seems a bit like Engrish) is meant to say "The physical sector is formed by separating the recording sector into two halves, then 26 bytes of sync code is added to each half". 2366/2 = 1183. (1183+26)+(1183+26)=2418. Also "The concocted physical sector has 4836 bytes which equals to the 2418 bytes before concocting." - concocted physical sector before concocting = physical sector, so "2418 bytes before concocting" = "physical sector has 2418 bytes". Further "proof":
: "[0026] In order to secure the compatibility with the read-only DVD, the rewritable DVD has a format so that the 2418 B data of one sector of the read-only DVD can be recorded in a user data region of one sector of the rewritable DVD as a unit. This data is called a second data signal." --https://archive.org/details/gov.uspto.patents.application.10769756/10769756-2008-05-02-00007-FOR/page/n3/mode/1up / https://archive.org/stream/gov.uspto.patents.application.10769756/10769756-2008-05-02-00007-FOR_djvu.txt
: https://archive.org/details/B-001-001-580/page/n151/mode/2up?q=%222418+bytes%22
Further proof in Table 5.7 Data Storage Characteristics of DVD:
: "Modulation: 8/16 (EFMPlus)
: Sector size (user data): 2048 bytes
: Logical sector size (data unit 1): 2064 (2048 + 12 header + 4 EDC)
: Recording sector size (data unit 2): 2366 bytes (2064 + 302 ECC)
: Unmodulated physical sector (data unit 3): 2418 bytes (2366 + 52 sync)
: Physical sector size: 4836 (2418 x 2 modulation)
: Error correction: Reed-Solomon product code (208,192,17) x (182,172,11)
: Error correction overhead: 15% (13% of recording sector: 308/2366)
: ECC block size: 16 sectors (32678 bytes user data, 37856 bytes total)
: Format overhead: 16% (37856/32678)" --https://archive.org/details/dvddemystified00tayl/page/238/mode/2up?q=%222418+bytes%22
What are these data units (data unit 1, data unit 2, and data unit 3)? 
*So I think the text should maybe be changed to "Each DVD unmodulated physical sector contains 2,418 bytes of data, 2,048 bytes of which are user data." --User123o987name (talk) 04:02, 4 January 2021 (UTC)
thread_title:  Each DVD sector contains 2418 bytes of data