# Anti-Skip CD Players, Why Not DVD's? **URL:** \ **Category:** Cafe Society\ **Created:** [March 30, 2015, 3:44am UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320 "2015-03-30T03:44:57Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![GreenElf](https://avatars.discourse-cdn.com/v4/letter/g/9de053/32.png) [@GreenElf](https://boards.straightdope.com/u/GreenElf)\ **Post date:** [March 30, 2015, 3:44am UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/1 "2015-03-30T03:44:57Z")
Even the most basic portable CD player has anti-skip technology. I have a Sony portable DVD player, and my screen will skip or freeze due to the slightest imperfection on the DVD’s playing surface, even just a tiny speck of debris which is commonly found on any surface. Why don’t they have anti-skip technology for a standard DVD player? ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [March 30, 2015, 4:46am UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/2 "2015-03-30T04:46:24Z")
Anti-skip for portable cd players was made to overcome the problem of laser mis-tracking due to vibration, shaking, or movement of the laser mechanism. It read the disc faster than it played it back and played from a buffer of stored music. If the laser mis-tracked you wouldn’t hear it as the music continued from the buffer and the laser eventually re-tracked and caught up to itself. Anti-skip doesn’t do anything for dirty scratched discs. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [March 30, 2015, 5:23am UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/3 "2015-03-30T05:23:34Z")
I know that the traditional way for a time traveler to realize what year he has woken up in is to see a newspaper cover and read the date, but of course that doesn’t work anymore now that news has moved onto the internet. But anways, I welcome you to the future, **GreenElf**. There was actually an invention called the “MP3 Player” that came out in the mid-90s (20 years ago), which replaced CDs, and in the last five years or so, MP3 has been supplanted by live streaming from services like Pandora and Spotify, where you tell it what you want to hear and the hamsters go look it up and start beaming it to you over the air. “Skipping” isn’t really a concern with these newer technologies, though with live streaming, you do need a data connection. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [March 30, 2015, 8:52am UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/4 "2015-03-30T08:52:28Z")
> [@GreenElf](#): > > Even the most basic portable CD player has anti-skip technology. I have a Sony portable DVD player, and my screen will skip or freeze due to the slightest imperfection on the DVD’s playing surface, even just a tiny speck of debris which is commonly found on any surface. Why don’t they have anti-skip technology for a standard DVD player? CD’s use a continuous stream of music: if you miss one value, you can just skip it and go on to the next value. DVD’s use compressed blocks. If you miss one value, you have to throw out the whole block. You can see the same thing on digital TV: when you change channels, you have to wait for the start of the next block, wait till the end of the block, decode it, then start showing it. That is why changing channels is so slow on digital TV. ---
**Author:** ![SJL4041](https://avatars.discourse-cdn.com/v4/letter/s/73ab20/32.png) [@SJL4041](https://boards.straightdope.com/u/SJL4041)\ **Post date:** [March 30, 2015, 12:23pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/5 "2015-03-30T12:23:53Z")
> [@Sage\_Rat](#): > > I know that the traditional way for a time traveler to realize what year he has woken up in is to see a newspaper cover and read the date, but of course that doesn’t work anymore now that news has moved onto the internet. > > But anways, I welcome you to the future, **GreenElf**. There was actually an invention called the “MP3 Player” that came out in the mid-90s (20 years ago), which replaced CDs, and in the last five years or so, MP3 has been supplanted by live streaming from services like Pandora and Spotify, where you tell it what you want to hear and the hamsters go look it up and start beaming it to you over the air. > > “Skipping” isn’t really a concern with these newer technologies, though with live streaming, you do need a data connection. Huh? You seriously misread the OP. It’s asking why DVD technology can’t mimic 20 year-old CD technology. And **Hampshire** and **Melbourne** already explained why the two technologies aren’t really analogous. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [March 30, 2015, 12:31pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/6 "2015-03-30T12:31:58Z")
Plus, portable DVDs are a small, “uncool” market - no major company sees the need to invest in improving the technology. They’d rather sell you a tablet instead. ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [March 30, 2015, 1:24pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/7 "2015-03-30T13:24:10Z")
> [@Melbourne](#): > > CD’s use a continuous stream of music: if you miss one value, you can just skip it and go on to the next value. > > DVD’s use compressed blocks. If you miss one value, you have to throw out the whole block. You can see the same thing on digital TV: when you change channels, you have to wait for the start of the next block, wait till the end of the block, decode it, then start showing it. That is why changing channels is so slow on digital TV. More specifically, Red Book CD audio discs do not use compression. They also don’t use encryption (which is why if you have one of those ‘copy-protected’ CDs from the early 2000s when everyone starting ripping them you’ll notice that the disc package will not contain [the official Red Book audio CD logo.](http://en.wikipedia.org/wiki/File:CDlogo.svg)) Anyway, because they don’t use compression they only need rudimentary error correction (parity bits), which means a large amount of data can be easily skipped with no loss in audio. I have several old CDs with ‘CD rot’, inch long clear lines right thru them yet the discs still play just fine (well, they ripped just fine the last time I used them! :D) > [@Alessan](#): > > Plus, portable DVDs are a small, “uncool” market - no major company sees the need to invest in improving the technology. They’d rather sell you a tablet instead. Are portable DVD players even still sold in the US?!? They were an example of something that went from a rich persons toy to a commodity incredibly fast. When they fisrt came out they cost like $1000! But within only a few years they were in blister packs in the checkout impulse-buy racks at electronic stores. ---
**Author:** ![E-DUB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/e-dub/32/403_2.png) [@E-DUB](https://boards.straightdope.com/u/E-DUB)\ **Post date:** [March 30, 2015, 2:02pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/8 "2015-03-30T14:02:13Z")
You can use a portable DVD player to make a neat drive-in movie theater on a model railroad. How many obsolete things can you work into one sentence? ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [March 30, 2015, 2:10pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/9 "2015-03-30T14:10:52Z")
> [@Hail\_Ants](#): > > Are portable DVD players even still sold in the US?!? yes they do. still for auto and picnic use. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [March 30, 2015, 2:19pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/10 "2015-03-30T14:19:37Z")
What can they do that your laptop can’t? ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [March 30, 2015, 2:31pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/11 "2015-03-30T14:31:26Z")
> [@Alessan](#): > > What can they do that your laptop can’t? Hang from the ceiling of your mini-van. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [March 30, 2015, 2:36pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/12 "2015-03-30T14:36:56Z")
That sounds unsafe on several levels. ---
**Author:** ![muldoonthief](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muldoonthief/32/3188_2.png) [@muldoonthief](https://boards.straightdope.com/u/muldoonthief)\ **Post date:** [March 30, 2015, 2:42pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/13 "2015-03-30T14:42:44Z")
> [@Alessan](#): > > What can they do that your laptop can’t? Be given to small children in the back of the car, without risking the need to purchase a new laptop. And the ones mounted to minivans usually either come with the car, or are professionally installed, so the risk of them falling is minimal. And they aren’t visible to the driver. ---
**Author:** ![Kamino\_Neko](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kamino_neko/32/34_2.png) [@Kamino\_Neko](https://boards.straightdope.com/u/Kamino_Neko)\ **Post date:** [March 30, 2015, 3:08pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/14 "2015-03-30T15:08:26Z")
> [@Alessan](#): > > That sounds unsafe on several levels. How is having a device physically attached to the car more unsafe than having a different, heavier, device sitting in the lap of the person behind the driver? ---
**Author:** ![Doug\_K](https://avatars.discourse-cdn.com/v4/letter/d/b5ac83/32.png) [@Doug\_K](https://boards.straightdope.com/u/Doug_K)\ **Post date:** [March 30, 2015, 3:15pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/15 "2015-03-30T15:15:36Z")
> [@Alessan](#): > > What can they do that your laptop can’t? Be replaced for [less than $50.00](http://www.amazon.com/Sylvania-SDVD7040B-Black-7-Inch-Portable-Player/dp/B003OWKM3G/ref=sr_1_1?s=electronics&ie=UTF8&qid=1427728457&sr=1-1&keywords=portable+dvd+player)if your kid breaks it. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [March 30, 2015, 3:20pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/16 "2015-03-30T15:20:37Z")
> [@Kamino\_Neko](#): > > How is having a device physically attached to the car more unsafe than having a different, heavier, device sitting in the lap of the person behind the driver? My mistake - I was imagining a portable DVD player hanging from the ceiling by a piece of twine tied to a nail, which is about my level of handicraft competence. You can see how one of those swinging around at head level could be considered somewhat dodgy in terms of safety. Still, don’t they sell specialized car TVs? Why not attach one of those instead of an ordinary DVD player? ---
**Author:** ![muldoonthief](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muldoonthief/32/3188_2.png) [@muldoonthief](https://boards.straightdope.com/u/muldoonthief)\ **Post date:** [March 30, 2015, 3:48pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/17 "2015-03-30T15:48:32Z")
> [@Alessan](#): > > My mistake - I was imagining a portable DVD player hanging from the ceiling by a piece of twine tied to a nail, which is about my level of handicraft competence. You can see how one of those swinging around at head level could be considered somewhat dodgy in terms of safety. > > Still, don’t they sell specialized car TVs? Why not attach one of those instead of an ordinary DVD player? I don’t think anyone buys the handheld DVD player like **Doug K.** linked to in order to mount it to your car. Either you buy a specialized one and have a car audio place mount it for you, or you buy a car with it already installed. Or you go the the easy way and buy the portable one for the kids. Which has the added advantages of being able to let each kid watch a different movie, and you don’t have to listen to “Let It Go” 6 times through the car sound system during your road trip. ---
**Author:** ![Doug\_K](https://avatars.discourse-cdn.com/v4/letter/d/b5ac83/32.png) [@Doug\_K](https://boards.straightdope.com/u/Doug_K)\ **Post date:** [March 30, 2015, 4:09pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/18 "2015-03-30T16:09:38Z")
> [@muldoonthief](#): > > I don’t think anyone buys the handheld DVD player like **Doug K.** linked to in order to mount it to your car. Either you buy a specialized one and have a car audio place mount it for you, or you buy a car with it already installed. Or you go the the easy way and buy the portable one for the kids. Which has the added advantages of being able to let each kid watch a different movie, and you don’t have to listen to “Let It Go” 6 times through the car sound system during your road trip. “Let It Go” is sweet relief after hearing “Fixer Upper” 10 times in a row. I haven’t seen the movie, but I swear “Fixer Upper” sounds like a rejected SNL skit being performed by a middle school drama class. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [March 30, 2015, 4:58pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/19 "2015-03-30T16:58:13Z")
i saw one where it had two screens with elastic straps to attach on the rear of auto front seats. kids listen with headphones. kids are pacified without tormenting adults. ---
**Author:** ![SJL4041](https://avatars.discourse-cdn.com/v4/letter/s/73ab20/32.png) [@SJL4041](https://boards.straightdope.com/u/SJL4041)\ **Post date:** [March 30, 2015, 5:07pm UTC](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320/20 "2015-03-30T17:07:49Z")
> [@Doug\_K](#): > > “Let It Go” is sweet relief after hearing “Fixer Upper” 10 times in a row. I haven’t seen the movie, but I swear “Fixer Upper” sounds like a rejected SNL skit being performed by a middle school drama class. His peculiar brain, dear / his thing thing with reindeer / that’s a little outside of nature’s laws. Poor Sven. [Next page](https://boards.straightdope.com/t/anti-skip-cd-players-why-not-dvds/716320.md?page=2)