Is a divx movie the same quality of the original DVD?

[pulse8]

Well, is it? Some people on this forum seem to think it is and I'd like to be proven wrong and to see what you folks think.

Edit: We all seem to agree that it's not lossless. Do you guys think it's the same quality?

Also changed the poll around.

 

[notfred]

no.

 

[Ameesh]

those people are horrendusly stupid and should be ashamed of themselves

 

[VirusDub]

Not even close.

 

[tweakmm]

<< those people are horrendusly stupid and should be ashamed of themselves >>


they should be beaten with blunt objects also

 

[ILikeSprite]

?

 

[Ameesh]

pulse could you name names so we can publicly ridicule them?

 

[goog40]

Yeah post the names please

 

[pulse8]

<< pulse could you name names so we can publicly ridicule them? >>



I'd rather not, but they might make an appearance to defend themselves.

And I should also point out that they haven't actually said the words lossless, but believe that taking a DVD and ripping it to divx yields the same quality video and thus making divx a lossless compression method.

 

[dowxp]

name one lossless codec of anykind. no codec will be the same exact quality as the real thing

 

[Justin218]

it's good, but not THAT good. no.

 

[notfred]

<< name one lossless codec of anykind. no codec will be the same exact quality as the real thing >>



gif

 

[pulse8]

<< name one lossless codec of anykind. no codec will be the same exact quality as the real thing >>



Well, there are lossless codecs for video, audio and data.

For video they are generally proprietary.

 

[Rison]

Where can I get Divx

 

[Ameesh]

well they must be one of the following:


a) blind : (there is a very visible difference in dvd(mpeg-2) and divx(mpeg-4)) no matter what kind of bit rate you choose for divx
b) deaf : there is no 5.1 dd or dts when using divx, (the wm9 codec will have dd 5.1 support, microsoft ownz jo0)
c) retarded : just because it doesnt seem like it to a deaf mute doesnt mean its lossless
d) all of the above


if they had an HD television with a progressive scan dvd player they will sing a different tune but even with my crappy home theater i know better.

 

[Ameesh]

<<

<< name one lossless codec of anykind. no codec will be the same exact quality as the real thing >>



gif >>



gif is not lossless! try making a text document and making that into a gif you'll see how crappy the compression algorithim works with that



zip or arj is a lossless codec

 

[tweakmm]

<< zip or arj is a lossless codec >>


or .rar or .tar, oh my!

 

[notfred]

<<

<<

<< name one lossless codec of anykind. no codec will be the same exact quality as the real thing >>



gif >>



gif is not lossless! try making a text document and making that into a gif you'll see how crappy the compression algorithim works with that



zip or arj is a lossless codec >>



Gif is a lossless compression format for 8bit color images. You're thinking of jpeg.

 

[Ameesh]

i think people are somewhat confused by defenitions:


lossless == compression occurs and when uncompressed data has exactly the same bit pattern as the original data
lossy == redundent data is eliminated to save space, quality is degraded but usually at an acceptible quality.

 

[notfred]

<< Where can I get Divx >>



tough one: divx.com

 

[royaldank]

shn is a lossless wav compression format.

 

[voodooguy]

Anyone who thinks that DivX is lossless is a moron.

DivX is a perceptual video codec. It is similar to mp3, which is a perceptual audio codec.

A high-enough bitrate mp3 will APPEAR to be identical to the original source material to 99.9% of all listeners. For mp3, the magic bitrate seems to be 192kbps CBR, or 256kbps CBR if you're an audiophile. Personally, I use 32kbps to 256kbps VBR. I get a perceptual result that is identical to 256kbps mp3's, but the average filesize is equivalent to a 160kbps mp3.

All this mp3 background is to help the reader to understand how perceptual codecs work.

Similar to mp3, a high-enough bitrate DivX will APPEAR to be identical to the original source material to 99.9% of all viewers. This is especially so with DivX v4.12 which calculates each frame separately as a slow-motion or high-motion frame. The magic bitrate for DivX'es seem to be ~ 700Mb for a 1.5 hour movie. (You do the math.) With longer movies, some artifacts may appear. As 800Mb and 900Mb CDR's become more popular, and as burners that support XL CDR's become more popular, this will become a non-issue.

To sum up: DivX is not lossless from an information theoretical point of view, but it will look that way from a perceptual point of view.

 

[pulse8]

<< DivX is not lossless from an information theoretical point of view, but it will look that way from a perceptual point of view. >>



Once again, you cannot compare the two. Your ears forgive more than your eyes.

edit: and since we all agree on this fact, I'll change the title...

 

[notfred]

Ameesh - here's that gif compressed image of text that you wanted.

 

[voodooguy]

<< Once again, you cannot compare the two. Your ears forgive more than your eyes.

edit: and since we all agree on this fact, I'll change the title... >>



You are reaching communal conclusions on your own.

What we both agree on is that DivX is lossy from an information theoretical point of view.

What we do not agree on is whether DivX is significantly different from the source DVD from a perceptual point of view.

I say no, you say yes, and there is no scientific way to decide who is right.

I do think however that the staggering popularity of DivX speaks against your thesis.