DEBATE-DivX IS a good format to convert to mpeg?

[baker]

Now listen to this carefully I presum most people here know how the divx codec works? Well it is suppose to work like mp3. Any information which our brain would not notice is not included in the final movie thus giving more room for the more important info and lowering the file size. Now people say this is a BAD format to convert to mpeg but think about this for a moment... If the info which is not included in the divx file is going to be ignored by the human brain anyway than won't it not make any difference to the resulting mpeg? Actually it should look BETTER as the divx movie will have less info and thus givng the mpeg more bitrate to give to the more important information. Now someone please tell me where I am going wrong. I know I must have made a mistake somewhere as everyone (and I do mean everyone) is saying dvd-divx-mpeg is a bad idea unless necessary (ie making a file small enough for downloading purposeis), now can someone please point out my errors or am I actualy right for a change? :->.

Plz don't shout out at me if I have made a HUGE mistake as I usually do.
Baker

[vitualis]

Is making a low bitrate MP3 from an existing MP3 better than from the original CD?

Is making a low quality JPEG from an existing JPEG better than from the original BMP or TIFF?

Obviously not. Quality once lost is lost for ever. Furthermore, the MPEG encoder can't differentiate between real detail and artifact. The first generation encoded video into DivX will contain artifacts. Thus, the MPEG encoder will waste bits trying to preserve the artifacts from the DivX...

If you think that the video quality from DVD --> DivX --> MPEG is better than directly from DVD --> MPEG, it would be because the video has become softer (i.e., detail has been lost) and easier to encode. To some, this subjectively may be "improved" quality. To some it is not.

However, if the perceived improvement of quality is purely from it being softened, then you might as well have just used a softening or slight blurring filter during encoding rather than take the roundabout step of encoding to DivX first.

IMHO, from a relatively perfect source like DVD, going straight from DVD to MPEG (i.e., FlaskMPEG + plugin or DVD2AVI via frameserving) is best. If you want to add a filter, then you can do so at your discretion.

Regards.

[oberkfell]

I can't comment on the technical terms of your post, but I have converted several DVDs-DIVX-MPEG. Not for the purpose of adding an extra step, just that I used use Gordian Knot to create DIVXs prior to purchasing a new surround system. Know all I create is XVCDs, VCDs and SVCDs. I found its a pain in the arse watching them on tv or wheeling my CPU over to the tv and watching them on the TV Screen.

Out of the 7 movies I have converted over to MPEG (XVCD, VCD, SVCD) only one looked as good as the original DIVX. American Beauty being that movie, and it had no high action scenes.

So, as a novice I would say you lose quality converting from DIVX to VCD, etc.

[bilbogod]

Thats interesting what you said about American Beauty because I found this as well. At the moment I am currently trying what Baker is talking about purely because I want to give Cyberimage's template a little whirl. I've got a burning curiosity to see what Platoon fitted onto one cdr will look like. At the moment I currently trying to create a good looking DivX before the conversion takes place. Platoon is 1 hour 54 mins.... this should be fun

[droolian01]

i agree with the cd to mp3 analogy, but i feel it should be stated more acurately as: cd to mp3 (128bit) to mp3(320bit) is equivalent to dvd to divx (high bitrate/size) to mpeg1/2.

The reason i suggest this is surely in the last convertion, there will be some(but minimal) generation loss as the compression ratio is infact an EXPANSSION ratio. I know that the mpeg1/2 encoder cannot differentiate between detail and artifact in the divx source, but if that sourse is very good(loww compression) divx then the final copy should be nearly the same as the intermediate one.
See my post http://www.vcdhelp.com/phpBB/viewtopic.php?t=77951&highlight=
especially my last comment.

[droolian01]

I also feel baker has a point, and the only fair way to compare is to keep bitrates/filesizes the same, and let the efficiency ot he codec decide:http://www.vcdhelp.com/phpBB/viewtopic.php?t=77951&highlight=
Divx wins the visual prize here.

[droolian01]

Sorry wrong link:http://nickyguides.digital-digest.com/compare-vcd.htm

[vitualis]

I believe that you've missed the point a bit...

I believe that baker wanted a discussion on DVD --> DivX --> S/VCD and the merits and disadvantages of doing so.

Regards.

[droolian01]

Oh.... if thats the case then your first reply is perfectly correct. As you suggested, why not use some filtering, that way you would have plenty of data to play with, but would of course be encoding a different film.

[baker]

Everyone here aprt from virtualas has lost the plot completely!!!!! please read my post again and think about what I am saying.

Baker