Surely DIVX is best archive format?

[droolian01]

This may be a dumb question, but i have noticed from different d/l stuff off morpheus that mpeg1 files often look better than divx, but they are often 4 or 5 times bigger than their divx equivalents (eg 45 min buffy episode - c.400mb vcd, <=100mb divx).

So, when i convert my caps to divx with nandub (still new to all this btw) if i convert a 45 min episode of something to say 350mb (to get two episodes on a cdr) this should provide more quality than a 400mb mpeg1 (same res etc).

I have read here that converting divx to, say mpeg2 (for the future when i eventually get a dvd writer- long time off!!) is like trying to 'fill a quart pot with a pint of water'. But if the divx looks good when you play it (because it is not very compressed for a divx file) converting it to mpeg2 should provide excellent quality. Therefore divx would be a good archive format.

People may respond - why not just convert your caps to mpeg2 now?
- i don't own or plan to own a dvd player
- watch all my dvd and divx on tv via scan converter

Am i completely missguided - comments appreciated.

[sommersby]

divx files when converted to vcd or svcd look like caca. If you are always going to use them as divx then storing them that way is fine, picture quality is good but 15 frames per second gives lousy motion playback in action scenes.

[Dave B]

While there are many DivX videos out there which look very, very good it does not necessarily mean that they are good archival formats or suitable for conversion to mpeg2.

The DivX algorithm works on the principle that the human eye is generally unable to see some details within a video - therefore video is compressed without these "features" in. My understanding is that it works on a principle similar to MP3, where inaudible sounds are filtered out from the music.

An MPG encoder, such as TMPGEnc does not look upon a video in the same way as a human eye and the video detail loss from DivX certainly effects the quality of the final conversion.

However saying this, if the DivX file is a reasonably high bitrate you should still be able to achieve reasonable results.

[droolian01]

Hi, thanks for the replies.
I think that divx is primarily used (and designed) for its compression abilities, so stuff gets encoded with that goal in mind, with the result that any mpeg2 derived from them look cac, so somersby is right.

But dave b, your analogy of divx with mp3 is excelent, and is exactly what i'm getting at. I tend to store/encode mp3 at >192 (mosly much higher) andthe sound is excelent with reasonble compression. So my theory is that if i encode my tv caps in divx with low compression/high quality, i should still get more stuff onto a cdr than mpeg1/2 with equivalent quality.

I have another idea - this is probably daft too - but if a divx is first converted to uncompressed avi with v.dub (and appropriately smoothed and filtered). then this file is used as the source for tmpenc, surely the quality should be excellent?
I can see only 2 flaws:
1 - time
2 - unnecessary as this is what happens anyway in the normal convertion proccess!!!

Am i barking up the wrong tree??? Thanks

[Igot2blues]

Artifacts generations increase exponentially thru generations!
Mpeg encoding works better on very good sources, good luminosity sharp edges etc. In my opinion a too lossy encoding like DIVX contains by itself too much temporal artifacts to be encoded properly by an MPEG2 encoder.
Filters applied to a whole film just add more smoothness and distorsions giving an out of focus image.
A good VHS equipment should give you a better result in quality time and price!

[Mirror_Image]

DivX can be a great archive format (due to small file size), but it all depends what you're going to do with it.

I capture cable TV (old movies from TMC, to be exact), using DivX 1500k CBR at 320x240 with postprocessing set to 6 to de-block and de-ring...then I leave the video alone, because it looks good enough!

I use Virtual Dub to MP3-compress the audio, adjust the audio interleave interval and video framerate to synch it, then burn it to a CD-R, splitting the file if necessary.

I just watch the movies on the PC. I don't make VCDs or SVCDs or anything like that. If I wanted to make VCD/SVCD/etc, I'd pick another capture format. If I want to watch a movie on the big screen with great picture quality, I go to Amazon or Best Buy and buy the DVD.

[homerpez]

DivX... it can be awesome, or it can be hell.

I have noticed the phenomenon, too... I've seen MPEG-1 clips at VCD bitrate which far and away look better than and MPEG-2 you can encode, or DivX.

On the other hand, I've seen DivX material that is perfect source material for an SVCD!

It all depends on re-encoding. MPEG-1 and MPEG-2 are clearly more useful than DivX is, because it's much more supported. But in the end, it's how it's encoded, and what you plan to play the movie back on later.

Settings, settings, and settings. The key to DivX is settings. It must be, since I have no good luck with it at all. I get blocks at full bitrate! I've personally found that MPEG-1, 2 is much more predictable, depending on which program you use to encode.

MPEG-1, 2, and DivX all stink as capture formats. Only AVI (as uncompressed as possible) is really good quality. But they all do fairly well as a format to compress TO.

[kinneera]

This really depends on how you define "archiving". True archiving would be something like raw AVI stored to a (data) tape backup and stored in a cool, dry place. See where I'm going with this?

Personally, I wouldn't touch Divx with a 10 foot pole, even for pseudo-archiving. I just think there is too much data loss involved if I have a high quality AVI available to begin with.

I'm also in the party that feels that converting from Divx back to SVCD is completely pointless, and is rarely beneficial even for VCD. Divx is a lossy codec, just like MPEG1 and MPEG2, so if it fits the same amount of video in half the space, twice as much information about the video has been lost. Converting it back to VCD (2x) or SVCD (4-6x) the avg bitrate of Divx) is an exercise in futility - you're trying to make something out nothing.

[droolian01]

Thanks again for the replies.
I was acting as a bit of a devil's advocate in posting this thread. Although i am still starting to get to grips with the practice of capturing and converting stuff, i have read these forums (and others, but these are the best!) quite extensively and know that everything you said is not only recieved wisdom, but when talking about bitrates etc "ye cana change the laws of physics, captain"., and i agree. BUT, call it naive optimism, i feel that if i have a divx file, convert it to raw avi, and this avi contains no macroblocks then this should make visually acceptable mpegs for future dvd writers to use. So having my cake now (watch/use divx) and eating it in the future (for dvd-r or whatever wins the format battle) - just hope the cake doesn't go off in the meantime!!!
Lots of testing to be done i think!