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Divx overrated vs DVD?
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sumsaris
Junior Member
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11. October 2005 @ 06:10 |
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Not to start a polemic or anything, but after being thoroughly exposed to the divx/xvid business from the decompressor point of view I recently jumped into the world of encoding and am a bit stumped. The short history is the following: With Pansasonic GS400 and Pinnacle 9.35 I've just finished editing, compiling and burning a 2 1/4 hr home movie. 100% DVD format no problem. 50% DVD format barely detectable differences. So I decided to experiment with xvid. It turns out that at 720x576 and 2000 fps the result is roughly equivalent to the 4000 fps of the 50% DVD (1/2 size). But hardly the 80% savings usually touted by everyone. I say this because anything under 1500 fps and things start to take a noticeable turn for the worse. I also tried the integrated Pinnacle mpg4 decoder and it was as bad at 2000 as xvid was at 1000. My source material are the original DV avi files themselves, and not the ripped DVD structures made from them. Also, I didn't use any q-pixel or GMC add-ons nor any processing filters. So, a priori considering the resolution, the quality seems quite satisfactory. However, I don't see why everyone lauds divx as being SO much more size-economical compared to DVD. The bargain I see is barely a 1/2-off sale. Is this perhaps because I'm a neophyte and aren't yet savvy to the smoothers, sharpeners, and what not tweaks, or simply because the notion of 'near DVD quality' is extremely subjective. Thanks for anyone's comments/help.
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celtic_d
AfterDawn Addict
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11. October 2005 @ 19:03 |
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fps = frames per second. So what do you mean by 2000fps? The human eye can't see 2000fps, let alone 4000 and no current hardware would be able to decode it realtime anway.
You talk about DivX, but then you test XviD? Now since most people would agree that XviD is capable of better quality than DivX, I guess you can draw a conclusion of DivX vs. MPEG2 by testing XviD, however it isn't the best nor the most direct approach. Besides, the XviD team never made bs marketing claims like 80% savings or any marketing claims for that matter.
Perhaps you mean bps (bits/sec)? That would make more sense.
So you are saying that XviD is comparable to MPEG2 with half the pixels and twice the bitrate? To me that sounds pretty good, especially since you can't really tell the difference between 1/2 and full res. So basically you are saying that XviD is comparible to MPEG2 at the same res with more than (?) twice the bitrate.
You might find that post processing makes things better for you at lower bitrates.
You might also want to test AVC/h.264.
This message has been edited since posting. Last time this message was edited on 11. October 2005 @ 19:06
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sumsaris
Junior Member
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12. October 2005 @ 13:06 |
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Well, celtic I clearly tried to condense my different tests a bit much. I'll try to approach the issue more directly and conclusively. My results show that MPEG4 compression (in this case XviD and the Pinnacle decoder which is supposed to be 'based on' the DIVX6) is at best the same quality at HALF the kbps (pardon the fps slip-up) of a low-grade DVD encode BOTH AT THE SAME RESOLUTION. With the Pinnacle coder it is the same quality at the SAME bitrate and resolution (i.e. you have to up the ante to 4000kbps to get the same quality. And this coupled with the somewhat reduced contrast and saturation with XviD. Could this be due to the de-interlacing (blend)filter I used? And I won't even get into the issue of the audio lag/accel when attempting to string several mini-XviD files together with the append feature of Vdubmod.
In other words, if a low-bit rate DVD encode gives roughly the same quality as a high-bit rate MPG4 encode (2000-4000 again) what's the point of it all? Perhaps at low resolutions for e-mail and file sharing, but then you've already got SVCD for that, haven't you?
I repeat my problem either stems from a lack of expertise in manipulating those countless filters within Vdubmod and elsewhere, or I'm right as to my contention that most people don't really have a clue when they say for example that a standard 1000 kbps MPG4 encode will give you 'nearly' good DVD quality at 1/4 to 1/8 the bitrate. It's seems vastly exagerrated.
A case is in point, Celtic, is your contention also that I 'can't really tell the difference between 1/2 and full resolution'. With all due respect, this is nonsense. I did head on tests of 720x576 vs 640x480 (only about 3/4) and on the computer the shimmering, artefacts, etc were flagrant for all but nearly static images. Granted the TV will smear over many of these defects, but in principle MPG4 is suited for the PC monitor not the analog tube. The fact that you imply the need to post-process in depth says what about the encode process by its own merits?
So MPG4 is not such a bad format, but it is hardly the miracle that I had at least been led to believe by untold numbers of internauts out there. But please prove me wrong people with any advice you can give.
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celtic_d
AfterDawn Addict
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12. October 2005 @ 21:12 |
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Quote:
50% DVD format barely detectable differences.
Quote:
can't really tell the difference between 1/2 and full res
barely detect the differences, can't really detect the differences. Both are basically the same thing. You said that you can hardly tell the difference between 1/2 DV res and full. That is what I meant and you said it, not me.
You shouldn't really be using any VDub filters since it means converting to RGB24 colour space. This reduces quality and slows encoding.
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sumsaris
Junior Member
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14. October 2005 @ 09:24 |
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Hmm, Celtic maybe we should discuss in French. OK, I'll try once more. To me, the difference between the 100% and 50% DVD quality settings (in say Pinnacle Studio 9) are barely discernable. It has to do with file size. As for Mpg4 to put it yet another way-at the same quality settings (as a given DVD encode): i.e. resolution, bitrate, file size, etc. it seems to me that xvid/divx format is 'slightly' better and not 'far' better than many would lead us (er, at least myself) to believe. Can I qualify that any more? Probably not without sitting down with you to do a head-on comparison. In short, with MPG4 you can certainly get some really reduced file sizes, but unfortunately you will also then get some really reduced video quality. So I'll stick to DVD. End of story. And your hesitation about the use of filters only tends to buttress my contention. But no hard feelings. Hey, next time let's discuss low-brow German beer festivals. We can all agree on those, right?
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nohelpme
Senior Member
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14. October 2005 @ 10:32 |
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In all honesty, I watch a lot of DivX so I would like to way in. I honestly like the dvix format better then dvd. I need to qualify that a little though, I don't care about menu's or extra features or deleted scenes. I just want the movie. So I am able to stick 3-4 DivX movies that are about 1.5 hours on 1 blank dvd. I love it. In terms of storage it makes more sense for me to. I have actually stopped using dvd shrinking for my backing up purposes and encode my backups to divx/xvid. Is it 100% as good as dvd? No...but i would say the difference is so small the gains pretty good.
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celtic_d
AfterDawn Addict
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14. October 2005 @ 19:46 |
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So you de-interlaced the XviD encode. How about the MPEG-2 one?
DivX format supports menus, etc. If you don't care about that, I would suggest just sticking with AVI as a container.
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