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Discussion Starter · #1 ·
So I got the pixel perfect mappings for the AE100 working and the first thing I did after watching part of a DVD was to fire up an MPEG4/ DivX encoded movie. I had a copy of O Brother Where Art Thou that I thought was pretty nice. Previously, I would use that to show someone that MPEG4 looked pretty nice on my 27" SVGA display.


The resolution was 640x272 and showed few compression artifacts. When I was playing around, I would try to make the movies at 720x480 originally but realized such a high resolution would make the compression very high. I reached a happy medium with making it 640 wide and it still looked fine (to me.)


So I went from:

27" 4:3 SVGA (blown up to 800x450) at around 10 feet

to

70" 16:9 AE100 (blown up to 856 x 480) at around 9 feet (new room with new setup.)


The jaggies on everything from the low resolution is hideous! I'm not normally bothered by small imperfections (like screendoor) but I couldn't help but simply staring at the edges of everything. This one that I liked so much is painful to watch, I can't imagine what bad ones I made earlier might be :) I did not try doing all the post-processing-processing effects that they have added in the DivX 5 series, but I don't think it will be helping that much.


I think the MPAA can get rid of the whole DivX problem by giving everyone FP. Yikes...


I'm about 1.6x screenwidths right now and the huge picture is bothering me more than the screendoor.
 

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Hi Namlemez:


___My sister and family actually watch DIVX 5.x rips on their non Hi-Def 53†RPTV! I watch it for 3 or 4 seconds … you know, just long enough to leave the room and throw up ;) Even she can see the difference between a std DVD played via S-Video from a TNT2 Ultra’s S-Video output compared to a DIVX RIP from the same but she refuses to spend the $3.00 to rent a DVD … When she comes over here, I hear, “yeah, but you spent so much on the display and HTPC and the cables and …â€. At least I’m smiling after both seeing and listening to a great scaled DD/DTS based film instead of looking for my Bifocals and hearing aid like they will in a matter of years … Just kidding of course ;)


___Good Luck


___Wayne R. Gerdes

___Hunt Club Farms Landscaping Ltd.

___ [email protected]
 

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How large is the DiVX file you're playing back? And does it have AC3? I just wanna have an idea of the amount of compression it has so I can begin weeping. I have a small DiVX collection (that looks fine on my POS TV) but when I get an AE100 I'll be sad if they're unwatchable.


-rick
 

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Discussion Starter · #4 ·
The DivX is about 700 megs with mp3 audio. It was made with Nandub and SBC and is done well. I have quite a lot, and I believe this was a good one.


I think I'm going to look into a DVD burner or something so I can store movies at the bitrate I think I need. :(
 

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I think you'll find that once you get over the huge storage requirements, and bump the resolution up (and compression down), your DivX movies will look great even displayed on such a large screen.


I have a 56" RPTV that I play my DivX (ver 5) movies on -- the movies are roughly 720x480 resolution, with the AC3 audio stream maintained and come out at about 2GB in size. Sure that's huge...but it's very close to the original DVD quality (at least to my eyes) and still less than 1/3 of the original movie size. Hard disks are cheap, load 'em up!


Have fun!
 

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If you would try an experiment I'd be grateful...


I usually encode my DVD's into DiVX and they come out around 1350MB each (that's my max for 2 hours worth... for over 2 hours I go to 1975) but I use an AC3 soundtrack. So... if my figures are correct:


2 hours @1350MB = 11.25MB/Min = 187.5KB/Sec


If 448Kb/s (56KB/s) is AC3 then 131.5KB/Sec or 1052Kb/s for video.


so... if you would take a 2 hour movie and encode it to DiVX at 1052kb/s video rate and let me know how it comes out I'd be grateful. Note that this would be the worst quality movie I'd have as I encode based upon target size rather than absolute bitrate. Anything over 2 hours I'd pump it up, and most movies are an hour and a half to an hour and 45 min or so.


1052kb/s doesn't include the audio track... oh, I also scale to 80% of width in order to have more bits per frame and to accomodate playback on slooooow systems.


Thanks in advance,


-rick
 

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I was told there would be no math on this test.... :p


I encode my movies using Divx5.0 @ 1800Kbps 2-pass VBR, preserving the AC3 audio track, and the quality is very good. Not quite DVD quality, but the space/quality tradeoff is a good one, and for critical viewing, I pull out the DVD and watch that (I only encode movies that I own).


Cheers,


Rich
 

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Discussion Starter · #8 ·
I've mentioned it in other threads so I did not go over it here...I would love to play with this more but I have no HTPC for a month to try it out with right now! :) When I did play with it, it was on an extra computer that has already been repurposed (I'm in the middle of setting up Linux on it right now actually.)


Given your specs, you say you crop the top and bottom bars off and make the width 576? You'll notice the one I had problems with was 640x272...


I think the bitrate on the one I tried was around 700kbps.
 

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I can get perfect quality but I encode at 1500 - 1700 kbps, using Two Pass.


Basically my rule of thumb is:


SUPER HIGH QUALITY SOURCE DVD (Not Superbit) (i.e. American Beauty)

4GB Source==2 GB DIVX Maybe as high 1900 kbps.


High Quality Source (Emperor and Assassin)

Around 1700 Kbps, although with bidirectional encoding I have been ending up with smaller files.


Lower quality Source (i.e. Sixties Movie)


1500 Kbps



From there compress down. I watch them on a 10' wide screen. No difference to the source.
 

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I can get adequate quality in a 1CD DivX file. I've found, though, that I NEED Windows XP to play it. The difference in playback quality is simply stunning. A number of people have been utterly shocked when they realized they were watching a DivX file on my 100" screen.


Obviously, it's not perfect. There's still quite a difference in quality. HOWEVER, for the HTPC, XP is the only way to go, in my book. (I use Windows 2000 for all other important systems, though. 2K is a much better OS overall.)


Try XP for DivX playback. You'll be impressed.
 

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Discussion Starter · #11 ·
nrubenstein,


How exactly is it different? Are you using WMP8 to play it back? What video card is this?
 

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I use divx 5.0X and it works great for me just use the gknot program on doom9.org and check the compresability test make sure your around 80 ~90 % for really good quality. Read the guides they help allot. I also use the ac3 audio with my divx files most are around 3 cd's some around 2 that means either 1.4 or 2 gig. My wife and most of my friend can never tell the difference between the divx and dvd on my 51 inch HDTV but i can and its not much of a difference. I also only encode movies that belong to me.
 

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Quote:
Originally posted by Namlemez
nrubenstein,


How exactly is it different? Are you using WMP8 to play it back? What video card is this?
The best way to describe it is that it's a LOT smoother. Yes, you lose a lot of detail, but XP just seems to play back video a lot more smoothly. Both in the way the frames are rendered and in the frame rate.


My HTPC:

MSI K7T Turbo

Athlon 1.4GHz

256MB PC133

HPT370 RAID ---> RAID 0 with WD400BB

Promise ATA100 ---> Deskstar 75GXP+CDR+DVD

Matrox G450 eTV

Hercules Fortissimo II (TOSlink to PS Audio Ultralink II DAC)


Output is at [email protected] for DVDs. DivX goes out at [email protected]
 

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I do a frame by frame comparison and theirs zero perceptible quality loss if you do not overcompress it this usually means about 40% of the original file.


I have not been succesful with AC3 audio. I will try it again now that I hear people are having good results with it...
 

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When you blow up junk you get junk. OK, now for the good news - XP does do a better job (MWP8) of doing Divix than anything else. I don't know why - but it is true; I have 95, 98, 2K, XP (&Linux RedHat, Mandrake).
 

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ahagen:


to get ac3 to work just download and install the nimo pack it has the ac3 decoder for divx with it then all you need to do is use zoomplayer to watch it.
 

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Discussion Starter · #17 ·
Sounds like you might be using VMR for playback in XP. It is a new feature they added that offloads the rendering of the movie to the 3d card. Basically, it shows up as a animated texture on two triangles. This sort of thing, as long as the resolution is low, is childs play for a good 3d card. Of course the side effect is you are losing some detail as you said. Maybe due to texture compression?


There's no reason a P3-800 should have that much trouble rendering it smoothly though. Do you have lots of stuff running in the background? Have you tried out the post-processing effects DivX 5 gives you say, using Zoomplayer?
 

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Two tidbits for those trying to get DivX encodes to play smoothly....


I have a dedicated "media-server" machine that plays DivX movies for my video distribution system (movies on demand!), and it is a celeron600 running WinXP home. Runs very smoothly. I don't use GMC, QPEL, and set the default post-processing level to a lower setting.


For smooth playback of DivX files with AC3, the most important thing is to tune the interleave settings. I use 128/128 for the preload (ms) and interleave (ms) for all movies...but depending on your soundcard (IE SB series) you may need to tweak this some. There's a good faq on doom9's forums in the audio encoding section.


Cheers,


Rich
 

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Discussion Starter · #19 ·
GMC, QPEL and the post-processing can only help. The problem sounds like your celeron might not be up to task of handling all those effects. They've also added those special "psychological" encoding tricks which are really nothing more than a smarter encoder. One of them simply attempts to compress more when you wouldn't notice and compress less in areas you will notice.
 

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It may be old news, but I hadn't seen it posted on this forum...


If, perchance, you're running a Matrox G400 video card and trying to play back DiVX movies you may notice that after a while the movies get jerky. This is due to a problem with the Matrox drivers not correctly setting up an overlay for the movies to play back in IF the movies' dimensions are not a perfect multiple of 16 (or is it 32... one of the two). There is a "hack" that fixes this problem by padding the outgoing stream with null in order to push the resolution to an even multiple of the above. It can be found by searching on google for "g400 divx". This has helped my playback on the machine that has the G400 in it.


Just an FYI.


-rick
 
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