DIVX6.4 VS. XVID1.1

[Bardmaster]

Hello - I'm an old hat at ripping but very new at encoding. Previously I would "archive my DVD collection" by using DVD Shrink and/or DVD Decryptor (and recode to DVD5 with Nero Recode), but now I'm into building a media server and streaming my video collection to my entertainment center (using D-Link DSM-520 over 54G wireless). I've been looking for the best quality-for-the-size video encoding formats, hoping to keep 2-hour movies at 2GB or under.

All that said, I've played with several programs that encode DVD's. The new-standard "ASF" MPEG-4 codec MP4 files, such as the ones created by Nero Recode 2 Digital, are rather large (owing to avg 3500 bitrate), somewhat grainy in picture quality, and my DSM-520 often has trouble with them, so this codec is out.

What remains, of course, is either DivX or XviD. I've managed to create wonderful quality, small-size (like 1.5GB for 2hrs) DivX movies using version 6.4 Pro in 2-pass mode (primary shell = XMPEG5, though I do get occasional crashes with it). But I've also tried AutoGK using XviD1.1 (also 2-pass) which looks pretty good too, and I've read a lot of people (including the creators of AutoGK) prefer XviD.

I've also heard that the DivX6 codec offers superior algorithms etc. and is an improvement over DivX5, which is what it seems a lot of the XviD lovers seem to be referring to.

I'm just wondering what other opinions are out there. I have a vast DVD library, and before I get too far with ripping and recoding I want to make sure I'm heading down the right path!

I'm leaning toward DivX6. What shell app for DivX6, which can be configured for 2-pass, do people prefer out there? AutoGK only supports DivX5. XMPEG and #1 DVD Ripper crash too frequently for me (Athlon X2 4400+, 2GB DDR400, ECS KV2 Extreme mobo), and I need something that can read IFO files and be able to capture only the main movie from a DVD ripped to an HDD folder (again, too many DVD's and too lazy).

(note: I've found the movie "Cars" to be a great test movie - high-res graphics, bright colors, lots of motion!)

[Squash]

Actually, newer versions of AutoGK (latest is 2.40) DO support DivX 6, including the latest 6.4. See this post from Lenox, AutoGK's developer:
http://forum.doom9.org/showthread.php?p=891574#post891574

It's apparently fully compatible for DivX Pro users such as yourself. I'm using DivX 6.4 Pro with AutoGK 2.40 and have not had any problems with it. (If people are using the free "DivX community codec" version then apparently they need to use AutoGK's stand-alone compatibility option in order to keep it from trying to use the advanced Divx features).

I've been using AutoGK since version 0.8 (around January, 2004) and have done hundreds of encodes since then, switching from Xvid to DivX and back from time to time as those codecs developed.

The only problems I've had using Xvid with AutoGK is when some other program would install a different Xvid build than the included Celtic Druid build; AutoGK is sensitive to that; symptoms included undersized files, etc. Also, some Xvid builds would give a lot of nvops, which would ruin the file for playback on the standalone player I was using at the time (Philips DVP642) due to a/v sync problems. Of course that wouldn't affect you since you're streaming.

I never had any problems using DivX with AutoGK, but sometimes the quality appeared better using Xvid, though I haven't noticed that in quite awhile.

I did a comparison a few weeks ago, encoding the same DVD using AutoGK 2.40, two-pass, to the same file size, first with the latest AutoGK Xvid (I believe it's Celtic Druid's 1.1.2), and then encoding it again, this time using DivX Pro 6.4 as the video codec. When they were done, I loaded each into its own instance of VdubMod and compared several dozen frames side-by-side. Based on my comparison, I kept the DivX. The difference was slight, however, and may have been influenced by my choice of movie ("Embrace of the Vampire", a lot of dark scenes, which DivX seemed to handle better). They both looked good, though. You might want to run a similar test using "Cars".

Encoding speed (within reasonable limits) doesn't matter to me. I have a single-core processor (Athlon XP 2800), so any comparison I could make would be negated by which codec makes the better use of your dual-core processor.

I have not done much work with the newer H.264/AVC/MPEG-4 codec options -- too slow to encode on my old computer, plus I'm generally watching my AVIs using a standalone player which doesn't support them.

As you can probably tell, I'm a big fan of AutoGK. For what it does, it's great. I've tried many of its competitors but keep coming back to it. It's the only free program I've ever donated to more than once.

Hope this helps.

Good luck.

[jagabo]

I've done some comparisons with Xvid 1.2 (multithreaded alpha version) and Divx 6.4. It's hard to do because they don't have exactly equivalent settings.

Xvid might have a slight edge in visual quality but the difference is small enough that it probably doesn't matter.

Divx is faster than Xvid at similar settings. Sometimes as much as 4x faster (I'm using a Core 2 Duo system).

Xvid does give you more control over internal settings. And one big advantage is the ability to specify a Display Aspect Ratio. So with Xvid you can take a 720x480 16:9 MPEG file and encode it at 720x480 and have it display with the correct 16:9 aspect ratio (if your player supports it). Divx is pretty much limited to square pixels.

Regarding 2-pass encoding: Since you aren't putting your files on CD or DVD you probably don't need specific file sizes. You should consider using constant quality (not to be confused with constant bitrate) encoding rather than 2-pass VBR. It's twice as fast and can deliver similar quality. With 2-pass VBR you know what the final file size will be but you don't really know the quality. With constant quality encoding you know what the quality will be but you don't know the final file size.

Divx calls this "1-pass quality based" encoding. Xvid calls it "single pass, target quantizer" encoding. A quantizer value of 2 will give results almost indistinguishable from the source even if you look at enlarged still frames. A value of 3 will get you video with a little macroblocking if you look at enlarged still frames but you won't notice them at normal playback speeds. With higher quantizers you'll get more and more macroblocks and smaller file sizes.

[Bardmaster]

Thanks for the posts, jagabo and Squash!

Squash: I'm running AutoGK 2.40 and clicked on the DivX radiobutton, but 1) there is no option to access the DivX6 settings - maybe need the normal Gordian Knot app?, and 2) when I dropped the job in the queue, it had reverted to its default XviD codec. After reading the online manual and seeing the need for DivX5 I just assumed this was why. But thanks for the link to Lenox's post, I'll go back and check again!

jagabo - you've got me wanting to run home from work and try the "1-pass quality based" approach with a 2 quantizer! I really need to set up remote access to my home PC... Curious: what shell app do you use?

[Bardmaster]

One other thing in relation to aspect ratio: other "one-click" (or a few clicks) apps I've tried, like Xilisoft DVD Ripper and InterVideo DVD Copy, end up encoding 16x9 movies as 4x3 for some odd reason! I was trying to figure out why my copy of Titanic was looking squashed on my TV compared to the DVD playback (about 1 inch more blackbars on top and bottom). I used AviCodec to check the file and it turns out it was encoded as 4x3! I'm guessing the TV had to squash to keep the original letterbox movie (actually 720x308 in the 720x480 frame, with the rest blackbar) all on the screen! You'd think that "keep aspect ratio" would auto-resolve such things!

XMPEG does autocrop, which resolves this issue. I'm assuming AutoGK does too - in fact it tends to determine its own aspect ratios if you have it on auto, some of which are a little unexpected. But I don't think I've run a 16x9 movie thru it yet.

[Squash]

AutoGK is designed for ease of use by people who don't know much about video encoding. To keep things simple, it determines the best codec settings based on the processing and output parameters you give it. That's where the "Auto" part of the name comes from. It does it very well. It does not allow direct access to codec settings that might confuse the inexperienced user (and possibly screw up the output).

It also handles such things as IVTC, re-sizing, color-correction, video noise reduction, audio conversion and volume normalization, etc., which can be somewhat complicated. If you want more control of such things there are some excellent programs available which will give you that.

The constant quality single-pass encoding that Jagabo refers to is used by AutoGK when you choose the "Target quality (in percentage)" option, but AutoGK will decide what quantizer to use based on the quality percentage you give it.

I don't know about the reverting to Xvid thing; I've never seen it. Just use Xvid, or uninstall then re-install DivX (it might help, you never know).

AutoGK does a good job of autocropping. If you need to fine-tune it, you can do so in the Hidden Options (Ctrl-F9). You can also override the input AR if needed. I've only had to use that once, when re-encoding an AVI someone else had made (badly). It worked fine.

Good luck.

[Bardmaster]

Thanks Squash! I'll give AutoGK another look tonight!

[jagabo]

I use AVISynth and VirtualDubMod to convert MPEG2 to Divx/Xvid AVI. Sometimes Just VirtualDUbMPEG2. This gives you complete access to the codecs' settings.