Divx 5.1 vs. WM9 vs. XVid?

[IWatchHDTV]

Up till now I've only encoded using Divx. With the new Divx 5.1, I think the quality on the "slow" setting is noticeably better than the "slowest" setting on Divx. 5.05 or earlier. On the other hand, the encoding time is almost 6 times as long. Since I don't want to give up either quality or speed, I'm considering trying some other codecs. Can you guys give me your impression of WM9 or XVid?

The first thing I'm interested in is encode speed. I'm now doing "standard/slow" 2 pass encoding with Divx 5.1 of 1080i HDTV streams resized to 1280x720, and I'm getting about 1/40'th realtime! So one hour of video takes almost 2 days to encode, and that's too long! Reading Doom9's codec comparison, it seems WM9 2-pass is about 2.5 times slower than Divx 5.05 on "slowest" 2 pass, which seems to make it about 2.5 times faster than Divx 5.1 on "standard/slow" 2 pass. But can you guys give me some real numbers on WM9 highest-quality 2-pass time vs. Divx 5.1 "slow" encode time? How about for XVid?

I'd also like to know about the quality. I'm encoding mostly hourlong tv shows (~40 mins of actual video) so they fit on 1 CD, so I use about 2000 kbps. I recently found out that the convention is to encode about 100 mins of video, kept at the original 1920x1080 resolution, using WM9, at 5-7 mbps, so they fit onto one DVD-R. Since I don't have a DVD writers, this isn't an option for me. So I'm only interested in the quality of the codecs at around 2mbps (or other "CDR size" bitrates).

Finally, I'm curious, what are people's general impressions of WM9 vs. Divx 5.1. I know that WM9 and XVid seem to edge out Divx 5.05 slightly. But since I think Divx 5.1 is much better than 5.05, I wonder if Divx managed to regain the quality (if not speed) crown? For people with more experience with other codecs, I'd really appreciate your words of wisdom!

[tiki4]

Sorry mate, I don't do HDTV but maybe I can give you some numbers and you can interpolate.

It seems, that current codecs have become very, very slow in their highest quality settings and your resolutions is also to be considered high-end.

WM9(VCM): 640x256, 2h movie takes around 2h first-pass and 10 h second-pass in highest quality mode.

RV9: around 10-12h for two-pass, EHQ=very high, same movie, don't have exact numbers there, so.

DivX 5.1, dunno, but is much too slow in its slowest setting for me.

XviD: in the range of RV9 in its highest quality mode, maybe slightly faster.

Hopefully someone can step in with more valid number, but I never really did real benchmarks.

My machine: Athlon XP 1600+, 512 MB DDR-RAM, Windows XP SP1.

Hm, quality is something very subjective these days, but I think you should give RV9 a shot. I can't really figure out how 2000 kBit files are looking, I don't have such resolutions (good old analogue TV).

tiki4

[Beastie Boy]

Since you are encoding at such high resolution, you clearly care about preserving details. IMHO, WMV9 easily beats DivX in this respect.
My recent encodes have been at 720x576 or 720x440 ish and the extra detail is very noticable with WMV9. Depending on the content I use between 2000 - 2700kbps so I think 2000kbps is a bit low for your frame size. Try it and see.
As regards speed, I get approx 8fps first pass, 2-4 fps second pass. (P4 2.53Ghz).
I have never used XviD and so cannot comment on this.

Just a thought. WME9 supports the use of anamorphic frames (non square pixels). To save bit-rate, you could encode at eg. 912x720 and have the player resize on playback. This would lose information from the original but I think it would be you best bet if you have to fit the files on a CD. As far as I know, only WMP9 will play the files back at the correct AR. I have started a thread here (http://forum.doom9.org/showthread.php?s=&threadid=63049) to try and find out if it is possible to use other players.

Finally, you can't beat doing some tests of your own. Let us know your opinion.

Cheers, Beastie.

[temporance]

In my experience, WMV9 really starts to suffer in comparison to DivX and xvid as the bitrate gets higher. WMV9's strength is at lower bitrates - below about 600kbit/s at typical DVD-rip resoltuions. But if you want to use these really low bitrates, you might be better with RV9.

Since you're trying to do something specific, you really have to test for yourself - let us know what you find. Each codec has it's particular characteristics, and everyone will have their favorite.

[LeonMcNichol]

Well, you are right. DivX has significantly increased its time to take to encode and episode at its slowest setting. We are talking about a 5-6x increase in time. (UGH!) But the quality is on par with XviD's current state (They finally fixed the B-Frame problem I was having!) and that's a great deal now. So I've switched back to XviD. It's way faster to encode. About 3-3.5 hours for both passes per 24 minute episode. I still like RV9 and actually encode to it once in a while, but I'm going to stick with XviD until I get a faster CPU. (Unless of course XviD starts to pull way of DivX in speed. >< By then I'll probably give up on encoding.)

Might I suggest trying out XviD with mostly the default values?

My computer is 1.2GHz TBird with 512MBs of PC100 SDRAM. So speed can be an issue. (Left to only encoding during the night.)

[SeeMoreDigital]

I've carried out high definition tests with all the codecs you mention and more!

It would seem that you have already found out that 720 vertical pixels is about the maximum image pixel frame height (resolution) you can encode using DivX, before shuttering on playback starts!

With WMV9 I have found that it's possible to encode using much larger frame sizes, even 1920x1080 (depending on the processing power of your PC) but 1440x816 is a better compromise - for full frame encodes!

One codec you did not mention was RealMedia9. I found this codec produced the best results overall at 1920x1080 and 1440x816. It was faster at encoding than WMV9 (and DivX) and produced better looking HD images at bitrates of between 2000 - 4000kbps. Even encodes between 1000 - 1500kbps were watchable!

Most of my tests were done using the WMV9(.wmv) HD T2 trailer that's available for download from one of the M$ websites.

In conclusion, it would seem that although it's possible to encode high def images using an Mpeg4 codec such as DivX and/or XviD. It's not yet possible to play back such files (in software or harware) without shuttering... well that's my experience anyway.

Cheers

[temporance]

LeonMcNichol:

I find that, in terms of quality and speed,

DivX on standard ~= xvid on default settings
DivX on slow ~= xvid on VHQ4

This is the general state of things, the codec's tend to leapfrog each other's performance with every new release, so if you make your comparison on a day that DivX is slightly ahead then you'll come to the conclusion that DivX is better. And vice versa.

After all, both codecs use the same technology under the hood, MPEG-4, so we'd expect them to converge on the same performance.

Also don't forget that xvid and DivX decoders have different postprocessing algorithms - at least some of the perceived difference probably comes down to this. If you really want to compare encoders, make sure you use the same decoder with the same settings when looking at the results.

[IWatchHDTV]

Thanks for all your feedback, even the contradictory ones about whether WM9 or Divx 5.1 has more details ;) I don't have time to run any tests now cause I just got dumped with a ton of work. But I'll definitely run some tests and let you know the results. Lastly, just a little point about details. My source is over the air HDTV TP streams, and personally, I don't think HDTV uses a high enough bitrate to get nice details in the picture. For example, in motion scenes, there's very apparent pixelation if you pause the picture (though you don't notice it as much watching in realtime). I think they should increase the HDTV bitrate from 19.2 Mbps to something like 30 Mbps, since pixelation kind of defeats the purpose of high resolution :p

[m3g42L0]

I've tried DivX 5.1 encoding with Dr DivX 1.0.3. Well, the encoding process is painfully slow. First pass took 25hrs for 640*336, 1300kbps, 2h14m movie on my P4-2.4C, 512Mb computer (slowest mode). Predicted time for second pass was about 12hrs (tired of waiting).

I've tested Divx 5.1 and WMV9 using Arizona Dream movie, where camera flies around tundra/river landscapes. There was no significant difference between 2 codecs, overall quality was low, details (like highlights on surface of the river and branches of the trees) were blurred.