H.264, XviD - Spell it out for me?

[Raga]

H.264 is a buzz-word I see all over the place. "State of the art", "Massive Quality - Minimal Files", as Apple puts it.

However if I'm not terribly missing it's just another MPEG4-codec isn't it? How much different are the results from an XviD-encoded file, in general, and how much slower / faster the process is?

x264 seems to be the open-source option that is freely available and produces good results.

Should I shift to using 264 now, or keep going with XviD as I've been doing up to now? Why?

[Skith]

here is are some links that discuss (and link to) more info about divx/xvid/h.264(AVC) and their features:

MP4 FAQ @ Doom9.org

MPEG-4 ASP Information (doom9.org)

I believe there was even a codec shootout article over at doom9 what compaired divx/xvid and h.264 (AVC).

[Baldrick]

I would wait, especially if you are going to use the open source x264 VFW Codec. They release new versions every other day with new improved encoding and features.

Nero Recode is another option if you want h264.

[Raga]

Since there isn't much around on XviD vs. X264 (links to good tests, anyone?), I guess I'll just give it a quick shot and see what happens. A quick comparison of XviD and x264:

Encoding times with XviD and x264
Source theme: People walking by, outdoors, daylight
Source specs: Unfiltered DV-footage, PAL 720x576, 500 frames (20 sec)
Codecs: XviD 1.0.3 / x264 build 270 - default settings

x264 400kbps - 51 sec - 9.8 fps
x264 1000kbps - 63 sec - 7.9 fps
x264 3000kbps - 81 sec - 6.2 fps
x264 5000kbps - 96 sec - 5.2 fps

xvid 400kbps - 22 sec - 22.7 fps
xvid 1000kbps - 24 sec - 20.8 fps
xvid 3000kbps - 28 sec - 17.9 fps
xvid 5000kbps - 31 sec - 16.1 fps

A peculiar effect, the encoding times that grow so dramatically with x264 - 5000kbps takes almost twice as much as 400kbps. With x264, the difference in time is 47%, with XviD it's 29%.

My main interest at the moment was to see the processing speeds. Nevertheless, some quick visual observations for the curious:

In the 400kbps version, XviD produces rather extreme blocking, to such an extent that I don't consider it watchable. x264 also shows signs of blocks yet it blurs them amicably, making the clip watchable. At 1000kbps, XviD produces a relatively crisp image with still a substantial quantity of artifacts, the crispness also comes at the cost of the artifacty edges of sharp lines and rapid movement. x264 produces an overall smooth and a bit blurred outcome, blending together fields with similar colors to such an extent that it's hard to point to a single, clearly visible artifact - obviously at the cost of detail in the midst of such fields.

At 3000kbps, the same trend continues - XviD is pretty crisp and produces slight artifacts around fast moving areas and sharp edges. x264 keeps smearing a bit, producing overall a more pleasant outcome for my taste. There's hardly any noticeable difference with 5000kbps.

Turning off the deblocking filter stops the blurring effect with x264 - at the cost of substantial, big artifacts in the 1000kbps version. Still, I prefer that to XviD's small artifacts all over the place.

I would have posted some captures from the samples, but I can't seem to be able to open x264 in VirtualDub. I should experiment with different sources - raw DV footage and DVD-source might behave quite differently. By the way, can I post images with 720px as the width, or do I have to resize to 640px? In this context, I'd rather avoid that if possible...