[Lossless] Ut Video Codec

[Cannonaire]

I've been using UTVideo since a few months before mirko has even heard of it and all the settings were in Japanese, do I get a gold star? It's a decent codec as long as you're careful with colourspace conversions as not all of them are handled correctly.

Are you referring to conversions between YCbCr and RGB, or between PC and TV scale? If the former, I would assume you would handle them properly using Avisynth then select the matching UTVideo format.

[Snowcrash]

Just a question about the colourspaces : what is the best profile to choose for editing ? RGB or YV ? I am not really sure about the difference.
The thing I know is that we need to be in YUV coulourspace to do an x264 encoding, so... ?

[Cannonaire]

DVDs are encoded in YUV colorspace (as far as I know there aren't any in RGB, but I could be totally wrong). Changing to RGB is not lossless, so it's best to keep it YUV if you can. If you must change colorspaces (such as if a filter requires it), it's best to keep conversions to a minimum. To be honest though, it's extremely unlikely you'll actually see a difference unless you do many conversions, which is possible if you don't pay attention to how you encode and which filters you use.

Just another note on this, I use Vegas for editing, and for some reason it hasn't worked well with YUV clips for me. What I do is make all my clips and keep them YV12 as the content was on the disc, then make scripts to make an RGB version of each one with the same name. I can edit with those ones pretty much lag-free, then when it comes time to do the final render I can bait-and-switch with the YV12 clips. The render goes slowly, but quality > speed when you're making a final render and not doing any actual editing.

[mirkosp]

If you have any version of premiere pro, working with YV12 clips (ULY0) is mighty fine. Be advised that some effects are YUV and other effects are RGB. CS5, afaik, will tell you which colorspace every effect works in. If you are using a version of premiere before pro, then it's safer to convert to RGB24 or RGB32 (you only really need to do 32 if you have alpha). Do keep in mind that YUV clips will be smaller than RGB clips, with YV12 being the smallest.
And yes, x264 requires YV12 input (well, it technically doesn't anymore, since it can internally convert the colourspace now, but still...), so if you keep everything in YV12 from start to end, it will be best.
PS: Since DVDs need to be MPEG-2, they are all YV12. Blu-ray discs can have more codecs, with them being H.264, VC-1, and MPEG-2. If it's H.264 or MPEG-2, it's pretty sure to be YV12 (could technically be other YUV, but don't think I've ever seen it myself). I don't know much about VC-1, I would assume that one is just YV12 as well, but don't count on it.

[Snowcrash]

Thanks for your replies =)
As I use Vegas, I will try both coulourspace to see if there is any difference about eventual lag (according Cannonaire, RGB seems to be more lag-free than YUV).

[Zarxrax]

Here are some hard numbers on the performance of this codec.
Test video is the movie My Neighbor Totoro, 848x480. I think this is a good real-world test clip.

UTvideo (better decoding speed)
Size: 30.1GB
Decode time: 187fps

UTvideo (better compression)
Size: 24.1GB
Decode time: 177fps

Lagarith
Size: 22.5GB
Decode time: 68fps

Huffyuv (Plane)
Size: 24.9GB
Decode time: 158fps


As you can see, UTvideo gives you quite some flexibility with its two different modes. The fast decode speed version was about 25% larger than the high compression version. The high compression version was about 7% larger than lagarith. This *might* be a big deal for some people, but I think at the large filesizes we are working with here, a 7% difference isn't very major.

As for decoding speed, the difference speaks for itself. For UTvideo, I strongly suspect that for both files, it was in fact being limited by the transfer speed of my hard disk. In other tests I have done, the high decode speed version actually outperforms the high compression version by about 30%.

Because both UTvideo clips maxed out my hard disk, there is absolutely no reason for me to even consider the fast decoding one. The high compression version is plenty fast already. Note that UTvideo performed 260% faster than Lagarith.
The high compression version of UTvideo also outperforms Huffyuv in both speed and filesize.

[Cannonaire]

Thanks for the numbers, Zarx! I probably wouldn't have run tests on that myself. This means I can stop using the fast decode option.

Although thinking about it, if you're doing a lot of heavy editing with effects taking a lot of CPU time, it might be nice using the fast decode over compressibility.

[Cannonaire]

Just an update, UTVideo 422 plays smoothly in Vegas (I'm using Vegas Movie Studio 10).

I haven't tried 420 because of various issues, but 422 is not having the same speed issues as I had with other YUV codecs in Vegas. Huzzah!

[Mister Hatt]

Something worth noting seeing as people are using lossless and this kinda makes lossless entirely not worthwhile: when you resample your chroma in smaller blocks (2x1 blocks of chroma rather than 2x2 - it's what happens when you 4:2:2 instead of 4:2:0), you are doing so losslessly as it just uses the same chroma value. However any effects and whatnot that you apply will be rendered in a 4:2:2 chroma space, which when you encode is resampled to 4:2:0 and you thus lose colour definition. This can cause anything from blocky jaggies to banding to blurring on any chroma edges. If you are exporting, make sure you render your effects at 4:2:0. x264 CAN support 4:2:2 but at this point in time it doesn't. Just a heads up.

[Cannonaire]

Thanks for the good advice, Mister Hatt.

That kinda messes up the way I was planning on doing things moving forward. From what I can tell, Vegas processes everything internally in RGB, but if I understand correctly it will pass unprocessed YCbCr stuff straight through. So basically as long as I just do straight cuts and no effects (lol) it will maintain the original quality. That really sucks... not to mention the color inconsistencies created when some stuff is processed and other stuff isn't. I'm starting to see why some people don't like Vegas. At the risk of getting slightly off-topic, does Premiere do this any better? I also read that After Effects processes in all RGB as well.

Lastly (and more on topic), UTVideo 420 seems to be working fine for me now, so hurray for smaller files!