DIVX5 with yuy yuv or yv

[Kamui-Dash]

Hi,
Im not so familiar with all these compression like YUY, YUV or YV12.
I was wondering what kind of compression through avisynth would make the divx5 lossless so I could reencode it to another format? Ive ran sum test with yuv and yuy through avisynth->vdub and its lesssharp than the orig file put into vdub, so I was wondering if any1 could help :D

Ive been trying to do a search on the forum but no luck :(

[Acaila]

Hi, and welcome to the forum.

Im not so familiar with all these compression like YUY, YUV or YV12.A good place to learn about colorspaces is this FOURCC (http://www.fourcc.org) page. Click on "YUV" for the colorspaces you mentioned.

In short, YUV is a group of colorspaces of which both YV12 and YUY2 are a part of. YUY2 keeps full horizontal and full vertical luminance resolution and 1/2 horizontal but full vertical chroma resolution. YV12 keeps full horizontal and full vertical luminance resolution and 1/2 horizontal and 1/2 vertical chroma resolution.

I was wondering what kind of compression through avisynth would make the divx5 lossless so I could reencode it to another format?The compression DivX uses is in itself lossy, nothing on the outside can change this. The best you can do is encode at the highest quality possible, this is 1-pass mode @ Quantizer 2, no B-frames. You can use this file as a starting point for further encodes. But it will always be lossy.

You can also give Marc FC's VBLE (http://forum.doom9.org/showthread.php?s=&threadid=38389&perpage=20&highlight=lossless%20codec%20marc&pagenumber=5) codec a try, it achieves better compression than HuffYUV and it's a lossless codec.

Ive ran sum test with yuv and yuy through avisynthDivX 5 takes the input from avisynth and compresses it with the YV12 colorspace. It doesn't matter what the input colorspace is, it will always return YV12.

[Kamui-Dash]

quote:
DivX 5 takes the input from avisynth and compresses it with the YV12 colorspace. It doesn't matter what the input colorspace is, it will always return YV12.

So what u say is its better to leave it as YV12 instead of using avs commands such as convert to rgb24/yuy2, am I correct? Anyway I prolly need to run tests to see it for myself. Many thanks to ur answers very much appriciated. :D

[Acaila]

Yes that's correct. Any colorspace conversion alters the picture and also slows things down a lot. Converting from one group to another, like RGB<->YUV does this more than converting within a group like YUY2<->YV12.

But sometimes you want to use a filter that doesn't support a certain colorspace, in that case you have to convert. It's best to avoid any colorspace conversions though.