RGB24 overlay

[Fluff]

Are there any mpeg2 / dvd decoders that do this kind of overlay?

I'm assuming it will be better than YUY2 or the YUVU. E.g. reds and yellows will be better.

[magician]

Why the hell you would need that?!? I mean, all DVD content is in YV12 colour space anyway and the only two things you should watch for are rendering engine (colour space conversion) and display calibration.

Video equipment and PCs are quite different in this... TVs, cameras and virtually anything related to video is designed for operation in YUV colour space, which has less bandwidth but better signal-to-noise ration. You know, sometimes less means more.

If you are into serious HTPC and Hi-Fi video stuff, you better inquire about display calibration and VMR9 vs overlay sort of things. Start with differences between (analog) YUV and (digital) YCbCr, namely CCIR601 definition of digital video signal and it's dynamic range (16-235 vs 0-255).

[Fluff]

My apologies. I'm way out of my depth.

My DVB-T card does overlays in YUY2,UYVY .

Which should I choose? I'm learning a bit on doom9 but most to be honest goes over my head.

I mean I would have thought that by now i would be able to choose a YV12 colour space as an overlay.

[Dr Mordrid]

Time for YUV 101

Also: I'm talking NTSC. PAL is different in that the color samples are phase shifted vertically. Don't ask

The names of the various formats are actually their fourCC's (four character codes). Windows uses the fourCC to indentify how the video data is organized.

YUV comes in two basic flavors: packed and planar.

In packed the Y (brightness), U (aka: Cb = Chroma blue) and V (aka: Cr = Chroma red) samples are packed together into macropixels that are stored in a single array. Planar YUV formats store them in separate arrays. What about Chroma green? That's calculated from the Y, U and V channels.

Both YUY2 and UYVY are packed YUV formats and are most often both available in codecs that use either. The main difference is that YUY2 has a slightly different component ordering within the UY_INT32 macropixel.

Both also use a 4:2:2 "colorspace", meaning that in a 720 wide frame there are 720 brightness samples and 360 color samples, with Cr and Cb being spread across each pair of horizontal pixels. The vertical pixels are all at full resolution. These sample spacings are called the fourCC's "sample periods" and they are given for each sample in both the horizontal and vertical planes.

This basically means that the B&W samples are at the frames full resolution while the color samples are spread across 2 horizontal pixels. Since the eye is more sentitive to B&W than color this cuts the video data rate with little visible loss while maintaining a high level of "edit-ability".

In terms of MPEG encoders UYVY is the second most popular YUV format used after YV12, but they don't use 4:2:2 as an output colorspace. 4:2:0 is the order of the day for that, but how that's organized is a whole other post.

Bottom line: there is very little, if any, practical difference between the two.

Dr. Mordrid