NUERNBERGER CHRISTOPHER PETER (Christopher.Nuernberger@xxxxxxxxxxxx): > It would be sweet and super trivial to map the fourcc code into the > v4l2 pixel format specifications. For instance, YUV420 maps to the > fourcc code of I420, with a GUID of 0x30323449. Apparently (according > to the xpert mailing list), "nobody uses anything but these codes". I > guess nobody who developes in the windows world would have been more > appropriate. Or anyone who reads video card specs, please don't be so pissy. If this change is made, I think we should also update the documentation to be more specific about the formats. For example, including the position of the chroma samples. MPEG1 and MPEG2 use different positioning of the chroma samples and there's no way in XVideo or V4L to know what position the source is using. Also, making the excursions and colourspace more explicit would be nice in some cases. The v4l2 documentation says that all YUV formats use Y'CbCr excursions and a colourspace corresponding to ITU-R BT.601, however in an old bttv v4l2 driver I tried, you could turn on an option to have it violate this, and XVideo makes no mention of the excursions it exports it although implicitly it is the same. > It took a bit of figuring to realize what was going on, perhaps the > v4l2 documentation could be added to? It would allow for closer > integration of video for linux and the X video extension. Chris Well, the v4l2 docs do say that one of their formats is known as YUY2 in the windows world. :) -- Billy Biggs vektor@xxxxxxxxxxxx
