On Fri, 19 Dec 2003, Michel Bardiaux wrote: > Trent Piepho wrote: > > The bt8x8 chip samples the video stream at a high horizontal resolution. I > > know that for NTSC, it's 756 pixels. I guess for PAL, it's 924. > > > > If you request less than full resolution, the bt8x8 scales the image down in > > hardware using a number of different filters. You even control the filters it > > uses, but I don't think v4l has the ability to set these things. > > > > I prefer software downscaling because what the hardware does is very > hardware-dependent. The hardware scaling wirks better with some cards > than others, and you dont have any control over it. And I did not find > statifactory documentation. For power-of-two downscaling, the quality > obtained by simple decimation was found acceptable by all my guinea pigs. I doubt you'll find any hardware the does worse scaling than simple decimation. I have a hard time thinking of what that would be.... > But I let the card do whatever is necessary to give me a 'standard' > full-size image. The 704x576 was derived from SIF. I found contradictory With a bt8x8 at least, when you request a 704x??? image the card is already scaling it for you. The bt8x8 ALWAYS horizontally scales your image. You're just scaling it again in software.
