Hi, On 5 Apr, this message from Richard A. Smith echoed through cyberspace: > I've used the saa7146 and v4l2 to do video in a window but that runs > the video across the PCI bus. > > They way we would like to do it is via the multimedia engine overlay > ability of the 69000 and one of the phillips saa type chips so we can > keep the video off the bus. We have an existing product that does > this with DOS and it works well. > > Our DOS product has the saa attached to the 69000 via the I2C bus. I wouldn't suppose you run the video across I2C, do you? > I've been doing some research and it looks like most of the pieces to > duplicate this under X exist but I haven't really found any reference > on how to put them all together. Or even if they will all work > together. First sort the hardware out, then the software ;-). Concerning the hardware, I don't know the 69000 chips. What kind of overlay input do they provide? You need to find out what format that is, and then loook for an saa chip that matches that input. I suppose you have the data sheet for the 69000 (probably a data _book_); they may have a reference design involving an overlay input. Most probably,the SAA7146 will not help you as it is designed to send video data over the PCI bus. Look for something like the SAA7196 (discontinued; Philips has a much more advanced replacement chip). > Theres the I2C in the kernel and I also see an I2C module for X but > it's not totally clear to me what I2C bridge(s) each of these are > capable of using. Since I2C in your design will be used to control the video chips, whether you bit-bang the 69000, some other chip (it can be as simple as two memory-mapped registers), or whether you go via a more high-level I2C driver doesn't really matter. Just get something in place so you can control your video chips. > The readme for 69000 options in X shows an overlay support option but > it claims that XVideo uses the same features and enableing it will > disable XVideo. Obviously, overlay and XVideo use the same blit engine that copies off-screen data into the visible framebuffer while doing some format conversion. But I suppose you wouldn't need XVideo anymore once you do overlay? > It dosen't really say anything about controling an > I2C device attached to it. You need to check the data sheet whether the 69000 provides an I2C bus controller. It might not.... > I was hoping somebody on this list could point me to some docs on > making this all work or at least let me know if I'm in for a whole > lotta driver work. I gotta try to put together an estimate of the > manpower needed. Hmm, hard to say from a distance. It really depends on what hardware design you come up with. The operational principle of your software, whether driver or application, can be quite easy. But any number of gory details may hide around the corner ,-) I'd suggest going for implementing a v4l-compatible driver, and using existing v4l apps on top of that. For the driver part, look at either: - the GATOS project for the ATI ALL-In-Wonder cards, which will probably be close in hardware design to what you are trying to do; - any of the v4l overlay drivers, if you consider the video chip as integrated into the grafics chip and disregard the PCI bus. Cheers Michel ------------------------------------------------------------------------- Michel Lanners | " Read Philosophy. Study Art. 23, Rue Paul Henkes | Ask Questions. Make Mistakes. L-1710 Luxembourg | email mlan@xxxxxx | http://www.cpu.lu/~mlan | Learn Always. "
