On Fri, 1 Sep 2000, Glen Schaff wrote: > I have not been able to find documentation on the DC10+, does anyone know > what compression chip it uses. Also, do I have access to dma both raw and > compressed video directly into ram on an embedded PCI SBC. See http://www.cicese.mx/~mirsev/Linux/DC10plus/ for the latest driver. It uses a Zoran 36067 PCI controller, and a 36060 JPEG compression chip. The '67 chip can DMA both the uncompressed data from video decoder (some philips chip) and the compressed stream from the '60 JPEG chip. However, the DMA channels are not created equal! The codec channel (jpeg) can DMA into non-contiguous memory buffers, like the bt848, though the bt848 DMA engine is much more powerful design. This means you can DMA into a ring of memmaped buffers using V4L, and everything is good. Well, as good as the design flaws of V4L allow anyway. The video channel is designed for on-screen overlay. It can only DMA one scan line, then skip a set amount, then DMA the next scanline, skip the same amount, etc. This is the layout of a rectangular window in video memory on most cards. If you want to DMA into system memory, you set the skip length between lines to 0, and then you need a contiguous buffer. This is bad, because if you ask Linux for a 1MB+ contiguous buffer, you won't get it! You have to set aside the memory for the buffers at boot time. I guess for a single purpose machine this isn't much of a problem.
