Trent, I found your response from Sept 1 (below). thanks, if I was to simultaneously enable JPEG and raw dma, could I just run raw dma for a few scan lines per field and continue to stay in sync with the bof on raw data? 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. -----Original Message----- From: video4linux-list-admin@xxxxxxxxxx [mailto:video4linux-list-admin@xxxxxxxxxx]On Behalf Of Trent Piepho Sent: Saturday, September 16, 2000 5:30 AM To: video4linux-list@xxxxxxxxxx Subject: Re: [V4L] DC10+ simultaneously deliver raw video and compressedJPEG? On Fri, 15 Sep 2000, Matt Sherer wrote: > Glen Schaff wrote: > > > I need access to the raw video stream on the DC10+, but I do not want to > > stop MJPEG compression. We are going to buy a bunch of these cards and I > > was wondering if anyone with experience here knows whether the DC10+ can > > simultaneously deliver raw video and compressed JPEG? > > Wondering if you got any off-line mail about this. I'm interested in doing > the same, and was looking at the Matrox cards, but it doesn't look like > they'll do it. Check the list archives, I answered this question in a message from sep 1st. _______________________________________________ Video4linux-list mailing list Video4linux-list@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/video4linux-list
