Michael Hunold wrote:
>
> Hello Klaus,
>
> > After having newly loaded the DVB driver, the first GRAB command
> > in VDR always produces an empty (all gray) image. Sometimes (rarely) the
> > first grabbed image looks as if it contains only one half picture (i.e.
> > every other scan line is gray).
>
> The driver initializes all capture buffers using a gray value.
> "saa7146_core.c" says:
>
> /* clear the ram out, no junk to the user
> note: 0x7f gives a nice grey field
> in RGB and YUV as well */
> memset(mem, 0x7f, quant*GRABBING_MEM_SIZE);
>
> So there is either something wrong with the order the capture ioctls are
> called or something in the driver is bogus, ie. it hands out a capture
> buffer that has not been captured to.
Here's what VDR essentially does:
struct video_capability vc;
result |= ioctl(videoDev, VIDIOCGCAP, &vc);
struct video_mmap vm;
vm.frame = 0;
vm.width = vc.maxwidth;
vm.height = vc.maxheight;
vm.format = VIDEO_PALETTE_RGB24;
result |= ioctl(videoDev, VIDIOCMCAPTURE, &vm);
result |= ioctl(videoDev, VIDIOCSYNC, &vm.frame);
I didn't write this myself, so I don't know whether this is actually
all correct. Can you see something obviously wrong here?
> > After that, all following GRABs work just fine.
>
> > I did several tests, but couldn't find anything in VDR or the driver
> > that might fix this. Can one of the driver developers perhaps come up
> > with an idea where to look and what to try in order to fix this?
>
> If it's driver related, then it's probably not worth the effort.
> Video4Linux-1 has serious issues regarding capturing, they are probably
> made even worse by the implementation in the early versions of my driver.
>
> I'm sorry, but I don't have the time and energy to fix that code. All
> this mess was the reason for me to abandon Video4Linux-1 in the past and
> start with a Video4Linux-2 driver from scratch.
>
> If this is getting a problem, use "dvb-kernel" instead and additionally
> switch over to Video4Linux-2.
It's not really a problem, just an inconvenience.
I would have fixed it if it was easy to fix, that's why I brought it up...
Klaus
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