Hi all, On Tue, Nov 8, 2011 at 1:50 AM, Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> wrote: > Em 29-10-2011 05:52, Laurent Pinchart escreveu: >> Hi Mauro, >> >> On Saturday 29 October 2011 00:30:12 Mauro Carvalho Chehab wrote: >>> Em 28-10-2011 14:42, Laurent Pinchart escreveu: >>>> On Friday 28 October 2011 03:31:53 Gilles Gigan wrote: >>>>> Hi, >>>>> I would like to know what is the correct way to switch the current >>>>> video input during capture on a card with a single BT878 chip and 4 >>>>> inputs >>>>> (http://store.bluecherry.net/products/PV%252d143-%252d-4-port-video-capt >>>>> ur e-card-%2830FPS%29-%252d-OEM.html). I tried doing it in two ways: - >>>>> using VIDIOC_S_INPUT to change the current input. While this works, the >>>>> next captured frame shows video from the old input in its top half and >>>>> video from the new input in the bottom half. >>> >>> This is is likely easy to fix. The driver has already a logic to prevent >>> changing the buffer while in the middle of a buffer filling. I suspect >>> that the BKL removal patches might have broken it somewhat, allowing >>> things like that. basically, it should be as simple as not allowing >>> changing the input at the top half. >> >> This will work optimally only if the input analog signals are synchronized, >> right ? If we switch to a new input right when the frame start, can the first >> frame captured on the new input be corrupted ? > > That's a good question. I'm not sure how those bttv cards solve it, but as > they're widely used on such configurations, I suspect that the hardware used > on those CCTV boards have some logic to keep them in sync. > >> >>> Please try the enclosed patch. >>> >>> Regards, >>> Mauro >>> >>> - >>> >>> bttv: Avoid switching the video input at the top half. >>> >>> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> >>> >>> diff --git a/drivers/media/video/bt8xx/bttv-driver.c >>> b/drivers/media/video/bt8xx/bttv-driver.c index 3dd0660..6a3be6f 100644 >>> --- a/drivers/media/video/bt8xx/bttv-driver.c >>> +++ b/drivers/media/video/bt8xx/bttv-driver.c >>> @@ -3978,7 +3978,7 @@ bttv_irq_switch_video(struct bttv *btv) >>> bttv_set_dma(btv, 0); >>> >>> /* switch input */ >>> - if (UNSET != btv->new_input) { >>> + if (! btv->curr.top && UNSET != btv->new_input) { >>> video_mux(btv,btv->new_input); >>> btv->new_input = UNSET; >>> } >> > > I am yet to try the above patch myself, but I have received feedback from another user and it seems it does not solve the issue. Will keep you posted as soon as I got around to testing it. Thanks Gilles -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
