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; >> } > -- 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
