Hi Javier, On Monday 19 December 2011 12:01:34 javier Martin wrote: > On 19 December 2011 01:19, Laurent Pinchart wrote: > > On Thursday 15 December 2011 17:02:47 javier Martin wrote: > >> Hi, > >> we are testing a logitech Webcam M/N: V-U0012 in the UVC tree (commit > >> ef7728797039bb6a20f22cc2d96ef72d9338cba0). > >> It is configured at 25fps, VGA. > >> > >> We've observed that the following debugging message appears sometimes > >> "Frame complete (FID bit toggled).". Whenever this happens a v4l2 > >> frame is lost (i.e. one sequence number has been skipped). > >> > >> Is this behavior expected? What could we do to avoid frame loss? > > > > Could you check the frame intervals to see if a frame is really lost, or > > if the driver erroneously reports frame loss ? > > Hi Laurent, > sequence number in the v4l2 buffer returned is one step bigger than > expected, however the timestamp difference with the previous buffer is > 40ms which is what it is expected at 25fps. > So, sequence number indicates a buffer has been lost but timestamp does > not. Could you please test the following patch ? >From e6d21947277ad7875e41a90d387db8a1160368b6 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> Date: Mon, 19 Dec 2011 12:54:20 +0100 Subject: [PATCH] uvcvideo: Toggle the stored FID bit when detecting a new frame The FID bit is used to detect the start of a new frame by comparing the value sent by the device with the last value stored in the driver. When a new frame is detected this way the last value isn't updated, which leads to the frame sequence being incremented twice. Fix this by toggling the stored FID bit correctly. Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> --- drivers/media/video/uvc/uvc_video.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/drivers/media/video/uvc/uvc_video.c b/drivers/media/video/uvc/uvc_video.c index c7e69b8..f61c36b 100644 --- a/drivers/media/video/uvc/uvc_video.c +++ b/drivers/media/video/uvc/uvc_video.c @@ -1031,6 +1031,7 @@ static int uvc_video_decode_start(struct uvc_streaming *stream, uvc_trace(UVC_TRACE_FRAME, "Frame complete (FID bit " "toggled).\n"); buf->state = UVC_BUF_STATE_READY; + stream->last_fid = fid; return -EAGAIN; } -- Regards, Laurent Pinchart -- 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
