On Thu, Nov 6, 2014 at 12:29 AM, Grazvydas Ignotas <notasas@xxxxxxxxx> wrote: > On Wed, Nov 5, 2014 at 4:05 PM, Laurent Pinchart > <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: >> Hi Rémi, >> >> On Tuesday 04 November 2014 22:41:44 Rémi Denis-Courmont wrote: >>> Le mardi 04 novembre 2014, 15:42:37 Rémi Denis-Courmont a écrit : >>> > Le 2014-11-04 14:58, Sakari Ailus a écrit : >>> > >> > Have you tried with a different application to see if the problem >>> > >> > persists? >>> > >> >>> > >> Tried mplayer and cheese now, and it seems they are not affected, so >>> > >> it's an issue with vlc. I wonder why it doesn't like newer flags.. >>> > >> >>> > >> Ohwell, sorry for the noise. >>> > > >>> > > I guess the newer VLC could indeed pay attention to the monotonic >>> > > timestamp flag. Remi, any idea? >>> > >>> > VLC takes the kernel timestamp, if monotonic, since version 2.1. >>> > Otherwise, it generates its own inaccurate timestamp. So either that >>> > code is wrong, or the kernel timestamps are. >>> >>> From a quick check with C920, the timestamps from the kernel are quite >>> jittery, and but seem to follow a pattern. When requesting a 10 Hz frame >>> rate, I actually get a frame interval of about 8/9 (i.e. 89ms) jumping to >>> 1/3 every approximately 2 seconds. >>> >>> From my user-space point of view, this is a kernel issue. The problem >>> probably just manifests when both VLC and Linux versions support monotonic >>> timestamps. >>> >>> Whether the root cause is in the kernel, the device driver or the firmware, >>> I can´t say. >> >> Would you be able to capture images from the C920 using yavta, with the >> uvcvideo trace parameter set to 4096, and send me both the yavta log and the >> kernel log ? Let's start with a capture sequence of 50 to 100 images. > > I've done 2 captures, if that helps: > http://notaz.gp2x.de/tmp/c920_yavta/ > > The second one was done using low exposure setting, which allows > camera to achieve higher frame rate. So, has anyone had time to look at these? Gražvydas -- 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
