Hi everybody, The V4L2 specification documents the v4l2_buffer timestamp field as "For input streams this is the system time (as returned by the gettimeofday() function) when the first data byte was captured." The system time is a pretty bad clock source to timestamp buffers, as it can jump back and forth in time. Using a monotonic clock, as returned by clock_gettime(CLOCK_MONOTONIC) (or ktime_get_ts() in the kernel), would be much more useful. Several drivers already use a monotonic clock instead of the system clock, which currently violates the V4L2 specification. As those drivers do the right thing from a technical point of view, I'd really hate "fixing" them by making them use gettimeofday(). We should instead fix the V4L2 specification to mandate the use of a monotonic clock (which could then also support hardware timestamps when they are available). Would such a change be acceptable ? -- 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
