Hi, 2014-11-04 23:32 GMT+00:00 Sakari Ailus <sakari.ailus@xxxxxx>: > Sakari Ailus wrote: >> yavta does, for example, print both the monotonic timestamp from the buffer >> and the time when the buffer has been dequeued: >> >> <URL:http://git.ideasonboard.org/yavta.git> >> >> $ yavta -c /dev/video0 >> >> should do it. The first timestamp is the buffer timestamp, and the latter is >> the one is taken when the buffer is dequeued (by yavta). I've done exaclty this with guvcview, and uvcvideo timestamps are completly unreliable, in some devices they may have just a bit of jitter, but in others, values go back and forth in time, making them totally unusable. Honestly I wouldn't trust device firmware to provide correct timestamps, or at least I would have the driver perform a couple of tests to make sure these are at least reasonable: within an expected interval (maybe comparing it to a reference monotonic clock) or at the very least making sure the current frame timestamp is not lower than the previous one. Regards, Paulo > > Removing the uvcvideo module and loading it again with trace=4096 before > capturing, and then kernel log would provide more useful information. > > -- > Sakari Ailus > sakari.ailus@xxxxxx -- 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
