Quote:
Originally Posted by [1ponders]
Jonathan, what would be the easiest way to set up for the timing of this event? Can i use my laptop clock if I do a syn with tick.usno.navy.mil just before time and then run an AVI during the process. If the start time is known and the frame rate is known then the rest, as they say should be history.  |
I'm relatively new to this, however I have a few answers for you
If you have any dropped frames they will skew the perceived time, also this would give you second level accuracy at best. I'm currently working on a capture application to timestamp AVI frames as they are recorded using time from GPS and NTP sources, for exactly this purpose. It currently supports primarily the Imaging Source cameras. Basically I am hoping to provide an alternative to the Kiwi-OSD for people using USB/Firewire cameras. In the long term the app will need to be non-free, as I am needing to pay for the API, but I will be providing it for free to any willing beta testers
I'm hoping to provide both lite and feature rich versions to keep the cost down for users who just need the basic features. Obviously any work/support/etc related to this will be kept off of IIS, as it is my own personal venture.
If you have a stable NTP server running on your laptop, and have adequate time for the clock to stabilise prior to your capture, NTP can be a viable clock option. The port of NTPD to Windows
can be found here. It will provide significantly better clock synchronisation than the bare bones SNTP implementation in Windows, as it actually attempts to discipline the system clock and not just periodically skew it.
However, as NTP requires a significant time to discipline a system clock, especially under Windows, I have additionally added support for directly reading a PPS and NMEA signal from a serial attached GPS receiver. The timing loop driven by this is capable of sub-millisecond accuracy, within tens of seconds of the GPS receiver acquiring a satellite lock, rather than the minutes to hours needed by NTP. GPS receiver hardware needed to support this is a Garmin 18x LVC in a serial configuration, as described and available
here, or a similar PPS capable serial GPS receiver with the PPS signal connected to the DCD pin. A unit in this configuration is around $100 AU if ordered from overseas, which isn't too bad considering what it provides.
Regards,
Eric