[time-nuts] Time Code generator

Chris Albertson albertson.chris at gmail.com
Wed Dec 8 16:54:15 UTC 2010


Adding time code to video would be redundant.  All video is already time coded.

It turns out the time code is required to support editing.  Editors
don't actually move
bits of video data around.  What they do is create and modify an "EDL"
which is a
text file with a list of all the cuts and effects to be applied.  The cuts are
defined by the time. For example a close up of an actor's face might
be specified
at "camera roll XX from time T1 to time T2".  Later during final
rendering the software
will search the video data for frames with the required time codes

But many consumer level cameras "fake" it by defining time = zero at
the start of a
tape or the first frame in memory.  If absolute time needs to be record on a
consumer level camera then I'd shoot a few frames of a digital clock and then
later in a video editor adjust the time code

OK, all that said there is a group of people who routinely record WWV
audio on their
video.  Amateur occultation timers do this.  These people use video
cameras through
telescopes to record when a asteroid passes in front of a star and
blocks its light.
This can produce very acuate orbital data for the asteroid and if enough people
all over the world record it you can even deduce the shape of the asteroid.


On Wed, Dec 8, 2010 at 5:27 AM,  <scmcgrath at gmail.com> wrote:
> When audio/video time code is specified if its on a audio track its called LTC or Longitudinal Time Code and is generally IRIG-B,   This is very uncommon these days as it went out of common use about the time 1" reel to reel was discontinued.
>
> Most common today on NTSC is VITC or vertical interval time code.  Its encoded as a series of pulses in the vertical blanking interval.   The display is generally called a 'Screen Burner'
> Sent from my Verizon Wireless BlackBerry
>
> -----Original Message-----
> From: "Collins, Graham" <CollinG at navcanada.ca>
> Sender: time-nuts-bounces at febo.com
> Date: Fri, 3 Dec 2010 07:28:13
> To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
> Reply-To: Discussion of precise time and frequency measurement
>        <time-nuts at febo.com>
> Subject: [time-nuts] Time Code generator
>
> On another list to which I subscribe, the question was asked about the
> suitability of recording WWV 2.5mhz audio as one track when recording
> off the air signals of interest as a time reference.
>
> The person who asked the question didn't really state his intentions but
> they seem very similar to my immediate needs. That is, simply a time
> reference - that is "the time", the start of the minute, and periodic
> references (i.e. seconds) between the announcements.
>
> It seems that recording the audio of something like WWV or CHU is ideal.
>
> However, another approach would be recording a more proper time code
> signal as you might have available from a "precision clock". Of course,
> a decoder would also be required.
>
> A quick Google search turned up lots of leads which I have yet to sort
> through. In the interim I thought I would pose the question to the
> learned members of this group for their suggestions. Keep in mind KISS
> and that a very high degree of accuracy is not required.
>
> Is there an opensource/freeware PC app that will generate an appropriate
> time code signal that can be recorded on one track of an audio recorder
> (either PC based i.e. Audacity or standalone) that will also decode via
> soundcard or other input?
>
>
> Cheers, Graham ve3gtc
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
=====
Chris Albertson
Redondo Beach, California




More information about the Time-nuts_lists.febo.com mailing list