Shop OBEX P1 Docs P2 Docs Learn Events
Video overlay (outside the propeller) — Parallax Forums

Video overlay (outside the propeller)

TookingsTookings Posts: 18
edited 2009-06-19 13:52 in Propeller 1
Howdy...the project uses a propeller, so this seemed the best forum...it is however, not about the propeller itself.

I'm working on a data logging project in an aircraft, with various sensors to the propeller...while also shooting video. I'm looking to overlay data on the video, but would much rather do this post-processing, and so far I'm not having much luck finding anything.

Essentially, it would be great if there was software (ideally, free...) that would allow me to give it a movie file along with a data file (created by the propeller, say a CSV in final form) with some sort of time codes and have it create the composite -- which configuration on how to display the data.

Nice bonuses for something that allows "plugins" to be written to create graphic interpretations of the data and/or perform the overlay creation in realtime. But text overlay form data into a saved movie file would work.

Does something like this exist? (I know it can be done on the propeller, but I don't have any need to do something like this on a code level...)

Thanks much!

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-06-19 00:08
    'Just curious: why not do it in real time with a Propeller-based overlay? It seems simpler than trying to synchronize multiple timecodes after the fact. If you don't want the original video covered by the overlay, would it work to encode the data in the closed-captioning lines? That way you could turn the overlay on or off during playback on a standard CC-equipped video monitor.

    -Phil
  • TookingsTookings Posts: 18
    edited 2009-06-19 00:32
    [noparse][[/noparse]quote]'Just curious: why not do it in real time with a Propeller-based overlay? It seems simpler than trying to synchronize multiple timecodes after the fact.

    Mainly, I'd like to be able to interpret the overlay in different ways from the same data, and easy to change by someone who may not be a programmer after the fact...and to keep the in plane gear fairly simple and independant.

    [noparse][[/noparse]quote]If you don't want the original video covered by the overlay, would it work to encode the data in the closed-captioning lines? That way you could turn the overlay on or off during playback on a standard CC-equipped video monitor.

    Hmmm...hadn't thought of that. Could be interesting.

    Ideally I was thinking recording the log entry at the same frame rate of the video. Then I just give the PC based software something like:

    count,voltage,altitude,bank,pitch
    1,13.8,3500,0,0
    2,13.7,3510,5,0
    3,13.8,3515,4,10

    etc...

    Then a more advanced version of the post-processing software would overlay a video from with say "13.8V" in the lower left, "3,515'" in the lower right, and a graphical attitude type indicator derived from the bank and pitch angles. Doing this in a PC would make advanced graphics easier to create (and modify) if some sort of software like this existed.

    If it doesn't exist...would have to weigh creating it in the prop or or firing up VC++ and learning how to work with video on a PC [noparse]:)[/noparse]
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-06-19 00:39
    This may sound a bit far-fetched, but it would be possible to encode the raw data in the vertical blanking lines of the video signal using a Propeller, similar to the way closed-captioning data are encoded. Then, during playback, a different Propeller program could recapture the encoded data and display it either text-formatted or graphically (or both), overlaid on the screen. That way the actual overlay format could be postponed until playback and changed at will.

    -Phil
  • TookingsTookings Posts: 18
    edited 2009-06-19 00:48
    That...is quite an interesting idea. [noparse]:)[/noparse]
  • TookingsTookings Posts: 18
    edited 2009-06-19 12:38
    Just a note in case anyone else is interested...this is a pretty incredible scripted video processing system:

    http://avisynth.org

    http://en.wikipedia.org/wiki/AviSynth

    ...although I'm leaning more towards doing it on the prop. Just FYI.
  • LawsonLawson Posts: 870
    edited 2009-06-19 13:52
    What I think you're looking for can be done with tools developed for the fan-subtitling community. I'm not versed in the details of fan-subtitling. Still, judging by the output I've seen I think this software would handle your overlays just fine. This Wikipedia Link to the SubStation Alpha file format looks like it's linked into enough information to do what you'd like.

    Lawson

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Lunch cures all problems! have you had lunch?
Sign In or Register to comment.