11 Replies Latest reply on Aug 11, 2010 8:15 PM by Jeff Barnett

    Detecting changes in video

    Jeff Barnett

      Greetings all. I'm new to video editing and Premiere.

       

      Is anyone aware of a plug-in or software that can detect changes in video? I have been setting up my camera to shoot lightning vids, then walking away for minutes at a time. Needless to say, the flashes can be as short as a couple of frames, and locating these extremely short sections of clips can be very time consuming when visually searching frame-by-frame.

       

      I would think there would be a need for something like this for not only my situation, but for nature video or surveillance. The ideal app would locate changes in the scene and mark or log the locations.

       

      Thanks for any advice.

       

      Jeff Barnett

        • 1. Re: Detecting changes in video
          Todd_Kopriva Level 8

          There's a great free plug-in for After Effects that detects scene changes:

          http://aescripts.com/magnum-the-edit-detector/

          It might do what you're looking for.

          1 person found this helpful
          • 2. Re: Detecting changes in video
            Colin Brougham Level 6

            What you're looking for is what is typically called "optical scene detection." Premiere doesn't do that (I don't know of any NLE that does, but I could be wrong), and it only does scene detection based on time-of-day (TOD) data written onto a DV tape--and that's only on capture.

             

            There are a few third-party apps you can find that might work for your needs, if you Google (does anyone even say "search" any more?) for "optical scene detection." I think one particularly compelling and complete piece of software is the somewhat oddly-titled HandySaw DS. It's not free, so depending on your level of need it might not be worth it, but it is pretty robust and has a lot of options. Beyond splitting clips into smaller parts, it also has the capability of outputting a "cut list" in a variety of EDL and NLE project formats. There is a demo, so give it a shot and see if it works for your purposes.

            1 person found this helpful
            • 3. Re: Detecting changes in video
              Jeff Barnett Level 1

              Thanks Todd! I just watched the demo, and while it isn't specifically designed to do what I need, it may well work. There is some kind of "sensitivity" control that may allow me to use it. I will try it and also contact the author to learn more.

               

              Again, thanks!

               

              Jeff

              • 4. Re: Detecting changes in video
                shooternz Level 6

                Possibility..

                 

                I would asume that there maybe a clap of thunder somewhere in the vicinity of a lightning flash.

                .

                Expand your audio track so you get very large waveforms and zoom in a bit.  Look for the spikes in the waveform.

                 

                You may find that an audio program such as Audition could b helpful in this regard as well.

                 

                 

                FWIW:

                If I was a serious lightning researcher /hunter ..I would set my camera up to roll on a light signal detected by a sensor (custom device) and set the camera for a ten second preroll on the record buffer.

                • 5. Re: Detecting changes in video
                  Jeff Barnett Level 1

                  Thank you Colin for your response. I'm a newbie, so when searching for this kind of thing the correct terminology is very helpful.

                   

                  For about 5 seconds I was excited when I read of the "scene detection" feature of PP. Of course, seconds was all it took to realize that it wasn't what I need. It's cool, but I will not likely be capturing taped video in the near future ... if ever.

                   

                  However, I become re-excited when I read your post. I knew I couldn't be the only person who has ever needed this functionality, so to discover that it actually has a proper name gives me hope that I'm on the right track. I will look into HandySaw DS. Also, I can do more focused "Googles" from here on. ;-)

                   

                  Thanks again!

                   

                  Jeff

                  • 6. Re: Detecting changes in video
                    Colin Brougham Level 6

                    Glad to help! You didn't mention the type of camera or footage you're using, so there may be some limitations on what HandySaw or any other application will accept, but it looks like HandySaw is able to use quite a range of footage so you might be OK with it. You'd probably want to set the threshhold very low so that those brief frame changes are detected and properly marked; experimentation is key here, and since this sounds like a hobby for you, you will likely have a higher tolerance for fiddling around than some of us

                     

                    I'd be interested to hear your results of this experiment.

                    • 7. Re: Detecting changes in video
                      Colin Brougham Level 6

                      Now that's simple genius...

                      • 8. Re: Detecting changes in video
                        Jeff Barnett Level 1

                        Hey, shooternzn (a guy who thinks like me!),

                         

                        Being the "audio" guy that I am, looking for thunder waveforms has occured to me if I am shooting outdoors. Alas, I have been shooting from indoors, at work, on the 20th floor of our office building. I tend to pick up more paper rustling, and "cube chatter" than thunder in the audio.

                         

                        Many years ago, as a serious amateur photographer, I spent much time chasing local thunderstorms trying to get a great lightning shot. Some were ok, but none were great. Now it's a new century, my interest hasn't abated, and I'm finally jumping into the great "new" world of video! I'm pretty fired up about this new interest and lightning still makes the hair stand up on my neck!  (In fact, it has twice in my life. I've actually been struck twice!) So, I'm still looking for the perfect lightning shot. Guess I want a good look at the perp that knocked me out! :-)

                         

                        Your suggestion is something I've pondered, but I've learned over the years that what can usually be accomplished with hardware, can often be done in software (assuming that some programmer "out there" is thinking the same way I am.) So, being a "lazy" lightning hunter, I'm looking for the easy way out, here.

                         

                        Thanks so much for the input. As my interest in nature video expands, this kind of option will be something to explore.

                         

                        Jeff

                        • 9. Re: Detecting changes in video
                          Jeff Barnett Level 1

                          At this point, it is a hobby. And try as I might, I couldn't find any mention of a "lightning detector" preset in my HF S20. There's crap like Fireworks, but no presets for Lightning! What good are presets anyway? Maybe I need a semi-pro or pro camera.

                           

                          I do have plenty of hobbyist time on my hands, but I will always be looking for the one button that does it all!

                           

                          I'll be sure to post the results of my search/experiments when I have them.

                           

                          Thanks and Peace, guys!

                           

                          Jeff

                          • 10. Re: Detecting changes in video
                            shooternz Level 6

                            Just so you know. (In case you were sceptical about existing technologies that maybe of use to you)

                             

                            Some Panasonic Cameras have the "Pre Record Function".  This enables a capture of footage at a small predetermined time prior the camera rolling.  ie. it captures footage from the past by using a buffer.

                             

                            next...Still photographers use slave units to remotely trigger other flash units.  They react to the flash.

                             

                            Not much of a leap to get one to activate a camera into roll to record mode.

                             

                            BTW - real  lightning hunters would go out in the weather and the action... 

                             

                            and ...dont ask me to crew for you either, with your track record of being struck. 

                            • 11. Re: Detecting changes in video
                              Jeff Barnett Level 1

                              Ok, wise guy! Are you telling me that you wouldn't chase lightning with me just because I've been hit before? Basic math: The odds are the same for me being struck now as they were the first time when I was 9. It's not like I go out wrapped in tin foil and climb trees to catch the perfect shot!

                               

                              And I'm sorry, but I ain't 18 no more ... I'm 55. I finally realized that I'm not indestructible like I was at that age. Besides, call me a weenie, but lightning images with interesting content (cityscape and North GA mountains in the distance), shot from within a giant Faraday cage (office building), is more visually interesting than from under the eaves of an aluminum strip shopping center with a tree shrouded 7-11 in the foreground! We have lots of trees here! LOL Like I said ... never found the great shot!

                               

                              Actually, my Canon does have a pre-roll function, but only 3 seconds, if I recall correctly. Really cool feature that I've used in conjunction with my remote to record a wren repeatedly returning to feed her hatchlings in a barn.

                               

                              I've used slaves for still work, but I'm not sure if I can get one to trigger my camcorder. I would either have to have some kind of PC (flash trigger) to infrared remote converter, or one that converts to the LANC input. Maybe other options, but I haven't discovered them.

                               

                              Thanks for the info, chuckle, and vote of confidence!

                               

                              Jeff