Wayne D's Blog

My latest video brings the classical lemon battery experiment into the new decade by using lemons to light an LED. Far from being difficult anyone can perform this experiment using galvanized roofing nails, some copper wire or older pennies, some clip leads and an LED. A voltmeter is helpful but not required if you follow the directions carefully. The widespread use of LED's for Christmas lights means you probably even have some LED's lying around the house. The video stars my 13 year old son Steven who didn't have any trouble getting the LED to light. You can also watch the video accompanied by text directions by clicking the How to Power an LED with Lemons link directly below the video.

This video was made for Howcast.com as part of their emerging film maker program which pays $50 for each completed video. Howcast supplies the script, voiceover track, graphical elements and cleared music. THey also supply a clear and concise document outlining their production standards. What they don't do is tell you what to shoot and how to edit it. For me it was the right mix of instructions and guidelines while still allowing a wide degree of creative freedom and flexibility. Howcast.com also provided extensive notes after I submitted the first cut of the video. Considering how many things I had goofed up I was surprised that they didn't just throw up their hands in disgust but instead they emailed a detailed list of issues along with suggestions on how to improve my video that were super helpful, encouraging and kind.

I certainly learned more about using Cinelerra, the Linux video editing package i used to edit the video. Cinelerra had all the features and tools I needed with the exception of one thing. The graphics supplied by Howcast are MOV's with an alpha channel which Cinelerra can't import. I didn't realize that the graphics videos even had an alpha channel until I had submitted the video to Howcast. I did find out that a newer version of Cinelerra for Centos 5 had been released after I had started editing the video. I decided that updating my video editing software in the middle of editing probably wasn't a good idea. What i ended up doing was using ffmpeg to convert the Howcast graphics videos into a series of PNG's which Cinelerra had no trouble importing.

To convert the video to png's using ffmpeg I used the following command: ffmpeg -i filename.mov -f image2 %3d.png
I then used a helpful tool called mkframelist which creates a list of the png's for importing into Cinelerra. Download it, put it in either /usr/bin or /usr/local/bin make it executable and use mkframelist -h to find out the syntax you need to use, I created saved the pg's for each graphic in a different subdirectory and used the following command:
ls *.png | mkframelist -r 30 > output.lst

All in all it was a great learning experience for me and assuming I can find a suitable topic for my next video I know what I can do to make the editing process more efficient and way less painful.