Concept check

We’re planning to do a promotion video for Alan, and we had some ideas that needed to be tested on the technical level. To find out if my latest idea for the project can be done with the means at our disposal, I created this little video of me singing with… me 😉 The quality isn’t that great, but that’s mostly because I worked with webm files as a basis and there were several conversion steps involved. I didn’t want to create a giant project just for a concept check. Enjoy!

I have to admit, I was surprised how well this worked. Here’s how I did it:

First, I filmed the guitar part. That was easy (even though I screwed up a bit at the end, but hey, after all it’s just a concept check.)

Then, I extracted the audio and put it on my MP3 player. I used in-ear phones, and only on one side (the left, obviously.) Then I recorded the second part, singing along with the recording from the first part.

I use Kdenlive for my cutting; so far I haven’t found anything better on Linux. The interface is very intuitive so you don’t have to dig into the manual before you can do the smallest kind of edit.

I imported both clips and put them on two separate video tracks. The hardest part was to align them, so that the audio from clip 2 matched the audio from clip 1 exactly.

The guitar part (clip 1) was on the first track, the singing part (clip 2) on the second. The two tracks are like layers in Gimp or Photoshop. I figured, all I needed to do was to hide part of the top layer — the part that covered my singing self on the bottom layer. In Gimp that’s pretty easy, in Kdenlive I had to employ some Google-Fu.

The first filter I needed is called “Scale and Tilt”. After you activate it, you’ll find the option to “clip” on all four sides in the filter configuration panel. I clipped on the left side:

(Click to enlarge)

Next, I had to add transparency to clip 1, aka the top layer. In Gimp, this is done through an alpha channel. For Kdenlive, that’s where the Google-Fu came in, because I couldn’t, for the life of me, figure it out. The trick is a transition called “Composite”. Right-click on the track, click “Add Transition” and then “Composite”. The transition shows up covering only a few seconds at the beginning of the track and needs to be scaled to the full length:

Only after I did that did I realize that the colors of the two videos didn’t match:

Click to enlarge

I applied several color filters, until I had it as close as I could get it. Unfortunately, there was still a very obvious discrepancy in the two parts of the table:

(Click to enlarge)

I also noticed at that point that I must have accidentally moved the camera when I took the DVD out. Fortunately, that was fairly easy to fix; there’s a filter called “Crop”, which I used to cut and move clip 1, so it would line up with clip 2. Fixing the table color took a little more extensive tinkering, though. I ended up cheating with a little help from the Gimp. I exported a frame from clip 2 to PNG and opened that in Gimp. Then I masked everything except the table:

(Checkerboard pattern is there only to visualize the transparency; click to enlarge)

I imported the picture shown above into the video project. Then I moved the two clips from tracks 1 and 2 to tracks 2 and 3, put the image on track 1 and resized it to match the length to the rest of the video. The image track also needs a Composite transition just like clip 1, otherwise the transparent part shows up as black and covers everything.

That was pretty much it. Now I just need to learn to sing harmony, then the whole thing would be a lot more interesting 😉

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