Edge / IoT

Off-The-Shelf Hacker: Open Source Video Production with Kdenlive

6 Jul 2019 6:00am, by

Trying to sell your ideas and projects to others requires promotion.

Walking around events, I promote my tech talks using my custom steampunk conference badge as a forward-facing, portable billboard. The Generation-5 badge has a Raspberry Pi 2, a 3.5-inch color LCD touchscreen and is capable of running short informational videos without freezes or flicker. It definitely attracts attention.

I use kdenlive to create tech demo videos. Although you could hack together a video on the badge (Raspberry Pi) in a pinch, it’s much easier and faster do it on a modern Linux notebook. Then just transfer it over to the badge when finished. Video promos work great Raspberry Pi machines. You can use the video on a Pi-powered big screen at your tech booth or at the entrance to your tech talk. A quick intro video, running on the projector screen could serve as an informative warm-up, before starting your talk. Maybe you could do a cool tech promo video for big monitors in your company lobby. Don’t forget to put them up on YouTube, as well.

TV commercials run around 30 seconds, so I follow their lead and keep my videos in the 30-second to two-minute range. This keeps the file size reasonable and easy to work with on a badge. The video we’ll discuss today is about 4MB in size. Keep in mind, the longer the video, the longer it will take to render, even on a fast notebook.

Let’s see how to build a basic tech promo videos using kdenlive.

Initial Concepts

My typical promo video has three parts, a title sequence, some content and closing credits. The videos run in a loop.

The title sequence appears at the beginning of the video and introduces the viewers to the promotional content, using text. Let’s build one.

Start kdenlive on your Linux notebook.

Main kdenlive screen

Click “add title clip” from the clip drop-down menu on the upper left part of the screen. It looks like a little film strip, just below the main file menu item. The title clip editor will appear and you can click on the text in the middle to type in your own message.

Kdenlive clip editor pop-up window

There are a lot of options on the clip editor. I usually change the font to something steampunk. Match your font to your marketing/advertising theme. You can also change the font color, position and size using the menus and tabs on the right side of the window. In our example clip, I used black as the font color with an orangish-beige background. Click on the “background” tab, next to the “properties” tab to set the clip background color. By default the color is transparent so unless you move the slider to the right, you won’t be able to see the results. Use a 255 value for no transparency.

You can also set the duration of the clip, in the box at the upper right part of the screen. Ten to fifteen seconds works well. Also much better to keep the text simple and direct. A person viewing the clip should quickly be able to grab your message instead of trying to comprehend a paragraph. Crisp, tight headlines rule.

When you’re happy with the title clip, hit OK at the bottom right to save your work. The clip editor will disappear and you can grab the new clip and move it down to the video 1 timeline.

Make sure to occasionally save your project using the “file” tab. Kdenlive is much more reliable these days, although it would be a shame to do a ton of work and lose it because you didn’t hit save once in a while.

Adding Clips

Now let’s insert a photo into the video timeline. Select “add clip” under the clip drop-down menu. A file list will pop-up allowing you to select a photo or a video clip. Today, we’ll just concentrate on photos.

Select a photo and click “OK” to bring the photo’s thumbnail into the clip list window. Select the photo from the list and drag it down to the video timeline. Left clicking the clip will let you move it right and left on the timeline. If you want to put a photo in between existing photos, you can move the clips to the right or up temporarily to another timeline. Left click and the hand cursor will grip a photo so you can move it around. Release the mouse button to drop the photo in your chosen spot.

In the sample video, I chose five of my infamous steampunk gadgets as the main content. The default duration for each photo clip is five seconds. If you want to increase the duration of a particular photo, you’ll have to move clips over so there is room for expansion. Likewise, if you want to shorten a photo clip, you’ll have to slide the clips together to take up the blank space. Unless, you want a spot where the screen is blank, in the video. Make sure you have enough room, then double click on a photo to bring up the “duration” menu. Adjust the duration, then click OK to make the change. Adjust clip spacing as needed.

Shameless Self-Promotion with the Credits Clip

What good is a promo video, unless people know how to contact you or your company? That’s the purpose of the final credits clip.

Go back to the clip menu and right click the title sequence clip. From the menu select “duplicate clip.” Double click the duplicate clip to bring up the clip editor. Double click on the text and edit it for your tagline, name, email and phone number. I like my text center justified. There is an “align” button in the lower right-hand section of the editor for that purpose. I also like to add a little embellishment with some hyphens and a lower case “o” in the middle, above and below the text. You can grab the text and move it around in the editor to center it on the screen, too. When everything looks good, hit OK to return to the kdenlive timelines. Now just drag the credit clip to the end of the timeline.

Periodically run through the whole video to see how it looks in the project monitor window. When satisfied with the video, render an output file with the render button. Lastly, copy the video file out to your target machine and run it.

kdenlive render window

This video took about four minutes to render, with the quality slider all the way to the right, on my aging duo-core ASUS notebook.

Here’s the finished sample video.

Wrap Up

Producing a simple video that you can display on a Pi-powered conference badge or digital signage is pretty fast with kdenlive. We’ve only touched on a few beginning techniques. You can start out simple and build from there. Kdenlive is a powerful video editor with a bunch of interesting features that you can surely leverage with a little imagination.

Be sure to take a look at the sample video, to get a quick overview of today’s work. In a follow-up article, we’ll look at ways to make the title clip old and scratchy, in keeping with the spirit of my ongoing steampunk projects theme. We’ll also explore various transitions, like fading to black between clips. These enhancements give the finished video a little more polish and professionalism. Videos are great for tech storytelling or promoting your next talk.

Catch Dr. Torq’s Off-The-Shelf Hacker column, each Saturday, only on The New Stack! Contact him directly for consulting, speaking appearances and commissioned projects at doc@drtorq.com or 407-718-3274.

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