Blender is the open source software for 3D modeling, animation, rendering, post-production, interactive creation and playback. Available for all major operating systems under the GNU Public License.
An often underestimated function of Blender is the Sequence Editor. It is a complete video editing system that allows you to combine multiple video channels and add effects to them. Even though it has a limited number of operations, you can use these to create powerful video edits (especially when you combine it with the animation power of Blender!) And, furthermore, it is extensible via a Plugin system quite alike the Texture plugins.
About this tutorial
This is a tutorial that I wrote for the Blender 2.0 Guide while I was working for Not a Number. It has now been made available under the Open Content License as part of the Blender Manual. Still, I'm proud of it :-)
Learning the Sequence Editor
This section shows you a practical video editing example exhibiting most of the Sequence Editor built in features. We will put together several Blender made animations to obtain some stunning effects. One frame of the resulting edited animation is shown below:
First Animation: two cubes
Let's start with something simple and see where it leads. Start a clean Blender and remove the default plane. Split the 3D window and switch one of the views to the camera view with NUM0. In the top-view, add a cube and move it just outside of the dotted square that indicates the camera view:
We want to create a simple animation of the cube moving into view, rotating once, and then disappearing. Set the animation end to 61 (set the End: value in the Anim Panel of the Scene Context, Render Buttons F10) and insert a LocRot KeyFrame on frame 1 with IKEY and selecting LocRot from the menu which appears. This will store both the location and the rotation of the cube on this frame.
Go to frame 21 (press UPARROW twice) and move the cube closer to the camera. Insert another KeyFrame. On Frame 41, keep the cube on the same location but rotate it 180 degrees and insert another KeyFrame.
Finally on frame 61 move the cube out of view, to the right and insert the last KeyFrame.
We will need two versions of the animation: one with a solid material and one with a WireFrame. For the material, we can use a plain white lit by two bright lamps - a white one and a blue one with an energy value of two:
For the WireFrame cube, set the material type to 'Wire' and change the color to green:
Enter an appropriate filename (for example 'cube_solid.avi') in the Pics field (first text button on top) of the Scene Context Render sub-context Output Panel (F10):
Render the animation with the white solid cube. This will save it to your disk. Save it as an AVI file. Use AVI Raw if possible, because it yields an higher quality - compression should be the last thing in the editing process - otherwise, if short of disk space use AVI Jpeg or AVI Codec, the first being less compressed and hence often of higher quality.
Now change the material to the green wire frame, render the animation again, saving the result as cube_wire.avi.
You now have a 'cube_solid.avi' and 'cube_wire.avi' on your hard disk. This is enough for our first sequence editing.
First Sequence: delayed wireframes
The first sequence will use only the wireframe animation - twice - to create an interesting effect. We will create multiple layers of video, give them a small time offset and add them together. This will simulate the 'glowing trail' effect that you see on radar screens.
Start a clean Blender file and change the 3D window to a Sequence Editor window by pressing SHIFT-F8 or by selecting the Sequence Editor icon: .
Add a movie to the window by pressing SHIFT-A and selecting Movie (see below) or by using the Add>>Movie Menu entry. From the File Select Window wich appears select the wireframe cube animation that you made before.
After you have selected and loaded the movie file, you will see a blue strip that represents it. After adding a strip, you are automatically in grab mode and the strip follows the mouse. The start and end frame are now displayed in the bar.
Take a closer look at the Sequence Editor screen now. Horizontally you see the time value. Vertically, you see the video 'channels'. Each channel can contain an image, a movie or an effect. By layering different channels on top of each other and applying effects, you can mix different sources together. If you select a video strip, its type, length and filename will be printed at the bottom of the window.
Move your video strip and let it start at frame 1. Place it in channel 1, that is on the bottom row and press LMB to finalize:
Tip: Lead-in, Lead-out and stills
You can add lead-in and lead-out frames by selecting the triangles at the start and end of the strip (they will turn purple) and dragging them out. In the same way, you can define the 'length' in frames of a still image.
Duplicate the movie strip with SHIFT-D, place the duplicate in channel 2 and shift it one frame to the right. We now have two layers of video on top of each other, but only one will display. To mix the two layers you need to apply an effect to them.
Select both strips and press SHIFT-A. Select ADD from the menu that pops up. Otherwise use the Add>>Effect>>Add.
To see what's happening split the sequence editor window and select the image button in the header:
This will activate the automatic preview. If you select a frame in the sequence editor window with the strips, the preview will be automatically updated (with all the effects applied!).
If you press ALT-A in the preview window, Blender will play back the animation. (Rendering of effects for the first time takes a lot of processing time, so don't expect a real-time preview!).
Tip: Windowless preview
If you do not like the separate render window, switch to the Render Buttons (F10) and select DispView in the bottom left.
Now it's time to add some more mayhem to this animation. Duplicate another movie layer and place it on channel 4. Add it to the existing ADD effect in video channel 3 with a new ADD effect. Repeat this once and you will have four WireFrame cubes in the preview window.
All the cubes have the same brightness now, but I would like to have a falloff in brightness. This is easily arranged: open an IPO window somewhere (F6) and select the sequence icon in its IPO Type Menu.
Select the first add strip (the one in channel 3), hold down CTRL and click LMB in the IPO window on a value of 1. This sets the brightness of this add operation to maximum. Repeat this for the other two add strips, but decrease the value a bit for each of them, say to around 0.6 and 0.3.
Depending on the ADD values that you have just set, your result should look something like this:
Now we already have 7 strips and we have only just begun with our sequencing! You can imagine that the screen can quickly become very crowded indeed. To make your project more manageable, select all strips (AKEY and BKEY work here, too!), press MKEY and press ENTER or click on the Make Meta pop up. Otherwise you can use the Strip>>Make Meta Strip Menu entry. The strips will now be combined into a meta-strip, and can be copied or moved as a whole.
With the meta strip selected, press NKEY and enter a name, for example 'Wire/Delay', to better remember what it is.
Continued on page 2...