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Cinelerra Tutorial - Rendering
When your masterpeice is complete, you will want to render the result to a new video file. To do this, choose Select All from the Edit menu, then Render from the File menu. This brings up the rendering dialog box. Enter the name and location of the file you want to create. Select a File Format of Quicktime for Linux. Use the spanner icons to select properties for audio and video. For audio, select Two's Complement compression (not compression at all - DV audio is not compressed), and 16-bit Linear. For video, select DV as the compression format. For Insertion Strategy select Insert Nothing as we only want to write a file at this point, not insert anything into our project.
If you want to transfer your finished project onto a DV tape, the Kino tutorial explains how.
Rendering Quirks
Using DV it is possible to capture video from the camera, do a cuts only edit, and export the result back to DV tape without any generation loss. This is because all the work is done digitally, and compression takes place only once: on the camera.
This is all well and good until you want to do special effects like fades, transitions and titling. As soon as you do this, the video must be decompressed, the effect applied, and the result re-compressed on the computer. Because video compression is a lossy process, each time you re-compress, the image quality becomes slightly worse.
Cinelerra is clever enough to only re-compress video when it really has to, i.e. when you do a fade, transition, or other video effect. Herein lies a snag. I have found that there is a noticeable difference between the video that has been re-compressed and the video that hasn't. This creates a somewhat jarring effect at the beginning and end of any fade, transition or title. This is Not Good.
There are two solutions. One is to avoid using any kind of video effect. This will be acceptable for simple projects and has the added advantage that there will be no generation loss from re-compression. Most projects will want to use some kind of effect, however, even if it is just to fade to black at the end.
I have found that it is possible to force Cinelerra to re-compress the whole project. This has the advantage that all the video looks the same. Any generation loss is not really noticeable if it only occurs once (try to avoid using clips that have already been re-compressed), and it is much better to have uniform looking video than to have sudden, jarring changes in quality.
To acheieve this, create an extra video track. Drag a static image onto it, and drag the ends of the static image so that it covers the entire length of the project. Then fade the image out so that it can't be seen. The presence of this image is enough to make Cinelerra re-compress the whole project and you will get uniform looking output. You may want to save this for the final render of your project, however, as the re-compression can be very slow.
A final quirk is that I have found that the timecode on the rendered output runs too quickly, and the 16:9 flag is not preserved, so any anamorphic video is not labelled as such and may appear distorted in some players. I'm not sure if this is the fault of Cinelerra or libdv. It shouldn't be a big problem though, as the video will still look fine when played back on a TV.
The End
I hope you have found this tutorial useful.