Thoroughly document how to do rendering
Submitted by Jeff F.T.
A common pain point for users is understanding how to use the render dialog, even though its design is much better than what it used to be.
The user manual explains the difference between rendering and saving, but does not really go into detail regarding:
What influences quality.
What codecs can be recommended depending on the context
Also document how to make bitrate/quality work depending on the codecs,, at least with theora, x264 and vp8: bug #627 (comment 66457)
Troubleshooting rendering errors or hangs. See also https://answers.launchpad.net/ubuntu/+faqs?field.actions.search=Search&field.search_text=pitivi
Some codecs require video resolution width and height to be multiples of 4, 8 or 16. Typically, always make sure that they're at least multiples of 2. Otherwise, some video codecs won't encode at all, sometimes they'll encode with suboptimal or broken results.
Speed: many codecs such as theora, x264 and vp8 have a "threads" option that you can set. For example, set it to 4 to have four simultaneous threads and better use your quad core processor. As such, rendering will be much faster. See also bug #323 (closed) and bug https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/issues/59.
Commandline rendering will be removed from pitivi 0.16 (the GES version), because "ges-launch" does that kind of thing. It can load a pitivi project and render it.
ges-launch is also able to preview (playback) a pitivi project.
ges-launch -p projevct.xptv -ro outpufile.o
See also (in the "help/C/" directory): codecscontainers.page, gstreamer.page, presets.page, projectsettings.page, rendering.page.
Imported from https://bugzilla.gnome.org/show_bug.cgi?id=683220