| contents | |
|---|---|
| clip matching | plugins necessary plugins |
| setup and render | |
| keyframes | watermark |
NB: set rendering output confinguration prior to editing, esp FPS
Blender or, as I call it, "Death from 1000 Cuts", is vast, almost an operating system. It is Python + FFmpeg based. KDenLive, the other major Linux GUI editor, is MLT based. Whether using Blender for animation or video (this post concerns video), a reasonably good understanding of keyframes goes a long ways. The reason is that, portions of edits which don't require keyframes can be done with a CLI editor. Blender is likely to be used for sliding text on or out of a frame, etc.
what has to match?
- frame rate(in ffmpeg: avg_frame_rate) must match in final edit. Having a uniform frame rate, dimensions, bitrate, and so on, makes for easier editing. So if just using a few varied clips, it's worthwhile to recode them to match, prior to importing. Obviously, frame rate will ultimately be forced in the final render, and it can be jerry-rigged during editing if desired...Dealing with Variable Framerates (7:03) Michael Chu, 2019. Audio unaffected by framerate, but we want the video to correspond. This is a manual solution when many clip-types are present.
- tbn, tbc, tbr These are ffmpeg(Blender's backend) names for timing information beyond the fps. The time_base (tbc) is simply the inverse of the time_scale (tbn), but there is not necessarily one frame for each tick of the timebase (see 2nd link below). Timescale (tbn) is often 90K. Variable names w/descriptions (page) GitHub, 2020. What each variable pertains to. Inaccurately substitutes "timebase" for "timescale".
Mismatch between clips (page) 2013. An example timing mismatch between clips. Timebase vs. Codec Time base (page) 2013. Variations between these two can lead to problems.
Container vs. Codec (page) Stack Oveflow, 2013.
Ffmepg timebase (page) Alibaba, 2018. Description of how obtained.
**NB: 90,000 is typical tbn because divisible by 24, 25, and 30, although 600 will work, a la Quicktime. - bit rate helpful if matched, varies in quality if not. Along with the i-frame interval, bit rate determiines the quality of a clip. It's OK for bit rate to differ across project clips -- they can still be fused -- as long as one understands that each clip's quality will vary accordingly.
- i-frame interval these can vary from clip to clip and change throughout editing as keyframes are needed. However, attention should be paid to this again at the final render to see that an efficient, hopefully dynamic, setting is selected. In ffmpeg itself, the i-frame interval is defined by "Groups of Pictures".
- PTS
setup (also render)
I strongly suggest configuring one's output render settings as the first step of any Blender project. A consistent framerate, codec, and other details set to the desired output, forces clips into alignment from the start. As a bare minimum, set the final rendering FPS when getting started. That being said, the final render requires i-frame interval adjustments. The newer codecs will do this dynamically, so that if there are periods of zero action, i-frame intervals can expand to, say, one every 10 seconds, etc.
Dealing with Variable Framerates (7:03) Michael Chu, 2019. Audio unaffected by framerate, but we want the video to correspond. This is a manual solution when many clip-types are present.
Blender 2.8 Setup (19:27) Mikeycal Meyers, 2019. Render settings begin at 5:00.
The directory structure follows a pretty standard setup with a user file in ~/.config/blender/[version]/startup.conf, but there are also files inside /usr/share/blender/, which is where add-ons seem to live. So it may be that there are configurations to save from both of these sources.
Keyframes (and other) in 2.8 (9:48) Code, Tech, and Tutorials, 2019. Solid inadvertent tour around the VSE via a simple edit. Shows how to do transitions simply without inserting them, pressing "i" for keyframe.
Blender 2.8 Setup (19:27) Mikeycal Meyers, 2019. Render settings begin at 5:00.
Ffmpeg blur box (14:48) Thilakanathan, 2019. Fast, but covers nearly everything. Rendering in last 5 minutes. Comments have a lot of tips.
render troubleshoot
I've put these rendering fixes at the top of the blog to help determine how to preventatively configure settings.
- grey timeline is rendered but appears to have a sheen of gray over entire playback, like through a dirty window. Inside the little camera icon, go all the way to the bottom "Color Management" and change it from Filmic to Standard.
keyframes
Video keyframes are a large editing topic I cover separately, but a few notes here. Fundamentally, keyframes are a hand-entered subset of i-frames, added by users. Since they are a sub-type of i-frame, all keyframes are i-frames, but not all i-frames are key frames.
- "i" to add, "Alt+i" to delete
- keyframes can be edited in Timeline, Dope Sheet, or Graph Editor. Only manually added keyframes appear in these editors, not generic i-frames. Keyframe manipulation (6:18) Michael Chu, 2020.
- the final render should eliminate as many keyframes as possible, to decrease the size of our output file
How to Delete all Keyframes (page) TechJunkie, 2018. This is in the older version of Blender but has loads of solid keyframe information.
Keyframes (and other) in 2.8 (9:48) Code, Tech, and Tutorials, 2019. Solid inadvertent tour around the VSE via a simple edit. Shows how to do transitions simply without inserting them, pressing "i" for keyframe.
plugins
Plugins appear to live in /usr/share/blender/[ver]/scripts/addons. There are some key ones to have
proxy encoding.
If a person has a gaming system, this is not a concern. However, many systems edit smoother if the video is proxied. The system is lags and jumps during playback. Proxying does not work well if a person has elaborate transitions that require exact keyframes and so on.
Proxy a clip or clips (4:17) Waylight Creations, 2019. How to deal with a slower system.
sound effects
Occasionally, we'd like a sound effect to this or that in blender without a video clip coming in and so on.
Inserting Sound effects in Blender(11:11) Oracles Stream School, 2020. OBS based tutorial, using the computer, not a capture card.
