Playblast: only render on keyed frames #72229

New Issue

Sybren A. Stüvel · 2019-12-06T12:15:36+01:00

Sybren A. Stüvel commented

2019-12-06 12:15:36 +01:00

When animating a character on twos (so every other frame has a key, and using constant interpolation) but the camera motion on ones, it can be hard to follow the character and properly inspect the motion.

This design task proposes a way to do a play-blast by only rendering those frames that have a keyframe, a feature requested by @PabloFournier on behalf of the Blender Studio animators.

The behaviour should be:

Animator selects one or more objects.
Animator clicks on View → 'Viewport Render Animated Frames Only' button (of course label subject to change)
Blender renders the appropriate range (same as View → Viewport Render Animation), but only those frames for which one or more of the selected objects have a keyframe.
The duration of a frame in the final video file should be such that the timing is still correct. In other words, rendered frames should not be stuck together at a fixed frame rate, but rather be displayed until the next animated frame. Rendering frames 1, 5, and 10 should show frame 1 also on frames 2-4, and frame 5 on frames 6-9.

When outputting images, duplicate the rendered frames on non-rendered frames. This will produce more files than strictly necessary, but it will make it much easier to later convert the images to a video. It will also make it possible to incrementally update the keyframe density while maintaining the same set of output files.

When outputting a video, this duplication may not be necessary, but is trivial to implement. Each frame could receive its own timecode, but that's harder to implement, and left as a nice-to-have for the future.

When animating a character on twos (so every other frame has a key, and using constant interpolation) but the camera motion on ones, it can be hard to follow the character and properly inspect the motion. This design task proposes a way to do a play-blast by only rendering those frames that have a keyframe, a feature requested by @PabloFournier on behalf of the Blender Studio animators. The behaviour should be: - Animator selects one or more objects. - Animator clicks on View → 'Viewport Render Animated Frames Only' button (of course label subject to change) - Blender renders the appropriate range (same as View → Viewport Render Animation), but only those frames for which one or more of the selected objects have a keyframe. - The duration of a frame in the final video file should be such that the timing is still correct. In other words, rendered frames should not be stuck together at a fixed frame rate, but rather be displayed until the next animated frame. Rendering frames 1, 5, and 10 should show frame 1 also on frames 2-4, and frame 5 on frames 6-9. When outputting images, duplicate the rendered frames on non-rendered frames. This will produce more files than strictly necessary, but it will make it much easier to later convert the images to a video. It will also make it possible to incrementally update the keyframe density while maintaining the same set of output files. When outputting a video, this duplication may not be necessary, but is trivial to implement. Each frame could receive its own timecode, but that's harder to implement, and left as a nice-to-have for the future.

Sybren A. Stüvel self-assigned this 2019-12-06 12:15:36 +01:00

Sybren A. Stüvel commented

2019-12-06 12:15:36 +01:00

Added subscribers: @dr.sybren, @JasonSchleifer, @Hjalti, @PabloFournier, @NachoConesa

Christian Brinkmann commented

2019-12-06 13:00:26 +01:00

Added subscriber: @p2or

Christian Brinkmann commented

2019-12-06 13:00:26 +01:00

Hey @dr.sybren,

If you are interested, I've already written something like that, might be one approach for reference https://github.com/p2or/blender-loom The addon also allows rendering via CLI as well as automatic encoding via ffmpeg.

Cheers,
Christian

Hey @dr.sybren, If you are interested, I've already written something like that, might be one approach for reference https://github.com/p2or/blender-loom The addon also allows rendering via CLI as well as automatic encoding via ffmpeg. Cheers, Christian

Sybren A. Stüvel commented

2019-12-06 13:57:12 +01:00

Hi @p2or, thanks for the pointer.