Implement real-time video logging

[dtch1997]

Investigate whether this is possible

Likely there is some open-source work that does this

In the worst case we might have to implement it?

[dtch1997]

Update: I figured out how to do this.

The README.md has instructions on using python -m utils.record_video to take a video of the simulation.
This produces a .mp4 file with a default 30fps frame rate.

To achieve real-time rendering, I used ffmpeg to increase the frame rate to 1000 fps. This is based on 1 / 0.001 simulation time step.

The command to do so is:

ffmpeg -i input.mp4 -r <OUTPUT_FPS> -filter:v "setpts=<RATIO>*PTS" output.mp4

where RATIO = INPUT_FPS / OUTPUT_FPS

Reference: https://trac.ffmpeg.org/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video

[dtch1997]

Update:

I realized that python -m utils.record_video is already doing a real time video (or close enough).

This is because the env_time_step is different from the sim_time_step. By default the former is 33x the latter (so 0.033s).
Doing some basic accounting. a 1000 frame video should thus last 33 seconds, and the actual video we got is 32 seconds. So it's real time, or close enough.

In summary:

python -m utils.record_video is enough to get a real time video