Add method to record a video

Author: rdesarz

examples/example_4_physics_simulation.py

@@ -1,5 +1,6 @@
 import math
 import argparse
+import subprocess
 from pathlib import Path
 
 import numpy as np
@@ -33,6 +34,46 @@
 )
 
 
+def process_video(simulation_duration: float, start_time: float = 0.0):
+    cmd = [
+        "ffprobe",
+        "-i",
+        "talos_run.mp4",
+        "-show_entries",
+        "format=duration",
+        "-v",
+        "quiet",
+        "-of",
+        "csv=p=0",
+    ]
+
+    out = subprocess.check_output(cmd).decode().strip()
+    video_duration = float(out)
+
+    ratio = simulation_duration / video_duration
+
+    cmd = [
+        "ffmpeg",
+        "-ss",
+        str(start_time / ratio),
+        "-i",
+        "talos_run.mp4",
+        "-filter:v",
+        f"setpts={ratio}*PTS",
+        "-r",
+        "60",
+        "-c:v",
+        "libx264",
+        "-crf",
+        "18",
+        "-preset",
+        "slow",
+        "talos_run_fixed.mp4",
+    ]
+
+    subprocess.run(cmd, check=True)
+
+
 def main():
     p = argparse.ArgumentParser()
     p.add_argument("--path-talos-data", type=Path, help="Path to talos_data root")
@@ -221,6 +262,8 @@ def main():
     rf_forces = np.zeros((len(phases), 1))
     lf_forces = np.zeros((len(phases), 1))
 
+    log_id = pb.startStateLogging(pb.STATE_LOGGING_VIDEO_MP4, "talos_run.mp4")
+
     # We start the walking phase
     for k, _ in enumerate(phases[:-2]):
         # Get the current configuration of the robot from the simulator
@@ -301,6 +344,10 @@ def main():
 
             rf_forces[k], lf_forces[k] = simulator.get_contact_forces()
 
+    pb.stopStateLogging(log_id)
+
+    process_video(t[-1], t_init + 2.0)
+
     if args.plot_results:
 
         zmp_ref_plot = np.zeros((zmp_ref.shape[0], 3))