suppress ffmpeg output

Summary: Restore the suppression of ffmpeg output.

Reviewed By: shapovalov

Differential Revision: D40296595

fbshipit-source-id: 41b2c14b6f6245f77e0ef6cc94fa7b41fbb83e33

pytorch3d/implicitron/tools/video_writer.py

@@ -116,7 +116,7 @@ def write_frame(
         self.frames.append(outfile)
         self.frame_num += 1
 
-    def get_video(self) -> str:
+    def get_video(self, quiet: bool = True) -> str:
         """
         Generate the video from the written frames.
 
@@ -155,8 +155,12 @@ def get_video(self) -> str:
                 "yuv420p",
                 self.out_path,
             ]
-
-            subprocess.check_call(args)
+            if quiet:
+                subprocess.check_call(
+                    args, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL
+                )
+            else:
+                subprocess.check_call(args)
         else:
             raise ValueError("no such output type %s" % str(self.output_format))