dont prevent sigint propagation for 'normal' ffmpeg calls (#37)

Author: almarklein

imageio_ffmpeg/_io.py

@@ -146,7 +146,7 @@ def read_frames(
         stdin=subprocess.PIPE,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
-        **_popen_kwargs()
+        **_popen_kwargs(prevent_sigint=True)
     )
 
     log_catcher = LogCatcher(p.stderr)
@@ -437,7 +437,7 @@ def write_frames(
         stdin=subprocess.PIPE,
         stdout=subprocess.PIPE,
         stderr=None,
-        **_popen_kwargs()
+        **_popen_kwargs(prevent_sigint=True)
     )
 
     # Note that directing stderr to a pipe on windows will cause ffmpeg

imageio_ffmpeg/_utils.py

@@ -52,20 +52,21 @@ def get_ffmpeg_exe():
     )
 
 
-def _popen_kwargs():
+def _popen_kwargs(prevent_sigint=False):
     startupinfo = None
     preexec_fn = None
     creationflags = 0
     if sys.platform.startswith("win"):
         # Stops executable from flashing on Windows (see #22)
         startupinfo = subprocess.STARTUPINFO()
         startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
-        # Prevent propagation of sigint (see #4)
-        creationflags = 0x00000200
-    else:
+    if prevent_sigint:
         # Prevent propagation of sigint (see #4)
         # https://stackoverflow.com/questions/5045771
-        preexec_fn = os.setpgrp  # the _pre_exec does not seem to work
+        if sys.platform.startswith("win"):
+            creationflags = 0x00000200
+        else:
+            preexec_fn = os.setpgrp  # the _pre_exec does not seem to work
     return {
         "startupinfo": startupinfo,
         "creationflags": creationflags,