WIP code for piping images into ffmpeg (subprocess.Popen)

tests/ffmpeg_subprocess_test.py

@@ -0,0 +1,31 @@
+import glob
+import shlex
+import subprocess
+
+templates = ['ffplay -autoexit -f image2pipe -framerate 60 -i -']
+args = [arg
+        for template in templates
+        for arg in shlex.split(template)]
+
+popen = subprocess.Popen(args, stdin=subprocess.PIPE)
+stream = popen.stdin
+
+imgs = glob.glob('images/*.png')
+imgs.sort()
+for img in imgs * 100:
+    with open(img, 'rb') as f:
+        stream.write(f.read())    # FIXME https://docs.python.org/3/library/subprocess.html#subprocess.Popen.stdin
+
+# Warning: Use communicate() rather than .stdin.write, .stdout.read or .stderr.read
+# to avoid deadlocks due to any of the other OS pipe buffers filling up and blocking
+# the child process.
+
+# communicate(): Interact with process: Send data to stdin. Read data from stdout and
+# stderr, until end-of-file is reached.
+
+# nope instant reject
+
+# https://stackoverflow.com/questions/9886654/difference-between-communicate-and-stdin-write-stdout-read-or-stderr-read
+
+stream.close()
+popen.wait()