Merge pull request #51 from kkroening/compile

Add `compile` operator

ffmpeg/_run.py

@@ -131,6 +131,16 @@ def get_args(stream_spec, overwrite_output=False):
     return args
 
 
+@output_operator()
+def compile(stream_spec, cmd='ffmpeg', **kwargs):
+    """Build command-line for ffmpeg."""
+    if isinstance(cmd, basestring):
+        cmd = [cmd]
+    elif type(cmd) != list:
+        cmd = list(cmd)
+    return cmd + get_args(stream_spec, **kwargs)
+
+
 @output_operator()
 def run(stream_spec, cmd='ffmpeg', **kwargs):
     """Run ffmpeg on node graph.
@@ -138,15 +148,11 @@ def run(stream_spec, cmd='ffmpeg', **kwargs):
     Args:
         **kwargs: keyword-arguments passed to ``get_args()`` (e.g. ``overwrite_output=True``).
     """
-    if isinstance(cmd, basestring):
+    _subprocess.check_call(compile(stream_spec, cmd, **kwargs))
-        cmd = [cmd]
-    elif type(cmd) != list:
-        cmd = list(cmd)
-    args = cmd + get_args(stream_spec, **kwargs)
-    _subprocess.check_call(args)
 
 
 __all__ = [
+    'compile',
     'get_args',
     'run',
 ]

ffmpeg/tests/test_ffmpeg.py

@@ -219,6 +219,12 @@ def test_filter_text_arg_str_escape():
 #    subprocess.check_call(['ffmpeg', '-version'])
 
 
+def test_compile():
+    out_file = ffmpeg.input('dummy.mp4').output('dummy2.mp4')
+    assert out_file.compile() == ['ffmpeg', '-i', 'dummy.mp4', 'dummy2.mp4']
+    assert out_file.compile(cmd='ffmpeg.old') == ['ffmpeg.old', '-i', 'dummy.mp4', 'dummy2.mp4']
+
+
 def test_run():
     stream = _get_complex_filter_example()
     ffmpeg.run(stream)