#80: add video_bitrate and audio_bitrate params

ffmpeg/_ffmpeg.py

@@ -62,12 +62,19 @@ def output(*streams_and_filename, **kwargs):
     Syntax:
         `ffmpeg.output(stream1[, stream2, stream3...], filename, **ffmpeg_args)`
 
+    Any supplied keyword arguments are passed to ffmpeg verbatim (e.g.
+    ``t=20``, ``f='mp4'``, ``acodec='pcm'``, ``vcodec='rawvideo'``,
+    etc.).  Some keyword-arguments are handled specially, as shown below.
+
+    Args:
+        video_bitrate: parameter for ``-b:v``, e.g. ``video_bitrate=1000``.
+        audio_bitrate: parameter for ``-b:a``, e.g. ``audio_bitrate=200``.
+        format: alias for ``-f`` parameter, e.g. ``format='mp4'``
+            (equivalent to ``f='mp4'``).
+
     If multiple streams are provided, they are mapped to the same
     output.
 
-    Any supplied kwargs are passed to ffmpeg verbatim (e.g. ``t=20``,
-    ``f='mp4'``, ``acodec='pcm'``, etc.).
-
     To tell ffmpeg to write to stdout, use ``pipe:`` as the filename.
 
     Official documentation: `Synopsis <https://ffmpeg.org/ffmpeg.html#Synopsis>`__

ffmpeg/_run.py

@@ -120,9 +120,12 @@ def _get_output_args(node, stream_name_map):
 
     kwargs = copy.copy(node.kwargs)
     filename = kwargs.pop('filename')
-    fmt = kwargs.pop('format', None)
-    if fmt:
-        args += ['-f', fmt]
+    if 'format' in kwargs:
+        args += ['-f', kwargs.pop('format')]
+    if 'video_bitrate' in kwargs:
+        args += ['-b:v', str(kwargs.pop('video_bitrate'))]
+    if 'audio_bitrate' in kwargs:
+        args += ['-b:a', str(kwargs.pop('audio_bitrate'))]
     args += _convert_kwargs_to_cmd_line_args(kwargs)
     args += [filename]
     return args

ffmpeg/tests/test_ffmpeg.py

@@ -237,6 +237,17 @@ def test_filter_asplit():
     ]
 
 
+
+def test__output__bitrate():
+    args = (
+        ffmpeg
+        .input('in')
+        .output('out', video_bitrate=1000, audio_bitrate=200)
+        .get_args()
+    )
+    assert args == ['-i', 'in', '-b:v', '1000', '-b:a', '200', 'out']
+
+
 def test_filter_normal_arg_escape():
     """Test string escaping of normal filter args (e.g. ``font`` param of ``drawtext`` filter)."""
     def _get_drawtext_font_repr(font):