ffmpeg_reader: set default streams automatically if unspecified

fix Zulko#869 Zulko#899

moviepy/video/io/ffmpeg_reader.py

@@ -344,8 +344,9 @@ def _reset_state(self):
  # should be ignored
  self._inside_output = False
 
- # flag which indicates that a default stream has not been found yet
- self._default_stream_found = False
+ # map from stream type to default stream
+ # if a default stream is not indicated, pick the first one available
+ self._default_streams = {}
 
  # current input file, stream and chapter, which will be built at runtime
  self._current_input_file = {"streams": []}
@@ -444,20 +445,13 @@ def parse(self):
  "stream_number": stream_number,
  "stream_type": stream_type_lower,
  "language": language,
- "default": not self._default_stream_found
- or line.endswith("(default)"),
+ "default": (stream_type_lower not in self._default_streams) and line.endswith("(default)"),
  }
- self._default_stream_found = True
 
  # for default streams, set their numbers globally, so it's
  # easy to get without iterating all
  if self._current_stream["default"]:
- self.result[
- f"default_{stream_type_lower}_input_number"
- ] = input_number
- self.result[
- f"default_{stream_type_lower}_stream_number"
- ] = stream_number
+ self._default_streams[stream_type_lower] = self._current_stream
 
  # exit chapter
  if self._current_chapter:
@@ -476,21 +470,20 @@ def parse(self):
  input_number
  ]
 
- # add new input file to self.result
+ # add new input file to result
  self.result["inputs"].append(self._current_input_file)
  self._current_input_file = {"input_number": input_number}
 
  # parse relevant data by stream type
  try:
- global_data, stream_data = self.parse_data_by_stream_type(
+ stream_data = self.parse_data_by_stream_type(
  stream_type, line
  )
  except NotImplementedError as exc:
  warnings.warn(
  f"{str(exc)}\nffmpeg output:\n\n{self.infos}", UserWarning
  )
  else:
- self.result.update(global_data)
  self._current_stream.update(stream_data)
  elif line.startswith(" Metadata:"):
  # enter group " Metadata:"
@@ -553,7 +546,7 @@ def parse(self):
  self._last_metadata_field_added = field
  self._current_chapter["metadata"][field] = value
 
- # last input file, must be included in self.result
+ # last input file, must be included in the result
  if self._current_input_file:
  self._current_input_file["streams"].append(self._current_stream)
  # include their chapters, if there are
@@ -563,6 +556,27 @@ def parse(self):
  ]
  self.result["inputs"].append(self._current_input_file)
 
+ # set any missing default automatically
+ for stream in self._current_input_file["streams"]:
+ if stream["stream_type"] not in self._default_streams:
+ self._default_streams[stream["stream_type"]] = stream
+ stream["default"] = True
+
+ # set some global info based on the defaults
+ for stream_type_lower, stream_data in self._default_streams.items():
+ self.result[f"default_{stream_type_lower}_input_number"] = stream_data["input_number"]
+ self.result[f"default_{stream_type_lower}_stream_number"] = stream_data["stream_number"]
+
+ if stream_type_lower == "audio":
+ self.result["audio_found"] = True
+ self.result["audio_fps"] = stream_data["fps"]
+ self.result["audio_bitrate"] = stream_data["bitrate"]
+ elif stream_type_lower == "video":
+ self.result["video_found"] = True
+ self.result["video_size"] = stream_data.get("size", None)
+ self.result["video_bitrate"] = stream_data.get("bitrate", None)
+ self.result["video_fps"] = stream_data["fps"]
+
  # some video duration utilities
  if self.result["video_found"] and self.check_duration:
  self.result["video_n_frames"] = int(
@@ -601,7 +615,7 @@ def parse_data_by_stream_type(self, stream_type, line):
  return {
  "Audio": self.parse_audio_stream_data,
  "Video": self.parse_video_stream_data,
- "Data": lambda _line: ({}, {}),
+ "Data": lambda _line: {},
  }[stream_type](line)
  except KeyError:
  raise NotImplementedError(
@@ -611,7 +625,7 @@ def parse_data_by_stream_type(self, stream_type, line):
 
  def parse_audio_stream_data(self, line):
  """Parses data from "Stream ... Audio" line."""
- global_data, stream_data = ({"audio_found": True}, {})
+ stream_data = {}
  try:
  stream_data["fps"] = int(re.search(r" (\d+) Hz", line).group(1))
  except (AttributeError, ValueError):
@@ -622,14 +636,11 @@ def parse_audio_stream_data(self, line):
  stream_data["bitrate"] = (
  int(match_audio_bitrate.group(1)) if match_audio_bitrate else None
  )
- if self._current_stream["default"]:
- global_data["audio_fps"] = stream_data["fps"]
- global_data["audio_bitrate"] = stream_data["bitrate"]
- return (global_data, stream_data)
+ return stream_data
 
  def parse_video_stream_data(self, line):
  """Parses data from "Stream ... Video" line."""
- global_data, stream_data = ({"video_found": True}, {})
+ stream_data = {}
 
  try:
  match_video_size = re.search(r" (\d+)x(\d+)[,\s]", line)
@@ -681,14 +692,7 @@ def parse_video_stream_data(self, line):
  fps = x * coef
  stream_data["fps"] = fps
 
- if self._current_stream["default"] or "video_size" not in self.result:
- global_data["video_size"] = stream_data.get("size", None)
- if self._current_stream["default"] or "video_bitrate" not in self.result:
- global_data["video_bitrate"] = stream_data.get("bitrate", None)
- if self._current_stream["default"] or "video_fps" not in self.result:
- global_data["video_fps"] = stream_data["fps"]
-
- return (global_data, stream_data)
+ return stream_data
 
  def parse_fps(self, line):
  """Parses number of FPS from a line of the ``ffmpeg -i`` command output."""