FFMPEG_VideoReader: set default video and audio stream automatically,…

… if ffmpeg doesn't specify them. Fix Zulko#869 Zulko#899

moviepy/video/io/ffmpeg_reader.py

@@ -341,8 +341,9 @@ 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": []}
@@ -422,16 +423,13 @@ def parse(self):
                     "stream_number": stream_number,
                     "stream_type": stream_type_lower,
                     "language": language if language != "und" else None,
-                    "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"]:
-                    result[f"default_{stream_type_lower}_input_number"] = input_number
-                    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:
@@ -456,15 +454,14 @@ def parse(self):
 
                 # 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:
-                    result.update(global_data)
                     self._current_stream.update(stream_data)
             elif line.startswith("    Metadata:"):
                 # enter group "    Metadata:"
@@ -522,6 +519,27 @@ def parse(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():
+            result[f"default_{stream_type_lower}_input_number"] = stream_data["input_number"]
+            result[f"default_{stream_type_lower}_stream_number"] = stream_data["stream_number"]
+
+            if stream_type_lower == "audio":
+                result["audio_found"] = True
+                result["audio_fps"] = stream_data["fps"]
+                result["audio_bitrate"] = stream_data["bitrate"]
+            elif stream_type_lower == "video":
+                result["video_found"] = True
+                result["video_size"] = stream_data.get("size", None)
+                result["video_bitrate"] = stream_data.get("bitrate", None)
+                result["video_fps"] = stream_data["fps"]
+
         # some video duration utilities
         if result["video_found"] and self.check_duration:
             result["video_n_frames"] = int(result["duration"] * result["video_fps"])
@@ -543,7 +561,7 @@ 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(
@@ -553,7 +571,7 @@ 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):
@@ -564,14 +582,11 @@ 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)
@@ -623,11 +638,7 @@ def parse_video_stream_data(self, line):
                 fps = x * coef
         stream_data["fps"] = fps
 
-        if self._current_stream["default"]:
-            global_data["video_size"] = stream_data.get("size", None)
-            global_data["video_bitrate"] = stream_data.get("bitrate", None)
-            global_data["video_fps"] = stream_data["fps"]
-        return (global_data, stream_data)
+        return stream_data
 
     def parse_fps(self, line):
         return float(re.search(r" (\d+.?\d*) fps", line).group(1))