Add pre-processor stage `video`

Related: #456, #5808

README.md

@@ -725,7 +725,7 @@ You can also fork the project on GitHub and run your fork's [build workflow](.gi
                                     screen, optionally prefixed with when to
                                     print it, separated by a ":". Supported
                                     values of "WHEN" are the same as that of
-                                    --use-postprocessor, and "video" (default).
+                                    --use-postprocessor (default: video).
                                     Implies --quiet. Implies --simulate unless
                                     --no-simulate or later stages of WHEN are
                                     used. This option can be used multiple times
@@ -979,18 +979,18 @@ You can also fork the project on GitHub and run your fork's [build workflow](.gi
     --ffmpeg-location PATH          Location of the ffmpeg binary; either the
                                     path to the binary or its containing directory
     --exec [WHEN:]CMD               Execute a command, optionally prefixed with
-                                    when to execute it (after_move if
+                                    when to execute it, separated by a ":".
-                                    unspecified), separated by a ":". Supported
+                                    Supported values of "WHEN" are the same as
-                                    values of "WHEN" are the same as that of
+                                    that of --use-postprocessor (default:
-                                    --use-postprocessor. Same syntax as the
+                                    after_move). Same syntax as the output
-                                    output template can be used to pass any
+                                    template can be used to pass any field as
-                                    field as arguments to the command. After
+                                    arguments to the command. After download, an
-                                    download, an additional field "filepath"
+                                    additional field "filepath" that contains
-                                    that contains the final path of the
+                                    the final path of the downloaded file is
-                                    downloaded file is also available, and if no
+                                    also available, and if no fields are passed,
-                                    fields are passed, %(filepath)q is appended
+                                    %(filepath)q is appended to the end of the
-                                    to the end of the command. This option can
+                                    command. This option can be used multiple
-                                    be used multiple times
+                                    times
     --no-exec                       Remove any previously defined --exec
     --convert-subs FORMAT           Convert the subtitles to another format
                                     (currently supported: ass, lrc, srt, vtt)
@@ -1028,14 +1028,16 @@ You can also fork the project on GitHub and run your fork's [build workflow](.gi
                                     postprocessor is invoked. It can be one of
                                     "pre_process" (after video extraction),
                                     "after_filter" (after video passes filter),
-                                    "before_dl" (before each video download),
+                                    "video" (after --format; before
-                                    "post_process" (after each video download;
+                                    --print/--output), "before_dl" (before each
-                                    default), "after_move" (after moving video
+                                    video download), "post_process" (after each
-                                    file to it's final locations), "after_video"
+                                    video download; default), "after_move"
-                                    (after downloading and processing all
+                                    (after moving video file to it's final
-                                    formats of a video), or "playlist" (at end
+                                    locations), "after_video" (after downloading
-                                    of playlist). This option can be used
+                                    and processing all formats of a video), or
-                                    multiple times to add different postprocessors
+                                    "playlist" (at end of playlist). This option
+                                    can be used multiple times to add different
+                                    postprocessors
 
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yt_dlp/YoutubeDL.py

@@ -2977,6 +2977,16 @@ class YoutubeDL:
 
         # Does nothing under normal operation - for backward compatibility of process_info
         self.post_extract(info_dict)
+
+        def replace_info_dict(new_info):
+            nonlocal info_dict
+            if new_info == info_dict:
+                return
+            info_dict.clear()
+            info_dict.update(new_info)
+
+        new_info, _ = self.pre_process(info_dict, 'video')
+        replace_info_dict(new_info)
         self._num_downloads += 1
 
         # info_dict['_filename'] needs to be set for backward compatibility
@@ -3090,13 +3100,6 @@ class YoutubeDL:
                for link_type, should_write in write_links.items()):
             return
 
-        def replace_info_dict(new_info):
-            nonlocal info_dict
-            if new_info == info_dict:
-                return
-            info_dict.clear()
-            info_dict.update(new_info)
-
         new_info, files_to_move = self.pre_process(info_dict, 'before_dl', files_to_move)
         replace_info_dict(new_info)
 

yt_dlp/options.py

@@ -277,6 +277,20 @@ def create_parser():
             out_dict[key] = out_dict.get(key, []) + [val] if append else val
         setattr(parser.values, option.dest, out_dict)
 
+    def when_prefix(default):
+        return {
+            'default': {},
+            'type': 'str',
+            'action': 'callback',
+            'callback': _dict_from_options_callback,
+            'callback_kwargs': {
+                'allowed_keys': '|'.join(map(re.escape, POSTPROCESS_WHEN)),
+                'default_key': default,
+                'multiple_keys': False,
+                'append': True,
+            },
+        }
+
     parser = _YoutubeDLOptionParser()
     alias_group = optparse.OptionGroup(parser, 'Aliases')
     Formatter = string.Formatter()
@@ -1086,28 +1100,16 @@ def create_parser():
         help='Do not download the video but write all related files (Alias: --no-download)')
     verbosity.add_option(
         '-O', '--print',
-        metavar='[WHEN:]TEMPLATE', dest='forceprint', default={}, type='str',
+        metavar='[WHEN:]TEMPLATE', dest='forceprint', **when_prefix('video'),
-        action='callback', callback=_dict_from_options_callback,
+        help=(
-        callback_kwargs={
-            'allowed_keys': 'video|' + '|'.join(map(re.escape, POSTPROCESS_WHEN)),
-            'default_key': 'video',
-            'multiple_keys': False,
-            'append': True,
-        }, help=(
             'Field name or output template to print to screen, optionally prefixed with when to print it, separated by a ":". '
-            'Supported values of "WHEN" are the same as that of --use-postprocessor, and "video" (default). '
+            'Supported values of "WHEN" are the same as that of --use-postprocessor (default: video). '
             'Implies --quiet. Implies --simulate unless --no-simulate or later stages of WHEN are used. '
             'This option can be used multiple times'))
     verbosity.add_option(
         '--print-to-file',
-        metavar='[WHEN:]TEMPLATE FILE', dest='print_to_file', default={}, type='str', nargs=2,
+        metavar='[WHEN:]TEMPLATE FILE', dest='print_to_file', nargs=2, **when_prefix('video'),
-        action='callback', callback=_dict_from_options_callback,
+        help=(
-        callback_kwargs={
-            'allowed_keys': 'video|' + '|'.join(map(re.escape, POSTPROCESS_WHEN)),
-            'default_key': 'video',
-            'multiple_keys': False,
-            'append': True,
-        }, help=(
             'Append given template to the file. The values of WHEN and TEMPLATE are same as that of --print. '
             'FILE uses the same syntax as the output template. This option can be used multiple times'))
     verbosity.add_option(
@@ -1629,16 +1631,10 @@ def create_parser():
         help='Location of the ffmpeg binary; either the path to the binary or its containing directory')
     postproc.add_option(
         '--exec',
-        metavar='[WHEN:]CMD', dest='exec_cmd', default={}, type='str',
+        metavar='[WHEN:]CMD', dest='exec_cmd', **when_prefix('after_move'),
-        action='callback', callback=_dict_from_options_callback,
+        help=(
-        callback_kwargs={
+            'Execute a command, optionally prefixed with when to execute it, separated by a ":". '
-            'allowed_keys': '|'.join(map(re.escape, POSTPROCESS_WHEN)),
+            'Supported values of "WHEN" are the same as that of --use-postprocessor (default: after_move). '
-            'default_key': 'after_move',
-            'multiple_keys': False,
-            'append': True,
-        }, help=(
-            'Execute a command, optionally prefixed with when to execute it (after_move if unspecified), separated by a ":". '
-            'Supported values of "WHEN" are the same as that of --use-postprocessor. '
             'Same syntax as the output template can be used to pass any field as arguments to the command. '
             'After download, an additional field "filepath" that contains the final path of the downloaded file '
             'is also available, and if no fields are passed, %(filepath)q is appended to the end of the command. '
@@ -1714,7 +1710,8 @@ def create_parser():
             'ARGS are a semicolon ";" delimited list of NAME=VALUE. '
             'The "when" argument determines when the postprocessor is invoked. '
             'It can be one of "pre_process" (after video extraction), "after_filter" (after video passes filter), '
-            '"before_dl" (before each video download), "post_process" (after each video download; default), '
+            '"video" (after --format; before --print/--output), "before_dl" (before each video download), '
+            '"post_process" (after each video download; default), '
             '"after_move" (after moving video file to it\'s final locations), '
             '"after_video" (after downloading and processing all formats of a video), '
             'or "playlist" (at end of playlist). '

yt_dlp/utils.py

@@ -3395,7 +3395,7 @@ def qualities(quality_ids):
     return q
 
 
-POSTPROCESS_WHEN = ('pre_process', 'after_filter', 'before_dl', 'post_process', 'after_move', 'after_video', 'playlist')
+POSTPROCESS_WHEN = ('pre_process', 'after_filter', 'video', 'before_dl', 'post_process', 'after_move', 'after_video', 'playlist')
 
 
 DEFAULT_OUTTMPL = {