1 files changed, 49 insertions, 0 deletions
diff --git a/youtube_dl/postprocessor/common.py b/youtube_dl/postprocessor/common.py
new file mode 100644
index 000000000..788f94d02
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+++ b/youtube_dl/postprocessor/common.py
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+from ..utils import PostProcessingError
+
+
+class PostProcessor(object):
+    """Post Processor class.
+
+    PostProcessor objects can be added to downloaders with their
+    add_post_processor() method. When the downloader has finished a
+    successful download, it will take its internal chain of PostProcessors
+    and start calling the run() method on each one of them, first with
+    an initial argument and then with the returned value of the previous
+    PostProcessor.
+
+    The chain will be stopped if one of them ever returns None or the end
+    of the chain is reached.
+
+    PostProcessor objects follow a "mutual registration" process similar
+    to InfoExtractor objects.
+    """
+
+    _downloader = None
+
+    def __init__(self, downloader=None):
+        self._downloader = downloader
+
+    def set_downloader(self, downloader):
+        """Sets the downloader for this PP."""
+        self._downloader = downloader
+
+    def run(self, information):
+        """Run the PostProcessor.
+
+        The "information" argument is a dictionary like the ones
+        composed by InfoExtractors. The only difference is that this
+        one has an extra field called "filepath" that points to the
+        downloaded file.
+
+        This method returns a tuple, the first element of which describes
+        whether the original file should be kept (i.e. not deleted - None for
+        no preference), and the second of which is the updated information.
+
+        In addition, this method may raise a PostProcessingError
+        exception if post processing fails.
+        """
+        return None, information  # by default, keep file and do nothing
+
+
+class AudioConversionError(PostProcessingError):
+    pass