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# Source code for mopidy.audio.scan

    from __future__ import (
        absolute_import, division, print_function, unicode_literals)

    import collections

    import pygst
    pygst.require('0.10')
    import gst  # noqa
    import gst.pbutils  # noqa

    from mopidy import exceptions
    from mopidy.audio import utils
    from mopidy.utils import encoding

    _missing_plugin_desc = gst.pbutils.missing_plugin_message_get_description

    _Result = collections.namedtuple(
        'Result', ('uri', 'tags', 'duration', 'seekable', 'mime', 'playable'))

    _RAW_AUDIO = gst.Caps(b'audio/x-raw-int; audio/x-raw-float')

    # TODO: replace with a scan(uri, timeout=1000, proxy_config=None)?
    class Scanner(object):
        """
        Helper to get tags and other relevant info from URIs.

        :param timeout: timeout for scanning a URI in ms
        :param proxy_config: dictionary containing proxy config strings.
        :type event: int
        """

        def __init__(self, timeout=1000, proxy_config=None):
            self._timeout_ms = int(timeout)
            self._proxy_config = proxy_config or {}

        def scan(self, uri):
            """
            Scan the given uri collecting relevant metadata.

            :param uri: URI of the resource to scan.
            :type event: string
            :return: A named tuple containing
                ``(uri, tags, duration, seekable, mime)``.
                ``tags`` is a dictionary of lists for all the tags we found.
                ``duration`` is the length of the URI in milliseconds, or
                :class:`None` if the URI has no duration. ``seekable`` is boolean.
                indicating if a seek would succeed.
            """
            tags, duration, seekable, mime = None, None, None, None
            pipeline = _setup_pipeline(uri, self._proxy_config)

            try:
                _start_pipeline(pipeline)
                tags, mime, have_audio = _process(pipeline, self._timeout_ms)
                duration = _query_duration(pipeline)
                seekable = _query_seekable(pipeline)
            finally:
                pipeline.set_state(gst.STATE_NULL)
                del pipeline

            return _Result(uri, tags, duration, seekable, mime, have_audio)

    # Turns out it's _much_ faster to just create a new pipeline for every as
    # decodebins and other elements don't seem to take well to being reused.
    def _setup_pipeline(uri, proxy_config=None):
        src = gst.element_make_from_uri(gst.URI_SRC, uri)
        if not src:
            raise exceptions.ScannerError('GStreamer can not open: %s' % uri)

        typefind = gst.element_factory_make('typefind')
        decodebin = gst.element_factory_make('decodebin2')

        pipeline = gst.element_factory_make('pipeline')
        pipeline.add_many(src, typefind, decodebin)
        gst.element_link_many(src, typefind, decodebin)

        if proxy_config:
            utils.setup_proxy(src, proxy_config)

        typefind.connect('have-type', _have_type, decodebin)
        decodebin.connect('pad-added', _pad_added, pipeline)

        return pipeline

    def _have_type(element, probability, caps, decodebin):
        decodebin.set_property('sink-caps', caps)
        struct = gst.Structure('have-type')
        struct['caps'] = caps.get_structure(0)
        element.get_bus().post(gst.message_new_application(element, struct))

    def _pad_added(element, pad, pipeline):
        sink = gst.element_factory_make('fakesink')
        sink.set_property('sync', False)

        pipeline.add(sink)
        sink.sync_state_with_parent()
        pad.link(sink.get_pad('sink'))

        if pad.get_caps().is_subset(_RAW_AUDIO):
            struct = gst.Structure('have-audio')
            element.get_bus().post(gst.message_new_application(element, struct))

    def _start_pipeline(pipeline):
        if pipeline.set_state(gst.STATE_PAUSED) == gst.STATE_CHANGE_NO_PREROLL:
            pipeline.set_state(gst.STATE_PLAYING)

    def _query_duration(pipeline):
        try:
            duration = pipeline.query_duration(gst.FORMAT_TIME, None)[0]
        except gst.QueryError:
            return None

        if duration < 0:
            return None
        else:
            return duration // gst.MSECOND

    def _query_seekable(pipeline):
        query = gst.query_new_seeking(gst.FORMAT_TIME)
        pipeline.query(query)
        return query.parse_seeking()[1]

    def _process(pipeline, timeout_ms):
        clock = pipeline.get_clock()
        bus = pipeline.get_bus()
        timeout = timeout_ms * gst.MSECOND
        tags, mime, have_audio, missing_description = {}, None, False, None

        types = (gst.MESSAGE_ELEMENT | gst.MESSAGE_APPLICATION | gst.MESSAGE_ERROR
                 | gst.MESSAGE_EOS | gst.MESSAGE_ASYNC_DONE | gst.MESSAGE_TAG)

        start = clock.get_time()
        while timeout > 0:
            message = bus.timed_pop_filtered(timeout, types)

            if message is None:
                break
            elif message.type == gst.MESSAGE_ELEMENT:
                if gst.pbutils.is_missing_plugin_message(message):
                    missing_description = encoding.locale_decode(
                        _missing_plugin_desc(message))
            elif message.type == gst.MESSAGE_APPLICATION:
                if message.structure.get_name() == 'have-type':
                    mime = message.structure['caps'].get_name()
                    if mime.startswith('text/') or mime == 'application/xml':
                        return tags, mime, have_audio
                elif message.structure.get_name() == 'have-audio':
                    have_audio = True
            elif message.type == gst.MESSAGE_ERROR:
                error = encoding.locale_decode(message.parse_error()[0])
                if missing_description:
                    error = '%s (%s)' % (missing_description, error)
                raise exceptions.ScannerError(error)
            elif message.type == gst.MESSAGE_EOS:
                return tags, mime, have_audio
            elif message.type == gst.MESSAGE_ASYNC_DONE:
                if message.src == pipeline:
                    return tags, mime, have_audio
            elif message.type == gst.MESSAGE_TAG:
                taglist = message.parse_tag()
                # Note that this will only keep the last tag.
                tags.update(utils.convert_taglist(taglist))

            timeout -= clock.get_time() - start

        raise exceptions.ScannerError('Timeout after %dms' % timeout_ms)

    if __name__ == '__main__':
        import os
        import sys

        import gobject

        from mopidy.utils import path

        gobject.threads_init()

        scanner = Scanner(5000)
        for uri in sys.argv[1:]:
            if not gst.uri_is_valid(uri):
                uri = path.path_to_uri(os.path.abspath(uri))
            try:
                result = scanner.scan(uri)
                for key in ('uri', 'mime', 'duration', 'playable', 'seekable'):
                    print('%-20s   %s' % (key, getattr(result, key)))
                print('tags')
                for tag, value in result.tags.items():
                    print('%-20s   %s' % (tag, value))
            except exceptions.ScannerError as error:
                print('%s: %s' % (uri, error))

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