Title pretty says it all. Here's a DIDL sample returned by MC which makes BubbleUPnP XML parser fail because of the missing "jr" namespace:
[AsyncTask #1 ] WARNING - 01:00:27.56 - LibraryFragment : device exception: org.xmlpull.v1.XmlPullParserException: undefined prefix: jr (position:START_TAG <{null}jr:volumelevel>@14:17 in java.io.InputStreamReader@23fac78)
context: Browse action
Manufacturer: JRiver, Inc.
Model Description: JRiver DLNA Server
Model Name: Media Center
Model Number: 20.0.50
bad XML: <DIDL-Lite xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/" xmlns:dlna="urn:schemas-dlna-org:device-1-0" xmlns:av="urn:schemas-sony-com:av" xmlns:pv="http://www.pv.com/pvns/">
<item id="F15346" parentID="2510" restricted="1">
<dc:title>Introduction By Jimmy Lyons</dc:title>
<upnp:class>object.item.audioItem.musicTrack</upnp:class>
<upnp:artist>Don Ellis Orchestra</upnp:artist>
<upnp:artist role="Performer">Don Ellis Orchestra</upnp:artist>
<upnp:artist role="AlbumArtist">Don Ellis</upnp:artist>
<dc:creator>Don Ellis Orchestra</dc:creator>
<upnp:album>'Live' At Monterey!</upnp:album>
<upnp:genre>Big Band</upnp:genre>
<upnp:originalTrackNumber>1</upnp:originalTrackNumber>
<dc:description>Collection of Render - ripped by Muscgate</dc:description>
<upnp:longDescription>Collection of Render - ripped by Muscgate</upnp:longDescription>
<upnp:playbackCount>239</upnp:playbackCount>
<jr:volumelevel>-2,4125</jr:volumelevel>
<jr:peaklevel>-1,1 dBTP; -1,1 Links; -2,0 Rechts</jr:peaklevel>
<dc:date>1966-01-01T00:00:00</dc:date>
<pv:playcount>239</pv:playcount>
<pv:lastPlayedTime>2014-12-23T16:13:05</pv:lastPlayedTime>
<pv:addedTime>1382364769</pv:addedTime>
<pv:modificationTime>1376849457</pv:modificationTime>
<upnp:albumArtURI dlna:profileID="JPEG_SM">http://192.168.192.21:52100/AArs/15346.jpg</upnp:albumArtURI>
<upnp:albumArtURI dlna:profileID="JPEG_TN">http://192.168.192.21:52100/AArt/15346.jpg</upnp:albumArtURI>
<res protocolInfo="http-get:*:audio/x-flac:DLNA.ORG_PN=FLAC;DLNA.ORG_OP=01;DLNA.ORG_CI=0;DLNA.ORG_FLAGS=01700000000000000000000000000000" duration="0:01:17.000" size="7181127" nrAudioChannels="2" sampleFrequency="44100" bitsPerSample="16" bitrate="86500">http://192.168.192.21:52100/Music/F15346.flac</res>
</item>
<item id="F15345" parentID="2510" restricted="1">
<dc:title>33 222 1 222</dc:title>
<upnp:class>object.item.audioItem.musicTrack</upnp:class>
<upnp:artist>Don Ellis Orchestra</upnp:artist>
<upnp:artist role="Performer">Don Ellis Orchestra</upnp:artist>
<upnp:artist role="AlbumArtist">Don Ellis</upnp:artist>
<dc:creator>Don Ellis Orchestra</dc:creator>
<upnp:album>'Live' At Monterey!</upnp:album>
<upnp:genre>Big Band</upnp:genre>
<upnp:originalTrackNumber>2</upnp:originalTrackNumber>
<dc:description>Collection of Render - ripped by Muscgate</dc:description>
<upnp:longDescription>Collection of Render - ripped by Muscgate</upnp:longDescription>
<upnp:playbackCount>239</upnp:playbackCount>
<jr:volumelevel>-11,20671</jr:volumelevel>
<jr:peaklevel>+0,3 dBTP; +0,3 Links; -0,7 Rechts</jr:peaklevel>
<dc:date>1966-01-01T00:00:00</dc:date>
<pv:playcount>239</pv:playcount>
<pv:lastPlayedTime>2014-11-01T08:42:02</pv:lastPlayedTime>
<pv:addedTime>1382364769</pv:addedTime>
<pv:modificationTime>1376849477</pv:modificationTime>
<upnp:albumArtURI dlna:profileID="JPEG_SM">http://192.168.192.21:52100/AArs/15345.jpg</upnp:albumArtURI>
<upnp:albumArtURI dlna:profileID="JPEG_TN">http://192.168.192.21:52100/AArt/15345.jpg</upnp:albumArtURI>
<res protocolInfo="http-get:*:audio/x-flac:DLNA.ORG_PN=FLAC;DLNA.ORG_OP=01;DLNA.ORG_CI=0;DLNA.ORG_FLAGS=01700000000000000000000000000000" duration="0:09:29.000" size="64884917" nrAudioChannels="2" sampleFrequency="44100" bitsPerSample="16" bitrate="113125">http://192.168.192.21:52100/Music/F15345.flac</res>
</item>
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