c++ DMS with subtitle support on LG smart tv with platinium library

I'm trying to implement a simple DMS that can provide subtitle information to the DMR -LG SmartTV - using platinium library.

I already succeeded to render video on the DMR and i already found where the DMR receive the information of the subtitle associated to the video file.

Sample request from the DMR:

    POST /upnp/services/ContentDirectory/control HTTP/1.1
HOST: 192.168.1.3:54444
CONTENT-LENGTH: 735
CONTENT-TYPE: text/xml; charset="utf-8"
SOAPACTION: "urn:schemas-upnp-org:service:ContentDirectory:1#Browse"
USER-AGENT: Linux/2.6.39.4.ps-110224-lg1152 UPnP/1.0 DLNADOC/1.50 INTEL_NMPR/2.0 LGE_DLNA_SDK/1.6.0

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"
s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
  <s:Body>
    <u:Browse xmlns:u="urn:schemas-upnp-org:service:ContentDirectory:1">
      <ObjectID>ea06</ObjectID>
      <BrowseFlag>BrowseDirectChildren</BrowseFlag>
      <Filter>@id,@parentID,@restricted,@childCount,dc:title,dc:creator,upnp:artist,upnp:class,dc:date,upnp:album,upnp:genre,res,res@size,res@duration,res@protection,res@bitrate,res@resolution,res@protocolInfo,res@nrAudioChannels,res@sampleFrequency,upnp:albumArtURI,upnp:albumArtURI@dlna:profileID, res@dlna:cleartextSize</Filter>
      <StartingIndex>0</StartingIndex>
      <RequestedCount>24</RequestedCount>
      <SortCriteria></SortCriteria>
    </u:Browse>
  </s:Body>
</s:Envelope>

now the response from a valid DMS that support subtitle display is:

HTTP/1.1 200 OK
SERVER: WINDOWS/5.1 UPnP/1.0 DLNADOC/1.50 Nero-MediaHome/4.5.20.145
CONTENT-TYPE: text/xml; charset=utf-8
EXT:
DATE: Mon, 14 Jan 2013 22:12:35 GMT
TRANSFER-ENCODING: chunked
CONNECTION: Keep-Alive
...
          <item id="ea13" parentID="ea06" restricted="1">
            <dc:date>2012-10-25</dc:date>
            <dc:title>video.avi</dc:title>
            <upnp:album>Filmes</upnp:album>
            <upnp:class>object.item.videoItem.movie</upnp:class>
            <res 
              bitrate="257570" duration="1:37:32" nrAudioChannels="6" 
              protocolInfo="http-get:*:video/avi:DLNA.ORG_OP=01;DLNA.ORG_CI=0;DLNA.ORG_FLAGS=01700000000000000000000000000000" 
              resolution="720x304" sampleFrequency="48000" size="1507196928">http://192.168.1.3:54444/server/80402875-CA74-4CCE-B7E0-D81CEF1913A2/D5E59F25/ea13?unknown-id</res>
            <res protocolInfo="http-get:*:text/srt:*">http://192.168.1.3:54444/server/80402875-CA74-4CCE-B7E0-D81CEF1913A2/3A2C7131/ea13?sub=video.srt</res>
          </item>

Now i'm trying to implement the same in my custom DMS, can anyone point me in the right direction or show any sample that implements subtitle info stored in res element as: srt_URL (content-type of response is text/srt)

Thanks

Solution

To add a SRT resource tag to UPnP item in Platinum, you should do at least the following. I don't claim the list being functional, complete or tested. It's just my best guess at what needs to be changed. If it doesn't immediately work as expected, i may not be able to help you more specifically. It's a navigation hint, not a driving assistance.

put your SRT file in the same folder as the media file, named the same way in some sensible way which would be easy for you to distinguish afterwards.
in PltMimeType.cpp add "srt","text/srt" to PLT_HttpFileRequestHandler_DefaultFileTypeMap. Platinum doesn't know SRT out of the box.
PltFileMediaServer.cpp is kinda dumb, it by default shows up all files found in a directory. It's an example, after all. You need to filter out SRTs from the visible listing by implementing PltFileMediaServer::ProcessFile filter.
still in PltFileMediaServer.cpp there is a method PLT_FileMediaServerDelegate::BuildFromFilePath. Here comes filepath which is the path of your media file (and ONLY that). Out of the filepath, you need to look in the folder whether there is a properly named subtitle file (with some NPT_File methods, look it up).
if there is, you must add extra PLT_MediaItemResource to the PLT_MediaObject* object. There is already one resource instance, but that's used exclusively for the media resource itself. Don't reuse it. You need to add another one, and IMO you need to set only resource.m_Uri (with BuildResourceUri) and resource.m_ProtocolInfo.
for m_ProtocolInfo, you need to call PLT_ProtocolInfo::GetProtocolInfo with parameter false so that the protocolInfo of your newly added <res> is not clobbered with DLNA profile id.