Re: [Tracker] Add support for OMA DRM Content format

["Lin, Mengdong" <mengdong lin intel com>]

Here is my change on Tracker GStreamer extractor and it works. Is this method doable? And Can I submit a 
patch for it?
For OMA DRM content format (DCF), it will try GStreamer at first. If GStreamer DRM-aware extensions are 
installed, then decodebin2 can recognize the original media type and extract rich meta data. Otherwise, the 
extractor will extract basic media type from the unencrypted file header, and mark it as a piece of music, 
video or image. Other mime types are not recognized yet and the nie:mimeType is not changed.

static TrackerExtractData data[] = {
        { "audio/*", extract_gstreamer_audio },
        { "video/*", extract_gstreamer_video },
        { "image/*", extract_gstreamer_image },
        /* Tell gstreamer to guess if mimetype guessing returns video also for audio files */
        { "image/svg+xml", extract_gstreamer_svg },
        { "video/3gpp", extract_gstreamer_guess },
        { "video/mp4", extract_gstreamer_guess },
        { "video/x-ms-asf", extract_gstreamer_guess },
+       /* DRM types */
+       { "application/vnd.oma.drm.content", extract_gstreamer_dcf},
        { NULL, NULL }
};

static void
extract_gstreamer_dcf (const gchar          *uri,
                        TrackerSparqlBuilder *preupdate,
                         TrackerSparqlBuilder *metadata)
{
        gint items;
        
        tracker_extract_gstreamer (uri, preupdate, metadata, EXTRACT_MIME_GUESS);       
        items = tracker_sparql_builder_get_length (metadata);
        if(0 == items)
        {
                g_debug("GStreamer has not OMA-DRM-aware extensions\n");
                extract_dcf_self(uri, preupdate, metadata);
        }               
}



/* Extract original MIME type from  DCF file header, no more information can be got from the file header. */
static void
extract_dcf_self (      const gchar          *uri,
                                        TrackerSparqlBuilder *preupdate,
                                        TrackerSparqlBuilder *metadata)
{
        gchar  *filename;
        goffset filesize;
        FILE * fp = NULL;
        guchar dcf_version;
        guchar content_type_len;
        guchar content_uri_len;
        gchar ori_mime_type[OMA_MAX_MIME_TYPE_LEN];     
        
        filename = g_filename_from_uri (uri, NULL, NULL);
        filesize = tracker_file_get_size (filename);
        if (filesize < 3) {     
                /* at least 3 bytes, version, original content MIME type length and uri length */
                g_free (filename);
                return;
        }
        
        fp = tracker_file_open (filename, "r", TRUE);
        if(!fp) return;
                
        if(1 != fread(&dcf_version, sizeof(gchar), 1, fp)) 
                goto bail;
        if(1 != dcf_version) goto bail; /* only support version 1.0 */          
        
        if(1 != fread(&content_type_len, sizeof(guchar), 1, fp)) 
                goto bail;
        if(1 != fread(&content_uri_len, sizeof(guchar), 1, fp)) 
                goto bail;
        
        memset(ori_mime_type, 0, OMA_MAX_MIME_TYPE_LEN);
        if(1 != fread(&ori_mime_type, content_type_len, 1, fp)) 
                goto bail;
                
        tracker_sparql_builder_predicate (metadata, "a");
        if(!memcmp(ori_mime_type, "audio", 5)) {        
                
                tracker_sparql_builder_object (metadata, "nmm:MusicPiece");
                tracker_sparql_builder_object (metadata, "nfo:Audio");
        }
        else if(!memcmp(ori_mime_type, "video", 5))     {
                tracker_sparql_builder_object (metadata, "nmm:Video");
        }
        else if(!memcmp(ori_mime_type, "image", 5)) {
                tracker_sparql_builder_object (metadata, "nfo:Image");
        }
        
        /* other types are not recognized yet */

bail:
        if(fp)
                tracker_file_close(fp, FALSE);
}