-Prologue- I can receive a DVB-H signal from Winter Olympics 2006 trial with a regular DVB-T PCI card, it's a 10 video services transport stream (5 Mbps) with time slicing and MPE-FEC enabled. I can dump the stream to disk and analyze it with no problem using dvbsnoop, so there is no DVB-H specific modulation type involved (e.g. 4k mode). Video is H264 and audio is AAC-LC, they are encapsulated in a multicast IP stream. Following Thomas' post (http://linuxtv.org/pipermail/linux-dvb/2006-February/007947.html) I tried to decode some video or audio data with VLC (I have also .sdp files) to no availability. After some investigations I found out that packets were not forwarded to L3 because of their MAC address and I could only receive packets in promiscuos mode, using i.e. tcpdump. -The problem- I think the actual implementation of dvb_net.c in DVB driver about MPE multicast IP datagrams is broken if time slicing and/or MPE-FEC are used. The dvb_net_sec() MPE parsing function forges ethernet headers like this: /* create ethernet header: */ eth[0]=pkt[0x0b]; eth[1]=pkt[0x0a]; eth[2]=pkt[0x09]; eth[3]=pkt[0x08]; eth[4]=pkt[0x04]; eth[5]=pkt[0x03]; but in ETSI EN 301 192 v1.4.1 this is the case only if MAC_address_range==0x06 in multiprotocol_encapsulation_info, in every other case the above assignments are wrong. -My problem- In my stream MAC_address_range==0x02, so only last two bytes of destination MAC are valid, first 4 bytes carry real_time_parameters used by MPE-FEC and time slicing and should be ignored (unless someone comes up with FEC decoding ;) ). In my case a quick and dirty hack would be (not tried yet): /* create ethernet header: */ eth[0]=0x01; eth[1]=0x00; eth[2]=0x5E; eth[3]=0x00; eth[4]=pkt[0x04]; eth[5]=pkt[0x03]; as per RFC 1112 multicast IP to MAC mapping, but I'm sure we can deal with it in a proper way. -The proper way- I think dvbnet should honor multiprotocol_encapsulation_info found in Data_broadcast_descriptor if data_broadcast_id==0x0005 (MPE), so it has to scan SDT first (don't know another way to check MAC_address_range value). Sorry but I have little or no idea of which modifications are needed, I'm pretty new to Linux DVB API. Suggestions are welcome, hope I didn't spread too much nonsense. Francesco Schiavarelli _______________________________________________ linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
