RTPPacket* FECDecoder::Recover()
{
BYTE aux[8];
QWORD lostMask = 0;
//Check we have media pacekts
if (!medias.size())
//Exit
return NULL;
//Get First packet
RTPPacket* first = medias.begin()->second;
//Get the SSRC
DWORD ssrc = first->GetSSRC();
//Get first media packet
DWORD minSeq = first->GetExtSeqNum();
//Iterator on seq
DWORD lastSeq = minSeq;
//Set to 0
memset(aux,0,8);
//Create writter
BitWritter w(aux,8);
//vector of lost pacekt seq
std::vector<DWORD> losts;
//For each media packet
for (RTPOrderedPackets::iterator it=medias.begin();it!=medias.end();++it)
{
//Get seq
DWORD cur = it->first;
//Insert lost
for (DWORD i=lastSeq+1;i<cur;++i)
{
//set mask bit to not present
w.Put(1,0);
//Add to the vecotr
losts.push_back(i);
}
//Set last seq
lastSeq = cur;
//set mask bit to present
w.Put(1,1);
}
//End it
w.Flush();
//Get mask
lostMask = get8(aux,0);
//Check we have lost pacekts
if (!losts.size())
//Exit
return NULL;
//For each lost packet
for(std::vector<DWORD>::iterator it=losts.begin();it!=losts.end();++it)
{
//Get lost packet sequence
DWORD seq = *it;
//Search FEC packets associated this media packet
for (FECOrderedData::iterator it2 = codes.begin();it2!=codes.end();++it2)
{
//Get FEC packet
FECData *fec = it2->second;
//Check if it is associated with this media pacekt in level 0
if (!fec->IsProtectedAtLevel0(seq))
//Next
continue;
//Get the seq difference between fec data and the media
// fec seq has to be <= media seq it fec data protect media data)
DWORD diff = seq-fec->GetBaseExtSeq();
//Shit mask of the lost packets to check the present ones from the base seq
QWORD mediaMask = lostMask << (fec->GetBaseExtSeq()-minSeq);
//Remove lost packet bit from the fec mask
QWORD fecMask = fec->GetLevel0Mask() & ~(((QWORD)1)<<(64-diff-1));
//Compare needed pacekts with actual pacekts, to check if we have all of them except the missing
if ((fecMask & mediaMask) == fecMask)
{
//Rocovered media data
BYTE recovered[MTU+SRTP_MAX_TRAILER_LEN] ZEROALIGNEDTO32;
//Get attributes
bool p = fec->GetRecoveryP();
bool x = fec->GetRecoveryX();
BYTE cc = fec->GetRecoveryCC();
bool m = fec->GetRecoveryM();
BYTE pt = fec->GetRecoveryType();
DWORD ts = fec->GetRecoveryTimestamp();
WORD l = fec->GetRecoveryLength();
//Get protection length
DWORD level0Size = fec->GetLevel0Size();
//Ensure there is enought size
if (level0Size>MTU)
{
//Error
Error("-FEC level 0 data size too big [%d]\n",level0Size);
//Skip this one
continue;
}
//Copy data
memcpy(recovered,fec->GetLevel0Data(),level0Size);
//Set value in temp buffer
set8(aux,0,fecMask);
//Get bit reader
BitReader r(aux,8);
//Read all media packet
while(r.Left())
{
//If the media packet is used to reconstrud the packet
if (r.Get(1))
{
//Get media packet
RTPPacket* media = medias[fec->GetBaseExtSeq()+r.GetPos()-1];
//Calculate receovered attributes
p ^= media->GetP();
x ^= media->GetX();
cc ^= media->GetCC();
m ^= media->GetMark();
pt ^= media->GetType();
ts ^= media->GetTimestamp();
l ^= media->GetMediaLength();
//Get data
BYTE *payload = media->GetMediaData();
//Calculate the xor
for (int i=0;i<fmin(media->GetMediaLength(),level0Size);++i)
//XOR
recovered[i] ^= payload[i];
}
}
//Create new video packet
RTPPacket* packet = new RTPPacket(MediaFrame::Video,pt);
//Set values
packet->SetP(p);
packet->SetX(x);
packet->SetMark(m);
packet->SetTimestamp(ts);
//Set sequence number
packet->SetSeqNum(seq);
//Set seq cycles
packet->SetSeqCycles(fec->GetBaseSeqCylcles());
//Set ssrc
packet->SetSSRC(ssrc);
//Set payload and recovered length
if (!packet->SetPayloadWithExtensionData(recovered,l))
{
//Delete packet
delete(packet);
//Error
Error("-FEC payload of recovered packet to big [%u]\n",(unsigned int)l);
//Skip
continue;
}
Debug("-recovered packet len:%u ts:%u pts:%u seq:%d\n",l,ts,packet->GetTimestamp() ,packet->GetSeqNum());
//Append the packet to the media packet list
if (AddPacket(packet))
//Return it if contained media
return packet;
else
//Discard and continue
delete(packet);
}
}
}
//Nothing found
return NULL;
}
int RTPPacketProcessor::ProcessRTPBlock(unsigned char *data,int len,unsigned long ip,int port,bool *collis,bool acceptlocalpackets,double localtsunit)
{
int status;
RTPPacket *packet;
*collis = false;
if (!initialized)
{
delete [] data;
return ERR_RTP_PACKETPROCESSORNOTINITIALIZED;
}
if ((status = GetRTPData(data,len,&packet)) < 0)
{
delete [] data;
return status;
}
if (packet != NULL) // valid packet
{
// check for collision with local ssrc and process further
if (contribsrcs->GetLocalSSRC() == htonl(packet->GetSSRC()))
{
// collision with local ssrc
if (ip == conn->GetLocalIP() && port == conn->GetSendPort())
{
if (!acceptlocalpackets)
{
delete packet;
return 0;
}
}
else
{
if (handlers->handlers[RTP_EXCEPTION_LOCALSSRCCOLLISION].handler != NULL)
CallLocalSSRCCollHandler(packet->GetSSRC(),ip,true,port);
delete packet;
*collis = true;
return 0;
}
}
status = sources->ProcessPacket(packet,ip,port,localtsunit);
if (status < 0)
{
delete packet;
/* On a collision we still want other data to be processed,
so we will not count this as an error */
if (status == ERR_RTP_COLLISIONBETWEENSSRCS)
return 0;
return status;
}
}
else // invalid packet
delete [] data;
return 0;
}
