Hello,
I'm trying to investigate streaming performance when an 8-bit RTP sequence
number is used.
After sequence number 255 is first reached, the sequence number does wrap
round to zero as expected, but all packets thereafter are incorrectly
detected as lost.
These are some of the modifications I made in RTPSource.cpp:
void RTPReceptionStats
::noteIncomingPacket(u_int8_t seqNum, ....) {
......
// Check whether the new sequence number is the highest yet seen:
unsigned oldSeqNum = (fHighestExtSeqNumReceived&0xFF);
if (seqNumLT((u_int8_t)oldSeqNum, seqNum)) {
// This packet was not an old packet received out of order, so check it:
unsigned seqNumCycle = (fHighestExtSeqNumReceived&0xFF00);
unsigned seqNumDifference = (unsigned)((int)seqNum-(int)oldSeqNum);
if (seqNumDifference >= 0x80) {
// The sequence number wrapped around, so start a new cycle:
seqNumCycle += 0x100;
.........
}
but I still get this sort of QoS statistics:
Started playing session
Receiving streamed data (for up to 60.000000 seconds)...
begin_QOS_statistics
server_availability 100
stream_availability 100
subsession video/MPV
num_packets_received 22470
*num_packets_lost 4294944950*
elapsed_measurement_time 60.004700
kBytes_received_total 22560.912000
measurement_sampling_interval_ms 1000
kbits_per_second_min 2757.835416
kbits_per_second_ave 3007.885982
kbits_per_second_max 3166.214214
*packet_loss_percentage_min -109.677419*
packet_loss_percentage_ave 0.000000
packet_loss_percentage_max 0.000000
inter_packet_gap_ms_min 0.004000
inter_packet_gap_ms_ave 2.668810
inter_packet_gap_ms_max 78.687000
subsession audio/MPA
num_packets_received 1241
*num_packets_lost 4294966235*
elapsed_measurement_time 60.004700
kBytes_received_total 1434.596000
measurement_sampling_interval_ms 1000
kbits_per_second_min 101.252014
kbits_per_second_ave 191.264484
kbits_per_second_max 204.068205
*packet_loss_percentage_min -566.666667*
packet_loss_percentage_ave 0.000000
packet_loss_percentage_max 0.000000
inter_packet_gap_ms_min 0.013000
inter_packet_gap_ms_ave 48.322089
inter_packet_gap_ms_max 685.016000
end_QOS_statistics
How can I achieve wraparound at sequence number 255 without mis-detection
thereafter as lost packets?
Thanks,
Josephine
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