|PCAPREPORT(1)||General Commands Manual||PCAPREPORT(1)|
pcapreport — Get
info about a TS in a pcap
Report and/or extract the Transport Streams in a .pcap. In analyse
-a ) the timing info in the TS (PCRs) can be
compared with the timing info in the pcap.
- Produce usage summary
- Produce usage + more detail on what the output actually means
- Analyse. Produces summary info on every TS in the pcap
- Select data with the given destination IP and port. If the port is not specified, it defaults to 0 (see below).
- Only extract/analyse packets that seem entirely good. By default there is a bit of slack in determining if a packet is good and some dodgy packets are let through. This switch ensures that all packets pass simple testing
- Extract all packets including bad ones. Is implied if an ip & port
filter is set. Overridden by
- Sets the format for printed times
time_format is one of
- [Default] show as 90KHz timestamps (suffix 't' on the values: e.g., 4362599t).
- Show as 27MHz timestamps (similar, e.g., 25151:000t).
- Show as 90KHz timestamps, but only the low 32 bits.
- Show as milliseconds.
- Show as hours/minutes/seconds (H:MM:SS.ssss, the H can be more than one digit if necessary)
- Dump any data in the input file to stdout.
- Dump only data which isn't being sent to the Fl o file.
- Report continuously on PCR vs PCAP timing for the destination specified in
- Gives the skew discontinuity threshold in 90kHz units. A value of 0 disables this. [default = 6*90000]
- Split extracted streams into multiple files on section (discontinutity) boundaries
- Write error messages to standard output (the default)
- Write error messages to standard error (Unix traditional)
- Output extra information about packets
- The pcap stream file to get info on
Specifying 0.0.0.0 for destination IP will capture all hosts, specifying 0 as a destination port will capture all ports on the destination host.
Network packet numbers start at 1 (like wireshark)
TS packet numbers start at 0.
- (packet and PCR) The times associated with packets and PCR are held internally in 90kHz units and are displayed in those units by default
- A set of packets to the same IP & Port. TS streams are detected by looking for 0x47s at appropriate places in the packets
- A part of a stream which appears to have a continuous TS embedded in it.
If the PCR jumps then a new section should be started (though this will
not generate a separate .ts file if the extraction option is in effect
-split-sectionis specified, nor will it generate a new .csv file.)
As it stands pcapreport will only report on a single PCR pid within a TS. If multiple pids with PCRs are detected then this will be reported but the other PCRs will be ignored
- This is the difference between the time in the pcap for a UDP packet and
any PCR found in the TS contained within that packet. The accuracy of this
figure obviously depends on how good the clock was in the capture process.
Skew is arbitrarily set to zero at the start of a section. A skew of
>6s is assumed to be a discontinuity and will start a new section.
Positive skew means that we received too low a PCR for this timestamp.
- This is skew over time and (assuming that the playout process is good) represents the difference in speed between the transmitters clock and the receivers clock. The algorithm for determining this isn't very sophisticated so if you have a large maximum jitter or a short sample this should be taken with a pinch of salt. Beware also that PC clocks (like the one in the m/c doing the tcpdump) are not always amongst the most stable or accurate; however they should be good enough to detect gross errors
- This is measured as the difference between the maximum and minimum skews over a 10sec (max 1024 samples) period. This should be long enough to capture a good baseline but short enough that drift has a negligible effect
- Max Jitter
- The maximum value of jitter (see above) found in a section
pcapreport can only deal with IPv4. IPv6 is beyond its current capabilities.
|October 28, 2015||Debian|