FreeCalypso > hg > gsm-codec-lib
annotate doc/RTP-analysis @ 173:aaa0380f9958
doc/RTP-analysis: document new tools
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Tue, 27 Dec 2022 00:00:57 +0000 |
parents | 8eb0e7a39409 |
children | 9fb22fa4d373 |
rev | line source |
---|---|
173
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
1 The present package includes a number of utilities for analyzing RTP streams |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
2 that have been captured with tcpdump or equivalent tools in pcap format. In |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
3 order to use any of these utilities, you need to have a pcap file (obviously), |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
4 and you need to identify the RTP stream to be analyzed or extracted by either |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
5 source or destination IP:port. All tools begin by applying a filter, |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
6 considering only those packets that are UDP in IPv4 (no IPv6 support currently), |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
7 and only those that match the specified source or destination IP:port. Every |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
8 matched packet is checked for a valid RTP header, and then the actual RTP stream |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
9 analysis or extraction takes place, depending on the specific tool: |
136
8eb0e7a39409
doc: document command line utilities
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
10 |
173
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
11 rtp-cont-check This program checks the selected RTP stream for continuity. It |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
12 verifies that every matched packet has the same SSRC, that the |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
13 sequence number always increments by 1 from each individual |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
14 packet to the next, and that the RTP header timestamp always |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
15 increments by 160 units. (The assumption is that the |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
16 application at hand is in the traditional telephony domain, |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
17 with a sampling rate of 8000 samples/s and 20 ms packetization |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
18 for RTP.) This tool also looks at the capture time deltas |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
19 between successive packets and reports the observed minimum and |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
20 maximum; by seeing min and max delta-T, a developer can easily |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
21 notice timing aberrations that aren't caught by RTP header |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
22 sequence number and timestamp checks. |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
23 |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
24 rtp-gsmfr-extr This program focuses on a single selected RTP stream like the |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
25 others, enforces its continuity just like rtp-cont-check, but |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
26 then further enforces that every RTP packet be one of these 3 |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
27 possibilities: a GSM FR1 codec frame, a GSM EFR codec frame or |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
28 a Themyscira BFI marker as defined in the RTP-BFI-extension |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
29 document. (The payload type number is NOT considered, only the |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
30 payload length and the characteristic signature of each of the |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
31 3 allowed possibilities.) The selected RTP stream is then |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
32 extracted and written into a gsmx file (see Binary-file-format), |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
33 which can then be analyzed with gsmrec-dump or decoded to |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
34 playable WAV with gsmfr-decode or gsmefr-decode. |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
35 |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
36 rtp-jitter-view This program analyzes a single selected RTP stream just like |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
37 rtp-cont-check, but instead of reporting minimum and maximum |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
38 time deltas for the entire stream, it prints the individual |
aaa0380f9958
doc/RTP-analysis: document new tools
Mychaela Falconia <falcon@freecalypso.org>
parents:
136
diff
changeset
|
39 capture time delta between every successive pair of packets. |