Recording

Recording captures decrypted RTP and RTCP packets to a PCAP file with accurate timestamps. Recordings operate at two independent layers that can run simultaneously:

• Full session: records all legs (all endpoints)
• Single leg: records one specific endpoint (e.g., for voicemail)

recording.start

{
  "id": "1",
  "method": "recording.start",
  "params": {
    "endpoint_id": null,
    "file_path": "/recordings/call-123.pcap"
  }
}

Param	Type	Default	Description
endpoint_id	string or null	optional (default: null)	null for full-session recording, endpoint ID for single leg
file_path	string	required	Absolute path within recording_dir. Symlinks are resolved; the real path must remain inside the configured directory

Response:

{"id":"1","result":{"recording_id":"..."}}

recording.stop

{"id":"2","method":"recording.stop","params":{"recording_id":"..."}}

Response:

{
  "id": "2",
  "result": {
    "file_path": "/recordings/call-123.pcap",
    "duration_ms": 30000,
    "packets": 1500,
    "dropped_packets": 0
  }
}

PCAP Format

• Link type: Ethernet
• Each packet has synthetic Ethernet/IPv4/UDP headers
• Endpoint addresses are deterministic: 10.{(N/254)+1}.0.{(N%254)+1}:10000 where N is the endpoint index
• Timestamps are wall-clock time from when the packet was received
• Both RTP media packets and RTCP reports are captured
• Packets are post-decryption (SRTP is unwrapped before recording)
• The PCAP file can be opened directly in Wireshark

Field	Description
file_path	Absolute path of the written PCAP file
duration_ms	Wall-clock recording duration
packets	Total packets written to the PCAP file
dropped_packets	Packets dropped due to disk I/O backpressure (see Bounded Channel below)

Bounded Channel

Recording uses a bounded channel (capacity 1000 packets) between the media path and the disk write task. If disk I/O stalls, packets are dropped from the recording rather than blocking the media path. Drops are logged at warn level and reported in the dropped_packets field of the recording.stop response.