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The PJSIP library (which includes the PJSUA API and related components) is commonly used for handling Voip (Voice over IP) and RTP (Real-time Transport Protocol) packets in Python, but there isn’t a specific library called PJSU2 that I’m aware of. You might have meant PJSIP.

If you’re looking to capture RTP packets using the PJSIP library, here’s how you could approach the task in Python:

Steps to Capture RTP Packets using PJSIP (Python)

1. Install PJSIP

You’ll need to first install PJSIP and its Python bindings. You can do this by following the official installation steps in the PJSIP documentation.

You can also try installing the pjsua bindings, but this may need to be built manually.

# Example installation for PJSIP with Python bindings
pip install pjsua

2. Set Up PJSUA and Initialise the Library

Once you have installed the PJSIP bindings, you can begin by initialising PJSIP and configuring a SIP account.

import pjsua as pj

# Create the library instance
lib = pj.Lib()

try:
    # Initialize the PJSUA library
    lib.init()

    # Create transport (UDP)
    transport = lib.create_transport(pj.TransportType.UDP)

    # Start the PJSUA library
    lib.start()

    print("PJSUA library started!")

except pj.Error as e:
    print(f"Error initializing PJSUA: {e}")
    exit(1)

3. Create RTP Packet Capture Function

To capture RTP packets, you can hook into PJSIP’s internal mechanisms and access raw packet data.

Below is an example of capturing RTP packets and printing the packet content:

import pjsua as pj

# Callback function to handle RTP packets
def rtp_callback(pkg, len):
    print("Received RTP packet:", pkg[:len])

# Initialize PJSIP
lib = pj.Lib()

try:
    # Initialize the library
    lib.init()

    # Create UDP transport for the SIP connection
    transport = lib.create_transport(pj.TransportType.UDP)

    # Start the library
    lib.start()

    print("Library started.")

    # Set up RTP logging, if applicable in your setup
    lib.set_rtp_callback(rtp_callback)

    # Keep the app running to capture RTP
    input("Press Enter to stop...\n")

except pj.Error as e:
    print(f"Error: {e}")
    exit(1)
finally:
    lib.destroy()

This sets up a basic RTP capture callback function that prints out the RTP packet each time one is received.

4. RTP Capture Output

This will show RTP packet data each time a packet is received. You can further modify this to log the packet content, analyze it, or write it to a file.

Capturing RTP with Wireshark (Alternative Method)

If you are dealing with RTP outside of PJSIP or looking for another way to capture RTP packets, you can use Wireshark to capture RTP packets on the network:

1. Start Wireshark and set a filter for RTP traffic.
   • Filter: udp.port == 5004 (common RTP port)
2. Capture the network traffic, and Wireshark will show the RTP packets with detailed information such as sequence numbers, timestamps, payload types, etc.

Additional Considerations:

• RTP Streams: Make sure you are dealing with the correct RTP stream (for instance, video/audio) and capture the appropriate ports.
• SIP Server Setup: Ensure that PJSIP or another SIP server is set up to correctly send RTP streams, which are typically used for voice/video communication.
• Network Interfaces: If you’re capturing traffic on your local machine, ensure you are sniffing the right network interface.

Let me know if you need further assistance with configuration or more detailed examples!