How to convert .pcap to .las file

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Hello, I am a complete freshman on Linux, ROS and velodyne so, Please help me with this. I want to process the velodyne data to create an point cloud. As velodyne give output in .pcap file want to convert it into .las file. So that i can use it for point cloud generation. I have a raw .pcap file that i want to convert..

I tried with converting pcap to txt with tshark it convrt successfully. Then tried to convert txt to las using txt2las command but it give me error.

Error:
WARNING: cannot parse '    Urgent pointer: 0
' with 'xyz'. skipping ...
WARNING: cannot parse '    [SEQ/ACK analysis]
' with 'xyz'. skipping ...
WARNING: cannot parse '        [This is an ACK to the segment in frame: 361]
' with 'xyz'. skipping ...
WARNING: cannot parse '        [The RTT to ACK the segment was: 48.340006000 seconds]
' with 'xyz'. skipping ...
WARNING: cannot parse '        [Bytes in flight: 5]
' with 'xyz'. skipping ...
WARNING: cannot parse 'MSN Messenger Service
' with 'xyz'. skipping ...
WARNING: cannot parse '    OUT\r\n
' with 'xyz'. skipping ...
WARNING: cannot parse '
' with 'xyz'. skipping ...
ERROR: could not parse any lines with 'xyz'

Can any one Plz Help me with this ???? Thank you :)