Send or receive timestamp (Unix): <int>.<int>  -- sec.usec decimal 
RTP payload type                  <int>        -- decimal
SSRC                              <int>        -- hexadecimal
RTP sequence no                   <int>        -- decimal
RTP timestamp                     <int>        -- decimal
marker bit                        0|1          -- character
Payload size                      <int>        -- # bytes, decimal