Re: [Ethereal-users] Decoding RTP?

[Craig Rodrigues <rodrigc@xxxxxxxxxxxx>]

Hi,

I have a RTP question for the protocol gurus out there.
I looked at RFC 1889 for RTP (http://www.ietf.org/rfc/rfc1889.txt)
and borrowed the following code from it:

/*
 *     * RTP data header
 *         */
typedef struct {
  unsigned int version:2;   /* protocol version */
  unsigned int p:1;         /* padding flag */
  unsigned int x:1;         /* header extension flag */
  unsigned int cc:4;        /* CSRC count */
  unsigned int m:1;         /* marker bit */
  unsigned int pt:7;        /* payload type */
  u_int16_t seq;              /* sequence number */
  u_int32_t ts;               /* timestamp */
  u_int32_t ssrc;             /* synchronization source */
  u_int32_t csrc[1];          /* optional CSRC list */
} rtp_hdr_t;  


I am running on i386 Linux.

I create a packet, where I set the version number to 2, the payload type to
32, and everything else to zero.  When I ship this packet over the
network via UDP, Ethereal decodes the packet with a version number of 0.
The first byte of the packet, according to Ethereal, is 0xa (10).

Am I doing things wrong?  Do I need to redefine my struct depending on
what byte order I am in?

Thanks.



-- 
Craig Rodrigues        
http://www.gis.net/~craigr    
rodrigc@xxxxxxxxxxxx