Hi I wanted to proxy multicast video to unicast like udpxy does: http://www.udpxy.com, but in C# since I could not find any suitable RTP library that I could use (they were eather too complex or I could't understand how to use them), I decided to port over one that udpxy uses rtp.c: https://github.com/pcherenkov/udpxy/blob/master/chipmunk/rtp.c
everything went fine (almost, as I didn't want to use pointers), until I wanted to translate RTP_Process to C#
RTP_Process in C
RTP_process( void** pbuf, size_t* len, int verify, FILE* log )
{
int rtp_padding = -1;
size_t front_skip = 0, back_skip = 0, pad_len = 0;
char* buf = NULL;
size_t pkt_len = 0;
assert( pbuf && len && log );
buf = *pbuf;
pkt_len = *len;
if( verify && !RTP_verify( buf, pkt_len, log ) )
return -1;
if( 0 != RTP_hdrlen( buf, pkt_len, &front_skip, log ) )
return -1;
rtp_padding = buf[0] & 0x20;
if( rtp_padding ) {
pad_len = buf[ pkt_len - 1 ];
}
back_skip += pad_len;
if( verify && (pkt_len < (front_skip + back_skip)) ) {
(void) tmfprintf( log, "RTP_process: invalid header "
"(skip [%lu] exceeds packet length [%lu])\n",
(u_long)(front_skip + back_skip), (u_long)pkt_len );
return -1;
}
/* adjust buffer/length to skip heading and padding */
/*
TRACE( (void)tmfprintf( log, "In: RTP buf=[%p] of [%lu] bytes, "
"fskip=[%ld], bskip=[%lu]\n",
(void*)buf, (u_long)pkt_len,
(u_long)front_skip, (u_long)back_skip ) );
*/
buf += front_skip;
pkt_len -= (front_skip + back_skip);
/*
TRACE( (void)tmfprintf( log, "Out RTP buf=[%p] of [%lu] bytes\n",
(void*)buf, (u_long)pkt_len ) );
*/
*pbuf = buf;
*len = pkt_len;
return 0;
}
RTP_Process in C#
public byte[] RTP_process(int verify)
{
/* process RTP package to retrieve the payload: set
* pbuf to the start of the payload area; set len to
* be equal payload's length
*
* @param pbuf address of pointer to beginning of RTP packet
* @param len pointer to RTP packet's length
* @param verify verify that it is an RTP packet if != 0
* @param log log file
*
* @return 0 if there was no error, -1 otherwise;
* set pbuf to point to beginning of payload and len
* be payload size in bytes
*/
int rtp_padding = -1;
int front_skip = 0, back_skip = 0, pad_len = 0;
int pkt_len = 0;
//assert(pbuf && len && log);
//buf = *pbuf;
pbuf = buf;
//pkt_len = *len;
len = pkt_len;
/*
if (verify != 1 && RTP_verify() != 1)
RTPOK = - 1;
if (0 != RTP_hdrlen(buf, pkt_len, front_skip)) //?????
RTPOK = - 1;
*/
rtp_padding = buf[0] & 0x20;
if (rtp_padding != -1) //???????
{
pad_len = buf[pkt_len - 1];
}
back_skip += pad_len;
if ((verify != -1) && (pkt_len < (front_skip + back_skip))) //???????
{
Console.WriteLine("RTP_process: invalid header (skip {0} exceeds packet length {1})\n", (long)(front_skip + back_skip), (long)pkt_len);
RTPOK = - 1;
}
/* adjust buffer/length to skip heading and padding */
/*
TRACE( (void)tmfprintf( log, "In: RTP buf=[%p] of [%lu] bytes, "
"fskip=[%ld], bskip=[%lu]\n",
(void*)buf, (u_long)pkt_len,
(u_long)front_skip, (u_long)back_skip ) );
*/
//buf += front_skip;
//pkt_len -= (front_skip + back_skip);
/*
TRACE( (void)tmfprintf( log, "Out RTP buf=[%p] of [%lu] bytes\n",
(void*)buf, (u_long)pkt_len ) );
*/
pbuf = buf;
len = pkt_len;
RTPOK = 0;
return pbuf;
}
here the problems started
1. buf += front_skip; complained that operator += cannot be applied to operands of type byte[] and int
then why did it work in RTP_Process in C and what is a C# equivalent of that
2. in
if (rtp_padding != -1) //???????
{
pad_len = buf[pkt_len - 1]; //There is an exeption trown: System.IndexOutOfRangeException: Index was outside the bounds of the array.
its clear that I interpreted and translated something the wrong way, but the onlything I would like to do is to get MPEG-TS frame out of RTP stream to then forward it to a TCP socket, so if anyone can suggest a better way of doing that I would love to hear it
Thanks for Anwsering and Best Regards }
