RTP header compression issue.

Ravi Kumar Fri, 31 Jul 2015 20:02:02 -0700

Hi,
I am trying to compress IP/UDP/RTP packet .But i am only getting 2 bytes of 
header compression out of 40(IP/UDP/RTP) bytes. The following is my 
program.Please check it and suggest me where i am going wrong.
Please help me ..
I am using O RTP library for rtp packet generation .
#include "rohc_rtp.h"
int runcond=1;
void stophandler(int signum){&nbsp; &nbsp; runcond=0;}


static int gen_random_num(const struct rohc_comp *const comp,void *const 
user_context){&nbsp; &nbsp; &nbsp; &nbsp; return rand();}
static bool rtp_detect(const unsigned char *const ip,&nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;const unsigned 
char *const udp,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp;const unsigned char *const payload,&nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;const unsigned 
int payload_size,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp;void *const rtp_private){&nbsp; &nbsp; uint16_t 
udp_dport;&nbsp; &nbsp; bool is_rtp;
&nbsp; &nbsp; /* check UDP destination port */&nbsp; &nbsp; 
memcpy(&amp;udp_dport, udp + 2, sizeof(uint16_t));&nbsp; &nbsp; 
if(ntohs(udp_dport) == 10042)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; /* we 
think that the UDP packet is a RTP packet */&nbsp; &nbsp; &nbsp; &nbsp; 
fprintf(stderr, "RTP packet detected (expected UDP port)\n");&nbsp; &nbsp; 
&nbsp; &nbsp; is_rtp = true;&nbsp; &nbsp; }&nbsp; &nbsp; else&nbsp; &nbsp; 
{&nbsp; &nbsp; &nbsp; &nbsp; /* we think that the UDP packet is not a RTP 
packet */&nbsp; &nbsp; &nbsp; &nbsp; fprintf(stderr, "RTP packet not detected 
(wrong UDP port)\n");&nbsp; &nbsp; &nbsp; &nbsp; is_rtp = false;&nbsp; &nbsp; }
&nbsp; &nbsp; return is_rtp;}
static void print_rohc_traces(void *const priv_ctxt,&nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
const rohc_trace_level_t level,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; const 
rohc_trace_entity_t entity,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; const int 
profile,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; const char *const format,&nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; ...){&nbsp; &nbsp; &nbsp; &nbsp; va_list args;&nbsp; &nbsp; 
&nbsp; &nbsp; va_start(args, format);&nbsp; &nbsp; &nbsp; &nbsp; 
vfprintf(stdout, format, args);&nbsp; &nbsp; &nbsp; &nbsp; va_end(args);}
int main(){&nbsp; &nbsp; &nbsp; &nbsp; char buffer[160]="",data[256]="";&nbsp; 
&nbsp; &nbsp; &nbsp; int i;&nbsp; &nbsp; &nbsp; &nbsp; FILE *infile;&nbsp; 
&nbsp; &nbsp; &nbsp; char *ssrc;&nbsp; &nbsp; &nbsp; &nbsp; uint32_t 
user_ts=0;&nbsp; &nbsp; &nbsp; &nbsp; int clockslide=0;&nbsp; &nbsp; &nbsp; 
&nbsp; int jitter=0;&nbsp; &nbsp; &nbsp; &nbsp; mblk_t *m=NULL;
&nbsp; &nbsp; &nbsp; &nbsp; uint8_t rtp_buffer[BUFFER_SIZE]="";&nbsp; &nbsp; 
&nbsp; &nbsp; struct rohc_buf rtp_r_packet = rohc_buf_init_empty(rtp_buffer, 
BUFFER_SIZE);
&nbsp; &nbsp; &nbsp; &nbsp; uint8_t rohc_buffer[BUFFER_SIZE]="";&nbsp; &nbsp; 
&nbsp; &nbsp; struct rohc_buf rohc_packet = rohc_buf_init_empty(rohc_buffer, 
BUFFER_SIZE);
&nbsp; &nbsp; &nbsp; &nbsp; struct rohc_comp *compressor=NULL;&nbsp; &nbsp; 
&nbsp; &nbsp; unsigned int *rtpheader = (unsigned int*)data;&nbsp; &nbsp; 
&nbsp; &nbsp; RtpSession *rtp_session=NULL;&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_status_t rohc_status;&nbsp; &nbsp; &nbsp; &nbsp; rtp_header_t *rtp_h;

&nbsp; &nbsp; &nbsp; &nbsp; printf("Testing RTP header compression\n");
&nbsp; &nbsp; &nbsp; &nbsp; /*create ROHC compressor */
&nbsp; &nbsp; &nbsp; &nbsp; compressor = rohc_comp_new2(ROHC_SMALL_CID, 
ROHC_SMALL_CID_MAX,gen_random_num, NULL);&nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp;if(compressor == NULL)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;{&nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; printf("Failed create the ROHC 
compressor\n");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return 
1;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;}
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;if(!rohc_comp_set_traces_cb2(compressor, 
print_rohc_traces, NULL))&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;{&nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; printf("failed to set the callback 
for traces on compressor\n");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; return 1;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;}

&nbsp; &nbsp; &nbsp; &nbsp; /* Compressor profile creation */
&nbsp; &nbsp; &nbsp; &nbsp; if(!rohc_comp_enable_profile(compressor, 
ROHC_PROFILE_RTP))&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; printf("failed to enable the RTP profile\n");&nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; /* cleanup compressor, then 
leave with an error code */&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; rohc_comp_free(compressor);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; return 1;&nbsp; &nbsp; &nbsp; &nbsp; }
&nbsp; &nbsp; &nbsp; &nbsp; /*Prepare Fake RTP packet */
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;/* Create the actual packet that we will be 
sending */
&nbsp; &nbsp; &nbsp; &nbsp; ortp_init();&nbsp; &nbsp; &nbsp; &nbsp; 
ortp_scheduler_init();&nbsp; &nbsp; &nbsp; &nbsp; 
rtp_session=rtp_session_new(RTP_SESSION_SENDONLY);&nbsp; &nbsp; &nbsp; &nbsp; 
rtp_session_set_scheduling_mode(rtp_session,1);&nbsp; &nbsp; &nbsp; &nbsp; 
rtp_session_set_blocking_mode(rtp_session,1);&nbsp; &nbsp; &nbsp; &nbsp; 
rtp_session_set_remote_addr(rtp_session,"192.168.1.36",5087);&nbsp; &nbsp; 
&nbsp; &nbsp; rtp_session_set_payload_type(rtp_session,0);&nbsp; &nbsp; &nbsp; 
&nbsp; ssrc=getenv("SSRC");&nbsp; &nbsp; &nbsp; &nbsp; if (ssrc!=NULL) {&nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; printf("using 
SSRC=%i.\n",atoi(ssrc));&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
rtp_session_set_ssrc(rtp_session,atoi(ssrc));&nbsp; &nbsp; &nbsp; &nbsp; 
}&nbsp; &nbsp; &nbsp; &nbsp; 
infile=fopen("/home/vravi/lat-tests/prepaid-press1-listen-lastcall.wav","r");&nbsp;
 &nbsp; &nbsp; &nbsp; if (infile==NULL) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nb
 sp; perror("Cannot open file");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; return -1;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; 
&nbsp; signal(SIGINT,stophandler);&nbsp; &nbsp; &nbsp; &nbsp; printf("Reading 
&nbsp;DATA FROM FILE AND CREATING RTP STREAM\n");&nbsp; &nbsp; &nbsp;while( 
((i=fread(buffer,1,160,infile))&gt;0) &amp;&amp; (runcond) )&nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_reset(&amp;rtp_r_packet);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; rohc_buf_reset(&amp;rohc_packet);&nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; m = 
rtp_session_create_packet_with_data(rtp_session,(char*)buffer,i,NULL);&nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ((rtp_header_t*) 
m-&gt;b_rptr)-&gt;seq_number = 156;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; ((rtp_header_t*) m-&gt;b_rptr)-&gt;timestamp = time(0);&nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; printf("SIZE OF A
 CTUAL RTP : &nbsp;&lt; %d &gt; , RTP &nbsp;HEADER LENGTH : &lt; %d &gt; , RTP 
PAYLOAD LENGTH : &lt; %d &gt; \n", 
&nbsp;msgdsize(m),rtpheader_size(m),rtppayload_size(m));

&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; rtp_r_packet.len = 5 * 
4 + 8 + 12 + rtppayload_size(m);&nbsp; &nbsp; &nbsp; &nbsp; // &nbsp; &nbsp; 
&nbsp;rtp_r_packet.len = 5 * 4 + 8 + 12 ;
&nbsp; &nbsp; &nbsp; &nbsp; /* IPv4 header */&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_byte_at(rtp_r_packet, 0) = 4 &lt;&lt; 4; /* IP version 4 */&nbsp; 
&nbsp; &nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 0) |= 5; /* IHL: minimal 
IPv4 header length (in 32-bit words) */&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_byte_at(rtp_r_packet, 1) = 0; /* TOS */&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_byte_at(rtp_r_packet, 2) = (rtp_r_packet.len &gt;&gt; 8) &amp; 0xff; 
/* Total Length */&nbsp; &nbsp; &nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 3) 
= rtp_r_packet.len &amp; 0xff;&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_byte_at(rtp_r_packet, 4) = 0; /* IP-ID */&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_byte_at(rtp_r_packet, 5) = 0;&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_byte_at(rtp_r_packet, 6) = 0; /* Fragment Offset and IP flags */&nbsp; 
&nbsp; &nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 7) = 0;&nbsp; &nbsp; &nbsp; 
&nbsp; rohc_buf_byte_at(rtp_r_packet, 8) = 1; /* TTL */&nbsp; &nbsp; &nbsp; 
&nbsp; rohc_buf_byte_at(rtp_r_pack
 et, 9) = 17; /* Protocol: UDP */&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_byte_at(rtp_r_packet, 10) = 0xa9; /* fake Checksum */&nbsp; &nbsp; 
&nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 11) = 0xa0;&nbsp; &nbsp; &nbsp; 
&nbsp; rohc_buf_byte_at(rtp_r_packet, 12) = 0x01; /* Source address */&nbsp; 
&nbsp; &nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 13) = 0x02;&nbsp; &nbsp; 
&nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 14) = 0x03;&nbsp; &nbsp; &nbsp; 
&nbsp; rohc_buf_byte_at(rtp_r_packet, 15) = 0x04;&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_byte_at(rtp_r_packet, 16) = 0x05; /* Destination address */&nbsp; 
&nbsp; &nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 17) = 0x06;&nbsp; &nbsp; 
&nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 18) = 0x07;&nbsp; &nbsp; &nbsp; 
&nbsp; rohc_buf_byte_at(rtp_r_packet, 19) = 0x08;
&nbsp; &nbsp; &nbsp; &nbsp; /* UDP header */&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_byte_at(rtp_r_packet, 20) = 0x42; /* source port */&nbsp; &nbsp; 
&nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 21) = 0x42;&nbsp; &nbsp; &nbsp; 
&nbsp; rohc_buf_byte_at(rtp_r_packet, 22) = 0x27; /* destination port = 10042 
*/&nbsp; &nbsp; &nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 23) = 0x3a;&nbsp; 
&nbsp; &nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 24) = 0x00; /* UDP length 
*/&nbsp; &nbsp; &nbsp; &nbsp; //rohc_buf_byte_at(rtp_r_packet, 25) = 8 + 
12;&nbsp; &nbsp; &nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 25) = 8 + 12 + 
rtppayload_size(m);&nbsp; &nbsp; &nbsp; &nbsp; rohc_buf_byte_at(rtp_r_packet, 
26) = 0x00; /* UDP checksum = 0 */&nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_byte_at(rtp_r_packet, 27) = 0x00;
&nbsp; &nbsp; &nbsp; &nbsp; /* RTP header */
// &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_append(&amp;rtp_r_packet, (uint8_t *)m-&gt;b_rptr , 
rtpheader_size(m));// &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
rohc_buf_append(&amp;rtp_r_packet, (uint8_t *)m-&gt;b_cont-&gt;b_rptr , 
rtppayload_size(m));

&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
memcpy(rohc_buf_data_at(rtp_r_packet, 28), (uint8_t 
*)m-&gt;b_rptr,rtpheader_size(m));
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; /* copy the payload 
just after the IP/UDP/RTP headers */
&nbsp; &nbsp; &nbsp; &nbsp; memcpy(rohc_buf_data_at(rtp_r_packet, 40), (uint8_t 
*)m-&gt;b_cont-&gt;b_rptr,rtppayload_size(m));
&nbsp; &nbsp; &nbsp; &nbsp; printf(" RTP detection Check uncompress \n");
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
if(!rohc_comp_set_rtp_detection_cb(compressor, rtp_detect, NULL))&nbsp; &nbsp; 
&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
printf("failed to set RTP detection callback\n");&nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; return 1;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; printf("IP/UDP/RTP PACKET SIZE BEFORE 
COMPRESSION : HEADER : &lt; %d &gt; , PAYLOAD : &lt; %d &gt; , TOTAL PACKET 
SIZE : &lt; %d &gt;\n" ,28 + rtpheader_size(m),rtppayload_size(m),28 + 
rtpheader_size(m) + rtppayload_size(m));&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; /*compress the packet */&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; rohc_status = rohc_compress4(compressor,rtp_r_packet, 
&amp;rohc_packet);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
if(rohc_status != ROHC_STATUS_OK)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; {&nbsp; &nbsp; 
 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; printf("compression of fake RTP 
packet failed: %s (%d)\n",rohc_strerror(rohc_status), rohc_status);&nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
rohc_comp_free(compressor);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; fclose(infile);&nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
rtp_session_destroy(rtp_session);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ortp_exit();&nbsp; &nbsp; &nbsp; 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return 1;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
&nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; /*Print the 
size of compressed one */
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
memset(buffer,0,sizeof(buffer));&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; 
&nbsp; &nbsp; fclose(infile);&nbsp; &nbsp; &nbsp; &nbsp; 
rtp_session_destroy(rtp_session);&nbsp; &nbsp; &nbsp; &nbsp; ortp_exit();// 
&nbsp; &nbsp; &nbsp;ortp_global_stats_display();

&nbsp; &nbsp; &nbsp; &nbsp; /* Free compressor */&nbsp; &nbsp; &nbsp; &nbsp; 
if(compressor){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
rohc_comp_free(compressor);&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; 
&nbsp; return 0;}
Regards,V Ravi Kumar

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[Rohc] IP/UDP/RTP header compression issue.

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