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RTC: Fast parse ssrc and find the publisher

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This commit is contained in:
winlin 2021-02-05 14:13:48 +08:00
parent cd06f2da0c
commit 80985c7307
3 changed files with 39 additions and 10 deletions
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31
trunk/src/kernel/srs_kernel_rtc_rtp.cpp
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@ -33,6 +33,37 @@ using namespace std;
#include <srs_kernel_utility.hpp>
#include <srs_kernel_flv.hpp>
uint32_t srs_rtp_fast_parse_ssrc(char* buf, int size)
{
/* @see https://tools.ietf.org/html/rfc1889#section-5.1
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|V=2|P|X| CC |M| PT | sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| synchronization source (SSRC) identifier |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| contributing source (CSRC) identifiers |
| .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
if (size < 12) {
return 0;
}
uint32_t value = 0;
char* pp = (char*)&value;
char* p = buf + 8;
pp[3] = *p++;
pp[2] = *p++;
pp[1] = *p++;
pp[0] = *p++;
return value;
}
// If value is newer than pre_value，return true; otherwise false
bool srs_seq_is_newer(uint16_t value, uint16_t pre_value)
{

3
trunk/src/kernel/srs_kernel_rtc_rtp.hpp
View file

@ -58,6 +58,9 @@ class SrsRtpRawPayload;
class SrsRtpFUAPayload2;
class SrsSharedPtrMessage;
// Fast parse the SSRC from RTP packet. Return 0 if invalid.
uint32_t srs_rtp_fast_parse_ssrc(char* buf, int size);
// The "distance" between two uint16 number, for example:
// distance(prev_value=3, value=5) === (int16_t)(uint16_t)((uint16_t)3-(uint16_t)5) === -2
// distance(prev_value=3, value=65534) === (int16_t)(uint16_t)((uint16_t)3-(uint16_t)65534) === 5