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RTP 发送 和接收 h265
2022-07-29 03:22:00 【qianbo_insist】
h265 发送RTP
首先RTP头部不变，其次，h265 头部为三字节,假定最大传输单元MTU为1400字节，并且包含头部12字节
/*F type layerId TID SE futype */
void send_rtp_h265(uint8_t *buf, int len, int last_packet_of_frame, uint32_t ts)
{
//RTPMuxContext *rtp_ctx = ctx->priv_data;
int rtp_payload_size = 1400 - 12;
int nal_type = (buf[0] >> 1) & 0x3F;
/* send it as one single NAL unit? */
if (len <= 1400) //小于对定的最大值时，直接发送（最大值一般小于mtu）
{
/* use the original NAL unit buffer and transmit it as RTP payload */
//rtp_send_data(buf, len, 0, ts);
}
else //大于最大值时进行fu分组发送
{
/* create the HEVC payload header and transmit the buffer as fragmentation units (FU) 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |F| Type | LayerId | TID | +-------------+-----------------+ F = 0 Type = 49 (fragmentation unit (FU)) LayerId = 0 TID = 1 */
buf[0] = 49 << 1;
buf[1] = 1;
//此处为paylaodhdr,规范赋值应该是替换hevc数据nal 的payloadhdr的type
//rtp_ctx->buf[0] = (buf[0] &0x81) | (49<<1);
//rtp_ctx->buf[1] = buf[1]
/* create the FU header 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |S|E| FuType | +---------------+ S = variable E = variable FuType = NAL unit type */
buf[2] = nal_type;
/* set the S bit: mark as start fragment */
buf[2] |= 1 << 7;
/* pass the original NAL header */
//此处要注意，当是分组的第一报数据时，应该覆盖掉前两个字节的数据，h264要覆盖前一个字节的数据，即是第一包要去除hevc帧数据的paylaodhdr
buf += 2;
len -= 2;
while (len > rtp_payload_size)
{
/* complete and send current RTP packet */
memcpy(&buf[12], buf, rtp_payload_size);
//rtp_send_data(buf, max_payload_size, 0,ts);
buf += rtp_payload_size;
len -= rtp_payload_size;
/* reset the S bit */
buf[2] &= ~(1 << 7);
}
/* set the E bit: mark as last fragment */
buf[2] |= 1 << 6;
/* complete and send last RTP packet */
memcpy(&buf[12], buf, len);
//rtp_send_data(buf, len + 2, last_packet_of_frame,ts);
}
}
下面看ffmpeg 如何封包
static void nal_send(AVFormatContext *s1, const uint8_t *buf, int size, int last)
{
RTPMuxContext *s = s1->priv_data;
enum AVCodecID codec = s1->streams[0]->codecpar->codec_id;
av_log(s1, AV_LOG_DEBUG, "Sending NAL %x of len %d M=%d\n", buf[0] & 0x1F, size, last);
if (size <= s->max_payload_size) {
//max_payload_size一般<= 1500
int buffered_size = s->buf_ptr - s->buf;
int header_size;
int skip_aggregate = 0;
if (codec == AV_CODEC_ID_H264) {
header_size = 1;
skip_aggregate = s->flags & FF_RTP_FLAG_H264_MODE0;
} else {
//h265 头两个字节，第二个字节是0x01;第一个字节表示NAL Type，具体哪些类型可以参考Hevc.h
header_size = 2;
}
// Flush buffered NAL units if the current unit doesn't fit
if (buffered_size + 2 + size > s->max_payload_size) {
flush_buffered(s1, 0);
buffered_size = 0;
}
// If we aren't using mode 0, and the NAL unit fits including the
// framing (2 bytes length, plus 1/2 bytes for the STAP-A/AP marker),
// write the unit to the buffer as a STAP-A/AP packet, otherwise flush
// and send as single NAL.
if (buffered_size + 2 + header_size + size <= s->max_payload_size &&
!skip_aggregate) {
if (buffered_size == 0) {
//发送第一个数据包
if (codec == AV_CODEC_ID_H264) {
*s->buf_ptr++ = 24;
} else {
*s->buf_ptr++ = 48 << 1; //hevc head flag Header 为96 后面一般会跟VPS,PPS,SPS等信息，这些包字节少，可以放在一起一次发送VPS,PPS,SSP之间插入两个字节表示各类型包长度。
*s->buf_ptr++ = 1;
}
}
AV_WB16(s->buf_ptr, size);
s->buf_ptr += 2; //数据包长度（两个字节表示）
memcpy(s->buf_ptr, buf, size);
s->buf_ptr += size;
s->buffered_nals++;
} else {
flush_buffered(s1, 0);
ff_rtp_send_data(s1, buf, size, last);
}
} else {
int flag_byte, header_size;
flush_buffered(s1, 0);
if (codec == AV_CODEC_ID_H264 && (s->flags & FF_RTP_FLAG_H264_MODE0)) {
av_log(s1, AV_LOG_ERROR,
"NAL size %d > %d, try -slice-max-size %d\n", size,
s->max_payload_size, s->max_payload_size);
return;
}
av_log(s1, AV_LOG_DEBUG, "NAL size %d > %d\n", size, s->max_payload_size);
if (codec == AV_CODEC_ID_H264) {
//视频类型为H264
uint8_t type = buf[0] & 0x1F;
uint8_t nri = buf[0] & 0x60;
s->buf[0] = 28; /* FU Indicator; Type = 28 ---> FU-A */
s->buf[0] |= nri;
s->buf[1] = type;
s->buf[1] |= 1 << 7;
buf += 1;
size -= 1;
flag_byte = 1;
header_size = 2;
} else {
uint8_t nal_type = (buf[0] >> 1) & 0x3F; // For hevc
/* * create the HEVC payload header and transmit the buffer as fragmentation units (FU) * * 0 1 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * |F| Type | LayerId | TID | * +-------------+-----------------+ * * F = 0 * Type = 49 (fragmentation unit (FU)) * LayerId = 0 * TID = 1 */
s->buf[0] = 49 << 1; //98只是Header，并不是真正意义上视频包类型。
s->buf[1] = 1; //固定不变
/* * create the FU header * * 0 1 2 3 4 5 6 7 * +-+-+-+-+-+-+-+-+ * |S|E| FuType | * +---------------+ * * S = variable * E = variable * FuType = NAL unit type */
s->buf[2] = nal_type; //该字节才表示真正意义上的数据类型
/* set the S bit: mark as start fragment */
s->buf[2] |= 1 << 7; //第一个数据包分片
/* pass the original NAL header */
buf += 2; //去掉两个字节的头
size -= 2;
flag_byte = 2;
header_size = 3;
}
while (size + header_size > s->max_payload_size) {
//中间数据包分片
memcpy(&s->buf[header_size], buf, s->max_payload_size - header_size);
ff_rtp_send_data(s1, s->buf, s->max_payload_size, 0);
buf += s->max_payload_size - header_size;
size -= s->max_payload_size - header_size;
s->buf[flag_byte] &= ~(1 << 7);
}
s->buf[flag_byte] |= 1 << 6;//最后一个数据包分片
memcpy(&s->buf[header_size], buf, size);
ff_rtp_send_data(s1, s->buf, size + header_size, last);
}
}
ffmpeg 把h264 和 h265 放在了一起，可以作为参考，ff_rtp_send_data 读者可以自己写出来，就是rtp 发送，udp 和 TCP 自行选择
解RTP包h265
#include <stdint.h>
#include <iostream>
#define AV_RB16(x) ((((const uint8_t*)(x))[0] << 8)|((const uint8_t*)(x))[1])
class H265Frame
{
public:
unsigned char m_firstfrag;
unsigned char m_lastfrag;
unsigned int m_buflen;
unsigned char *m_buf;
public:
H265Frame();
~H265Frame();
int handleHevcFrame(uint16_t seq,uint32_t timestamp,const uint8_t *buf, int len);
private:
int handleHevcRtpPackage(uint16_t seq,uint32_t timestamp,const uint8_t *buf, int len,uint8_t *outbuf,int *outlen);
void handleFragPackage(const uint8_t *buf, int len,int start_bit,const uint8_t *nal_header,int nal_header_len,uint8_t *outbuf,int *outlen);
int handleAggregatedPacket(const uint8_t *buf, int len,uint8_t *outbuf, int *outlen);
};
实现：
using namespace std;
static const uint8_t start_sequence[] = {
0x00, 0x00, 0x00, 0x01 };
H265Frame::H265Frame ()
{
m_firstfrag = 0;
m_lastfrag = 0;
m_buflen = 0;
m_buf = new unsigned char [1*1024*1024];
}
H265Frame::~H265Frame ()
{
delete [] m_buf;
}
int H265Frame::handleHevcFrame(uint16_t seq,uint32_t timestamp,const uint8_t *buf, int len){
int nal_type = 0;
unsigned char outbuf[2048]={
0};
int outlen=0;
nal_type = handleHevcRtpPackage(seq,timestamp,buf,len,outbuf,&outlen);
if(nal_type < 0){
return -1;
}
if(nal_type == 49){
//first
if(m_firstfrag){
memcpy(m_buf,outbuf,outlen);
m_buflen = outlen;
return 0;
}
//end
else if(m_lastfrag){
memcpy(m_buf+m_buflen,outbuf,outlen);
m_buflen += outlen;
return 1;
}
//mid
else{
memcpy(m_buf+m_buflen,outbuf,outlen);
m_buflen += outlen;
return 0;
}
}
memcpy(m_buf,outbuf,outlen);
m_buflen = outlen;
return 1;
}
/* handle one hevc rtp package */
int H265Frame::handleHevcRtpPackage(uint16_t seq,uint32_t timestamp,const uint8_t *buf, int len,uint8_t *outbuf,int *outlen){
int ret = -1;
int tid, lid, nal_type;
int first_fragment, last_fragment, fu_type;
uint8_t new_nal_header[2];
//ori
const uint8_t *rtp_pl = buf;
/* * decode the HEVC payload header according to section 4 of draft version 6: * * 0 1 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * |F| Type | LayerId | TID | * +-------------+-----------------+ * * Forbidden zero (F): 1 bit * NAL unit type (Type): 6 bits * NUH layer ID (LayerId): 6 bits * NUH temporal ID plus 1 (TID): 3 bits */
nal_type = (buf[0] >> 1) & 0x3f;
lid = ((buf[0] << 5) & 0x20) | ((buf[1] >> 3) & 0x1f);
tid = buf[1] & 0x07;
/* sanity check for correct layer ID */
if (lid) {
/* future scalable or 3D video coding extensions */
cout << "Multi-layer HEVC coding\n";
return ret;
}
/* sanity check for correct temporal ID */
if (!tid) {
cout << "Illegal temporal ID in RTP/HEVC packet\n";
return ret;
}
/* sanity check for correct NAL unit type */
if (nal_type > 50) {
cout << "Unsupported (HEVC) NAL type (" << nal_type << ")\n";
return ret;
}
//process
switch (nal_type) {
/* video parameter set (VPS) */
case 32:
/* sequence parameter set (SPS) */
case 33:
/* picture parameter set (PPS) */
case 34:
/* supplemental enhancement information (SEI) */
case 39:
/* single NAL unit packet */
default:
//cout << "nal_type:" << nal_type << "\n";
ret = nal_type;
/* the outlen */
*outlen = sizeof(start_sequence) + len;
/* A/V packet: copy start sequence */
memcpy(outbuf, start_sequence, sizeof(start_sequence));
/* A/V packet: copy NAL unit data */
memcpy(outbuf+ sizeof(start_sequence), buf, len);
break;
/* aggregated packet (AP) - with two or more NAL units */
case 48:
//cout << "nal_type:" << nal_type << "\n";
buf += 2;
len -= 2;
//handl aggregated p
if(handleAggregatedPacket(buf, len,outbuf,outlen) == 0){
ret = nal_type;
}
break;
/* fragmentation unit (FU) */
case 49:
/* pass the HEVC payload header (two bytes) */
buf += 2;
len -= 2;
/* * decode the FU header * * 0 1 2 3 4 5 6 7 * +-+-+-+-+-+-+-+-+ * |S|E| FuType | * +---------------+ * * Start fragment (S): 1 bit * End fragment (E): 1 bit * FuType: 6 bits */
first_fragment = buf[0] & 0x80;
last_fragment = buf[0] & 0x40;
fu_type = buf[0] & 0x3f;
m_firstfrag = first_fragment;
m_lastfrag = last_fragment;
/* pass the HEVC FU header (one byte) */
buf += 1;
len -= 1;
//cout << "nal_type:" << nal_type << " FU type:" << fu_type << " first_frag:" << first_fragment << " last_frag:" << last_fragment << " with " << len <<" bytes\n";
/* sanity check for size of input packet: 1 byte payload at least */
if (len <= 0) {
return -1;
}
if (first_fragment && last_fragment) {
return -1;
}
ret = nal_type;
/*modify nal header*/
new_nal_header[0] = (rtp_pl[0] & 0x81) | (fu_type << 1);
new_nal_header[1] = rtp_pl[1];
handleFragPackage(buf, len, first_fragment,new_nal_header, sizeof(new_nal_header), outbuf,outlen);
break;
/* PACI packet */
case 50:
/* Temporal scalability control information (TSCI) */
cout << "****[hevc] unhandled hevc package : " << nal_type << "\n";
cout << "PACI packets for RTP/HEVC\n";
break;
}
return ret;
}
/* * process one hevc frag package,add the startcode and nal header only when the package set start_bit */
void H265Frame::handleFragPackage(const uint8_t *buf, int len,int start_bit,const uint8_t *nal_header,int nal_header_len,uint8_t *outbuf,int *outlen){
int tot_len = len;
int pos = 0;
if (start_bit)
tot_len += sizeof(start_sequence) + nal_header_len;
if (start_bit) {
memcpy(outbuf + pos, start_sequence, sizeof(start_sequence));
pos += sizeof(start_sequence);
memcpy(outbuf + pos, nal_header, nal_header_len);
pos += nal_header_len;
}
memcpy(outbuf + pos, buf, len);
*outlen = tot_len;
}
/* aggregated packet (AP) - with two or more NAL units * we add start_sequence_code_header for every NAL unit */
int H265Frame::handleAggregatedPacket(const uint8_t *buf, int len,uint8_t *outbuf, int *outlen)
{
int pass = 0;
int total_length = 0;
uint8_t *dst = NULL;
// first we are going to figure out the total size
for (pass = 0; pass < 2; pass++) {
const uint8_t *src = buf;
int src_len = len;
while (src_len > 2) {
uint16_t nal_size = AV_RB16(src);
// consume the length of the aggregate
src += 2;
src_len -= 2;
if (nal_size <= src_len) {
if (pass == 0) {
// counting
total_length += sizeof(start_sequence) + nal_size;
} else {
// copying
memcpy(dst, start_sequence, sizeof(start_sequence));
dst += sizeof(start_sequence);
memcpy(dst, src, nal_size);
dst += nal_size;
}
} else {
cout << "[HEVC] Aggregated error,nal size exceeds length: " << nal_size << " " << src_len << "\n";
return -1;
}
// eat what we handled
src += nal_size;
src_len -= nal_size;
}
if (pass == 0) {
dst = outbuf;
*outlen = total_length;
}
}
return 0;
}
以上代码可以作为参考
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