分享一段H264视频和AAC音频的RTP封包代码

1. H264视频的RTP封包

static int h264_parse(Track *tr, uint8_t *data, size_t len)
{
h264_priv *priv = tr->private_data;
//    double nal_time; // see page 9 and 7.4.1.2
size_t nalsize = 0, index = 0;
uint8_t *p, *q;
if (priv->is_avc) {
while (1) {
unsigned int i;
if(index >= len) break;
//get the nal size
nalsize = 0;
for(i = 0; i < priv->nal_length_size; i++)
nalsize = (nalsize << 8) | data[index++];
if(nalsize <= 1 || nalsize > len) {
if(nalsize == 1) {
index++;
continue;
} else {
fnc_log(FNC_LOG_VERBOSE, "[h264] AVC: nal size %d", nalsize);
break;
}
}
if (DEFAULT_MTU >= nalsize) {
mparser_buffer_write(tr,
tr->properties.pts,
tr->properties.dts,
tr->properties.frame_duration,
1,
data + index, nalsize);
fnc_log(FNC_LOG_VERBOSE, "[h264] single NAL");
} else {
// single NAL, to be fragmented, FU-A;
frag_fu_a(data + index, nalsize, DEFAULT_MTU, tr);
}
index += nalsize;
}
} else {
//seek to the first startcode
for (p = data; p<data + len - 3; p++) {
if (p[0] == 0 && p[1] == 0 && p[2] == 1) {
break;
}
}
if (p >= data + len) return ERR_PARSE;
while (1) {
//seek to the next startcode [0 0 1]
for (q = p; q<data+len-3;q++) {
if (q[0] == 0 && q[1] == 0 && q[2] == 1) {
break;
}
}
if (q >= data + len) break;
if (DEFAULT_MTU >= q - p) {
fnc_log(FNC_LOG_VERBOSE, "[h264] Sending NAL %d",p[0]&0x1f);
mparser_buffer_write(tr,
tr->properties.pts,
tr->properties.dts,
tr->properties.frame_duration,
1,
p, q - p);
fnc_log(FNC_LOG_VERBOSE, "[h264] single NAL");
} else {
//FU-A
fnc_log(FNC_LOG_VERBOSE, "[h264] frags");
frag_fu_a(p, q - p, DEFAULT_MTU, tr);
}
p = q;
}
// last NAL
fnc_log(FNC_LOG_VERBOSE, "[h264] last NAL %d",p[0]&0x1f);
if (DEFAULT_MTU >= len - (p - data)) {
fnc_log(FNC_LOG_VERBOSE, "[h264] no frags");
mparser_buffer_write(tr,
tr->properties.pts,
tr->properties.dts,
tr->properties.frame_duration,
1,
p, len - (p - data));
} else {
//FU-A
fnc_log(FNC_LOG_VERBOSE, "[h264] frags");
frag_fu_a(p, len - (p - data), DEFAULT_MTU, tr);
}
}
fnc_log(FNC_LOG_VERBOSE, "[h264] Frame completed");
return ERR_NOERROR;
}

 

2. AAC的RTP封包

static int aac_parse(Track *tr, uint8_t *data, size_t len)
{
//XXX handle the last packet on EOF
int off = 0;
uint32_t payload = DEFAULT_MTU - AU_HEADER_SIZE;
uint8_t *packet = g_malloc0(DEFAULT_MTU);
if(!packet) return ERR_ALLOC;
// trim away extradata
//    data += AAC_EXTRA;
//    len -= AAC_EXTRA;
packet[0] = 0x00;
packet[1] = 0x10;
packet[2] = (len & 0x1fe0) >> 5;
packet[3] = (len & 0x1f) << 3;
if (len > payload) {
while (len > payload) {
memcpy(packet + AU_HEADER_SIZE, data + off, payload);
mparser_buffer_write(tr,
tr->properties.pts,
tr->properties.dts,
tr->properties.frame_duration,
0,
packet, DEFAULT_MTU);
len -= payload;
off += payload;
}
}
memcpy(packet + AU_HEADER_SIZE, data + off, len);
mparser_buffer_write(tr,
tr->properties.pts,
tr->properties.dts,
tr->properties.frame_duration,
1,
packet, len + AU_HEADER_SIZE);
g_free(packet);
return ERR_NOERROR;
}

 

上面的变量 AU_HEADER_SIZE=4

 

/* au header

      +---------------------------------------+

      |     AU-size                           |

      +---------------------------------------+

      |     AU-Index / AU-Index-delta         |

      +---------------------------------------+

      |     CTS-flag                          |

      +---------------------------------------+

      |     CTS-delta                         |

      +---------------------------------------+

      |     DTS-flag                          |

      +---------------------------------------+

      |     DTS-delta                         |

      +---------------------------------------+

      |     RAP-flag                          |

      +---------------------------------------+

      |     Stream-state                      |

      +---------------------------------------+

*/