分享一段H264视频和AAC音频的RTP封包代码

转自http://blog.csdn.net/moruite/archive/2010/12/28/6102758.aspx

 

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                      |

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

*/