在使用flash cs/builder开发rtmp视频应用时，我们时常会在nc.connect的时候再传递一个对象作为连接信息发送给服务端。用于验证，确认连接用户，获取用户信息等等操作。
当我们使用ffmpeg来开发android,ios,pc版的rtmp应用时,已经为我们提供了非常方便的传参来实现。
先来看源代码：定位到libavformat/rtmpproto.c文件

static int rtmp_write_amf_data(URLContext *s, char *param, uint8_t **p)
{
    char *field, *value;
    char type;

    /* The type must be B for Boolean, N for number, S for string, O for
     * object, or Z for null. For Booleans the data must be either 0 or 1 for
     * FALSE or TRUE, respectively. Likewise for Objects the data must be
     * 0 or 1 to end or begin an object, respectively. Data items in subobjects
     * may be named, by prefixing the type with 'N' and specifying the name
     * before the value (ie. NB:myFlag:1). This option may be used multiple times
     * to construct arbitrary AMF sequences. */
    if (param[0] && param[1] == ':') {
        type = param[0];
        value = param + 2;
    } else if (param[0] == 'N' && param[1] && param[2] == ':') {
        type = param[1];
        field = param + 3;
        value = strchr(field, ':');
        if (!value)
            goto fail;
        *value = '';
        value++;

        ff_amf_write_field_name(p, field);
    } else {
        goto fail;
    }

    switch (type) {
    case 'B':
        ff_amf_write_bool(p, value[0] != '0');
        break;
    case 'S':
        ff_amf_write_string(p, value);
        break;
    case 'N':
        ff_amf_write_number(p, strtod(value, NULL));
        break;
    case 'Z':
        ff_amf_write_null(p);
        break;
    case 'O':
        if (value[0] != '0')
            ff_amf_write_object_start(p);
        else
            ff_amf_write_object_end(p);
        break;
    default:
        goto fail;
        break;
    }

    return 0;

fail:
    av_log(s, AV_LOG_ERROR, "Invalid AMF parameter: %sn", param);
    return AVERROR(EINVAL);
}

可以看出，支持基本的String，Boolean，Number，Null，Object
好,我们先用flash创建包含一段信息的连接

 var myObj = new Object();
 myObj.myId = 21;
 myObj.myName = 'ALiang';
 myObj.isVIP = true;

 nc.connect(StringUtil.trim(uriInput.text),myObj);

抓包看

在ffmpeg中,按规则,书写为:

"O:1 NN:myId:22 NS:myName:YHLiang NB:isVIIP:0 O:0"

抓包结果

碉堡了:D