librtmp使用扩展时间戳时服务器会将连接断开解释资料.docx

1、librtmp使用扩展时间戳时服务器会将连接断开解释资料rtmpdump的librtmp时间戳有问题，服务器会断开连接分类： ffmpeg c+ linux open-source 2013-10-28 21:49 700人阅读 评论(7) 收藏 举报# header0x44 0xff 0xff 0xff 0x00 0x01 0x19 0x08# extended timestamp0x7f 0xff 0xf8 0x00 # body 0xaf 0x01 0x01 0x400x22 0x80 0xa3 0x7f 0xf8 0x85 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x

2、2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d

3、0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d #header0xc4 # extended timestamp# error here#body0x2d 0x

4、2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d

5、0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d 0x2d对于0xC这种后续的chunk包的extended timestamp该不该发，rtmp协议中说是不发，但是FMLE是发的，推流超过4.5小时就需要用extended timestamp了。rtmpdump里面的librtmp，不会发这个包，（ffm

6、peg里面用-enable-librtmp就会使用这个rtmp的库），而且是在开始就会发这个包。6.1.3. Extended Timestampplain view plaincopyprint?1 This field is transmitted only when the normal time stamp in the 2 chunk message header is set to 0x00ffffff. If normal time stamp is 3 set to any value less than 0x00ffffff, this field MUST NOT be 4

7、 present. This field MUST NOT be present if the timestamp field is not 5 present. Type 3 chunks MUST NOT have this field. This field is transmitted only when the normal time stamp in thechunk message header is set to 0x00ffffff. If normal time stamp isset to any value less than 0x00ffffff, this fiel

8、d MUST NOT bepresent. This field MUST NOT be present if the timestamp field is notpresent. Type 3 chunks MUST NOT have this field.有可能是adobe变更了这个协议，也就是说，FMLE给FMS，FMS给flash-player，都是带这个时间戳的。收包时，服务器端则需要检测下，若接下来的4字节不是extended timestamp，那么就忽略就好了。发包时，只能采取配置，要么发，要么不发。默认发就好了。看nginx-rtmp代码：cpp view plaincopy

9、print?6 ngx_rtmp_recv(ngx_event_t *rev) 7 8 for( ; ) 9 /* parse headers */ 10 if (b-pos = b-start) 11 /* chunk basic header */ 12 fmt = (*p 6) & 0x03; 13 csid = *p+ & 0x3f; 14 if (fmt little-endian 4b */ 16 pp = (u_char*)timestamp; 17 ext = (timestamp = 0x00ffffff); 18 if (fmt little-endian 4b type*

10、/ 20 pp = (u_char*)&h-mlen; 21 h-type = *(uint8_t*)p+; 22 if (fmt = 0) 23 /* stream: little-endian 4b - little-endian 4b */ 24 pp = (u_char*)&h-msid; 25 26 27 28 /* extended header */ 29 if (ext) 30 pp = (u_char*)timestamp; 31 pp3 = *p+; 32 pp2 = *p+; 33 pp1 = *p+; 34 pp0 = *p+; 35 ngx_rtmp_recv(ngx

11、_event_t *rev) for( ; ) /* parse headers */ if (b-pos = b-start) /* chunk basic header */ fmt = (*p 6) & 0x03; csid = *p+ & 0x3f; if (fmt little-endian 4b */ pp = (u_char*)timestamp; ext = (timestamp = 0x00ffffff); if (fmt little-endian 4b type*/ pp = (u_char*)&h-mlen; h-type = *(uint8_t*)p+; if (fm

12、t = 0) /* stream: little-endian 4b - little-endian 4b */ pp = (u_char*)&h-msid; /* extended header */ if (ext) pp = (u_char*)timestamp; pp3 = *p+; pp2 = *p+; pp1 = *p+; pp0 = *p+; 可见，不管是什么chunk，只要有extended-timestamp，nginx-rtmp都会读这个。所以nginx-rtmp对接FMLE是没有问题的，对接librtmp有问题。更好的做法是判断下读出来的extended timestam

13、p是否是和之前的一样，如果不是一样说明没有发，就忽略。nginx-rtmp发包的逻辑：cpp view plaincopyprint?36 ngx_rtmp_prepare_message 37 38 /* create fmt3 header for successive fragments */ 39 thsize = p - out-buf-pos; 40 ngx_memcpy(th, out-buf-pos, thsize); 41 th0 |= 0xc0; 42 /* message header */ 43 if (fmt play_time_fix) 59 ngx_memcpy(

14、&ththsize, p - 4, 4); 60 thsize += 4; 61 62 ngx_rtmp_prepare_message /* create fmt3 header for successive fragments */ thsize = p - out-buf-pos; ngx_memcpy(th, out-buf-pos, thsize); th0 |= 0xc0; /* message header */ if (fmt play_time_fix) ngx_memcpy(&ththsize, p - 4, 4); thsize += 4; nginx-rtmp还特意说明

15、了flash客户端就是和rtmp规范不一样。out-buf-pos就是指向包的第一个chunk，若有extended-timestamp，那么肯定会在第一个包加上extended timestamp；后面还有个th和thsize，就是给后续的type=3的chunk包的，会加上这4字节的extended timestamp：cpp view plaincopyprint?63 /* This CONTRADICTS the standard 64 * but thats the way flash client 65 * wants data to be encoded; 66 * ffmpe

16、g complains */ 67 if (cscf-play_time_fix) 68 ngx_memcpy(&ththsize, p - 4, 4); 69 thsize += 4; 70 71 72 /* append headers to successive fragments */ 73 for(out = out-next; out; out = out-next) 74 out-buf-pos -= thsize; 75 ngx_memcpy(out-buf-pos, th, thsize); 76 /* This CONTRADICTS the standard * but

17、thats the way flash client * wants data to be encoded; * ffmpeg complains */ if (cscf-play_time_fix) ngx_memcpy(&ththsize, p - 4, 4); thsize += 4; /* append headers to successive fragments */ for(out = out-next; out; out = out-next) out-buf-pos -= thsize; ngx_memcpy(out-buf-pos, th, thsize); 所以nginx

18、-rtmp收发包都是需要这个extended-timestamp，对于chunk type为3的包。另外，把chunksize设置大一点，最大是65536，避免发type=3的chunk包，也是一个很好的方法。不过视频的I帧一般较大，超过64KB也有可能。The maximum chunk size can be 65536 bytes and minimum 128 bytes.按照这种规则，即type=3的chunk也发extended-timestamp，是没有问题：FMLE一直没有断开，客户端也没有断开。服务器端是srs(simple rtmp server)，也没有断开：时间已经超过了24位，使用extended-timestamp：plain view plaincopyprint?77 (gdb) p /x 21039918 78 $1 = 0x1410b2e (gdb) p /x 21039918$1 = 0x1410b2e而nginx呢，是采用第一个包发完全的extended-timestamp，但是后续都是发type=1的chunk，即时间戳差值。完毕。