[FFmpeg-trac] #7810(undetermined:new): ffmpeg will automatically pause (Konx KW01 gen2)

[FFmpeg]

#7810: ffmpeg will automatically pause (Konx KW01 gen2)
-------------------------------------+-------------------------------------
             Reporter:  branqueira   |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:
             Keywords:  rtsp         |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------

Comment (by branqueira):

 I found the cause of the problem, the answer is in the log file
 "trace3.log"

 We want to use tcp instead of udp and ffmpeg responds : "Nonmatching
 transport in server reply".

 This means that the server wants to use udp while the client
 (rtsp_transport tcp) only uses tcp.


 {{{
         /* Fail if the server responded with another lower transport mode
          * than what we requested. */
         if (reply->transports[0].lower_transport != lower_transport) {
             av_log(s, AV_LOG_ERROR, "Nonmatching transport in server
 reply\n");
             err = AVERROR_INVALIDDATA;
             goto fail;
         }
 }}}


 The ffmpeg client sends this SETUP request:

 {{{

 SETUP rtsp://5.51.X.Y:554/onvif1/track1 RTSP/1.0

 Transport: RTP/AVP/TCP;unicast;interleaved=0-1
 CSeq: 4
 User-Agent: Lavf58.26.101
 }}}

 The client requests to use tcp (RTP / AVP / TCP)

 The server responds with:


 {{{
 Transport:
 RTP/AVP;unicast;destination=82.255.9.82;source=192.168.1.100;interleaved=0-1
 }}}



 note the server didn't add TCP (RTP/AVP)

 if we read the specification https://www.ietf.org/rfc/rfc2326.txt page 58,
 we see that the default transport protocol is UDP when nothing is
 specified.

 this value is retrieved in the "rtsp_parse_transport" method


 {{{
 if (!av_strcasecmp (transport_protocol, "rtp")) {
             get_word_sep(profile, sizeof(profile), "/;,", &p);
                         printf("********** profile : %s\n", profile);
             lower_transport[0] = '\0';
             /* rtp/avp/<protocol> */
             if (*p == '/') {
                                 printf("********** protocol");
                 get_word_sep(lower_transport, sizeof(lower_transport),
                              ";,", &p);
             }
             th->transport = RTSP_TRANSPORT_RTP;
 }}}


 we try to recover the transport protocol but since * p is not equal to "/"
 the value of lower_transport is empty.

 then we define the value of the protocol but since lower_transport is
 empty:


 {{{
 if (!av_strcasecmp(lower_transport, "TCP"))
                th->lower_transport = RTSP_LOWER_TRANSPORT_TCP;
            else
                th->lower_transport = RTSP_LOWER_TRANSPORT_UDP;
 }}}

 UDP is chosen


 By doing a hack to test my reasoning by modifying the code slightly:


 {{{
    if (!av_strcasecmp(lower_transport, "TCP"))
                th->lower_transport = RTSP_LOWER_TRANSPORT_TCP;
            else
                th->lower_transport = RTSP_LOWER_TRANSPORT_TCP; //beurg
 dirty hack, it's just for test

 }}}


 Now it's work



 In conclusion, ffmpeg respects the specification, it is not the case of my
 camera :(

--
Ticket URL: <https://trac.ffmpeg.org/ticket/7810#comment:6>
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