[FFmpeg-trac] #3127(undetermined:new): Video stream publishing via RTMPT

[FFmpeg]

#3127: Video stream publishing via RTMPT
-------------------------------------+-------------------------------------
             Reporter:  goodvinj     |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  important    |                Component:
              Version:  git-master   |  undetermined
             Keywords:               |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
-------------------------------------+-------------------------------------

Comment (by goodvinj):

 I've found the reason of hangs in "avio_open":

 "rtmp_http_open" tries to read server reply with unique id and calls
 "ffurl_read".

 It expects that "ffurl_read" returns AVERROR_EOF on completion, but
 "ffurl_read" returns 0.

 It's because "ffurl_read" calls "retry_transfer_wrapper" which calls
 "http_read" (as transfer_func).
 "http_read" returns AVERROR_EOF, but there is the code:
 {{{
         } else if (ret < 1)
             return (ret < 0 && ret != AVERROR_EOF) ? ret : len;
 }}}
 so "retry_transfer_wrapper" returns len==0 instead of AVERROR_EOF, and
 "ffurl_read" returns 0.

 Then "rtmp_http_open" calls "ffurl_read" and so on.

 I'd fixed this by the following code in "rtmp_http_open":
 {{{
     for (;;) {
         ret = ffurl_read(rt->stream, rt->client_id + off,
 sizeof(rt->client_id) - off);
         if (ret == 0 || ret == AVERROR_EOF)
             break;
         if (ret < 0)
             goto fail;
         off += ret;
         if (off == sizeof(rt->client_id)) {
             ret = AVERROR(EIO);
             goto fail;
         }
     }
 }}}

 Next issue occurs in "rtmp_handshake" (it hangs too).
 On handshake "rtmp_http_read" is called, "rtmp_http_read" calls
 "ffurl_read" and expects AVERROR_EOF on completion. But "ffurl_read"
 returns 0 again, so we get an infinite loop there.
 I'd changed "rtmp_http_read":
 {{{
     do {
         ret = ffurl_read(rt->stream, buf + off, size);
         if (ret < 0 && ret != AVERROR_EOF)
             return ret;

         if (ret == 0 || ret == AVERROR_EOF) {
             if (rt->finishing) {
 }}}

 ----

 After these changes I'd reverted all my changes and changed only these
 lines in "retry_transfer_wrapper":
 {{{
         } else if (ret < 1)
             return (ret < 0 && ret != AVERROR_EOF) ? ret : len;
 }}}
 to
 {{{
         } else if (ret < 1)
             return (ret < 0) ? ret : len;
 }}}

 Now FFMPEG sends video over RTMPT (without librtmp support).

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/3127#comment:3>
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