CURLOPT_INTERLEAVEFUNCTION(3)

1CURLOPT_INTERLEAVEFUNCTION(3c)url_easy_setopt optionCsURLOPT_INTERLEAVEFUNCTION(3)
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NAME

6       CURLOPT_INTERLEAVEFUNCTION  -  callback  function  for RTSP interleaved
7       data
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SYNOPSIS

10       #include <curl/curl.h>
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12       size_t interleave_callback(void *ptr, size_t size, size_t nmemb,
13                                  void *userdata);
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15       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_INTERLEAVEFUNCTION,
16                                 interleave_callback);
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DESCRIPTION

19       Pass a pointer to your callback function, which should match the proto‐
20       type shown above.
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22       This  callback  function  gets  called by libcurl as soon as it has re‐
23       ceived interleaved RTP data. This function gets called for each $ block
24       and therefore contains exactly one upper-layer protocol unit (e.g.  one
25       RTP packet). Curl writes the interleaved header as well as the included
26       data  for each call. The first byte is always an ASCII dollar sign. The
27       dollar sign is followed by a one byte channel identifier and then  a  2
28       byte  integer  length  in network byte order. See RFC2326 Section 10.12
29       for more information on how RTP interleaving behaves. If unset  or  set
30       to NULL, curl will use the default write function.
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32       Interleaved RTP poses some challenges for the client application. Since
33       the stream data is sharing the RTSP control connection, it is  critical
34       to  service the RTP in a timely fashion. If the RTP data is not handled
35       quickly, subsequent response processing may become unreasonably delayed
36       and  the connection may close. The application may use CURL_RTSPREQ_RE‐
37       CEIVE to service RTP data when no requests are desired. If the applica‐
38       tion makes a request, (e.g.  CURL_RTSPREQ_PAUSE) then the response han‐
39       dler will process any pending RTP data before marking  the  request  as
40       finished.
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42       The CURLOPT_INTERLEAVEDATA(3) is passed in the userdata argument in the
43       callback.
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DEFAULT

46       NULL, the interleave data is then passed to the regular write function:
47       CURLOPT_WRITEFUNCTION(3).
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PROTOCOLS

50       RTSP
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EXAMPLE

53       static size_t rtp_write(void *ptr, size_t size, size_t nmemb, void *user)
54       {
55         struct local *l = (struct local *)user;
56         /* take care of the packet in 'ptr', then return... */
57         return size * nmemb;
58       }
59       {
60         struct local rtp_data;
61         curl_easy_setopt(curl, CURLOPT_INTERLEAVEFUNCTION, rtp_write);
62         curl_easy_setopt(curl, CURLOPT_INTERLEAVEDATA, &rtp_data);
63       }
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AVAILABILITY

66       Added in 7.20.0
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RETURN VALUE

69       Returns  CURLE_OK  if the option is supported, and CURLE_UNKNOWN_OPTION
70       if not.
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