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
23       received interleaved RTP data. This function gets  called  for  each  $
24       block  and  therefore  contains  exactly  one upper-layer protocol unit
25       (e.g.  one RTP packet). Curl writes the interleaved header as  well  as
26       the included data for each call. The first byte is always an ASCII dol‐
27       lar sign. The dollar sign is followed by a one byte channel  identifier
28       and  then  a  2  byte integer length in network byte order. See RFC2326
29       Section 10.12 for more information on how RTP interleaving behaves.  If
30       unset or set 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
37       CURL_RTSPREQ_RECEIVE to service RTP data when no requests are  desired.
38       If the application makes a request, (e.g.  CURL_RTSPREQ_PAUSE) then the
39       response handler will process any pending RTP data before  marking  the
40       request as 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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