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                     23: .TH CURLOPT_INTERLEAVEFUNCTION 3 "March 23, 2020" "libcurl 7.70.0" "curl_easy_setopt options"
                     24: 
                     25: .SH NAME
                     26: CURLOPT_INTERLEAVEFUNCTION \- callback function for RTSP interleaved data
                     27: .SH SYNOPSIS
                     28: .nf
                     29: #include <curl/curl.h>
                     30: 
                     31: size_t interleave_callback(void *ptr, size_t size, size_t nmemb,
                     32:                            void *userdata);
                     33: 
                     34: CURLcode curl_easy_setopt(CURL *handle, CURLOPT_INTERLEAVEFUNCTION,
                     35:                           interleave_callback);
                     36: .SH DESCRIPTION
                     37: Pass a pointer to your callback function, which should match the prototype
                     38: shown above.
                     39: 
                     40: This callback function gets called by libcurl as soon as it has received
                     41: interleaved RTP data. This function gets called for each $ block and therefore
                     42: contains exactly one upper-layer protocol unit (e.g.  one RTP packet). Curl
                     43: writes the interleaved header as well as the included data for each call. The
                     44: first byte is always an ASCII dollar sign. The dollar sign is followed by a
                     45: one byte channel identifier and then a 2 byte integer length in network byte
                     46: order. See \fIRFC2326 Section 10.12\fP for more information on how RTP
                     47: interleaving behaves. If unset or set to NULL, curl will use the default write
                     48: function.
                     49: 
                     50: Interleaved RTP poses some challenges for the client application. Since the
                     51: stream data is sharing the RTSP control connection, it is critical to service
                     52: the RTP in a timely fashion. If the RTP data is not handled quickly,
                     53: subsequent response processing may become unreasonably delayed and the
                     54: connection may close. The application may use \fICURL_RTSPREQ_RECEIVE\fP to
                     55: service RTP data when no requests are desired. If the application makes a
                     56: request, (e.g.  \fICURL_RTSPREQ_PAUSE\fP) then the response handler will
                     57: process any pending RTP data before marking the request as finished.
                     58: 
                     59: The \fICURLOPT_INTERLEAVEDATA(3)\fP is passed in the \fIuserdata\fP argument in
                     60: the callback.
                     61: .SH DEFAULT
                     62: NULL, the interleave data is then passed to the regular write function:
                     63: \fICURLOPT_WRITEFUNCTION(3)\fP.
                     64: .SH PROTOCOLS
                     65: RTSP
                     66: .SH EXAMPLE
                     67: .nf
                     68: static size_t rtp_write(void *ptr, size_t size, size_t nmemb, void *user)
                     69: {
                     70:   struct local *l = (struct local *)user;
                     71:   /* take care of the packet in 'ptr', then return... */
                     72:   return size * nmemb;
                     73: }
                     74: {
                     75:   struct local rtp_data;
                     76:   curl_easy_setopt(curl, CURLOPT_INTERLEAVEFUNCTION, rtp_write);
                     77:   curl_easy_setopt(curl, CURLOPT_INTERLEAVEDATA, &rtp_data);
                     78: }
                     79: .fi
                     80: .SH AVAILABILITY
                     81: Added in 7.20.0
                     82: .SH RETURN VALUE
                     83: Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
                     84: .SH "SEE ALSO"
                     85: .BR CURLOPT_INTERLEAVEDATA "(3), " CURLOPT_RTSP_REQUEST "(3), "