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CURLOPT_INTERLEAVEFUNCTION(3)       libcurl      CURLOPT_INTERLEAVEFUNCTION(3)


NAME

       CURLOPT_INTERLEAVEFUNCTION - callback for RTSP interleaved data


SYNOPSIS

       #include <curl/curl.h>

       size_t interleave_callback(void *ptr, size_t size, size_t nmemb,
                                  void *userdata);

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_INTERLEAVEFUNCTION,
                                 interleave_callback);


DESCRIPTION

       Pass a pointer to your callback function, which should match the
       prototype shown above.

       This callback function gets called by libcurl as soon as it has
       received interleaved RTP data. This function gets called for each $
       block and therefore contains exactly one upper-layer protocol unit
       (e.g.  one RTP packet). Curl writes the interleaved header as well as
       the included data for each call. The first byte is always an ASCII
       dollar sign. The dollar sign is followed by a one byte channel
       identifier and then a 2 byte integer length in network byte order. See
       RFC2326 Section 10.12 for more information on how RTP interleaving
       behaves. If unset or set to NULL, curl will use the default write
       function.

       Interleaved RTP poses some challenges for the client application. Since
       the stream data is sharing the RTSP control connection, it is critical
       to service the RTP in a timely fashion. If the RTP data is not handled
       quickly, subsequent response processing may become unreasonably delayed
       and the connection may close. The application may use
       CURL_RTSPREQ_RECEIVE to service RTP data when no requests are desired.
       If the application makes a request, (e.g.  CURL_RTSPREQ_PAUSE) then the
       response handler will process any pending RTP data before marking the
       request as finished.

       The CURLOPT_INTERLEAVEDATA(3) is passed in the userdata argument in the
       callback.

       Your callback should return the number of bytes actually taken care of.
       If that amount differs from the amount passed to your callback
       function, it will signal an error condition to the library. This will
       cause the transfer to get aborted and the libcurl function used will
       return CURLE_WRITE_ERROR.

       You can also abort the transfer by returning CURL_WRITEFUNC_ERROR.
       (7.87.0)


DEFAULT

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


PROTOCOLS

       RTSP


EXAMPLE

       static size_t rtp_write(void *ptr, size_t size, size_t nmemb, void *user)
       {
         struct local *l = (struct local *)user;
         /* take care of the packet in 'ptr', then return... */
         return size * nmemb;
       }
       {
         struct local rtp_data;
         curl_easy_setopt(curl, CURLOPT_INTERLEAVEFUNCTION, rtp_write);
         curl_easy_setopt(curl, CURLOPT_INTERLEAVEDATA, &rtp_data);
       }


AVAILABILITY

       Added in 7.20.0


RETURN VALUE

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


SEE ALSO

       CURLOPT_INTERLEAVEDATA(3), CURLOPT_RTSP_REQUEST(3),

ibcurl 8.1.2                    April 26, 2023   CURLOPT_INTERLEAVEFUNCTION(3)

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