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  RFC  2326  Section  10.12  for  more  information  on  how  RTP
       interleaving behaves. If unset or set to NULL, curl uses 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 processes 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 signals an error condition to
       the  library.  This  causes  the  transfer  to abort and the libcurl function used returns
       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

       struct local {
         void *custom;
       };

       static size_t rtp_write(void *ptr, size_t size, size_t nmemb, void *userp)
       {
         struct local *l = userp;
         printf("our ptr: %p\n", l->custom);
         /* take care of the packet in 'ptr', then return... */
         return size * nmemb;
       }

       int main(void)
       {
         struct local rtp_data;
         CURL *curl = curl_easy_init();
         if(curl) {
           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)