GNURLOPT_INTERLEAVEFUNCTION(3)

💅 GNURLOPT_INTERLEAVEFUNCTION(3) 💅

okay bestie, quick vibe check: we're in the curl_easy_setopt options manual, and this page is all about CURLOPT_INTERLEAVEFUNCTION. no cap, it's the callback glow-up for RTSP interleaved data. ✨

💖 NAME 💖

CURLOPT_INTERLEAVEFUNCTION — callback function for RTSP interleaved data 🎀

✨ SYNOPSIS ✨

#include <gnurl/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 🌸

okay so you pass a pointer to your callback function, and it has to match the prototype up there. literally match it, bestie. 🫶

libcurl calls this callback as soon as it has received interleaved RTP data. It gets called for each $ block, so each call contains exactly one upper-layer protocol unit (e.g. one RTP packet). Curl writes the interleaved header as well as the included data for every call. The first byte is always an ASCII dollar sign ($). That 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 this is 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. 🦋

🎀 DEFAULT 🎀

NULL, the interleave data is then passed to the regular write function: CURLOPT_WRITEFUNCTION(3). lowkey a fallback slay. ✨

🌈 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 🧚

the refs are: CURLOPT_INTERLEAVEDATA(3), CURLOPT_RTSP_REQUEST(3), — yes, trailing comma and all, because that's what the page says. 💅

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shoutout to libcurl 7.37.0 and the date 19 Jun 2014 for the footer vibes, periodt. 💖✨