CURLOPT_INTERLEAVEDATA(3)

CURLOPT_INTERLEAVEDATA 💅

okay bestie, so this is a page from the libcurl manual — the library functions manual, to be exact — and it's all about CURLOPT_INTERLEAVEDATA, which is genuinely one of those tiny options that makes the whole RTSP thing work. no cap. let's get into it 🎀

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✨ NAME ✨

CURLOPT_INTERLEAVEDATA — the pointer that gets passed to the RTSP interleave callback, periodt.

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🌸 SYNOPSIS 🌸

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_INTERLEAVEDATA, void *pointer);

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🦋 DESCRIPTION 🦋

So here's the vibe: this is the userdata pointer that gets handed over to CURLOPT_INTERLEAVEFUNCTION(3) whenever interleaved RTP data shows up. like, it's the little bag of stuff you get to carry into your callback. 💖

and lowkey important: if you never set the interleave function callback, this pointer literally isn't used anywhere. it just sits there. main character energy with no scene to be in, honestly. 😭

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⭐ DEFAULT ⭐

NULL

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🌈 PROTOCOLS 🌈

this functionality affects rtsp only. iykyk. 🫶

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🔥 EXAMPLE 🔥

here's the whole little program, copied exactly so you can steal it:

struct local {
  void *custom;
};
static size_t rtp_write(void *ptr, size_t size, size_t nmemb, void *userp)
{
  struct local *l = userp;
  printf("my pointer: %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);

    curl_easy_perform(curl);
  }
}

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💜 AVAILABILITY 💜

added in curl 7.20.0 — vintage, but iconic. 👑

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✨ RETURN VALUE ✨

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK — slay — and non-zero means an error occurred, so go check libcurl-errors(3) for what went wrong. 💀

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🎀 SEE ALSO 🎀

• CURLOPT_INTERLEAVEFUNCTION(3)
• CURLOPT_RTSP_REQUEST(3)

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fr fr bestie, don't set CURLOPT_INTERLEAVEDATA without CURLOPT_INTERLEAVEFUNCTION — the page says the pointer isn't used anywhere if the callback isn't set. that's just facts. 🙈

okay that's the whole page, hope your RTSP journey is cute and your packets are interleaved beautifully 🌸💅

this libcurl page is dated 2026-10-12 and comes from the libcurl source — bye bestie, mwah! 💖🦋