MP4(3)

💖 MP4BinaryToBase64 💖

okay bestie so this is a page from the MP4 File Format Library, and it lives in section 3 of the manual — that's the MP4(3) zone, the C library function corner of the man world 🫶. Lowkey the whole thing is about one tiny iconic little function that turns your crunchy binary bytes into a cute little base 64 string. Slay. Let's get into it ✨

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✨ NAME ✨

MP4BinaryToBase64 — converts binary data to a base 64 string 💅

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🌸 SYNTAX 🌸

#include <mp4.h>

char* MP4BinaryToBase64(
     const u_int8_t* pData,
     u_int32_t dataSize
)

not me showing you the exact signature, character for character, because that's the whole vibe 🔥

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🎀 ARGUMENTS 🎀

• pData — the pointer to the binary data, bestie. It's the raw stuff. It's const, so don't even think about touching it 🙈
• dataSize — the size in bytes of that binary data. Yes, bytes. It's a u_int32_t. It's giving "I counted, trust me" 💜

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👑 RETURN VALUES 👑

• Upon success: a null terminated string representing the data in base 64. So iconic. So well behaved.
• Upon error: NULL. 😭 yeah. check for it. please.

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🌈 DESCRIPTION 🌈

MP4BinaryToBase64 converts binary data to a base 64 string. Periodt.

The way this encoding works is it maps groups of 6 bits into the character set [A-Za-z0-9+/=]. That's the whole alphabet, no cap. And the string it hands back is sitting in malloc'd memory, so 👏 the 👏 caller 👏 is 👏 responsible 👏 for 👏 free'ing 👏 the 👏 memory. I'm serious. That's your job now. main character responsibility energy 🧚

This utility is useful for generating the SDP descriptions for some RTP payloads. ykyk 🦋

Example, because examples eat every time:

0x12, 0xAB -> "Eqs="

literally that. two lil bytes walk in, a four character base 64 string walks out. ate 💅

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💀 SEE ALSO 💀

• MP4(3) — go read the whole library page, bestie, it's the mothership 🎀

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and that's the page!! 💖 it's from Cisco Systems Inc., it's Version 0.9, and it's hanging out in the MP4(3) section of the manual. go forth and free your malloc'd strings, queen 👑✨🌈