MIX_Generate(3)

💖 MIX_Generate(3) — the SDL_mixer3 glow-up edition 💖

okay bestie, welcome to the manual page for MIX_Generate, straight outta the SDL_mixer3 FUNCTIONS section of the SDL_mixer man pages. it's giving "make the mixer do its little thing without an actual audio device" and honestly? iconic. let's get into it 🎀

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✨ NAME ✨

MIX_Generate — Generate mixer output when not driving an audio device. no cap, that's literally the whole job description.

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✨ SYNOPSIS ✨

#include <SDL3_mixer/SDL_mixer.h>

int MIX_Generate(MIX_Mixer *mixer, void *buffer, int buflen);

look at her. three arguments, one int coming back at you. clean, simple, slay 💅

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✨ DESCRIPTION ✨

so here's the tea ☕ — SDL_mixer lets you build MIX_Mixer objects that are not hooked up to an audio device at all. you do that by calling MIX_CreateMixer() instead of MIX_CreateMixerDevice(). and those mixers? they just sit there. they will not generate output until you explicitly ask them to through this function. girl is waiting for instructions, fr fr.

the caller can request as much audio as they want, as long as buflen is a multiple of the sample frame size that was specified when the mixer was created. like, for example: if you're requesting stereo Sint16 audio, then buflen has to be a multiple of 4 — that's 2 bytes-per-channel times 2 channels. math is math 💀

the mixer will mix as quickly as possible. like, no throttle, no chill. since it works in sample frames instead of time, it can potentially generate enormous amounts of audio in a small amount of time. main character energy, but in bytes.

on success, this always fills buffer with buflen bytes of audio. and if all the playing tracks finish mixing? it fills the remaining buffer with silence. respectful. 💜

every single call to this function picks up right where it left off — playing tracks keep mixing from the exact point the previous call completed, and so on. between each call you can change the mixer state in literally any way you want: tracks can be added, played, stopped, changed, removed, whatever. effectively this function does the same thing SDL_mixer does internally when the audio device needs more audio to play. it's the behind-the-scenes intern, but you get to schedule the shifts 🫶

🚫 the important boundary, bestie: this function can not be used with mixers from MIX_CreateMixerDevice(). those ones generate audio as needed internally. they don't need you micromanaging them.

this function returns the number of _bytes_ of real audio mixed, which might be less than buflen. and here's the nuance — while all buflen bytes of buffer will be initialized, if the available tracks to mix run out, the end of the buffer gets initialized with silence. that silence will not be counted in the return value. so the caller has the option to identify how much of the buffer has legitimate contents vs. appended silence. as such, any value >= 0 signifies success. a return value of -1 means failure (out of memory, invalid parameters, etc). noted. 📝

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✨ FUNCTION PARAMETERS ✨

• mixer — the mixer for which to generate more audio. the one receiving the vibes.
• buffer — a pointer to a buffer to store audio in. where the audio goes to live.
• buflen — the number of bytes to store in buffer. how much room you're giving it.

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✨ RETURN VALUE ✨

returns the number of bytes of mixed audio — discounting appended silence — on success, or -1 on failure. and if it fails? call SDL_GetError() for more information. she'll tell you what went wrong, bestie 😭

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✨ THREAD SAFETY ✨

it is safe to call this function from any thread. multithreaded queen 👑

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✨ AVAILABILITY ✨

this function is available since SDL_mixer 3.0.0. been here since the beginning of the 3.x era, and she's thriving 🌸

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✨ SEE ALSO ✨

• MIX_CreateMixer(3)

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and that's the whole page, periodt. this little love letter comes to you from SDL_mixer, version 3.2.4 — go forth and generate responsibly, bestie 🦋✨💖