MIX_TrackMixCallback(3type)

📦
version 3.2.4 · 2 versions
, in fedora 44

✨ MIX_TrackMixCallback ✨

okay bestie, welcome to the MIX_TrackMixCallback(3type) page, part of the SDL_mixer3 datatypes era 💅 (yes we're in the DATATYPES section, it's giving reference-material realness 🎀)

🌸 NAME 🌸

MIX_TrackMixCallback — a callback that fires when a MIX_Track is mixing at various stages. like, she literally shows up at multiple points of the process, no cap 👑

🦋 SYNOPSIS 🦋

#include <SDL3_mixer/SDL_mixer.h>

typedef void (SDLCALL *MIX_TrackMixCallback)(void *userdata, MIX_Track *track, const SDL_AudioSpec *spec, float *pcm, int samples);

💖 DESCRIPTION 💖

So this callback gets fired for different parts of the mixing pipeline, and it hands your app full visibility 👀 into the audio data being generated at those various stages. it's giving backstage pass, fr fr.

the audio data passed through here is not const data — like, at all. the app is permitted to change it in any way it likes, and those changes will propagate through the mixing pipeline. glow-up your samples, they'll carry through the whole chain ✨.

an audiospec is provided. different tracks might be in different formats, and an app needs to be able to handle that, but SDL_mixer always does its mixing work in 32-bit float samples — even if the inputs or the final output are not floating point. so as such, spec->format will always be SDL_AUDIO_F32, and pcm is hardcoded to be a float pointer. periodt 💅.

samples is the number of float values pointed to by pcm: samples, not sample frames! 😭 there are no promises how many samples will be provided per-callback, and this number can vary wildly from call to call, depending on many factors. she's unpredictable like that 🙈.

⚠️ okay this part is important bestie: making changes to the track during this callback is undefined behavior. change the data in pcm but not the track itself. do not touch the track. i am so serious 💀

🫶 FUNCTION PARAMETERS 🫶

  • userdata — an opaque pointer provided by the app for its personal use. it's yours, do whatever, she's not judging 🎀
  • track — the track that is being mixed. the main character in question 👑
  • spec — the format of the data in pcm.
  • pcm — the raw PCM data in float32 format. the actual goods 🍓
  • samples — the number of float values pointed to by pcm.

🌈 AVAILABILITY 🌈

this datatype is available since SDL_mixer 3.0.0. she's been iconic for a minute 💜

⭐ SEE ALSO ⭐

and that's the whole page, bestie 🦋 mwah 💋 this was brought to you by the SDL_mixer source, version SDL_mixer 3.2.4 — stay slaying, and remember: change the pcm, never the track 💖✨

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