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.TH Mix_SetPostMix 3 "SDL_mixer 3.0.0" "SDL_mixer" "SDL_mixer3 FUNCTIONS"
.SH NAME
Mix_SetPostMix \- Set a function that is called after all mixing is performed\[char46]
.SH SYNOPSIS
.nf
.B #include \(dqSDL3_mixer/SDL_mixer.h\(dq
.PP
.BI "void Mix_SetPostMix(void (SDLCALL *mix_func)(void *udata, Uint8 *stream, int len), void *arg);
.fi
.SH DESCRIPTION
This can be used to provide real-time visual display of the audio stream or
add a custom mixer filter for the stream data\[char46]

The callback will fire every time SDL_mixer is ready to supply more data to
the audio device, after it has finished all its mixing work\[char46] This runs
inside an SDL audio callback, so it's important that the callback return
quickly, or there could be problems in the audio playback\[char46]

The data provided to the callback is in the format that the audio device
was opened in, and it represents the exact waveform SDL_mixer has mixed
from all playing chunks and music for playback\[char46] You are allowed to modify
the data, but it cannot be resized (so you can't add a reverb effect that
goes past the end of the buffer without saving some state between runs to
add it into the next callback, or resample the buffer to a smaller size to
speed it up, etc)\[char46]

The
.BR arg
pointer supplied here is passed to the callback as-is, for
whatever the callback might want to do with it (keep track of some ongoing
state, settings, etc)\[char46]

Passing a NULL callback disables the post-mix callback until such a time as
a new one callback is set\[char46]

There is only one callback available\[char46] If you need to mix multiple inputs,
be prepared to handle them from a single function\[char46]

.SH FUNCTION PARAMETERS
.TP
.I mix_func
the callback function to become the new post-mix callback\[char46]
.TP
.I arg
a pointer that is passed, untouched, to the callback\[char46]
.SH AVAILABILITY
This function is available since SDL_mixer 3\[char46]0\[char46]0\[char46]

.SH SEE ALSO
.BR Mix_HookMusic (3)