(This function is part of SDL_mixer, a separate library from SDL.)

MIX_SetTrackCookedCallback

Set a callback that fires when the mixer has transformed a track's audio.

Header File

Syntax

bool MIX_SetTrackCookedCallback(MIX_Track *track, MIX_TrackMixCallback cb, void *userdata);

Function Parameters

MIX_Track *	track	the track to assign this callback to.
MIX_TrackMixCallback	cb	the function to call when the track mixes. May be NULL.
void *	userdata	an opaque pointer provided to the callback for its own personal use.

Return Value

(bool) Returns true on success or false on failure; call SDL_GetError() for more information.

Remarks

As a track needs to mix more data, it pulls from its input (a MIX_Audio, an SDL_AudioStream, etc). This input might be a compressed file format, like MP3, so a little more data is uncompressed from it.

Once the track has PCM data to start operating on, and its raw callback has completed, it will begin to transform the audio: gain, fading, frequency ratio, 3D positioning, etc.

A callback can be fired after all these transformations, but before the transformed data is mixed into other tracks. This lets an app view the data at the last moment that it is still a part of this track. It can also change the data in any way it pleases during this callback, and the mixer will continue as if this data came directly from the input.

Each track has its own unique cooked callback.

Passing a NULL callback here is legal; it disables this track's callback.

Version

This function is available since SDL_mixer 3.0.0.