###### (This is the documentation for SDL3, which is the current stable version. [SDL2](https://wiki.libsdl.org/SDL2/) was the previous version!) # SDL_SetAudioStreamFrequencyRatio Change the frequency ratio of an audio stream. ## Header File Defined in [](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_audio.h) ## Syntax ```c bool SDL_SetAudioStreamFrequencyRatio(SDL_AudioStream *stream, float ratio); ``` ## Function Parameters | | | | | ------------------------------------ | ---------- | ----------------------------------------------------------------------- | | [SDL_AudioStream](SDL_AudioStream) * | **stream** | the stream the frequency ratio is being changed. | | float | **ratio** | the frequency ratio. 1.0 is normal speed. Must be between 0.01 and 100. | ## Return Value (bool) Returns true on success or false on failure; call [SDL_GetError](SDL_GetError)() for more information. ## Remarks The frequency ratio is used to adjust the rate at which input data is consumed. Changing this effectively modifies the speed and pitch of the audio. A value greater than 1.0 will play the audio faster, and at a higher pitch. A value less than 1.0 will play the audio slower, and at a lower pitch. This is applied during [SDL_GetAudioStreamData](SDL_GetAudioStreamData), and can be continuously changed to create various effects. ## Thread Safety It is safe to call this function from any thread, as it holds a stream-specific mutex while running. ## Version This function is available since SDL 3.0.0. ## See Also - [SDL_GetAudioStreamFrequencyRatio](SDL_GetAudioStreamFrequencyRatio) - [SDL_SetAudioStreamFormat](SDL_SetAudioStreamFormat) ---- [CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction), [CategoryAudio](CategoryAudio)