SDL Mixer/Audio setting frequency for individual samples

Ric · May 12, 2018, 5:21pm

Hi
I would like the possibility to set the playback frequency for each individual sound sample just before it’s called to play; not just ‘once and for all’ during initializing with the Mix_OpenAudio() function. Or maintained in that function but then adjusted by some float factor sent as an argument to the Mix_PlayChannel() function,
were 1.0 would correspond to un-altered and 1.3 to 30% increased playback frequency. Maybe even a negative number to play the sample backwards; -0.5 for half speed backwards fo example.

This could lead to saving resources/memory; not having to use as many samples if one could use
fewer ones more liberally.

Acry · May 12, 2018, 5:27pm

gist.github.com

https://gist.github.com/danilolc/9fff54a8cb9ddc04b9bd82df7badb610

change_frequency.c

//Danilo Lemos - 2017
//change_frequency.c
//======================
//A small function to play a SDL_mixer's chunk in a different frequency.
//It was written to be used on the Pekka Kana 2 SDL2 game project, and is free to use and edit.

#include <SDL2/SDL_mixer.h>
#include <stdio.h>

#define MIX_CHANNELS 8 //Number of channels used

This file has been truncated. show original

Not tested here.

Cheers,
–Cass