test_tempo_sox.c

#include <iostream>
#include <sox.h>
#include <assert.h>
#include <cstring>
#include <vector>

using namespace std;


int main() {
    sox_init();

    char*  buffer;
    size_t buffer_size;

    sox_format_t* input = sox_open_read("/home/egor/hello.wav", NULL, NULL, NULL);
    //sox_format_t* out;

    sox_format_t* output = sox_open_memstream_write(&buffer, &buffer_size,
                                                 &input->signal, &input->encoding, "raw", NULL);
    //assert(output = sox_open_write("/home/egor/hello_processed.wav", &input->signal, NULL, NULL, NULL, NULL));
    sox_effects_chain_t* chain = sox_create_effects_chain(&input->encoding, &output->encoding);

    char* sox_args[10];
    //input effect

    sox_effect_t* e = sox_create_effect(sox_find_effect("input"));
    sox_args[0] = (char*)input;
    assert(sox_effect_options(e, 1, sox_args) == SOX_SUCCESS);
    assert(sox_add_effect(chain, e, &input->signal, &input->signal) ==
           SOX_SUCCESS);
    free(e);

    e = sox_create_effect(sox_find_effect("tempo"));
    std::string tempo_str = "1.01";
    sox_args[0] = (char*)tempo_str.c_str();
    assert(sox_effect_options(e, 1, sox_args) == SOX_SUCCESS);
    assert(sox_add_effect(chain, e, &input->signal,&input->signal) ==
           SOX_SUCCESS);
    free(e);


    e = sox_create_effect(sox_find_effect("output"));
    sox_args[0] = (char*)output;
    assert(sox_effect_options(e, 1, sox_args) == SOX_SUCCESS);
    assert(sox_add_effect(chain, e, &input->signal, &input->signal) ==
           SOX_SUCCESS);
    free(e);
    sox_flow_effects(chain, NULL, NULL);


    static const size_t maxSamples=4096;
    sox_sample_t samples[maxSamples];

    std::vector<sox_sample_t> audio_buffer;
    for (size_t r; 0 != (r=sox_read(output,samples,maxSamples));)
        for(int i=0;i<r ;i++)
            audio_buffer.push_back(samples[i]);

    std::cout << audio_buffer.size() << std::endl;
    sox_delete_effects_chain(chain);

    sox_close(input);
    sox_close(output);
    free(buffer);

    return 0;
}