CODEWITHSUNDEEP
c++caudio-recordingalsasox
Chris
Chris

Reputation: 1027

Recording using sox in c/c++

I am trying to record sound using microphone and sox library in C/C++.

sox_open_read("default", &_input->signal, NULL, NULL)

I am trying to use default input device. I am getting the error

formats: can't open input file `default': No such file or directory

Which I guess is caused because I did not pass the last argument: filetype and sox tries to find a file with name 'default'.
Sox lists:

What should I pass to the sox_open_read function as the last parameter to use a microphone as an input?

Upvotes: 1

Views: 1444

Answers (1)

Chris
Chris

Reputation: 1027

As the last parameter to sox_open_read function for microphone input, one of the audio devices drivers should be passed. In my case, it is 'alsa'.
Example:

#include <sox.h>
#include <memory>

sox_signalinfo_t _intermediateSignal;
sox_format_t* input;
sox_format_t* output;
sox_effects_chain_t* effectsChain;

void addEffect(std::string effectName, sox_format_t* options) {
    std::unique_ptr<sox_effect_t> effect(sox_create_effect(sox_find_effect(effectName.c_str())));
    char *args[] = {reinterpret_cast<char *>(options)};
    sox_effect_options(effect.get(), 1, args);
    sox_add_effect(effectsChain, effect.get(), &_intermediateSignal, &input->signal);
}

int main() {
    if (sox_init() != SOX_SUCCESS)
        throw std::runtime_error("Could not initialise SOX.");

    input = sox_open_read("default", NULL, NULL, "alsa");
    output = sox_open_write("recorded.wav", &input->signal, NULL, NULL, NULL, NULL);
    if (!input || !output)
        throw std::runtime_error("SOX I/O error");

    _intermediateSignal = input->signal;

    effectsChain = sox_create_effects_chain(&input->encoding, &output->encoding);

    if (!effectsChain)
        throw std::runtime_error("SOX could not initialize effects chain.");

    addEffect("input", input);
    addEffect("output", output);

    sox_flow_effects(effectsChain, NULL, NULL);
    sox_quit();
}

This example will never finish as sox_flow_effects call blocks the execution. Once the program is killed with ctrl+c, recorded.wav contains recorded audio.

Upvotes: 1

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