looper/backends/playback/sdl_mixer_x/sdl_mixer_x.cpp

#include "sdl_mixer_x.hpp"
#include <endian.h>
#include <filesystem>
#include "file_backend.hpp"
#include <stddef.h>
#include <log.hpp>
#include <util.hpp>
#include <string.h>
std::optional<uint64_t> SDLMixerXBackend::get_max_samples() {
    return 4096;
}
void SDLMixerXBackend::load(const char *filename) {
    memset(&spec, 0, sizeof(spec));
    spec.callback = NULL;
    spec.channels = 2;
    spec.userdata = NULL;
    spec.format = AUDIO_F32SYS;
    spec.freq = 48000;
    spec.samples = get_max_samples().value();
    spec.size = spec.samples * 4 * spec.channels;
    Mix_InitMixer(&spec, SDL_FALSE);
    mixer = Mix_GetGeneralMixer();
    {
        std::filesystem::path fpath = std::string(filename);
        fpath = fpath.parent_path() / fpath.stem();

        std::string fpath_str = fpath.string();
        std::vector<std::string> soundfonts = {fpath_str + ".sf2", fpath_str + ".dls"};
        std::string sf_path_str = "";
        bool any_path_exists = false;
        for (auto sf_path : soundfonts) {
            if (std::filesystem::exists(sf_path)) {
                any_path_exists = true;
                sf_path_str += ";" + sf_path;
            }
        }
        if (any_path_exists) {
            sf_path_str = sf_path_str.substr(1);
            Mix_SetSoundFonts(sf_path_str.c_str());
        } else {
            Mix_SetSoundFonts(NULL);
        }
    }
    DEBUG.writefln("Opening file: %s", filename);
    file = open_file(filename);
    DEBUG.writeln("Loading file...");
    this->music = nullptr;
    Mix_Music *output = Mix_LoadMUS_RW(get_sdl_file(this->file), SDL_TRUE);
    if (output == nullptr) {
        ERROR.writefln("Error occurred: %s", Mix_GetError());
        throw std::exception();
    }
    if (Mix_PlayMusicStream(output, -1) < 0) {
        ERROR.writefln("Error occurred: %s", Mix_GetError());
        this->music = output;
    	throw std::exception();
    }
    Mix_ResumeMusicStream(output);
    length = Mix_MusicDuration(output);
    current_file = std::string(filename);
    const char *title_tag = Mix_GetMusicTitleTag(output);
    // Check for an empty string, which indicates there's no title tag.
    if (title_tag[0] == '\0') {
        std::filesystem::path path(current_file);
        current_title = path.stem().string();
    } else {
        current_title = std::string(title_tag);
    }
    this->music = output;
    streams.clear();
    PlaybackStream stream;
    stream.id = 0;
    stream.length = Mix_MusicDuration(output);
    stream.name = current_title;
    streams.push_back(stream);
    open = true;
    initial = true;
}
void SDLMixerXBackend::switch_stream(int idx) {
    seek(0.0);
}
void SDLMixerXBackend::seek(double position) {
    if (music == nullptr || file == nullptr) {
        open = false;
        return;
    }
    Mix_SetMusicPositionStream(music, position);
}
size_t SDLMixerXBackend::render(void *buf, size_t maxlen) {
    if (music == nullptr || file == nullptr) {
        open = false;
        return 0;
    }
    if (initial) {
        seek(0.0);
    }
    size_t i = 0;
    size_t bytes_per_iter = maxlen;
    if (bytes_per_iter > spec.size) {
        bytes_per_iter = spec.size;
    }
    // Remove partial sample frames.
    bytes_per_iter /= sizeof(float);
    bytes_per_iter *= sizeof(float);
    while (i < maxlen) {
    	if (i + bytes_per_iter > maxlen) {
     		bytes_per_iter = maxlen - i;
	        // Remove partial sample frames.
	        bytes_per_iter /= sizeof(float);
	        bytes_per_iter *= sizeof(float);
     	}
	    mixer(NULL, (Uint8*)(buf) + i, bytes_per_iter);
    	i += bytes_per_iter;
    }
    if (get_position() > (((double)maxlen) / ((double)spec.freq))) {
        if (initial) {
            seek(0.0);
        }
        initial = false;
    }
    return i;
}
double SDLMixerXBackend::get_position() {
    if (music == nullptr || file == nullptr) {
        open = false;
        return 0.0;
    }
    return Mix_GetMusicPosition(music);
}
SDLMixerXBackend::SDLMixerXBackend() {
    Mix_Init(MIX_INIT_FLAC|MIX_INIT_MID|MIX_INIT_MOD|MIX_INIT_MP3|MIX_INIT_OGG|MIX_INIT_OPUS|MIX_INIT_WAVPACK);
}
SDLMixerXBackend::~SDLMixerXBackend() {
    Mix_Quit();
}
void SDLMixerXBackend::cleanup() {
    streams.clear();
    position = 0.0;
    rate = 0.0;
    memset(&spec, 0, sizeof(spec));
    current_file = "";
    current_title = "";
    length = 0.0;
    if (music != nullptr) {
        Mix_HaltMusicStream(music);
        Mix_FreeMusic(music);
    }
    Mix_SetSoundFonts(NULL);
    mixer = nullptr;
    music = nullptr;
    delete file;
    file = nullptr;
    open = false;
    Mix_CloseAudio();
}