SGC Format

SGC is a separate file format used for storing cutscene voice lines.

struct SGC {
    SGCFile files[];
    // padding to 0x4000
    char data[]; // each file's data has padding between them to next multiple of 0x1000
}

SGC files are organized in alphabetical order.

Actual sound data is stored in Nintendo's DSP ADPCM format (on Gamecube).

struct SGCFile {
    char name[16];
    uint32_t sample_rate;
    uint32_t data_position; // byte offset for the file's data. The first file will have an offset of 0x4000
    uint32_t data_length;
    uint32_t channels; // Not actually sure what this is, but it's always 1, and all files are in mono :)
    uint16_t coef[16]; // DSP coefficients
}

SGCFile contains a highly simplified DSP ADPCM header.