As part of MC ParamUpmix structure, there is defined a flag: ``` typedef struct ivas_mc_paramupmix_enc_data_structure { ... bool first_frame; } MC_PARAMUPMIX_ENC_DATA, *MC_PARAMUPMIX_ENC_HANDLE; ``` while it holds values `first_frame = 0` or `first_frame = 1`. Strictly speaking, the data type of this parameter should be `int16_t` to avoid data type mismatch. Alternatively, the flag could hold `first_frame = false` or `first_frame = true` but this is less preferable as the codec does not use `bool` except of the application layer.