case FF_OPT_TYPE_FLOAT: snprintf(buf, buf_len, "%f" , *(float *)dst);break;
case FF_OPT_TYPE_DOUBLE: snprintf(buf, buf_len, "%f" , *(double *)dst);break;
case FF_OPT_TYPE_RATIONAL: snprintf(buf, buf_len, "%d/%d", ((AVRational*)dst)->num, ((AVRational*)dst)->den);break;
case FF_OPT_TYPE_FLOAT: snprintf(buf, buf_len, "%f" , *(float *)dst);break;
case FF_OPT_TYPE_DOUBLE: snprintf(buf, buf_len, "%f" , *(double *)dst);break;
case FF_OPT_TYPE_RATIONAL: snprintf(buf, buf_len, "%d/%d", ((AVRational*)dst)->num, ((AVRational*)dst)->den);break;