This is a yellow cloth (actually its color yellow + orange, we normally see same as a color of cloth of monk). All visitors are invited to donate and write something on the yellow cloth as later the cloth will be used for wrapping around the bottom of the chedi when they are full of inscription.
Part of the ceremony was the parade around the Chedi. The band, really Thai music instruments had been waiting for the senior official, and some of locals who take part the ceremony finish paying respect to the Buddha Image and the band will lead the parade.
By the time we get there, there was a ceremony at the temple and I saw some official of the province, some important persons of the province and a lot locals take part the ceremony. As I knew the purpose of the ceremony to get the donation for further religious activities of the Phra Prathom Chedi Temple.