self.mdpr_pos = bw.tell();
bw.write_chunk(b"MDPR", 0, 0)?;
self.mdpr_pos = bw.tell();
bw.write_chunk(b"MDPR", 0, 0)?;
bw.write_u32be(0)?; //max br
bw.write_u32be(0)?; //avg br
bw.write_u32be(0)?; //max ps
bw.write_u32be(0)?; //max br
bw.write_u32be(0)?; //avg br
bw.write_u32be(0)?; //max ps