+ _ => { // B
+ let mut mbtype = br.read_cb(&self.tables.mbtype_b_cb)? as usize;
+ while mbtype == 14 { mbtype = br.read_cb(&self.tables.mbtype_b_cb)? as usize; }
+
+ let is_coded = (H263_MBTYPE_B_CAPS[mbtype] & H263_MBB_CAP_CODED) != 0;
+ let is_intra = (H263_MBTYPE_B_CAPS[mbtype] & H263_MBB_CAP_INTRA) != 0;
+ let dquant = (H263_MBTYPE_B_CAPS[mbtype] & H263_MBB_CAP_DQUANT) != 0;
+ let is_fwd = (H263_MBTYPE_B_CAPS[mbtype] & H263_MBB_CAP_FORWARD) != 0;
+ let is_bwd = (H263_MBTYPE_B_CAPS[mbtype] & H263_MBB_CAP_BACKWARD) != 0;
+
+ let cbp = if is_coded {
+ let cbpc = br.read_cb(&self.tables.cbpc_b_cb)?;
+ let mut cbpy = br.read_cb(&self.tables.cbpy_cb)?;
+ if !is_intra { cbpy ^= 0xF; }
+ (cbpy << 2) | (cbpc & 3)
+ } else { 0 };
+
+ if dquant {
+ let idx = br.read(2)? as usize;
+ q = ((q as i16) + (H263_DQUANT_TAB[idx] as i16)) as u8;
+ }
+println!(" MB B {}.{} cbp = {:X} @ {} ({} {})", sstate.mb_x, sstate.mb_y, cbp, br.tell(), mbtype, is_intra);
+
+ if is_intra {
+ let binfo = BlockInfo::new(Type::I, cbp, q);
+ return Ok(binfo);
+ }
+
+ let mut binfo = BlockInfo::new(Type::B, cbp, q);
+ if is_fwd {
+ let mvec: [MV; 1] = [decode_mv(br, &self.tables.mv_cb)?];
+ binfo.set_mv(&mvec);
+ }
+ if is_bwd {
+ let mvec: [MV; 1] = [decode_mv(br, &self.tables.mv_cb)?];
+ binfo.set_b_mv(&mvec);
+ }
+ Ok(binfo)
+ },