+ } else {
+ if !self.shuf.has_refs() {
+ return Err(DecoderError::MissingReference);
+ }
+ }
+
+ let psrc = &src[if self.has_alpha { 3 } else { 0 }..aoffset];
+ self.decode_planes(br, &mut dframe, &mut bc, &hdr, psrc, false)?;
+
+ if self.has_alpha {
+ let asrc = &src[aoffset + 3..];
+ let mut bc = BoolCoder::new(asrc)?;
+ let ahdr = br.parse_header(&mut bc)?;
+ validate!(ahdr.mb_w == hdr.mb_w && ahdr.mb_h == hdr.mb_h);
+ std::mem::swap(&mut self.models, &mut self.amodels);
+ let ret = self.decode_planes(br, &mut dframe, &mut bc, &ahdr, asrc, true);
+ std::mem::swap(&mut self.models, &mut self.amodels);
+ if let Err(err) = ret {
+ return Err(err);
+ }