nihav-core/src/codecs/h263/decoder.rs

   1 //use std::mem;
   2 use crate::frame::*;
   3 use super::super::*;
   4 use super::super::blockdsp;
   5 use super::*;
   6 //use super::code::*;
   7 use crate::formats;
   8
   9 #[allow(dead_code)]
  10 struct MVInfo {
  11     mv:         Vec<MV>,
  12     mb_w:       usize,
  13     mb_stride:  usize,
  14     mb_start:   usize,
  15     top:        bool,
  16     mvmode:     MVMode,
  17 }
  18
  19 impl MVInfo {
  20     fn new() -> Self { MVInfo{ mv: Vec::new(), mb_w: 0, mb_stride: 0, mb_start: 0, top: true, mvmode: MVMode::Old } }
  21     fn reset(&mut self, mb_w: usize, mb_start: usize, mvmode: MVMode) {
  22         self.mb_start  = mb_start;
  23         self.mb_w      = mb_w;
  24         self.mb_stride = mb_w * 2;
  25         self.mv.resize(self.mb_stride * 3, ZERO_MV);
  26         self.mvmode    = mvmode;
  27     }
  28     fn update_row(&mut self) {
  29         self.mb_start = self.mb_w + 1;
  30         self.top      = false;
  31         for i in 0..self.mb_stride {
  32             self.mv[i] = self.mv[self.mb_stride * 2 + i];
  33         }
  34     }
  35     #[allow(non_snake_case)]
  36     fn predict(&mut self, mb_x: usize, blk_no: usize, use4: bool, diff: MV, first_line: bool, first_mb: bool) -> MV {
  37         let A;
  38         let B;
  39         let C;
  40         let last = mb_x == self.mb_w - 1;
  41         match blk_no {
  42             0 => {
  43                     if mb_x != self.mb_start {
  44                         A = if !first_mb   { self.mv[self.mb_stride + mb_x * 2 - 1] } else { ZERO_MV };
  45                         B = if !first_line { self.mv[                 mb_x * 2] } else { A };
  46                         C = if !first_line && !last { self.mv[mb_x * 2 + 2] } else { ZERO_MV };
  47                     } else {
  48                         A = ZERO_MV; B = ZERO_MV; C = ZERO_MV;
  49                     }
  50                 },
  51             1 => {
  52                     A = self.mv[self.mb_stride + mb_x * 2];
  53                     B = if !first_line { self.mv[mb_x * 2 + 1] } else { A };
  54                     C = if !first_line && !last { self.mv[mb_x * 2 + 2] } else { ZERO_MV/*A*/ };
  55                 },
  56             2 => {
  57                     A = if mb_x != self.mb_start { self.mv[self.mb_stride * 2 + mb_x * 2 - 1] } else { ZERO_MV };
  58                     B = self.mv[self.mb_stride + mb_x * 2];
  59                     C = self.mv[self.mb_stride + mb_x * 2 + 1];
  60                 },
  61             3 => {
  62                     A = self.mv[self.mb_stride * 2 + mb_x * 2];
  63                     B = self.mv[self.mb_stride * 1 + mb_x * 2 + 1];
  64                     C = self.mv[self.mb_stride * 1 + mb_x * 2];
  65                 },
  66             _ => { return ZERO_MV; }
  67         }
  68         let pred_mv = MV::pred(A, B, C);
  69         let new_mv = MV::add_umv(pred_mv, diff, self.mvmode);
  70         if !use4 {
  71             self.mv[self.mb_stride * 1 + mb_x * 2 + 0] = new_mv;
  72             self.mv[self.mb_stride * 1 + mb_x * 2 + 1] = new_mv;
  73             self.mv[self.mb_stride * 2 + mb_x * 2 + 0] = new_mv;
  74             self.mv[self.mb_stride * 2 + mb_x * 2 + 1] = new_mv;
  75         } else {
  76             match blk_no {
  77                 0 => { self.mv[self.mb_stride * 1 + mb_x * 2 + 0] = new_mv; },
  78                 1 => { self.mv[self.mb_stride * 1 + mb_x * 2 + 1] = new_mv; },
  79                 2 => { self.mv[self.mb_stride * 2 + mb_x * 2 + 0] = new_mv; },
  80                 3 => { self.mv[self.mb_stride * 2 + mb_x * 2 + 1] = new_mv; },
  81                 _ => {},
  82             };
  83         }
  84
  85         new_mv
  86     }
  87     fn set_zero_mv(&mut self, mb_x: usize) {
  88         self.mv[self.mb_stride * 1 + mb_x * 2 + 0] = ZERO_MV;
  89         self.mv[self.mb_stride * 1 + mb_x * 2 + 1] = ZERO_MV;
  90         self.mv[self.mb_stride * 2 + mb_x * 2 + 0] = ZERO_MV;
  91         self.mv[self.mb_stride * 2 + mb_x * 2 + 1] = ZERO_MV;
  92     }
  93     fn get_mv(&self, mb_x: usize, blk_no: usize) -> MV {
  94         self.mv[self.mb_stride + mb_x * 2 + (blk_no & 1) + (blk_no >> 1) * self.mb_stride]
  95     }
  96 }
  97
  98 #[allow(dead_code)]
  99 #[derive(Clone,Copy)]
 100 struct BMB {
 101     num_mv: usize,
 102     mv_f:   [MV; 4],
 103     mv_b:   [MV; 4],
 104     fwd:    bool,
 105     blk:    [[i16; 64]; 6],
 106     cbp:    u8,
 107 }
 108
 109 impl BMB {
 110     fn new() -> Self { BMB {blk: [[0; 64]; 6], cbp: 0, fwd: false, mv_f: [ZERO_MV; 4], mv_b: [ZERO_MV; 4], num_mv: 0} }
 111 }
 112
 113 #[derive(Clone,Copy)]
 114 struct PredCoeffs {
 115     hor: [[i16; 8]; 6],
 116     ver: [[i16; 8]; 6],
 117 }
 118
 119 const ZERO_PRED_COEFFS: PredCoeffs = PredCoeffs { hor: [[0; 8]; 6], ver: [[0; 8]; 6] };
 120
 121 pub struct H263BaseDecoder {
 122     w:          usize,
 123     h:          usize,
 124     mb_w:       usize,
 125     mb_h:       usize,
 126     num_mb:     usize,
 127     ftype:      Type,
 128     ipbs:       IPBShuffler,
 129     next_ts:    u16,
 130     last_ts:    u16,
 131     tsdiff:     u16,
 132     has_b:      bool,
 133     b_data:     Vec<BMB>,
 134     pred_coeffs: Vec<PredCoeffs>,
 135     is_gob:     bool,
 136     slice_reset: bool,
 137     may_have_b_frames: bool,
 138     mv_data:    Vec<BlockMVInfo>,
 139 }
 140
 141 #[inline]
 142 fn clip_dc(dc: i16) -> i16 {
 143     if dc < 0 { 0 }
 144     else if dc > 2046 { 2046 }
 145     else { (dc + 1) & !1 }
 146 }
 147
 148 #[inline]
 149 fn clip_ac(ac: i16) -> i16 {
 150     if ac < -2048 { -2048 }
 151     else if ac > 2047 { 2047 }
 152     else { ac }
 153 }
 154
 155 #[allow(dead_code)]
 156 impl H263BaseDecoder {
 157     pub fn new_with_opts(is_gob: bool, slice_reset: bool, may_have_b_frames: bool) -> Self {
 158         H263BaseDecoder{
 159             w: 0, h: 0, mb_w: 0, mb_h: 0, num_mb: 0,
 160             ftype: Type::Special,
 161             ipbs: IPBShuffler::new(),
 162             last_ts: 0, next_ts: 0, tsdiff: 0,
 163             has_b: false, b_data: Vec::new(),
 164             pred_coeffs: Vec::new(),
 165             is_gob, slice_reset,
 166             may_have_b_frames,
 167             mv_data: Vec::new(),
 168         }
 169     }
 170     pub fn new(is_gob: bool) -> Self {
 171         Self::new_with_opts(is_gob, true, false)
 172     }
 173     pub fn new_b_frames(is_gob: bool) -> Self {
 174         Self::new_with_opts(is_gob, true, true)
 175     }
 176
 177     pub fn is_intra(&self) -> bool { self.ftype == Type::I }
 178     pub fn get_frame_type(&self) -> FrameType {
 179         match self.ftype {
 180             Type::I       => FrameType::I,
 181             Type::P       => FrameType::P,
 182             Type::B       => FrameType::B,
 183             Type::PB      => FrameType::P,
 184             Type::Skip    => FrameType::Skip,
 185             Type::Special => FrameType::Skip,
 186         }
 187     }
 188     pub fn get_dimensions(&self) -> (usize, usize) { (self.w, self.h) }
 189
 190     pub fn parse_frame(&mut self, bd: &mut BlockDecoder, bdsp: &BlockDSP) -> DecoderResult<NABufferType> {
 191         let pinfo = bd.decode_pichdr()?;
 192         let mut mvi = MVInfo::new();
 193         let mut mvi2 = MVInfo::new();
 194         let mut cbpi = CBPInfo::new();
 195
 196 //todo handle res change
 197         self.w = pinfo.w;
 198         self.h = pinfo.h;
 199         self.mb_w = (pinfo.w + 15) >> 4;
 200         self.mb_h = (pinfo.h + 15) >> 4;
 201         self.num_mb = self.mb_w * self.mb_h;
 202         self.ftype = pinfo.mode;
 203         self.has_b = pinfo.is_pb();
 204
 205         if self.has_b {
 206             self.mv_data.truncate(0);
 207         }
 208
 209         let save_b_data = pinfo.mode.is_ref() && self.may_have_b_frames;
 210         if save_b_data {
 211             self.mv_data.truncate(0);
 212         }
 213         let is_b = pinfo.mode == Type::B;
 214
 215         let tsdiff = if pinfo.is_pb() { pinfo.ts.wrapping_sub(self.last_ts) >> 1 }
 216                      else { self.last_ts.wrapping_sub(self.next_ts) >> 1 };
 217         let bsdiff = if pinfo.is_pb() { (pinfo.get_pbinfo().get_trb() as u16) << 7 }
 218                      else { pinfo.ts.wrapping_sub(self.next_ts) >> 1 };
 219
 220         let fmt = formats::YUV420_FORMAT;
 221         let vinfo = NAVideoInfo::new(self.w, self.h, false, fmt);
 222         let bufinfo = alloc_video_buffer(vinfo, 4)?;
 223         let mut buf = bufinfo.get_vbuf().unwrap();
 224
 225         let mut slice = if self.is_gob {
 226                 SliceInfo::get_default_slice(&pinfo)
 227             } else {
 228                 bd.decode_slice_header(&pinfo)?
 229             };
 230         mvi.reset(self.mb_w, 0, pinfo.get_mvmode());
 231         if is_b || pinfo.is_pb() {
 232             mvi2.reset(self.mb_w, 0, pinfo.get_mvmode());
 233         }
 234         cbpi.reset(self.mb_w);
 235
 236         let mut blk: [[i16; 64]; 6] = [[0; 64]; 6];
 237         let mut sstate = SliceState::new(pinfo.mode == Type::I);
 238         let mut mb_pos = 0;
 239         let apply_acpred = (pinfo.mode == Type::I) && pinfo.plusinfo.is_some() && pinfo.plusinfo.unwrap().aic;
 240         if apply_acpred {
 241             self.pred_coeffs.truncate(0);
 242             self.pred_coeffs.resize(self.mb_w * self.mb_h, ZERO_PRED_COEFFS);
 243         }
 244         sstate.quant = slice.quant;
 245         for mb_y in 0..self.mb_h {
 246             for mb_x in 0..self.mb_w {
 247                 for i in 0..6 { for j in 0..64 { blk[i][j] = 0; } }
 248
 249                 if slice.is_at_end(mb_pos) || (slice.needs_check() && mb_pos > 0 && bd.is_slice_end()) {
 250                     slice = bd.decode_slice_header(&pinfo)?;
 251                     if !self.is_gob && self.slice_reset {
 252                         mvi.reset(self.mb_w, mb_x, pinfo.get_mvmode());
 253                         if is_b || pinfo.is_pb() {
 254                             mvi2.reset(self.mb_w, mb_x, pinfo.get_mvmode());
 255                         }
 256                         cbpi.reset(self.mb_w);
 257                         sstate.reset_slice(mb_x, mb_y);
 258                         sstate.quant = slice.quant;
 259                     }
 260                 }
 261
 262                 let binfo = bd.decode_block_header(&pinfo, &slice, &sstate)?;
 263                 let cbp = binfo.get_cbp();
 264                 cbpi.set_cbp(mb_x, cbp);
 265                 cbpi.set_q(mb_x, binfo.get_q());
 266                 sstate.quant = binfo.get_q();
 267                 if binfo.is_intra() {
 268                     if save_b_data {
 269                         self.mv_data.push(BlockMVInfo::Intra);
 270                     }
 271                     for i in 0..6 {
 272                         bd.decode_block_intra(&binfo, &sstate, binfo.get_q(), i, (cbp & (1 << (5 - i))) != 0, &mut blk[i])?;
 273                         if apply_acpred && (binfo.acpred != ACPredMode::None) {
 274                             let has_b = (i == 1) || (i == 3) || !sstate.first_mb;
 275                             let has_a = (i == 2) || (i == 3) || !sstate.first_line;
 276                             let (b_mb, b_blk) = if has_b {
 277                                     if (i == 1) || (i == 3) {
 278                                         (mb_pos, i - 1)
 279                                     } else if i < 4 {
 280                                         (mb_pos - 1, i + 1)
 281                                     } else {
 282                                         (mb_pos - 1, i)
 283                                     }
 284                                 } else { (0, 0) };
 285                             let (a_mb, a_blk) = if has_a {
 286                                     if (i == 2) || (i == 3) {
 287                                         (mb_pos, i - 2)
 288                                     } else if i < 4 {
 289                                         (mb_pos - self.mb_w, i + 2)
 290                                     } else {
 291                                         (mb_pos - self.mb_w, i)
 292                                     }
 293                                 } else { (0, 0) };
 294                             match binfo.acpred {
 295                                 ACPredMode::DC   => {
 296                                             let dc;
 297                                             if has_a && has_b {
 298                                                 dc = (self.pred_coeffs[b_mb].hor[b_blk][0] + self.pred_coeffs[a_mb].ver[a_blk][0]) / 2;
 299                                             } else if has_a {
 300                                                 dc = self.pred_coeffs[a_mb].ver[a_blk][0];
 301                                             } else if has_b {
 302                                                 dc = self.pred_coeffs[b_mb].hor[b_blk][0];
 303                                             } else {
 304                                                 dc = 1024;
 305                                             }
 306                                             blk[i][0] = clip_dc(blk[i][0] + dc);
 307                                         },
 308                                 ACPredMode::Hor  => {
 309                                         if has_b {
 310                                             for k in 0..8 {
 311                                                 blk[i][k * 8] += self.pred_coeffs[b_mb].hor[b_blk][k];
 312                                             }
 313                                             for k in 1..8 {
 314                                                 blk[i][k * 8] = clip_ac(blk[i][k * 8]);
 315                                             }
 316                                         } else {
 317                                             blk[i][0] += 1024;
 318                                         }
 319                                         blk[i][0] = clip_dc(blk[i][0]);
 320                                     },
 321                                 ACPredMode::Ver  => {
 322                                         if has_a {
 323                                             for k in 0..8 {
 324                                                 blk[i][k] += self.pred_coeffs[a_mb].ver[a_blk][k];
 325                                             }
 326                                             for k in 1..8 {
 327                                                 blk[i][k] = clip_ac(blk[i][k]);
 328                                             }
 329                                         } else {
 330                                             blk[i][0] += 1024;
 331                                         }
 332                                         blk[i][0] = clip_dc(blk[i][0]);
 333                                     },
 334                                 ACPredMode::None => {},
 335                             };
 336                             for t in 0..8 { self.pred_coeffs[mb_pos].hor[i][t] = blk[i][t * 8]; }
 337                             for t in 0..8 { self.pred_coeffs[mb_pos].ver[i][t] = blk[i][t]; }
 338                         }
 339                         bdsp.idct(&mut blk[i]);
 340                     }
 341                     blockdsp::put_blocks(&mut buf, mb_x, mb_y, &blk);
 342                     mvi.set_zero_mv(mb_x);
 343                     if is_b {
 344                         mvi2.set_zero_mv(mb_x);
 345                     } else if pinfo.is_pb() {
 346                         mvi2.predict(mb_x, 0, false, binfo.get_mv2(0), sstate.first_line, sstate.first_mb);
 347                     }
 348                 } else if (binfo.mode != Type::B) && !binfo.is_skipped() {
 349                     if binfo.get_num_mvs() == 1 {
 350                         let mv = mvi.predict(mb_x, 0, false, binfo.get_mv(0), sstate.first_line, sstate.first_mb);
 351                         if save_b_data {
 352                             self.mv_data.push(BlockMVInfo::Inter_1MV(mv));
 353                         }
 354                         if let Some(ref srcbuf) = self.ipbs.get_lastref() {
 355                             bdsp.copy_blocks(&mut buf, srcbuf, mb_x * 16, mb_y * 16, 16, 16, mv);
 356                         }
 357                         if pinfo.is_pb() {
 358                             mvi2.predict(mb_x, 0, false, binfo.get_mv(0), sstate.first_line, sstate.first_mb);
 359                         }
 360                     } else {
 361                         let mut mv: [MV; 4] = [ZERO_MV, ZERO_MV, ZERO_MV, ZERO_MV];
 362                         for blk_no in 0..4 {
 363                             mv[blk_no] = mvi.predict(mb_x, blk_no, true, binfo.get_mv(blk_no), sstate.first_line, sstate.first_mb);
 364                             if let Some(ref srcbuf) = self.ipbs.get_lastref() {
 365                                 bdsp.copy_blocks(&mut buf, srcbuf,
 366                                                  mb_x * 16 + (blk_no & 1) * 8,
 367                                                  mb_y * 16 + (blk_no & 2) * 4, 8, 8, mv[blk_no]);
 368                             }
 369                         }
 370                         if pinfo.is_pb() {
 371                             for blk_no in 0..4 {
 372                                 mvi2.predict(mb_x, blk_no, true, binfo.get_mv(blk_no), sstate.first_line, sstate.first_mb);
 373                             }
 374                         }
 375                         if save_b_data {
 376                             self.mv_data.push(BlockMVInfo::Inter_4MV(mv));
 377                         }
 378                     }
 379                     for i in 0..6 {
 380                         bd.decode_block_inter(&binfo, &sstate, binfo.get_q(), i, ((cbp >> (5 - i)) & 1) != 0, &mut blk[i])?;
 381                         bdsp.idct(&mut blk[i]);
 382                     }
 383                     blockdsp::add_blocks(&mut buf, mb_x, mb_y, &blk);
 384                     if is_b && !pinfo.is_pb() {
 385                         mvi2.set_zero_mv(mb_x);
 386                     }
 387                 } else if binfo.mode != Type::B {
 388                     self.mv_data.push(BlockMVInfo::Inter_1MV(ZERO_MV));
 389                     mvi.set_zero_mv(mb_x);
 390                     if is_b || pinfo.is_pb() {
 391                         mvi2.set_zero_mv(mb_x);
 392                     }
 393                     if let Some(ref srcbuf) = self.ipbs.get_lastref() {
 394                         bdsp.copy_blocks(&mut buf, srcbuf, mb_x * 16, mb_y * 16, 16, 16, ZERO_MV);
 395                     }
 396                 } else {
 397                     let ref_mv_info = self.mv_data[mb_pos];
 398                     let has_fwd = binfo.get_num_mvs() > 0;
 399                     let has_bwd = binfo.get_num_mvs2() > 0;
 400 //todo refactor
 401                     if has_fwd || has_bwd {
 402                         let fwd_mv;
 403                         if has_fwd {
 404                             fwd_mv = mvi.predict(mb_x, 0, false, binfo.get_mv(0), sstate.first_line, sstate.first_mb);
 405                         } else {
 406                             fwd_mv = ZERO_MV;
 407                             mvi.set_zero_mv(mb_x);
 408                         }
 409                         let bwd_mv;
 410                         if has_bwd {
 411                             bwd_mv = mvi2.predict(mb_x, 0, false, binfo.get_mv2(0), sstate.first_line, sstate.first_mb);
 412                         } else {
 413                             bwd_mv = ZERO_MV;
 414                             mvi2.set_zero_mv(mb_x);
 415                         }
 416                         if let (Some(ref fwd_buf), Some(ref bck_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
 417                             if has_fwd && has_bwd {
 418                                 bdsp.copy_blocks(&mut buf, fwd_buf, mb_x * 16, mb_y * 16, 16, 16, fwd_mv);
 419                                 bdsp.avg_blocks (&mut buf, bck_buf, mb_x * 16, mb_y * 16, 16, 16, bwd_mv);
 420                             } else if has_fwd {
 421                                 bdsp.copy_blocks(&mut buf, fwd_buf, mb_x * 16, mb_y * 16, 16, 16, fwd_mv);
 422                             } else {
 423                                 bdsp.copy_blocks(&mut buf, bck_buf, mb_x * 16, mb_y * 16, 16, 16, bwd_mv);
 424                             }
 425                         }
 426                     } else {
 427                         if let BlockMVInfo::Inter_4MV(mvs) = ref_mv_info {
 428                             for blk_no in 0..4 {
 429                                 let ref_mv = mvs[blk_no];
 430                                 let ref_mv_fwd = ref_mv.scale(bsdiff, tsdiff);
 431                                 let ref_mv_bwd = ref_mv - ref_mv_fwd;
 432                                 let xoff = mb_x * 16 + (blk_no & 1) * 8;
 433                                 let yoff = mb_y * 16 + (blk_no & 2) * 4;
 434                                 if let (Some(ref fwd_buf), Some(ref bck_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
 435                                     bdsp.copy_blocks(&mut buf, fwd_buf, xoff, yoff, 8, 8, ref_mv_fwd);
 436                                     bdsp.avg_blocks (&mut buf, bck_buf, xoff, yoff, 8, 8, ref_mv_bwd);
 437                                 }
 438                             }
 439                         } else {
 440                             let ref_mv = if let BlockMVInfo::Inter_1MV(mv_) = ref_mv_info { mv_ } else { ZERO_MV };
 441                             let ref_mv_fwd = ref_mv.scale(bsdiff, tsdiff);
 442                             let ref_mv_bwd = MV::b_sub(ref_mv, ref_mv_fwd, ZERO_MV, bsdiff, tsdiff);
 443
 444                             if let (Some(ref fwd_buf), Some(ref bck_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
 445                                 bdsp.copy_blocks(&mut buf, fwd_buf, mb_x * 16, mb_y * 16, 16, 16, ref_mv_fwd);
 446                                 bdsp.avg_blocks (&mut buf, bck_buf, mb_x * 16, mb_y * 16, 16, 16, ref_mv_bwd);
 447                             }
 448                         }
 449                         mvi.set_zero_mv(mb_x);
 450                         mvi2.set_zero_mv(mb_x);
 451                     }
 452                     if cbp != 0 {
 453                         for i in 0..6 {
 454                             bd.decode_block_inter(&binfo, &sstate, binfo.get_q(), i, ((cbp >> (5 - i)) & 1) != 0, &mut blk[i])?;
 455                             bdsp.idct(&mut blk[i]);
 456                         }
 457                         blockdsp::add_blocks(&mut buf, mb_x, mb_y, &blk);
 458                     }
 459                 }
 460                 if pinfo.is_pb() {
 461                     let mut b_mb = BMB::new();
 462                     let cbp = binfo.get_cbp_b();
 463                     let bq = (((pinfo.get_pbinfo().get_dbquant() + 5) as u16) * (binfo.get_q() as u16)) >> 2;
 464                     let bquant;
 465                     if bq < 1 { bquant = 1; }
 466                     else if bq > 31 { bquant = 31; }
 467                     else { bquant = bq as u8; }
 468
 469                     b_mb.cbp = cbp;
 470                     for i in 0..6 {
 471                         bd.decode_block_inter(&binfo, &sstate, bquant, i, (cbp & (1 << (5 - i))) != 0, &mut b_mb.blk[i])?;
 472                         bdsp.idct(&mut b_mb.blk[i]);
 473                     }
 474
 475                     let is_fwd = binfo.is_b_fwd();
 476                     b_mb.fwd = is_fwd;
 477                     if binfo.get_num_mvs() != 4 {
 478                         let ref_mv = mvi2.get_mv(mb_x, 0);
 479                         let b_mv = if binfo.is_intra() { binfo.get_mv2(1) } else { binfo.get_mv2(0) };
 480                         let src_mv = if is_fwd { ZERO_MV } else { ref_mv.scale(bsdiff, tsdiff) };
 481                         let mv_f = MV::add_umv(src_mv, b_mv, pinfo.get_mvmode());
 482                         let mv_b = MV::b_sub(ref_mv, mv_f, b_mv, bsdiff, tsdiff);
 483                         b_mb.mv_f[0] = mv_f;
 484                         b_mb.mv_b[0] = mv_b;
 485                         b_mb.num_mv = 1;
 486                     } else {
 487                         for blk_no in 0..4 {
 488                             let src_mv = if is_fwd { ZERO_MV } else { mvi2.get_mv(mb_x, blk_no).scale(bsdiff, tsdiff) };
 489                             let mv_f = MV::add_umv(src_mv, binfo.get_mv2(0), pinfo.get_mvmode());
 490                             let mv_b = MV::b_sub(mvi2.get_mv(mb_x, blk_no), mv_f, binfo.get_mv2(0), bsdiff, tsdiff);
 491                             b_mb.mv_f[blk_no] = mv_f;
 492                             b_mb.mv_b[blk_no] = mv_b;
 493                         }
 494                         b_mb.num_mv = 4;
 495                     }
 496                     self.b_data.push(b_mb);
 497                 }
 498                 sstate.next_mb();
 499                 mb_pos += 1;
 500             }
 501             if let Some(plusinfo) = pinfo.plusinfo {
 502                 if plusinfo.deblock {
 503                     bdsp.filter_row(&mut buf, mb_y, self.mb_w, &cbpi);
 504                 }
 505             }
 506             mvi.update_row();
 507             if is_b || pinfo.is_pb() {
 508                 mvi2.update_row();
 509             }
 510             cbpi.update_row();
 511             sstate.new_row();
 512         }
 513
 514         if pinfo.mode.is_ref() {
 515             self.ipbs.add_frame(buf);
 516             self.next_ts = self.last_ts;
 517             self.last_ts = pinfo.ts;
 518             self.tsdiff  = tsdiff;
 519         }
 520
 521         Ok(bufinfo)
 522     }
 523     pub fn flush(&mut self) {
 524         self.ipbs.clear();
 525     }
 526
 527     pub fn get_bframe(&mut self, bdsp: &BlockDSP) -> DecoderResult<NABufferType> {
 528         if !self.has_b || self.ipbs.get_lastref().is_none() || self.ipbs.get_nextref().is_none() {
 529             return Err(DecoderError::MissingReference);
 530         }
 531         self.has_b = false;
 532
 533         let fmt = formats::YUV420_FORMAT;
 534         let vinfo = NAVideoInfo::new(self.w, self.h, false, fmt);
 535         let bufinfo = alloc_video_buffer(vinfo, 4)?;
 536         let mut b_buf = bufinfo.get_vbuf().unwrap();
 537
 538         if let (Some(ref bck_buf), Some(ref fwd_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
 539             recon_b_frame(&mut b_buf, fwd_buf, bck_buf, self.mb_w, self.mb_h, self.b_data.as_slice(), bdsp);
 540         }
 541
 542         self.b_data.truncate(0);
 543         Ok(bufinfo)
 544     }
 545 }
 546
 547 fn recon_b_frame(b_buf: &mut NAVideoBuffer<u8>, bck_buf: &NAVideoBuffer<u8>, fwd_buf: &NAVideoBuffer<u8>,
 548                  mb_w: usize, mb_h: usize, b_data: &[BMB], bdsp: &BlockDSP) {
 549     let mut cbpi = CBPInfo::new();
 550     let mut cur_mb = 0;
 551     cbpi.reset(mb_w);
 552     for mb_y in 0..mb_h {
 553         for mb_x in 0..mb_w {
 554             let num_mv = b_data[cur_mb].num_mv;
 555             let is_fwd = b_data[cur_mb].fwd;
 556             let cbp    = b_data[cur_mb].cbp;
 557             cbpi.set_cbp(mb_x, cbp);
 558             if num_mv == 1 {
 559                 bdsp.copy_blocks(b_buf, fwd_buf, mb_x * 16, mb_y * 16, 16, 16, b_data[cur_mb].mv_b[0]);
 560                 if !is_fwd {
 561                     bdsp.avg_blocks(b_buf, bck_buf, mb_x * 16, mb_y * 16, 16, 16, b_data[cur_mb].mv_f[0]);
 562                 }
 563             } else {
 564                 for blk_no in 0..4 {
 565                     let xpos = mb_x * 16 + (blk_no & 1) * 8;
 566                     let ypos = mb_y * 16 + (blk_no & 2) * 4;
 567                     bdsp.copy_blocks(b_buf, fwd_buf, xpos, ypos, 8, 8, b_data[cur_mb].mv_b[blk_no]);
 568                     if !is_fwd {
 569                         bdsp.avg_blocks(b_buf, bck_buf, xpos, ypos, 8, 8, b_data[cur_mb].mv_f[blk_no]);
 570                     }
 571                 }
 572             }
 573             if cbp != 0 {
 574                 blockdsp::add_blocks(b_buf, mb_x, mb_y, &b_data[cur_mb].blk);
 575             }
 576             cur_mb += 1;
 577         }
 578         cbpi.update_row();
 579     }
 580 }