nihav-codec-support/src/codecs/h263/decoder.rs

   1 //use std::mem;
   2 use nihav_core::codecs::DecoderError;
   3 use nihav_core::frame::*;
   4 use super::super::*;
   5 use super::super::blockdsp;
   6 use super::*;
   7 //use super::code::*;
   8 use nihav_core::formats;
   9
  10 #[allow(dead_code)]
  11 struct MVInfo {
  12     mv:         Vec<MV>,
  13     mb_w:       usize,
  14     mb_stride:  usize,
  15     mb_start:   usize,
  16     top:        bool,
  17     mvmode:     MVMode,
  18 }
  19
  20 impl MVInfo {
  21     fn new() -> Self { MVInfo{ mv: Vec::new(), mb_w: 0, mb_stride: 0, mb_start: 0, top: true, mvmode: MVMode::Old } }
  22     fn reset(&mut self, mb_w: usize, mb_start: usize, mvmode: MVMode) {
  23         self.mb_start  = mb_start;
  24         self.mb_w      = mb_w;
  25         self.mb_stride = mb_w * 2 + 2;
  26         self.mv.resize(self.mb_stride * 3, ZERO_MV);
  27         self.mvmode    = mvmode;
  28     }
  29     fn update_row(&mut self) {
  30         self.mb_start = self.mb_w + 1;
  31         self.top      = false;
  32         for i in 0..self.mb_stride {
  33             self.mv[i] = self.mv[self.mb_stride * 2 + i];
  34         }
  35     }
  36     #[allow(non_snake_case)]
  37     fn predict(&mut self, mb_x: usize, blk_no: usize, use4: bool, diff: MV, first_line: bool, first_mb: bool) -> MV {
  38         let A;
  39         let B;
  40         let C;
  41         let last = mb_x == self.mb_w - 1;
  42         match blk_no {
  43             0 => {
  44                     if mb_x != self.mb_start {
  45                         A = if !first_mb   { self.mv[self.mb_stride + mb_x * 2 - 1] } else { ZERO_MV };
  46                         B = if !first_line { self.mv[                 mb_x * 2] } else { A };
  47                         C = if !first_line && !last { self.mv[mb_x * 2 + 2] } else { ZERO_MV };
  48                     } else {
  49                         A = ZERO_MV; B = ZERO_MV; C = ZERO_MV;
  50                     }
  51                 },
  52             1 => {
  53                     A = self.mv[self.mb_stride + mb_x * 2];
  54                     B = if !first_line { self.mv[mb_x * 2 + 1] } else { A };
  55                     C = if !first_line && !last { self.mv[mb_x * 2 + 2] } else { ZERO_MV/*A*/ };
  56                 },
  57             2 => {
  58                     A = if mb_x != self.mb_start { self.mv[self.mb_stride * 2 + mb_x * 2 - 1] } else { ZERO_MV };
  59                     B = self.mv[self.mb_stride + mb_x * 2];
  60                     C = self.mv[self.mb_stride + mb_x * 2 + 1];
  61                 },
  62             3 => {
  63                     A = self.mv[self.mb_stride * 2 + mb_x * 2];
  64                     B = self.mv[self.mb_stride * 1 + mb_x * 2 + 1];
  65                     C = self.mv[self.mb_stride * 1 + mb_x * 2];
  66                 },
  67             _ => { return ZERO_MV; }
  68         }
  69         let pred_mv = MV::pred(A, B, C);
  70         let new_mv = MV::add_umv(pred_mv, diff, self.mvmode);
  71         if !use4 {
  72             self.mv[self.mb_stride * 1 + mb_x * 2 + 0] = new_mv;
  73             self.mv[self.mb_stride * 1 + mb_x * 2 + 1] = new_mv;
  74             self.mv[self.mb_stride * 2 + mb_x * 2 + 0] = new_mv;
  75             self.mv[self.mb_stride * 2 + mb_x * 2 + 1] = new_mv;
  76         } else {
  77             match blk_no {
  78                 0 => { self.mv[self.mb_stride * 1 + mb_x * 2 + 0] = new_mv; },
  79                 1 => { self.mv[self.mb_stride * 1 + mb_x * 2 + 1] = new_mv; },
  80                 2 => { self.mv[self.mb_stride * 2 + mb_x * 2 + 0] = new_mv; },
  81                 3 => { self.mv[self.mb_stride * 2 + mb_x * 2 + 1] = new_mv; },
  82                 _ => {},
  83             };
  84         }
  85
  86         new_mv
  87     }
  88     fn set_zero_mv(&mut self, mb_x: usize) {
  89         self.mv[self.mb_stride * 1 + mb_x * 2 + 0] = ZERO_MV;
  90         self.mv[self.mb_stride * 1 + mb_x * 2 + 1] = ZERO_MV;
  91         self.mv[self.mb_stride * 2 + mb_x * 2 + 0] = ZERO_MV;
  92         self.mv[self.mb_stride * 2 + mb_x * 2 + 1] = ZERO_MV;
  93     }
  94     fn get_mv(&self, mb_x: usize, blk_no: usize) -> MV {
  95         self.mv[self.mb_stride + mb_x * 2 + (blk_no & 1) + (blk_no >> 1) * self.mb_stride]
  96     }
  97 }
  98
  99 #[allow(dead_code)]
 100 #[derive(Clone,Copy)]
 101 struct BMB {
 102     num_mv: usize,
 103     mv_f:   [MV; 4],
 104     mv_b:   [MV; 4],
 105     fwd:    bool,
 106     blk:    [[i16; 64]; 6],
 107     cbp:    u8,
 108 }
 109
 110 impl BMB {
 111     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} }
 112 }
 113
 114 #[derive(Clone,Copy)]
 115 struct PredCoeffs {
 116     hor: [[i16; 8]; 6],
 117     ver: [[i16; 8]; 6],
 118 }
 119
 120 const ZERO_PRED_COEFFS: PredCoeffs = PredCoeffs { hor: [[0; 8]; 6], ver: [[0; 8]; 6] };
 121
 122 pub struct H263BaseDecoder {
 123     w:          usize,
 124     h:          usize,
 125     mb_w:       usize,
 126     mb_h:       usize,
 127     num_mb:     usize,
 128     ftype:      Type,
 129     ipbs:       IPBShuffler,
 130     next_ts:    u16,
 131     last_ts:    u16,
 132     tsdiff:     u16,
 133     has_b:      bool,
 134     b_data:     Vec<BMB>,
 135     pred_coeffs: Vec<PredCoeffs>,
 136     is_gob:     bool,
 137     slice_reset: bool,
 138     may_have_b_frames: bool,
 139     mv_data:    Vec<BlockMVInfo>,
 140 }
 141
 142 #[inline]
 143 fn clip_dc(dc: i16) -> i16 {
 144     if dc <= 0 { 0 }
 145     else if dc > 2046 { 2047 }
 146     else { dc | 1 }
 147 }
 148
 149 #[inline]
 150 fn clip_ac(ac: i16) -> i16 {
 151     if ac < -2048 { -2048 }
 152     else if ac > 2047 { 2047 }
 153     else { ac }
 154 }
 155
 156 #[allow(dead_code)]
 157 impl H263BaseDecoder {
 158     pub fn new_with_opts(is_gob: bool, slice_reset: bool, may_have_b_frames: bool) -> Self {
 159         H263BaseDecoder{
 160             w: 0, h: 0, mb_w: 0, mb_h: 0, num_mb: 0,
 161             ftype: Type::Special,
 162             ipbs: IPBShuffler::new(),
 163             last_ts: 0, next_ts: 0, tsdiff: 0,
 164             has_b: false, b_data: Vec::new(),
 165             pred_coeffs: Vec::new(),
 166             is_gob, slice_reset,
 167             may_have_b_frames,
 168             mv_data: Vec::new(),
 169         }
 170     }
 171     pub fn new(is_gob: bool) -> Self {
 172         Self::new_with_opts(is_gob, true, false)
 173     }
 174     pub fn new_b_frames(is_gob: bool) -> Self {
 175         Self::new_with_opts(is_gob, true, true)
 176     }
 177
 178     pub fn is_intra(&self) -> bool { self.ftype == Type::I }
 179     pub fn get_frame_type(&self) -> FrameType {
 180         match self.ftype {
 181             Type::I       => FrameType::I,
 182             Type::P       => FrameType::P,
 183             Type::B       => FrameType::B,
 184             Type::PB      => FrameType::P,
 185             Type::Skip    => FrameType::Skip,
 186             Type::Special => FrameType::Skip,
 187         }
 188     }
 189     pub fn get_dimensions(&self) -> (usize, usize) { (self.w, self.h) }
 190
 191     pub fn parse_frame(&mut self, bd: &mut BlockDecoder, bdsp: &BlockDSP) -> DecoderResult<NABufferType> {
 192         let pinfo = bd.decode_pichdr()?;
 193         let mut mvi = MVInfo::new();
 194         let mut mvi2 = MVInfo::new();
 195         let mut cbpi = CBPInfo::new();
 196
 197 //todo handle res change
 198         self.w = pinfo.w;
 199         self.h = pinfo.h;
 200         self.mb_w = (pinfo.w + 15) >> 4;
 201         self.mb_h = (pinfo.h + 15) >> 4;
 202         self.num_mb = self.mb_w * self.mb_h;
 203         self.ftype = pinfo.mode;
 204         self.has_b = pinfo.is_pb();
 205
 206         if self.has_b {
 207             self.mv_data.truncate(0);
 208         }
 209
 210         let save_b_data = pinfo.mode.is_ref() && self.may_have_b_frames;
 211         if save_b_data {
 212             self.mv_data.truncate(0);
 213         }
 214         let is_b = pinfo.mode == Type::B;
 215
 216         let tsdiff = if pinfo.is_pb() { pinfo.ts.wrapping_sub(self.last_ts) >> 1 }
 217                      else { self.last_ts.wrapping_sub(self.next_ts) >> 1 };
 218         let bsdiff = if pinfo.is_pb() { (pinfo.get_pbinfo().get_trb() as u16) << 7 }
 219                      else { pinfo.ts.wrapping_sub(self.next_ts) >> 1 };
 220
 221         let fmt = formats::YUV420_FORMAT;
 222         let vinfo = NAVideoInfo::new(self.w, self.h, false, fmt);
 223         let bufinfo = alloc_video_buffer(vinfo, 4)?;
 224         let mut buf = bufinfo.get_vbuf().unwrap();
 225
 226         let mut slice = if self.is_gob {
 227                 SliceInfo::get_default_slice(&pinfo)
 228             } else {
 229                 bd.decode_slice_header(&pinfo)?
 230             };
 231         mvi.reset(self.mb_w, 0, pinfo.get_mvmode());
 232         if is_b || pinfo.is_pb() {
 233             mvi2.reset(self.mb_w, 0, pinfo.get_mvmode());
 234         }
 235         cbpi.reset(self.mb_w);
 236
 237         let mut blk: [[i16; 64]; 6] = [[0; 64]; 6];
 238         let mut sstate = SliceState::new(pinfo.mode == Type::I);
 239         let mut mb_pos = 0;
 240         let apply_acpred = (pinfo.mode == Type::I) && pinfo.plusinfo.is_some() && pinfo.plusinfo.unwrap().aic;
 241         if apply_acpred {
 242             self.pred_coeffs.truncate(0);
 243             self.pred_coeffs.resize(self.mb_w * self.mb_h, ZERO_PRED_COEFFS);
 244         }
 245         sstate.quant = slice.quant;
 246         for mb_y in 0..self.mb_h {
 247             for mb_x in 0..self.mb_w {
 248                 for i in 0..6 { for j in 0..64 { blk[i][j] = 0; } }
 249
 250                 if slice.is_at_end(mb_pos) || (slice.needs_check() && mb_pos > 0 && bd.is_slice_end()) {
 251                     slice = bd.decode_slice_header(&pinfo)?;
 252                     if !self.is_gob && self.slice_reset {
 253                         mvi.reset(self.mb_w, mb_x, pinfo.get_mvmode());
 254                         if is_b || pinfo.is_pb() {
 255                             mvi2.reset(self.mb_w, mb_x, pinfo.get_mvmode());
 256                         }
 257                         cbpi.reset(self.mb_w);
 258                         sstate.reset_slice(mb_x, mb_y);
 259                         sstate.quant = slice.quant;
 260                     }
 261                 }
 262
 263                 let binfo = bd.decode_block_header(&pinfo, &slice, &sstate)?;
 264                 let cbp = binfo.get_cbp();
 265                 cbpi.set_cbp(mb_x, cbp);
 266                 cbpi.set_q(mb_x, binfo.get_q());
 267                 sstate.quant = binfo.get_q();
 268                 if binfo.is_intra() {
 269                     if save_b_data {
 270                         self.mv_data.push(BlockMVInfo::Intra);
 271                     }
 272                     for i in 0..6 {
 273                         bd.decode_block_intra(&binfo, &sstate, binfo.get_q(), i, (cbp & (1 << (5 - i))) != 0, &mut blk[i])?;
 274                         if apply_acpred && (binfo.acpred != ACPredMode::None) {
 275                             let has_b = (i == 1) || (i == 3) || !sstate.first_mb;
 276                             let has_a = (i == 2) || (i == 3) || !sstate.first_line;
 277                             let (b_mb, b_blk) = if has_b {
 278                                     if (i == 1) || (i == 3) {
 279                                         (mb_pos, i - 1)
 280                                     } else if i < 4 {
 281                                         (mb_pos - 1, i + 1)
 282                                     } else {
 283                                         (mb_pos - 1, i)
 284                                     }
 285                                 } else { (0, 0) };
 286                             let (a_mb, a_blk) = if has_a {
 287                                     if (i == 2) || (i == 3) {
 288                                         (mb_pos, i - 2)
 289                                     } else if i < 4 {
 290                                         (mb_pos - self.mb_w, i + 2)
 291                                     } else {
 292                                         (mb_pos - self.mb_w, i)
 293                                     }
 294                                 } else { (0, 0) };
 295                             match binfo.acpred {
 296                                 ACPredMode::DC   => {
 297                                             let dc;
 298                                             if has_a && has_b {
 299                                                 dc = (self.pred_coeffs[b_mb].hor[b_blk][0] + self.pred_coeffs[a_mb].ver[a_blk][0]) / 2;
 300                                             } else if has_a {
 301                                                 dc = self.pred_coeffs[a_mb].ver[a_blk][0];
 302                                             } else if has_b {
 303                                                 dc = self.pred_coeffs[b_mb].hor[b_blk][0];
 304                                             } else {
 305                                                 dc = 1024;
 306                                             }
 307                                             blk[i][0] = clip_dc(blk[i][0] + dc);
 308                                         },
 309                                 ACPredMode::Hor  => {
 310                                         if has_b {
 311                                             for k in 0..8 {
 312                                                 blk[i][k * 8] += self.pred_coeffs[b_mb].hor[b_blk][k];
 313                                             }
 314                                             for k in 1..8 {
 315                                                 blk[i][k * 8] = clip_ac(blk[i][k * 8]);
 316                                             }
 317                                         } else {
 318                                             blk[i][0] += 1024;
 319                                         }
 320                                         blk[i][0] = clip_dc(blk[i][0]);
 321                                     },
 322                                 ACPredMode::Ver  => {
 323                                         if has_a {
 324                                             for k in 0..8 {
 325                                                 blk[i][k] += self.pred_coeffs[a_mb].ver[a_blk][k];
 326                                             }
 327                                             for k in 1..8 {
 328                                                 blk[i][k] = clip_ac(blk[i][k]);
 329                                             }
 330                                         } else {
 331                                             blk[i][0] += 1024;
 332                                         }
 333                                         blk[i][0] = clip_dc(blk[i][0]);
 334                                     },
 335                                 ACPredMode::None => {},
 336                             };
 337                             for t in 0..8 { self.pred_coeffs[mb_pos].hor[i][t] = blk[i][t * 8]; }
 338                             for t in 0..8 { self.pred_coeffs[mb_pos].ver[i][t] = blk[i][t]; }
 339                         }
 340                         bdsp.idct(&mut blk[i]);
 341                     }
 342                     blockdsp::put_blocks(&mut buf, mb_x, mb_y, &blk);
 343                     mvi.set_zero_mv(mb_x);
 344                     if is_b {
 345                         mvi2.set_zero_mv(mb_x);
 346                     } else if pinfo.is_pb() {
 347                         mvi2.predict(mb_x, 0, false, binfo.get_mv2(0), sstate.first_line, sstate.first_mb);
 348                     }
 349                 } else if (binfo.mode != Type::B) && !binfo.is_skipped() {
 350                     if binfo.get_num_mvs() == 1 {
 351                         let mv = mvi.predict(mb_x, 0, false, binfo.get_mv(0), sstate.first_line, sstate.first_mb);
 352                         if save_b_data {
 353                             self.mv_data.push(BlockMVInfo::Inter_1MV(mv));
 354                         }
 355                         if let Some(ref srcbuf) = self.ipbs.get_lastref() {
 356                             bdsp.copy_blocks(&mut buf, srcbuf.clone(), mb_x * 16, mb_y * 16, mv);
 357                         }
 358                         if pinfo.is_pb() {
 359                             mvi2.predict(mb_x, 0, false, binfo.get_mv(0), sstate.first_line, sstate.first_mb);
 360                         }
 361                     } else {
 362                         let mut mv: [MV; 4] = [ZERO_MV, ZERO_MV, ZERO_MV, ZERO_MV];
 363                         for blk_no in 0..4 {
 364                             mv[blk_no] = mvi.predict(mb_x, blk_no, true, binfo.get_mv(blk_no), sstate.first_line, sstate.first_mb);
 365                         }
 366                         if let Some(ref srcbuf) = self.ipbs.get_lastref() {
 367                             bdsp.copy_blocks8x8(&mut buf, srcbuf.clone(), mb_x * 16, mb_y * 16, &mv);
 368                         }
 369                         if pinfo.is_pb() {
 370                             for blk_no in 0..4 {
 371                                 mvi2.predict(mb_x, blk_no, true, binfo.get_mv(blk_no), sstate.first_line, sstate.first_mb);
 372                             }
 373                         }
 374                         if save_b_data {
 375                             self.mv_data.push(BlockMVInfo::Inter_4MV(mv));
 376                         }
 377                     }
 378                     for i in 0..6 {
 379                         bd.decode_block_inter(&binfo, &sstate, binfo.get_q(), i, ((cbp >> (5 - i)) & 1) != 0, &mut blk[i])?;
 380                         bdsp.idct(&mut blk[i]);
 381                     }
 382                     blockdsp::add_blocks(&mut buf, mb_x, mb_y, &blk);
 383                     if is_b && !pinfo.is_pb() {
 384                         mvi2.set_zero_mv(mb_x);
 385                     }
 386                 } else if binfo.mode != Type::B {
 387                     self.mv_data.push(BlockMVInfo::Inter_1MV(ZERO_MV));
 388                     mvi.set_zero_mv(mb_x);
 389                     if is_b || pinfo.is_pb() {
 390                         mvi2.set_zero_mv(mb_x);
 391                     }
 392                     if let Some(ref srcbuf) = self.ipbs.get_lastref() {
 393                         bdsp.copy_blocks(&mut buf, srcbuf.clone(), mb_x * 16, mb_y * 16, ZERO_MV);
 394                     }
 395                 } else {
 396                     let ref_mv_info = self.mv_data[mb_pos];
 397                     let has_fwd = binfo.get_num_mvs() > 0;
 398                     let has_bwd = binfo.get_num_mvs2() > 0;
 399 //todo refactor
 400                     if has_fwd || has_bwd {
 401                         let fwd_mv;
 402                         if has_fwd {
 403                             fwd_mv = mvi.predict(mb_x, 0, false, binfo.get_mv(0), sstate.first_line, sstate.first_mb);
 404                         } else {
 405                             fwd_mv = ZERO_MV;
 406                             mvi.set_zero_mv(mb_x);
 407                         }
 408                         let bwd_mv;
 409                         if has_bwd {
 410                             bwd_mv = mvi2.predict(mb_x, 0, false, binfo.get_mv2(0), sstate.first_line, sstate.first_mb);
 411                         } else {
 412                             bwd_mv = ZERO_MV;
 413                             mvi2.set_zero_mv(mb_x);
 414                         }
 415                         if let (Some(ref fwd_buf), Some(ref bck_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
 416                             if has_fwd && has_bwd {
 417                                 bdsp.copy_blocks(&mut buf, fwd_buf.clone(), mb_x * 16, mb_y * 16, fwd_mv);
 418                                 bdsp.avg_blocks (&mut buf, bck_buf.clone(), mb_x * 16, mb_y * 16, bwd_mv);
 419                             } else if has_fwd {
 420                                 bdsp.copy_blocks(&mut buf, fwd_buf.clone(), mb_x * 16, mb_y * 16, fwd_mv);
 421                             } else {
 422                                 bdsp.copy_blocks(&mut buf, bck_buf.clone(), mb_x * 16, mb_y * 16, bwd_mv);
 423                             }
 424                         }
 425                     } else {
 426                         if let BlockMVInfo::Inter_4MV(mvs) = ref_mv_info {
 427                             let mut mv_f = [ZERO_MV; 4];
 428                             let mut mv_b = [ZERO_MV; 4];
 429                             for blk_no in 0..4 {
 430                                 let ref_mv = mvs[blk_no];
 431                                 let ref_mv_fwd = ref_mv.scale(bsdiff, tsdiff);
 432                                 let ref_mv_bwd = ref_mv - ref_mv_fwd;
 433                                 mv_f[blk_no] = ref_mv_fwd;
 434                                 mv_b[blk_no] = ref_mv_bwd;
 435                             }
 436                             if let (Some(ref fwd_buf), Some(ref bck_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
 437                                 bdsp.copy_blocks8x8(&mut buf, fwd_buf.clone(), mb_x * 16, mb_y * 16, &mv_f);
 438                                 bdsp.avg_blocks8x8 (&mut buf, bck_buf.clone(), mb_x * 16, mb_y * 16, &mv_b);
 439                             }
 440                         } else {
 441                             let ref_mv = if let BlockMVInfo::Inter_1MV(mv_) = ref_mv_info { mv_ } else { ZERO_MV };
 442                             let ref_mv_fwd = ref_mv.scale(bsdiff, tsdiff);
 443                             let ref_mv_bwd = MV::b_sub(ref_mv, ref_mv_fwd, ZERO_MV, bsdiff, tsdiff);
 444
 445                             if let (Some(ref fwd_buf), Some(ref bck_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
 446                                 bdsp.copy_blocks(&mut buf, fwd_buf.clone(), mb_x * 16, mb_y * 16, ref_mv_fwd);
 447                                 bdsp.avg_blocks (&mut buf, bck_buf.clone(), mb_x * 16, mb_y * 16, ref_mv_bwd);
 448                             }
 449                         }
 450                         mvi.set_zero_mv(mb_x);
 451                         mvi2.set_zero_mv(mb_x);
 452                     }
 453                     if cbp != 0 {
 454                         for i in 0..6 {
 455                             bd.decode_block_inter(&binfo, &sstate, binfo.get_q(), i, ((cbp >> (5 - i)) & 1) != 0, &mut blk[i])?;
 456                             bdsp.idct(&mut blk[i]);
 457                         }
 458                         blockdsp::add_blocks(&mut buf, mb_x, mb_y, &blk);
 459                     }
 460                 }
 461                 if pinfo.is_pb() {
 462                     let mut b_mb = BMB::new();
 463                     let cbp = binfo.get_cbp_b();
 464                     let bq = (((pinfo.get_pbinfo().get_dbquant() + 5) as u16) * (binfo.get_q() as u16)) >> 2;
 465                     let bquant;
 466                     if bq < 1 { bquant = 1; }
 467                     else if bq > 31 { bquant = 31; }
 468                     else { bquant = bq as u8; }
 469
 470                     b_mb.cbp = cbp;
 471                     for i in 0..6 {
 472                         bd.decode_block_inter(&binfo, &sstate, bquant, i, (cbp & (1 << (5 - i))) != 0, &mut b_mb.blk[i])?;
 473                         bdsp.idct(&mut b_mb.blk[i]);
 474                     }
 475
 476                     let is_fwd = binfo.is_b_fwd();
 477                     b_mb.fwd = is_fwd;
 478                     if binfo.get_num_mvs() != 4 {
 479                         let ref_mv = mvi2.get_mv(mb_x, 0);
 480                         let b_mv = if binfo.is_intra() { binfo.get_mv2(1) } else { binfo.get_mv2(0) };
 481                         let src_mv = if is_fwd { ZERO_MV } else { ref_mv.scale(bsdiff, tsdiff) };
 482                         let mv_f = MV::add_umv(src_mv, b_mv, pinfo.get_mvmode());
 483                         let mv_b = MV::b_sub(ref_mv, mv_f, b_mv, bsdiff, tsdiff);
 484                         b_mb.mv_f[0] = mv_f;
 485                         b_mb.mv_b[0] = mv_b;
 486                         b_mb.num_mv = 1;
 487                     } else {
 488                         for blk_no in 0..4 {
 489                             let src_mv = if is_fwd { ZERO_MV } else { mvi2.get_mv(mb_x, blk_no).scale(bsdiff, tsdiff) };
 490                             let mv_f = MV::add_umv(src_mv, binfo.get_mv2(0), pinfo.get_mvmode());
 491                             let mv_b = MV::b_sub(mvi2.get_mv(mb_x, blk_no), mv_f, binfo.get_mv2(0), bsdiff, tsdiff);
 492                             b_mb.mv_f[blk_no] = mv_f;
 493                             b_mb.mv_b[blk_no] = mv_b;
 494                         }
 495                         b_mb.num_mv = 4;
 496                     }
 497                     self.b_data.push(b_mb);
 498                 }
 499                 sstate.next_mb();
 500                 mb_pos += 1;
 501             }
 502             if let Some(plusinfo) = pinfo.plusinfo {
 503                 if plusinfo.deblock {
 504                     bdsp.filter_row(&mut buf, mb_y, self.mb_w, &cbpi);
 505                 }
 506             }
 507             mvi.update_row();
 508             if is_b || pinfo.is_pb() {
 509                 mvi2.update_row();
 510             }
 511             cbpi.update_row();
 512             sstate.new_row();
 513         }
 514
 515         if pinfo.mode.is_ref() {
 516             self.ipbs.add_frame(buf);
 517             self.next_ts = self.last_ts;
 518             self.last_ts = pinfo.ts;
 519             self.tsdiff  = tsdiff;
 520         }
 521
 522         Ok(bufinfo)
 523     }
 524     pub fn flush(&mut self) {
 525         self.ipbs.clear();
 526     }
 527
 528     pub fn get_bframe(&mut self, bdsp: &BlockDSP) -> DecoderResult<NABufferType> {
 529         if !self.has_b || self.ipbs.get_lastref().is_none() || self.ipbs.get_nextref().is_none() {
 530             return Err(DecoderError::MissingReference);
 531         }
 532         self.has_b = false;
 533
 534         let fmt = formats::YUV420_FORMAT;
 535         let vinfo = NAVideoInfo::new(self.w, self.h, false, fmt);
 536         let bufinfo = alloc_video_buffer(vinfo, 4)?;
 537         let b_buf = bufinfo.get_vbuf().unwrap();
 538
 539         if let (Some(ref bck_buf), Some(ref fwd_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
 540             recon_b_frame(b_buf, fwd_buf.clone(), bck_buf.clone(), self.mb_w, self.mb_h, self.b_data.as_slice(), bdsp);
 541         }
 542
 543         self.b_data.truncate(0);
 544         Ok(bufinfo)
 545     }
 546 }
 547
 548 fn recon_b_frame(mut b_buf: NAVideoBufferRef<u8>, bck_buf: NAVideoBufferRef<u8>, fwd_buf: NAVideoBufferRef<u8>,
 549                  mb_w: usize, mb_h: usize, b_data: &[BMB], bdsp: &BlockDSP) {
 550     let mut cbpi = CBPInfo::new();
 551     let mut cur_mb = 0;
 552     cbpi.reset(mb_w);
 553     for mb_y in 0..mb_h {
 554         for mb_x in 0..mb_w {
 555             let num_mv = b_data[cur_mb].num_mv;
 556             let is_fwd = b_data[cur_mb].fwd;
 557             let cbp    = b_data[cur_mb].cbp;
 558             cbpi.set_cbp(mb_x, cbp);
 559             if num_mv == 1 {
 560                 bdsp.copy_blocks(&mut b_buf, fwd_buf.clone(), mb_x * 16, mb_y * 16, b_data[cur_mb].mv_b[0]);
 561                 if !is_fwd {
 562                     bdsp.avg_blocks(&mut b_buf, bck_buf.clone(), mb_x * 16, mb_y * 16, b_data[cur_mb].mv_f[0]);
 563                 }
 564             } else {
 565                 bdsp.copy_blocks8x8(&mut b_buf, fwd_buf.clone(), mb_x * 16, mb_y * 16, &b_data[cur_mb].mv_b);
 566                 if !is_fwd {
 567                     bdsp.avg_blocks8x8(&mut b_buf, bck_buf.clone(), mb_x * 16, mb_y * 16, &b_data[cur_mb].mv_f);
 568                 }
 569             }
 570             if cbp != 0 {
 571                 blockdsp::add_blocks(&mut b_buf, mb_x, mb_y, &b_data[cur_mb].blk);
 572             }
 573             cur_mb += 1;
 574         }
 575         cbpi.update_row();
 576     }
 577 }