split nihav-codec-support crate from nihav-core

The former is intended just for NihAV decoders, the latter is for both
NihAV crates and for the code using NihAV.

1 files changed, 581 insertions, 0 deletions

diff --git a/nihav-codec-support/src/codecs/h263/decoder.rs b/nihav-codec-support/src/codecs/h263/decoder.rs
new file mode 100644
index 0000000..929854a
--- /dev/null
+++ b/nihav-codec-support/src/codecs/h263/decoder.rs
@@ -0,0 +1,581 @@
+//use std::mem;
+use nihav_core::codecs::DecoderError;
+use nihav_core::frame::*;
+use super::super::*;
+use super::super::blockdsp;
+use super::*;
+//use super::code::*;
+use nihav_core::formats;
+
+#[allow(dead_code)]
+struct MVInfo {
+    mv:         Vec<MV>,
+    mb_w:       usize,
+    mb_stride:  usize,
+    mb_start:   usize,
+    top:        bool,
+    mvmode:     MVMode,
+}
+
+impl MVInfo {
+    fn new() -> Self { MVInfo{ mv: Vec::new(), mb_w: 0, mb_stride: 0, mb_start: 0, top: true, mvmode: MVMode::Old } }
+    fn reset(&mut self, mb_w: usize, mb_start: usize, mvmode: MVMode) {
+        self.mb_start  = mb_start;
+        self.mb_w      = mb_w;
+        self.mb_stride = mb_w * 2;
+        self.mv.resize(self.mb_stride * 3, ZERO_MV);
+        self.mvmode    = mvmode;
+    }
+    fn update_row(&mut self) {
+        self.mb_start = self.mb_w + 1;
+        self.top      = false;
+        for i in 0..self.mb_stride {
+            self.mv[i] = self.mv[self.mb_stride * 2 + i];
+        }
+    }
+    #[allow(non_snake_case)]
+    fn predict(&mut self, mb_x: usize, blk_no: usize, use4: bool, diff: MV, first_line: bool, first_mb: bool) -> MV {
+        let A;
+        let B;
+        let C;
+        let last = mb_x == self.mb_w - 1;
+        match blk_no {
+            0 => {
+                    if mb_x != self.mb_start {
+                        A = if !first_mb   { self.mv[self.mb_stride + mb_x * 2 - 1] } else { ZERO_MV };
+                        B = if !first_line { self.mv[                 mb_x * 2] } else { A };
+                        C = if !first_line && !last { self.mv[mb_x * 2 + 2] } else { ZERO_MV };
+                    } else {
+                        A = ZERO_MV; B = ZERO_MV; C = ZERO_MV;
+                    }
+                },
+            1 => {
+                    A = self.mv[self.mb_stride + mb_x * 2];
+                    B = if !first_line { self.mv[mb_x * 2 + 1] } else { A };
+                    C = if !first_line && !last { self.mv[mb_x * 2 + 2] } else { ZERO_MV/*A*/ };
+                },
+            2 => {
+                    A = if mb_x != self.mb_start { self.mv[self.mb_stride * 2 + mb_x * 2 - 1] } else { ZERO_MV };
+                    B = self.mv[self.mb_stride + mb_x * 2];
+                    C = self.mv[self.mb_stride + mb_x * 2 + 1];
+                },
+            3 => {
+                    A = self.mv[self.mb_stride * 2 + mb_x * 2];
+                    B = self.mv[self.mb_stride * 1 + mb_x * 2 + 1];
+                    C = self.mv[self.mb_stride * 1 + mb_x * 2];
+                },
+            _ => { return ZERO_MV; }
+        }
+        let pred_mv = MV::pred(A, B, C);
+        let new_mv = MV::add_umv(pred_mv, diff, self.mvmode);
+        if !use4 {
+            self.mv[self.mb_stride * 1 + mb_x * 2 + 0] = new_mv;
+            self.mv[self.mb_stride * 1 + mb_x * 2 + 1] = new_mv;
+            self.mv[self.mb_stride * 2 + mb_x * 2 + 0] = new_mv;
+            self.mv[self.mb_stride * 2 + mb_x * 2 + 1] = new_mv;
+        } else {
+            match blk_no {
+                0 => { self.mv[self.mb_stride * 1 + mb_x * 2 + 0] = new_mv; },
+                1 => { self.mv[self.mb_stride * 1 + mb_x * 2 + 1] = new_mv; },
+                2 => { self.mv[self.mb_stride * 2 + mb_x * 2 + 0] = new_mv; },
+                3 => { self.mv[self.mb_stride * 2 + mb_x * 2 + 1] = new_mv; },
+                _ => {},
+            };
+        }
+
+        new_mv
+    }
+    fn set_zero_mv(&mut self, mb_x: usize) {
+        self.mv[self.mb_stride * 1 + mb_x * 2 + 0] = ZERO_MV;
+        self.mv[self.mb_stride * 1 + mb_x * 2 + 1] = ZERO_MV;
+        self.mv[self.mb_stride * 2 + mb_x * 2 + 0] = ZERO_MV;
+        self.mv[self.mb_stride * 2 + mb_x * 2 + 1] = ZERO_MV;
+    }
+    fn get_mv(&self, mb_x: usize, blk_no: usize) -> MV {
+        self.mv[self.mb_stride + mb_x * 2 + (blk_no & 1) + (blk_no >> 1) * self.mb_stride]
+    }
+}
+
+#[allow(dead_code)]
+#[derive(Clone,Copy)]
+struct BMB {
+    num_mv: usize,
+    mv_f:   [MV; 4],
+    mv_b:   [MV; 4],
+    fwd:    bool,
+    blk:    [[i16; 64]; 6],
+    cbp:    u8,
+}
+
+impl BMB {
+    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} }
+}
+
+#[derive(Clone,Copy)]
+struct PredCoeffs {
+    hor: [[i16; 8]; 6],
+    ver: [[i16; 8]; 6],
+}
+
+const ZERO_PRED_COEFFS: PredCoeffs = PredCoeffs { hor: [[0; 8]; 6], ver: [[0; 8]; 6] };
+
+pub struct H263BaseDecoder {
+    w:          usize,
+    h:          usize,
+    mb_w:       usize,
+    mb_h:       usize,
+    num_mb:     usize,
+    ftype:      Type,
+    ipbs:       IPBShuffler,
+    next_ts:    u16,
+    last_ts:    u16,
+    tsdiff:     u16,
+    has_b:      bool,
+    b_data:     Vec<BMB>,
+    pred_coeffs: Vec<PredCoeffs>,
+    is_gob:     bool,
+    slice_reset: bool,
+    may_have_b_frames: bool,
+    mv_data:    Vec<BlockMVInfo>,
+}
+
+#[inline]
+fn clip_dc(dc: i16) -> i16 {
+    if dc < 0 { 0 }
+    else if dc > 2046 { 2046 }
+    else { (dc + 1) & !1 }
+}
+
+#[inline]
+fn clip_ac(ac: i16) -> i16 {
+    if ac < -2048 { -2048 }
+    else if ac > 2047 { 2047 }
+    else { ac }
+}
+
+#[allow(dead_code)]
+impl H263BaseDecoder {
+    pub fn new_with_opts(is_gob: bool, slice_reset: bool, may_have_b_frames: bool) -> Self {
+        H263BaseDecoder{
+            w: 0, h: 0, mb_w: 0, mb_h: 0, num_mb: 0,
+            ftype: Type::Special,
+            ipbs: IPBShuffler::new(),
+            last_ts: 0, next_ts: 0, tsdiff: 0,
+            has_b: false, b_data: Vec::new(),
+            pred_coeffs: Vec::new(),
+            is_gob, slice_reset,
+            may_have_b_frames,
+            mv_data: Vec::new(),
+        }
+    }
+    pub fn new(is_gob: bool) -> Self {
+        Self::new_with_opts(is_gob, true, false)
+    }
+    pub fn new_b_frames(is_gob: bool) -> Self {
+        Self::new_with_opts(is_gob, true, true)
+    }
+
+    pub fn is_intra(&self) -> bool { self.ftype == Type::I }
+    pub fn get_frame_type(&self) -> FrameType {
+        match self.ftype {
+            Type::I       => FrameType::I,
+            Type::P       => FrameType::P,
+            Type::B       => FrameType::B,
+            Type::PB      => FrameType::P,
+            Type::Skip    => FrameType::Skip,
+            Type::Special => FrameType::Skip,
+        }
+    }
+    pub fn get_dimensions(&self) -> (usize, usize) { (self.w, self.h) }
+
+    pub fn parse_frame(&mut self, bd: &mut BlockDecoder, bdsp: &BlockDSP) -> DecoderResult<NABufferType> {
+        let pinfo = bd.decode_pichdr()?;
+        let mut mvi = MVInfo::new();
+        let mut mvi2 = MVInfo::new();
+        let mut cbpi = CBPInfo::new();
+
+//todo handle res change
+        self.w = pinfo.w;
+        self.h = pinfo.h;
+        self.mb_w = (pinfo.w + 15) >> 4;
+        self.mb_h = (pinfo.h + 15) >> 4;
+        self.num_mb = self.mb_w * self.mb_h;
+        self.ftype = pinfo.mode;
+        self.has_b = pinfo.is_pb();
+
+        if self.has_b {
+            self.mv_data.truncate(0);
+        }
+
+        let save_b_data = pinfo.mode.is_ref() && self.may_have_b_frames;
+        if save_b_data {
+            self.mv_data.truncate(0);
+        }
+        let is_b = pinfo.mode == Type::B;
+
+        let tsdiff = if pinfo.is_pb() { pinfo.ts.wrapping_sub(self.last_ts) >> 1 }
+                     else { self.last_ts.wrapping_sub(self.next_ts) >> 1 };
+        let bsdiff = if pinfo.is_pb() { (pinfo.get_pbinfo().get_trb() as u16) << 7 }
+                     else { pinfo.ts.wrapping_sub(self.next_ts) >> 1 };
+
+        let fmt = formats::YUV420_FORMAT;
+        let vinfo = NAVideoInfo::new(self.w, self.h, false, fmt);
+        let bufinfo = alloc_video_buffer(vinfo, 4)?;
+        let mut buf = bufinfo.get_vbuf().unwrap();
+
+        let mut slice = if self.is_gob {
+                SliceInfo::get_default_slice(&pinfo)
+            } else {
+                bd.decode_slice_header(&pinfo)?
+            };
+        mvi.reset(self.mb_w, 0, pinfo.get_mvmode());
+        if is_b || pinfo.is_pb() {
+            mvi2.reset(self.mb_w, 0, pinfo.get_mvmode());
+        }
+        cbpi.reset(self.mb_w);
+
+        let mut blk: [[i16; 64]; 6] = [[0; 64]; 6];
+        let mut sstate = SliceState::new(pinfo.mode == Type::I);
+        let mut mb_pos = 0;
+        let apply_acpred = (pinfo.mode == Type::I) && pinfo.plusinfo.is_some() && pinfo.plusinfo.unwrap().aic;
+        if apply_acpred {
+            self.pred_coeffs.truncate(0);
+            self.pred_coeffs.resize(self.mb_w * self.mb_h, ZERO_PRED_COEFFS);
+        }
+        sstate.quant = slice.quant;
+        for mb_y in 0..self.mb_h {
+            for mb_x in 0..self.mb_w {
+                for i in 0..6 { for j in 0..64 { blk[i][j] = 0; } }
+
+                if slice.is_at_end(mb_pos) || (slice.needs_check() && mb_pos > 0 && bd.is_slice_end()) {
+                    slice = bd.decode_slice_header(&pinfo)?;
+                    if !self.is_gob && self.slice_reset {
+                        mvi.reset(self.mb_w, mb_x, pinfo.get_mvmode());
+                        if is_b || pinfo.is_pb() {
+                            mvi2.reset(self.mb_w, mb_x, pinfo.get_mvmode());
+                        }
+                        cbpi.reset(self.mb_w);
+                        sstate.reset_slice(mb_x, mb_y);
+                        sstate.quant = slice.quant;
+                    }
+                }
+
+                let binfo = bd.decode_block_header(&pinfo, &slice, &sstate)?;
+                let cbp = binfo.get_cbp();
+                cbpi.set_cbp(mb_x, cbp);
+                cbpi.set_q(mb_x, binfo.get_q());
+                sstate.quant = binfo.get_q();
+                if binfo.is_intra() {
+                    if save_b_data {
+                        self.mv_data.push(BlockMVInfo::Intra);
+                    }
+                    for i in 0..6 {
+                        bd.decode_block_intra(&binfo, &sstate, binfo.get_q(), i, (cbp & (1 << (5 - i))) != 0, &mut blk[i])?;
+                        if apply_acpred && (binfo.acpred != ACPredMode::None) {
+                            let has_b = (i == 1) || (i == 3) || !sstate.first_mb;
+                            let has_a = (i == 2) || (i == 3) || !sstate.first_line;
+                            let (b_mb, b_blk) = if has_b {
+                                    if (i == 1) || (i == 3) {
+                                        (mb_pos, i - 1)
+                                    } else if i < 4 {
+                                        (mb_pos - 1, i + 1)
+                                    } else {
+                                        (mb_pos - 1, i)
+                                    }
+                                } else { (0, 0) };
+                            let (a_mb, a_blk) = if has_a {
+                                    if (i == 2) || (i == 3) {
+                                        (mb_pos, i - 2)
+                                    } else if i < 4 {
+                                        (mb_pos - self.mb_w, i + 2)
+                                    } else {
+                                        (mb_pos - self.mb_w, i)
+                                    }
+                                } else { (0, 0) };
+                            match binfo.acpred {
+                                ACPredMode::DC   => {
+                                            let dc;
+                                            if has_a && has_b {
+                                                dc = (self.pred_coeffs[b_mb].hor[b_blk][0] + self.pred_coeffs[a_mb].ver[a_blk][0]) / 2;
+                                            } else if has_a {
+                                                dc = self.pred_coeffs[a_mb].ver[a_blk][0];
+                                            } else if has_b {
+                                                dc = self.pred_coeffs[b_mb].hor[b_blk][0];
+                                            } else {
+                                                dc = 1024;
+                                            }
+                                            blk[i][0] = clip_dc(blk[i][0] + dc);
+                                        },
+                                ACPredMode::Hor  => {
+                                        if has_b {
+                                            for k in 0..8 {
+                                                blk[i][k * 8] += self.pred_coeffs[b_mb].hor[b_blk][k];
+                                            }
+                                            for k in 1..8 {
+                                                blk[i][k * 8] = clip_ac(blk[i][k * 8]);
+                                            }
+                                        } else {
+                                            blk[i][0] += 1024;
+                                        }
+                                        blk[i][0] = clip_dc(blk[i][0]);
+                                    },
+                                ACPredMode::Ver  => {
+                                        if has_a {
+                                            for k in 0..8 {
+                                                blk[i][k] += self.pred_coeffs[a_mb].ver[a_blk][k];
+                                            }
+                                            for k in 1..8 {
+                                                blk[i][k] = clip_ac(blk[i][k]);
+                                            }
+                                        } else {
+                                            blk[i][0] += 1024;
+                                        }
+                                        blk[i][0] = clip_dc(blk[i][0]);
+                                    },
+                                ACPredMode::None => {},
+                            };
+                            for t in 0..8 { self.pred_coeffs[mb_pos].hor[i][t] = blk[i][t * 8]; }
+                            for t in 0..8 { self.pred_coeffs[mb_pos].ver[i][t] = blk[i][t]; }
+                        }
+                        bdsp.idct(&mut blk[i]);
+                    }
+                    blockdsp::put_blocks(&mut buf, mb_x, mb_y, &blk);
+                    mvi.set_zero_mv(mb_x);
+                    if is_b {
+                        mvi2.set_zero_mv(mb_x);
+                    } else if pinfo.is_pb() {
+                        mvi2.predict(mb_x, 0, false, binfo.get_mv2(0), sstate.first_line, sstate.first_mb);
+                    }
+                } else if (binfo.mode != Type::B) && !binfo.is_skipped() {
+                    if binfo.get_num_mvs() == 1 {
+                        let mv = mvi.predict(mb_x, 0, false, binfo.get_mv(0), sstate.first_line, sstate.first_mb);
+                        if save_b_data {
+                            self.mv_data.push(BlockMVInfo::Inter_1MV(mv));
+                        }
+                        if let Some(ref srcbuf) = self.ipbs.get_lastref() {
+                            bdsp.copy_blocks(&mut buf, srcbuf, mb_x * 16, mb_y * 16, 16, 16, mv);
+                        }
+                        if pinfo.is_pb() {
+                            mvi2.predict(mb_x, 0, false, binfo.get_mv(0), sstate.first_line, sstate.first_mb);
+                        }
+                    } else {
+                        let mut mv: [MV; 4] = [ZERO_MV, ZERO_MV, ZERO_MV, ZERO_MV];
+                        for blk_no in 0..4 {
+                            mv[blk_no] = mvi.predict(mb_x, blk_no, true, binfo.get_mv(blk_no), sstate.first_line, sstate.first_mb);
+                            if let Some(ref srcbuf) = self.ipbs.get_lastref() {
+                                bdsp.copy_blocks(&mut buf, srcbuf,
+                                                 mb_x * 16 + (blk_no & 1) * 8,
+                                                 mb_y * 16 + (blk_no & 2) * 4, 8, 8, mv[blk_no]);
+                            }
+                        }
+                        if pinfo.is_pb() {
+                            for blk_no in 0..4 {
+                                mvi2.predict(mb_x, blk_no, true, binfo.get_mv(blk_no), sstate.first_line, sstate.first_mb);
+                            }
+                        }
+                        if save_b_data {
+                            self.mv_data.push(BlockMVInfo::Inter_4MV(mv));
+                        }
+                    }
+                    for i in 0..6 {
+                        bd.decode_block_inter(&binfo, &sstate, binfo.get_q(), i, ((cbp >> (5 - i)) & 1) != 0, &mut blk[i])?;
+                        bdsp.idct(&mut blk[i]);
+                    }
+                    blockdsp::add_blocks(&mut buf, mb_x, mb_y, &blk);
+                    if is_b && !pinfo.is_pb() {
+                        mvi2.set_zero_mv(mb_x);
+                    }
+                } else if binfo.mode != Type::B {
+                    self.mv_data.push(BlockMVInfo::Inter_1MV(ZERO_MV));
+                    mvi.set_zero_mv(mb_x);
+                    if is_b || pinfo.is_pb() {
+                        mvi2.set_zero_mv(mb_x);
+                    }
+                    if let Some(ref srcbuf) = self.ipbs.get_lastref() {
+                        bdsp.copy_blocks(&mut buf, srcbuf, mb_x * 16, mb_y * 16, 16, 16, ZERO_MV);
+                    }
+                } else {
+                    let ref_mv_info = self.mv_data[mb_pos];
+                    let has_fwd = binfo.get_num_mvs() > 0;
+                    let has_bwd = binfo.get_num_mvs2() > 0;
+//todo refactor
+                    if has_fwd || has_bwd {
+                        let fwd_mv;
+                        if has_fwd {
+                            fwd_mv = mvi.predict(mb_x, 0, false, binfo.get_mv(0), sstate.first_line, sstate.first_mb);
+                        } else {
+                            fwd_mv = ZERO_MV;
+                            mvi.set_zero_mv(mb_x);
+                        }
+                        let bwd_mv;
+                        if has_bwd {
+                            bwd_mv = mvi2.predict(mb_x, 0, false, binfo.get_mv2(0), sstate.first_line, sstate.first_mb);
+                        } else {
+                            bwd_mv = ZERO_MV;
+                            mvi2.set_zero_mv(mb_x);
+                        }
+                        if let (Some(ref fwd_buf), Some(ref bck_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
+                            if has_fwd && has_bwd {
+                                bdsp.copy_blocks(&mut buf, fwd_buf, mb_x * 16, mb_y * 16, 16, 16, fwd_mv);
+                                bdsp.avg_blocks (&mut buf, bck_buf, mb_x * 16, mb_y * 16, 16, 16, bwd_mv);
+                            } else if has_fwd {
+                                bdsp.copy_blocks(&mut buf, fwd_buf, mb_x * 16, mb_y * 16, 16, 16, fwd_mv);
+                            } else {
+                                bdsp.copy_blocks(&mut buf, bck_buf, mb_x * 16, mb_y * 16, 16, 16, bwd_mv);
+                            }
+                        }
+                    } else {
+                        if let BlockMVInfo::Inter_4MV(mvs) = ref_mv_info {
+                            for blk_no in 0..4 {
+                                let ref_mv = mvs[blk_no];
+                                let ref_mv_fwd = ref_mv.scale(bsdiff, tsdiff);
+                                let ref_mv_bwd = ref_mv - ref_mv_fwd;
+                                let xoff = mb_x * 16 + (blk_no & 1) * 8;
+                                let yoff = mb_y * 16 + (blk_no & 2) * 4;
+                                if let (Some(ref fwd_buf), Some(ref bck_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
+                                    bdsp.copy_blocks(&mut buf, fwd_buf, xoff, yoff, 8, 8, ref_mv_fwd);
+                                    bdsp.avg_blocks (&mut buf, bck_buf, xoff, yoff, 8, 8, ref_mv_bwd);
+                                }
+                            }
+                        } else {
+                            let ref_mv = if let BlockMVInfo::Inter_1MV(mv_) = ref_mv_info { mv_ } else { ZERO_MV };
+                            let ref_mv_fwd = ref_mv.scale(bsdiff, tsdiff);
+                            let ref_mv_bwd = MV::b_sub(ref_mv, ref_mv_fwd, ZERO_MV, bsdiff, tsdiff);
+
+                            if let (Some(ref fwd_buf), Some(ref bck_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
+                                bdsp.copy_blocks(&mut buf, fwd_buf, mb_x * 16, mb_y * 16, 16, 16, ref_mv_fwd);
+                                bdsp.avg_blocks (&mut buf, bck_buf, mb_x * 16, mb_y * 16, 16, 16, ref_mv_bwd);
+                            }
+                        }
+                        mvi.set_zero_mv(mb_x);
+                        mvi2.set_zero_mv(mb_x);
+                    }
+                    if cbp != 0 {
+                        for i in 0..6 {
+                            bd.decode_block_inter(&binfo, &sstate, binfo.get_q(), i, ((cbp >> (5 - i)) & 1) != 0, &mut blk[i])?;
+                            bdsp.idct(&mut blk[i]);
+                        }
+                        blockdsp::add_blocks(&mut buf, mb_x, mb_y, &blk);
+                    }
+                }
+                if pinfo.is_pb() {
+                    let mut b_mb = BMB::new();
+                    let cbp = binfo.get_cbp_b();
+                    let bq = (((pinfo.get_pbinfo().get_dbquant() + 5) as u16) * (binfo.get_q() as u16)) >> 2;
+                    let bquant;
+                    if bq < 1 { bquant = 1; }
+                    else if bq > 31 { bquant = 31; }
+                    else { bquant = bq as u8; }
+
+                    b_mb.cbp = cbp;
+                    for i in 0..6 {
+                        bd.decode_block_inter(&binfo, &sstate, bquant, i, (cbp & (1 << (5 - i))) != 0, &mut b_mb.blk[i])?;
+                        bdsp.idct(&mut b_mb.blk[i]);
+                    }
+
+                    let is_fwd = binfo.is_b_fwd();
+                    b_mb.fwd = is_fwd;
+                    if binfo.get_num_mvs() != 4 {
+                        let ref_mv = mvi2.get_mv(mb_x, 0);
+                        let b_mv = if binfo.is_intra() { binfo.get_mv2(1) } else { binfo.get_mv2(0) };
+                        let src_mv = if is_fwd { ZERO_MV } else { ref_mv.scale(bsdiff, tsdiff) };
+                        let mv_f = MV::add_umv(src_mv, b_mv, pinfo.get_mvmode());
+                        let mv_b = MV::b_sub(ref_mv, mv_f, b_mv, bsdiff, tsdiff);
+                        b_mb.mv_f[0] = mv_f;
+                        b_mb.mv_b[0] = mv_b;
+                        b_mb.num_mv = 1;
+                    } else {
+                        for blk_no in 0..4 {
+                            let src_mv = if is_fwd { ZERO_MV } else { mvi2.get_mv(mb_x, blk_no).scale(bsdiff, tsdiff) };
+                            let mv_f = MV::add_umv(src_mv, binfo.get_mv2(0), pinfo.get_mvmode());
+                            let mv_b = MV::b_sub(mvi2.get_mv(mb_x, blk_no), mv_f, binfo.get_mv2(0), bsdiff, tsdiff);
+                            b_mb.mv_f[blk_no] = mv_f;
+                            b_mb.mv_b[blk_no] = mv_b;
+                        }
+                        b_mb.num_mv = 4;
+                    }
+                    self.b_data.push(b_mb);
+                }
+                sstate.next_mb();
+                mb_pos += 1;
+            }
+            if let Some(plusinfo) = pinfo.plusinfo {
+                if plusinfo.deblock {
+                    bdsp.filter_row(&mut buf, mb_y, self.mb_w, &cbpi);
+                }
+            }
+            mvi.update_row();
+            if is_b || pinfo.is_pb() {
+                mvi2.update_row();
+            }
+            cbpi.update_row();
+            sstate.new_row();
+        }
+
+        if pinfo.mode.is_ref() {
+            self.ipbs.add_frame(buf);
+            self.next_ts = self.last_ts;
+            self.last_ts = pinfo.ts;
+            self.tsdiff  = tsdiff;
+        }
+
+        Ok(bufinfo)
+    }
+    pub fn flush(&mut self) {
+        self.ipbs.clear();
+    }
+
+    pub fn get_bframe(&mut self, bdsp: &BlockDSP) -> DecoderResult<NABufferType> {
+        if !self.has_b || self.ipbs.get_lastref().is_none() || self.ipbs.get_nextref().is_none() {
+            return Err(DecoderError::MissingReference);
+        }
+        self.has_b = false;
+
+        let fmt = formats::YUV420_FORMAT;
+        let vinfo = NAVideoInfo::new(self.w, self.h, false, fmt);
+        let bufinfo = alloc_video_buffer(vinfo, 4)?;
+        let mut b_buf = bufinfo.get_vbuf().unwrap();
+
+        if let (Some(ref bck_buf), Some(ref fwd_buf)) = (self.ipbs.get_nextref(), self.ipbs.get_lastref()) {
+            recon_b_frame(&mut b_buf, fwd_buf, bck_buf, self.mb_w, self.mb_h, self.b_data.as_slice(), bdsp);
+        }
+
+        self.b_data.truncate(0);
+        Ok(bufinfo)
+    }
+}
+
+fn recon_b_frame(b_buf: &mut NAVideoBuffer<u8>, bck_buf: &NAVideoBuffer<u8>, fwd_buf: &NAVideoBuffer<u8>,
+                 mb_w: usize, mb_h: usize, b_data: &[BMB], bdsp: &BlockDSP) {
+    let mut cbpi = CBPInfo::new();
+    let mut cur_mb = 0;
+    cbpi.reset(mb_w);
+    for mb_y in 0..mb_h {
+        for mb_x in 0..mb_w {
+            let num_mv = b_data[cur_mb].num_mv;
+            let is_fwd = b_data[cur_mb].fwd;
+            let cbp    = b_data[cur_mb].cbp;
+            cbpi.set_cbp(mb_x, cbp);
+            if num_mv == 1 {
+                bdsp.copy_blocks(b_buf, fwd_buf, mb_x * 16, mb_y * 16, 16, 16, b_data[cur_mb].mv_b[0]);
+                if !is_fwd {
+                    bdsp.avg_blocks(b_buf, bck_buf, mb_x * 16, mb_y * 16, 16, 16, b_data[cur_mb].mv_f[0]);
+                }
+            } else {
+                for blk_no in 0..4 {
+                    let xpos = mb_x * 16 + (blk_no & 1) * 8;
+                    let ypos = mb_y * 16 + (blk_no & 2) * 4;
+                    bdsp.copy_blocks(b_buf, fwd_buf, xpos, ypos, 8, 8, b_data[cur_mb].mv_b[blk_no]);
+                    if !is_fwd {
+                        bdsp.avg_blocks(b_buf, bck_buf, xpos, ypos, 8, 8, b_data[cur_mb].mv_f[blk_no]);
+                    }
+                }
+            }
+            if cbp != 0 {
+                blockdsp::add_blocks(b_buf, mb_x, mb_y, &b_data[cur_mb].blk);
+            }
+            cur_mb += 1;
+        }
+        cbpi.update_row();
+    }
+}