Split H263 encoder and decoder from common code.

Originally committed as revision 21109 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 1131 insertions, 0 deletions

diff --git a/libavcodec/ituh263dec.c b/libavcodec/ituh263dec.c
new file mode 100644
index 0000000000..f415d77299
--- /dev/null
+++ b/libavcodec/ituh263dec.c
@@ -0,0 +1,1131 @@
+/*
+ * ITU H263 bitstream decoder
+ * Copyright (c) 2000,2001 Fabrice Bellard
+ * H263+ support.
+ * Copyright (c) 2001 Juan J. Sierralta P
+ * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file libavcodec/ituh263dec.c
+ * h263 decoder.
+ */
+
+//#define DEBUG
+#include <limits.h>
+
+#include "dsputil.h"
+#include "avcodec.h"
+#include "mpegvideo.h"
+#include "h263.h"
+#include "mathops.h"
+#include "unary.h"
+#include "flv.h"
+#include "mpeg4video.h"
+
+//#undef NDEBUG
+//#include <assert.h>
+
+// The defines below define the number of bits that are read at once for
+// reading vlc values. Changing these may improve speed and data cache needs
+// be aware though that decreasing them may need the number of stages that is
+// passed to get_vlc* to be increased.
+#define MV_VLC_BITS 9
+#define H263_MBTYPE_B_VLC_BITS 6
+#define CBPC_B_VLC_BITS 3
+
+static const int h263_mb_type_b_map[15]= {
+    MB_TYPE_DIRECT2 | MB_TYPE_L0L1,
+    MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP,
+    MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT,
+                      MB_TYPE_L0                                 | MB_TYPE_16x16,
+                      MB_TYPE_L0   | MB_TYPE_CBP                 | MB_TYPE_16x16,
+                      MB_TYPE_L0   | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
+                      MB_TYPE_L1                                 | MB_TYPE_16x16,
+                      MB_TYPE_L1   | MB_TYPE_CBP                 | MB_TYPE_16x16,
+                      MB_TYPE_L1   | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
+                      MB_TYPE_L0L1                               | MB_TYPE_16x16,
+                      MB_TYPE_L0L1 | MB_TYPE_CBP                 | MB_TYPE_16x16,
+                      MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
+    0, //stuffing
+    MB_TYPE_INTRA4x4                | MB_TYPE_CBP,
+    MB_TYPE_INTRA4x4                | MB_TYPE_CBP | MB_TYPE_QUANT,
+};
+
+void ff_h263_show_pict_info(MpegEncContext *s){
+    if(s->avctx->debug&FF_DEBUG_PICT_INFO){
+    av_log(s->avctx, AV_LOG_DEBUG, "qp:%d %c size:%d rnd:%d%s%s%s%s%s%s%s%s%s %d/%d\n",
+         s->qscale, av_get_pict_type_char(s->pict_type),
+         s->gb.size_in_bits, 1-s->no_rounding,
+         s->obmc ? " AP" : "",
+         s->umvplus ? " UMV" : "",
+         s->h263_long_vectors ? " LONG" : "",
+         s->h263_plus ? " +" : "",
+         s->h263_aic ? " AIC" : "",
+         s->alt_inter_vlc ? " AIV" : "",
+         s->modified_quant ? " MQ" : "",
+         s->loop_filter ? " LOOP" : "",
+         s->h263_slice_structured ? " SS" : "",
+         s->avctx->time_base.den, s->avctx->time_base.num
+    );
+    }
+}
+
+/***********************************************/
+/* decoding */
+
+VLC ff_h263_intra_MCBPC_vlc;
+VLC ff_h263_inter_MCBPC_vlc;
+VLC ff_h263_cbpy_vlc;
+static VLC mv_vlc;
+static VLC h263_mbtype_b_vlc;
+static VLC cbpc_b_vlc;
+
+/* init vlcs */
+
+/* XXX: find a better solution to handle static init */
+void h263_decode_init_vlc(MpegEncContext *s)
+{
+    static int done = 0;
+
+    if (!done) {
+        done = 1;
+
+        INIT_VLC_STATIC(&ff_h263_intra_MCBPC_vlc, INTRA_MCBPC_VLC_BITS, 9,
+                 ff_h263_intra_MCBPC_bits, 1, 1,
+                 ff_h263_intra_MCBPC_code, 1, 1, 72);
+        INIT_VLC_STATIC(&ff_h263_inter_MCBPC_vlc, INTER_MCBPC_VLC_BITS, 28,
+                 ff_h263_inter_MCBPC_bits, 1, 1,
+                 ff_h263_inter_MCBPC_code, 1, 1, 198);
+        INIT_VLC_STATIC(&ff_h263_cbpy_vlc, CBPY_VLC_BITS, 16,
+                 &ff_h263_cbpy_tab[0][1], 2, 1,
+                 &ff_h263_cbpy_tab[0][0], 2, 1, 64);
+        INIT_VLC_STATIC(&mv_vlc, MV_VLC_BITS, 33,
+                 &mvtab[0][1], 2, 1,
+                 &mvtab[0][0], 2, 1, 538);
+        init_rl(&ff_h263_rl_inter, ff_h263_static_rl_table_store[0]);
+        init_rl(&rl_intra_aic, ff_h263_static_rl_table_store[1]);
+        INIT_VLC_RL(ff_h263_rl_inter, 554);
+        INIT_VLC_RL(rl_intra_aic, 554);
+        INIT_VLC_STATIC(&h263_mbtype_b_vlc, H263_MBTYPE_B_VLC_BITS, 15,
+                 &h263_mbtype_b_tab[0][1], 2, 1,
+                 &h263_mbtype_b_tab[0][0], 2, 1, 80);
+        INIT_VLC_STATIC(&cbpc_b_vlc, CBPC_B_VLC_BITS, 4,
+                 &cbpc_b_tab[0][1], 2, 1,
+                 &cbpc_b_tab[0][0], 2, 1, 8);
+    }
+}
+
+int ff_h263_decode_mba(MpegEncContext *s)
+{
+    int i, mb_pos;
+
+    for(i=0; i<6; i++){
+        if(s->mb_num-1 <= ff_mba_max[i]) break;
+    }
+    mb_pos= get_bits(&s->gb, ff_mba_length[i]);
+    s->mb_x= mb_pos % s->mb_width;
+    s->mb_y= mb_pos / s->mb_width;
+
+    return mb_pos;
+}
+
+/**
+ * decodes the group of blocks header or slice header.
+ * @return <0 if an error occurred
+ */
+static int h263_decode_gob_header(MpegEncContext *s)
+{
+    unsigned int val, gfid, gob_number;
+    int left;
+
+    /* Check for GOB Start Code */
+    val = show_bits(&s->gb, 16);
+    if(val)
+        return -1;
+
+        /* We have a GBSC probably with GSTUFF */
+    skip_bits(&s->gb, 16); /* Drop the zeros */
+    left= get_bits_left(&s->gb);
+    //MN: we must check the bits left or we might end in a infinite loop (or segfault)
+    for(;left>13; left--){
+        if(get_bits1(&s->gb)) break; /* Seek the '1' bit */
+    }
+    if(left<=13)
+        return -1;
+
+    if(s->h263_slice_structured){
+        if(get_bits1(&s->gb)==0)
+            return -1;
+
+        ff_h263_decode_mba(s);
+
+        if(s->mb_num > 1583)
+            if(get_bits1(&s->gb)==0)
+                return -1;
+
+        s->qscale = get_bits(&s->gb, 5); /* SQUANT */
+        if(get_bits1(&s->gb)==0)
+            return -1;
+        gfid = get_bits(&s->gb, 2); /* GFID */
+    }else{
+        gob_number = get_bits(&s->gb, 5); /* GN */
+        s->mb_x= 0;
+        s->mb_y= s->gob_index* gob_number;
+        gfid = get_bits(&s->gb, 2); /* GFID */
+        s->qscale = get_bits(&s->gb, 5); /* GQUANT */
+    }
+
+    if(s->mb_y >= s->mb_height)
+        return -1;
+
+    if(s->qscale==0)
+        return -1;
+
+    return 0;
+}
+
+/**
+ * finds the next resync_marker
+ * @param p pointer to buffer to scan
+ * @param end pointer to the end of the buffer
+ * @return pointer to the next resync_marker, or end if none was found
+ */
+const uint8_t *ff_h263_find_resync_marker(const uint8_t *restrict p, const uint8_t * restrict end)
+{
+    assert(p < end);
+
+    end-=2;
+    p++;
+    for(;p<end; p+=2){
+        if(!*p){
+            if     (!p[-1] && p[1]) return p - 1;
+            else if(!p[ 1] && p[2]) return p;
+        }
+    }
+    return end+2;
+}
+
+/**
+ * decodes the group of blocks / video packet header.
+ * @return bit position of the resync_marker, or <0 if none was found
+ */
+int ff_h263_resync(MpegEncContext *s){
+    int left, pos, ret;
+
+    if(s->codec_id==CODEC_ID_MPEG4){
+        skip_bits1(&s->gb);
+        align_get_bits(&s->gb);
+    }
+
+    if(show_bits(&s->gb, 16)==0){
+        pos= get_bits_count(&s->gb);
+        if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4)
+            ret= mpeg4_decode_video_packet_header(s);
+        else
+            ret= h263_decode_gob_header(s);
+        if(ret>=0)
+            return pos;
+    }
+    //OK, it's not where it is supposed to be ...
+    s->gb= s->last_resync_gb;
+    align_get_bits(&s->gb);
+    left= get_bits_left(&s->gb);
+
+    for(;left>16+1+5+5; left-=8){
+        if(show_bits(&s->gb, 16)==0){
+            GetBitContext bak= s->gb;
+
+            pos= get_bits_count(&s->gb);
+            if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4)
+                ret= mpeg4_decode_video_packet_header(s);
+            else
+                ret= h263_decode_gob_header(s);
+            if(ret>=0)
+                return pos;
+
+            s->gb= bak;
+        }
+        skip_bits(&s->gb, 8);
+    }
+
+    return -1;
+}
+
+int h263_decode_motion(MpegEncContext * s, int pred, int f_code)
+{
+    int code, val, sign, shift, l;
+    code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
+
+    if (code == 0)
+        return pred;
+    if (code < 0)
+        return 0xffff;
+
+    sign = get_bits1(&s->gb);
+    shift = f_code - 1;
+    val = code;
+    if (shift) {
+        val = (val - 1) << shift;
+        val |= get_bits(&s->gb, shift);
+        val++;
+    }
+    if (sign)
+        val = -val;
+    val += pred;
+
+    /* modulo decoding */
+    if (!s->h263_long_vectors) {
+        l = INT_BIT - 5 - f_code;
+        val = (val<<l)>>l;
+    } else {
+        /* horrible h263 long vector mode */
+        if (pred < -31 && val < -63)
+            val += 64;
+        if (pred > 32 && val > 63)
+            val -= 64;
+
+    }
+    return val;
+}
+
+
+/* Decodes RVLC of H.263+ UMV */
+static int h263p_decode_umotion(MpegEncContext * s, int pred)
+{
+   int code = 0, sign;
+
+   if (get_bits1(&s->gb)) /* Motion difference = 0 */
+      return pred;
+
+   code = 2 + get_bits1(&s->gb);
+
+   while (get_bits1(&s->gb))
+   {
+      code <<= 1;
+      code += get_bits1(&s->gb);
+   }
+   sign = code & 1;
+   code >>= 1;
+
+   code = (sign) ? (pred - code) : (pred + code);
+   dprintf(s->avctx,"H.263+ UMV Motion = %d\n", code);
+   return code;
+
+}
+
+/**
+ * read the next MVs for OBMC. yes this is a ugly hack, feel free to send a patch :)
+ */
+static void preview_obmc(MpegEncContext *s){
+    GetBitContext gb= s->gb;
+
+    int cbpc, i, pred_x, pred_y, mx, my;
+    int16_t *mot_val;
+    const int xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
+    const int stride= s->b8_stride*2;
+
+    for(i=0; i<4; i++)
+        s->block_index[i]+= 2;
+    for(i=4; i<6; i++)
+        s->block_index[i]+= 1;
+    s->mb_x++;
+
+    assert(s->pict_type == FF_P_TYPE);
+
+    do{
+        if (get_bits1(&s->gb)) {
+            /* skip mb */
+            mot_val = s->current_picture.motion_val[0][ s->block_index[0] ];
+            mot_val[0       ]= mot_val[2       ]=
+            mot_val[0+stride]= mot_val[2+stride]= 0;
+            mot_val[1       ]= mot_val[3       ]=
+            mot_val[1+stride]= mot_val[3+stride]= 0;
+
+            s->current_picture.mb_type[xy]= MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
+            goto end;
+        }
+        cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
+    }while(cbpc == 20);
+
+    if(cbpc & 4){
+        s->current_picture.mb_type[xy]= MB_TYPE_INTRA;
+    }else{
+        get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
+        if (cbpc & 8) {
+            if(s->modified_quant){
+                if(get_bits1(&s->gb)) skip_bits(&s->gb, 1);
+                else                  skip_bits(&s->gb, 5);
+            }else
+                skip_bits(&s->gb, 2);
+        }
+
+        if ((cbpc & 16) == 0) {
+                s->current_picture.mb_type[xy]= MB_TYPE_16x16 | MB_TYPE_L0;
+                /* 16x16 motion prediction */
+                mot_val= h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
+                if (s->umvplus)
+                   mx = h263p_decode_umotion(s, pred_x);
+                else
+                   mx = h263_decode_motion(s, pred_x, 1);
+
+                if (s->umvplus)
+                   my = h263p_decode_umotion(s, pred_y);
+                else
+                   my = h263_decode_motion(s, pred_y, 1);
+
+                mot_val[0       ]= mot_val[2       ]=
+                mot_val[0+stride]= mot_val[2+stride]= mx;
+                mot_val[1       ]= mot_val[3       ]=
+                mot_val[1+stride]= mot_val[3+stride]= my;
+        } else {
+            s->current_picture.mb_type[xy]= MB_TYPE_8x8 | MB_TYPE_L0;
+            for(i=0;i<4;i++) {
+                mot_val = h263_pred_motion(s, i, 0, &pred_x, &pred_y);
+                if (s->umvplus)
+                  mx = h263p_decode_umotion(s, pred_x);
+                else
+                  mx = h263_decode_motion(s, pred_x, 1);
+
+                if (s->umvplus)
+                  my = h263p_decode_umotion(s, pred_y);
+                else
+                  my = h263_decode_motion(s, pred_y, 1);
+                if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
+                  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
+                mot_val[0] = mx;
+                mot_val[1] = my;
+            }
+        }
+    }
+end:
+
+    for(i=0; i<4; i++)
+        s->block_index[i]-= 2;
+    for(i=4; i<6; i++)
+        s->block_index[i]-= 1;
+    s->mb_x--;
+
+    s->gb= gb;
+}
+
+static void h263_decode_dquant(MpegEncContext *s){
+    static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
+
+    if(s->modified_quant){
+        if(get_bits1(&s->gb))
+            s->qscale= modified_quant_tab[get_bits1(&s->gb)][ s->qscale ];
+        else
+            s->qscale= get_bits(&s->gb, 5);
+    }else
+        s->qscale += quant_tab[get_bits(&s->gb, 2)];
+    ff_set_qscale(s, s->qscale);
+}
+
+static int h263_decode_block(MpegEncContext * s, DCTELEM * block,
+                             int n, int coded)
+{
+    int code, level, i, j, last, run;
+    RLTable *rl = &ff_h263_rl_inter;
+    const uint8_t *scan_table;
+    GetBitContext gb= s->gb;
+
+    scan_table = s->intra_scantable.permutated;
+    if (s->h263_aic && s->mb_intra) {
+        rl = &rl_intra_aic;
+        i = 0;
+        if (s->ac_pred) {
+            if (s->h263_aic_dir)
+                scan_table = s->intra_v_scantable.permutated; /* left */
+            else
+                scan_table = s->intra_h_scantable.permutated; /* top */
+        }
+    } else if (s->mb_intra) {
+        /* DC coef */
+        if(s->codec_id == CODEC_ID_RV10){
+#if CONFIG_RV10_DECODER
+          if (s->rv10_version == 3 && s->pict_type == FF_I_TYPE) {
+            int component, diff;
+            component = (n <= 3 ? 0 : n - 4 + 1);
+            level = s->last_dc[component];
+            if (s->rv10_first_dc_coded[component]) {
+                diff = rv_decode_dc(s, n);
+                if (diff == 0xffff)
+                    return -1;
+                level += diff;
+                level = level & 0xff; /* handle wrap round */
+                s->last_dc[component] = level;
+            } else {
+                s->rv10_first_dc_coded[component] = 1;
+            }
+          } else {
+                level = get_bits(&s->gb, 8);
+                if (level == 255)
+                    level = 128;
+          }
+#endif
+        }else{
+            level = get_bits(&s->gb, 8);
+            if((level&0x7F) == 0){
+                av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
+                if(s->error_recognition >= FF_ER_COMPLIANT)
+                    return -1;
+            }
+            if (level == 255)
+                level = 128;
+        }
+        block[0] = level;
+        i = 1;
+    } else {
+        i = 0;
+    }
+    if (!coded) {
+        if (s->mb_intra && s->h263_aic)
+            goto not_coded;
+        s->block_last_index[n] = i - 1;
+        return 0;
+    }
+retry:
+    for(;;) {
+        code = get_vlc2(&s->gb, rl->vlc.table, TEX_VLC_BITS, 2);
+        if (code < 0){
+            av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
+            return -1;
+        }
+        if (code == rl->n) {
+            /* escape */
+            if (CONFIG_FLV_DECODER && s->h263_flv > 1) {
+                ff_flv2_decode_ac_esc(&s->gb, &level, &run, &last);
+            } else {
+                last = get_bits1(&s->gb);
+                run = get_bits(&s->gb, 6);
+                level = (int8_t)get_bits(&s->gb, 8);
+                if(level == -128){
+                    if (s->codec_id == CODEC_ID_RV10) {
+                        /* XXX: should patch encoder too */
+                        level = get_sbits(&s->gb, 12);
+                    }else{
+                        level = get_bits(&s->gb, 5);
+                        level |= get_sbits(&s->gb, 6)<<5;
+                    }
+                }
+            }
+        } else {
+            run = rl->table_run[code];
+            level = rl->table_level[code];
+            last = code >= rl->last;
+            if (get_bits1(&s->gb))
+                level = -level;
+        }
+        i += run;
+        if (i >= 64){
+            if(s->alt_inter_vlc && rl == &ff_h263_rl_inter && !s->mb_intra){
+                //Looks like a hack but no, it's the way it is supposed to work ...
+                rl = &rl_intra_aic;
+                i = 0;
+                s->gb= gb;
+                s->dsp.clear_block(block);
+                goto retry;
+            }
+            av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
+            return -1;
+        }
+        j = scan_table[i];
+        block[j] = level;
+        if (last)
+            break;
+        i++;
+    }
+not_coded:
+    if (s->mb_intra && s->h263_aic) {
+        h263_pred_acdc(s, block, n);
+        i = 63;
+    }
+    s->block_last_index[n] = i;
+    return 0;
+}
+
+static int h263_skip_b_part(MpegEncContext *s, int cbp)
+{
+    DECLARE_ALIGNED(16, DCTELEM, dblock[64]);
+    int i, mbi;
+
+    /* we have to set s->mb_intra to zero to decode B-part of PB-frame correctly
+     * but real value should be restored in order to be used later (in OBMC condition)
+     */
+    mbi = s->mb_intra;
+    s->mb_intra = 0;
+    for (i = 0; i < 6; i++) {
+        if (h263_decode_block(s, dblock, i, cbp&32) < 0)
+            return -1;
+        cbp+=cbp;
+    }
+    s->mb_intra = mbi;
+    return 0;
+}
+
+static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
+{
+    int c, mv = 1;
+
+    if (pb_frame < 3) { // h.263 Annex G and i263 PB-frame
+        c = get_bits1(gb);
+        if (pb_frame == 2 && c)
+            mv = !get_bits1(gb);
+    } else { // h.263 Annex M improved PB-frame
+        mv = get_unary(gb, 0, 4) + 1;
+        c = mv & 1;
+        mv = !!(mv & 2);
+    }
+    if(c)
+        *cbpb = get_bits(gb, 6);
+    return mv;
+}
+
+int ff_h263_decode_mb(MpegEncContext *s,
+                      DCTELEM block[6][64])
+{
+    int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
+    int16_t *mot_val;
+    const int xy= s->mb_x + s->mb_y * s->mb_stride;
+    int cbpb = 0, pb_mv_count = 0;
+
+    assert(!s->h263_pred);
+
+    if (s->pict_type == FF_P_TYPE) {
+        do{
+            if (get_bits1(&s->gb)) {
+                /* skip mb */
+                s->mb_intra = 0;
+                for(i=0;i<6;i++)
+                    s->block_last_index[i] = -1;
+                s->mv_dir = MV_DIR_FORWARD;
+                s->mv_type = MV_TYPE_16X16;
+                s->current_picture.mb_type[xy]= MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
+                s->mv[0][0][0] = 0;
+                s->mv[0][0][1] = 0;
+                s->mb_skipped = !(s->obmc | s->loop_filter);
+                goto end;
+            }
+            cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
+            if (cbpc < 0){
+                av_log(s->avctx, AV_LOG_ERROR, "cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
+                return -1;
+            }
+        }while(cbpc == 20);
+
+        s->dsp.clear_blocks(s->block[0]);
+
+        dquant = cbpc & 8;
+        s->mb_intra = ((cbpc & 4) != 0);
+        if (s->mb_intra) goto intra;
+
+        if(s->pb_frame && get_bits1(&s->gb))
+            pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
+        cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
+
+        if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
+            cbpy ^= 0xF;
+
+        cbp = (cbpc & 3) | (cbpy << 2);
+        if (dquant) {
+            h263_decode_dquant(s);
+        }
+
+        s->mv_dir = MV_DIR_FORWARD;
+        if ((cbpc & 16) == 0) {
+            s->current_picture.mb_type[xy]= MB_TYPE_16x16 | MB_TYPE_L0;
+            /* 16x16 motion prediction */
+            s->mv_type = MV_TYPE_16X16;
+            h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
+            if (s->umvplus)
+               mx = h263p_decode_umotion(s, pred_x);
+            else
+               mx = h263_decode_motion(s, pred_x, 1);
+
+            if (mx >= 0xffff)
+                return -1;
+
+            if (s->umvplus)
+               my = h263p_decode_umotion(s, pred_y);
+            else
+               my = h263_decode_motion(s, pred_y, 1);
+
+            if (my >= 0xffff)
+                return -1;
+            s->mv[0][0][0] = mx;
+            s->mv[0][0][1] = my;
+
+            if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
+               skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
+        } else {
+            s->current_picture.mb_type[xy]= MB_TYPE_8x8 | MB_TYPE_L0;
+            s->mv_type = MV_TYPE_8X8;
+            for(i=0;i<4;i++) {
+                mot_val = h263_pred_motion(s, i, 0, &pred_x, &pred_y);
+                if (s->umvplus)
+                  mx = h263p_decode_umotion(s, pred_x);
+                else
+                  mx = h263_decode_motion(s, pred_x, 1);
+                if (mx >= 0xffff)
+                    return -1;
+
+                if (s->umvplus)
+                  my = h263p_decode_umotion(s, pred_y);
+                else
+                  my = h263_decode_motion(s, pred_y, 1);
+                if (my >= 0xffff)
+                    return -1;
+                s->mv[0][i][0] = mx;
+                s->mv[0][i][1] = my;
+                if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
+                  skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
+                mot_val[0] = mx;
+                mot_val[1] = my;
+            }
+        }
+    } else if(s->pict_type==FF_B_TYPE) {
+        int mb_type;
+        const int stride= s->b8_stride;
+        int16_t *mot_val0 = s->current_picture.motion_val[0][ 2*(s->mb_x + s->mb_y*stride) ];
+        int16_t *mot_val1 = s->current_picture.motion_val[1][ 2*(s->mb_x + s->mb_y*stride) ];
+//        const int mv_xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
+
+        //FIXME ugly
+        mot_val0[0       ]= mot_val0[2       ]= mot_val0[0+2*stride]= mot_val0[2+2*stride]=
+        mot_val0[1       ]= mot_val0[3       ]= mot_val0[1+2*stride]= mot_val0[3+2*stride]=
+        mot_val1[0       ]= mot_val1[2       ]= mot_val1[0+2*stride]= mot_val1[2+2*stride]=
+        mot_val1[1       ]= mot_val1[3       ]= mot_val1[1+2*stride]= mot_val1[3+2*stride]= 0;
+
+        do{
+            mb_type= get_vlc2(&s->gb, h263_mbtype_b_vlc.table, H263_MBTYPE_B_VLC_BITS, 2);
+            if (mb_type < 0){
+                av_log(s->avctx, AV_LOG_ERROR, "b mb_type damaged at %d %d\n", s->mb_x, s->mb_y);
+                return -1;
+            }
+
+            mb_type= h263_mb_type_b_map[ mb_type ];
+        }while(!mb_type);
+
+        s->mb_intra = IS_INTRA(mb_type);
+        if(HAS_CBP(mb_type)){
+            s->dsp.clear_blocks(s->block[0]);
+            cbpc = get_vlc2(&s->gb, cbpc_b_vlc.table, CBPC_B_VLC_BITS, 1);
+            if(s->mb_intra){
+                dquant = IS_QUANT(mb_type);
+                goto intra;
+            }
+
+            cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
+
+            if (cbpy < 0){
+                av_log(s->avctx, AV_LOG_ERROR, "b cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
+                return -1;
+            }
+
+            if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
+                cbpy ^= 0xF;
+
+            cbp = (cbpc & 3) | (cbpy << 2);
+        }else
+            cbp=0;
+
+        assert(!s->mb_intra);
+
+        if(IS_QUANT(mb_type)){
+            h263_decode_dquant(s);
+        }
+
+        if(IS_DIRECT(mb_type)){
+            s->mv_dir = MV_DIR_FORWARD | MV_DIR_BACKWARD | MV_DIRECT;
+            mb_type |= ff_mpeg4_set_direct_mv(s, 0, 0);
+        }else{
+            s->mv_dir = 0;
+            s->mv_type= MV_TYPE_16X16;
+//FIXME UMV
+
+            if(USES_LIST(mb_type, 0)){
+                int16_t *mot_val= h263_pred_motion(s, 0, 0, &mx, &my);
+                s->mv_dir = MV_DIR_FORWARD;
+
+                mx = h263_decode_motion(s, mx, 1);
+                my = h263_decode_motion(s, my, 1);
+
+                s->mv[0][0][0] = mx;
+                s->mv[0][0][1] = my;
+                mot_val[0       ]= mot_val[2       ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
+                mot_val[1       ]= mot_val[3       ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
+            }
+
+            if(USES_LIST(mb_type, 1)){
+                int16_t *mot_val= h263_pred_motion(s, 0, 1, &mx, &my);
+                s->mv_dir |= MV_DIR_BACKWARD;
+
+                mx = h263_decode_motion(s, mx, 1);
+                my = h263_decode_motion(s, my, 1);
+
+                s->mv[1][0][0] = mx;
+                s->mv[1][0][1] = my;
+                mot_val[0       ]= mot_val[2       ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
+                mot_val[1       ]= mot_val[3       ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
+            }
+        }
+
+        s->current_picture.mb_type[xy]= mb_type;
+    } else { /* I-Frame */
+        do{
+            cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
+            if (cbpc < 0){
+                av_log(s->avctx, AV_LOG_ERROR, "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
+                return -1;
+            }
+        }while(cbpc == 8);
+
+        s->dsp.clear_blocks(s->block[0]);
+
+        dquant = cbpc & 4;
+        s->mb_intra = 1;
+intra:
+        s->current_picture.mb_type[xy]= MB_TYPE_INTRA;
+        if (s->h263_aic) {
+            s->ac_pred = get_bits1(&s->gb);
+            if(s->ac_pred){
+                s->current_picture.mb_type[xy]= MB_TYPE_INTRA | MB_TYPE_ACPRED;
+
+                s->h263_aic_dir = get_bits1(&s->gb);
+            }
+        }else
+            s->ac_pred = 0;
+
+        if(s->pb_frame && get_bits1(&s->gb))
+            pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
+        cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
+        if(cbpy<0){
+            av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
+            return -1;
+        }
+        cbp = (cbpc & 3) | (cbpy << 2);
+        if (dquant) {
+            h263_decode_dquant(s);
+        }
+
+        pb_mv_count += !!s->pb_frame;
+    }
+
+    while(pb_mv_count--){
+        h263_decode_motion(s, 0, 1);
+        h263_decode_motion(s, 0, 1);
+    }
+
+    /* decode each block */
+    for (i = 0; i < 6; i++) {
+        if (h263_decode_block(s, block[i], i, cbp&32) < 0)
+            return -1;
+        cbp+=cbp;
+    }
+
+    if(s->pb_frame && h263_skip_b_part(s, cbpb) < 0)
+        return -1;
+    if(s->obmc && !s->mb_intra){
+        if(s->pict_type == FF_P_TYPE && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
+            preview_obmc(s);
+    }
+end:
+
+        /* per-MB end of slice check */
+    {
+        int v= show_bits(&s->gb, 16);
+
+        if(get_bits_count(&s->gb) + 16 > s->gb.size_in_bits){
+            v>>= get_bits_count(&s->gb) + 16 - s->gb.size_in_bits;
+        }
+
+        if(v==0)
+            return SLICE_END;
+    }
+
+    return SLICE_OK;
+}
+
+/* most is hardcoded. should extend to handle all h263 streams */
+int h263_decode_picture_header(MpegEncContext *s)
+{
+    int format, width, height, i;
+    uint32_t startcode;
+
+    align_get_bits(&s->gb);
+
+    startcode= get_bits(&s->gb, 22-8);
+
+    for(i= get_bits_left(&s->gb); i>24; i-=8) {
+        startcode = ((startcode << 8) | get_bits(&s->gb, 8)) & 0x003FFFFF;
+
+        if(startcode == 0x20)
+            break;
+    }
+
+    if (startcode != 0x20) {
+        av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
+        return -1;
+    }
+    /* temporal reference */
+    i = get_bits(&s->gb, 8); /* picture timestamp */
+    if( (s->picture_number&~0xFF)+i < s->picture_number)
+        i+= 256;
+    s->current_picture_ptr->pts=
+    s->picture_number= (s->picture_number&~0xFF) + i;
+
+    /* PTYPE starts here */
+    if (get_bits1(&s->gb) != 1) {
+        /* marker */
+        av_log(s->avctx, AV_LOG_ERROR, "Bad marker\n");
+        return -1;
+    }
+    if (get_bits1(&s->gb) != 0) {
+        av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
+        return -1;      /* h263 id */
+    }
+    skip_bits1(&s->gb);         /* split screen off */
+    skip_bits1(&s->gb);         /* camera  off */
+    skip_bits1(&s->gb);         /* freeze picture release off */
+
+    format = get_bits(&s->gb, 3);
+    /*
+        0    forbidden
+        1    sub-QCIF
+        10   QCIF
+        7       extended PTYPE (PLUSPTYPE)
+    */
+
+    if (format != 7 && format != 6) {
+        s->h263_plus = 0;
+        /* H.263v1 */
+        width = h263_format[format][0];
+        height = h263_format[format][1];
+        if (!width)
+            return -1;
+
+        s->pict_type = FF_I_TYPE + get_bits1(&s->gb);
+
+        s->h263_long_vectors = get_bits1(&s->gb);
+
+        if (get_bits1(&s->gb) != 0) {
+            av_log(s->avctx, AV_LOG_ERROR, "H263 SAC not supported\n");
+            return -1; /* SAC: off */
+        }
+        s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
+        s->unrestricted_mv = s->h263_long_vectors || s->obmc;
+
+        s->pb_frame = get_bits1(&s->gb);
+        s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
+        skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
+
+        s->width = width;
+        s->height = height;
+        s->avctx->sample_aspect_ratio= (AVRational){12,11};
+        s->avctx->time_base= (AVRational){1001, 30000};
+    } else {
+        int ufep;
+
+        /* H.263v2 */
+        s->h263_plus = 1;
+        ufep = get_bits(&s->gb, 3); /* Update Full Extended PTYPE */
+
+        /* ufep other than 0 and 1 are reserved */
+        if (ufep == 1) {
+            /* OPPTYPE */
+            format = get_bits(&s->gb, 3);
+            dprintf(s->avctx, "ufep=1, format: %d\n", format);
+            s->custom_pcf= get_bits1(&s->gb);
+            s->umvplus = get_bits1(&s->gb); /* Unrestricted Motion Vector */
+            if (get_bits1(&s->gb) != 0) {
+                av_log(s->avctx, AV_LOG_ERROR, "Syntax-based Arithmetic Coding (SAC) not supported\n");
+            }
+            s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
+            s->h263_aic = get_bits1(&s->gb); /* Advanced Intra Coding (AIC) */
+            s->loop_filter= get_bits1(&s->gb);
+            s->unrestricted_mv = s->umvplus || s->obmc || s->loop_filter;
+
+            s->h263_slice_structured= get_bits1(&s->gb);
+            if (get_bits1(&s->gb) != 0) {
+                av_log(s->avctx, AV_LOG_ERROR, "Reference Picture Selection not supported\n");
+            }
+            if (get_bits1(&s->gb) != 0) {
+                av_log(s->avctx, AV_LOG_ERROR, "Independent Segment Decoding not supported\n");
+            }
+            s->alt_inter_vlc= get_bits1(&s->gb);
+            s->modified_quant= get_bits1(&s->gb);
+            if(s->modified_quant)
+                s->chroma_qscale_table= ff_h263_chroma_qscale_table;
+
+            skip_bits(&s->gb, 1); /* Prevent start code emulation */
+
+            skip_bits(&s->gb, 3); /* Reserved */
+        } else if (ufep != 0) {
+            av_log(s->avctx, AV_LOG_ERROR, "Bad UFEP type (%d)\n", ufep);
+            return -1;
+        }
+
+        /* MPPTYPE */
+        s->pict_type = get_bits(&s->gb, 3);
+        switch(s->pict_type){
+        case 0: s->pict_type= FF_I_TYPE;break;
+        case 1: s->pict_type= FF_P_TYPE;break;
+        case 2: s->pict_type= FF_P_TYPE;s->pb_frame = 3;break;
+        case 3: s->pict_type= FF_B_TYPE;break;
+        case 7: s->pict_type= FF_I_TYPE;break; //ZYGO
+        default:
+            return -1;
+        }
+        skip_bits(&s->gb, 2);
+        s->no_rounding = get_bits1(&s->gb);
+        skip_bits(&s->gb, 4);
+
+        /* Get the picture dimensions */
+        if (ufep) {
+            if (format == 6) {
+                /* Custom Picture Format (CPFMT) */
+                s->aspect_ratio_info = get_bits(&s->gb, 4);
+                dprintf(s->avctx, "aspect: %d\n", s->aspect_ratio_info);
+                /* aspect ratios:
+                0 - forbidden
+                1 - 1:1
+                2 - 12:11 (CIF 4:3)
+                3 - 10:11 (525-type 4:3)
+                4 - 16:11 (CIF 16:9)
+                5 - 40:33 (525-type 16:9)
+                6-14 - reserved
+                */
+                width = (get_bits(&s->gb, 9) + 1) * 4;
+                skip_bits1(&s->gb);
+                height = get_bits(&s->gb, 9) * 4;
+                dprintf(s->avctx, "\nH.263+ Custom picture: %dx%d\n",width,height);
+                if (s->aspect_ratio_info == FF_ASPECT_EXTENDED) {
+                    /* aspected dimensions */
+                    s->avctx->sample_aspect_ratio.num= get_bits(&s->gb, 8);
+                    s->avctx->sample_aspect_ratio.den= get_bits(&s->gb, 8);
+                }else{
+                    s->avctx->sample_aspect_ratio= ff_h263_pixel_aspect[s->aspect_ratio_info];
+                }
+            } else {
+                width = h263_format[format][0];
+                height = h263_format[format][1];
+                s->avctx->sample_aspect_ratio= (AVRational){12,11};
+            }
+            if ((width == 0) || (height == 0))
+                return -1;
+            s->width = width;
+            s->height = height;
+
+            if(s->custom_pcf){
+                int gcd;
+                s->avctx->time_base.den= 1800000;
+                s->avctx->time_base.num= 1000 + get_bits1(&s->gb);
+                s->avctx->time_base.num*= get_bits(&s->gb, 7);
+                if(s->avctx->time_base.num == 0){
+                    av_log(s, AV_LOG_ERROR, "zero framerate\n");
+                    return -1;
+                }
+                gcd= av_gcd(s->avctx->time_base.den, s->avctx->time_base.num);
+                s->avctx->time_base.den /= gcd;
+                s->avctx->time_base.num /= gcd;
+            }else{
+                s->avctx->time_base= (AVRational){1001, 30000};
+            }
+        }
+
+        if(s->custom_pcf){
+            skip_bits(&s->gb, 2); //extended Temporal reference
+        }
+
+        if (ufep) {
+            if (s->umvplus) {
+                if(get_bits1(&s->gb)==0) /* Unlimited Unrestricted Motion Vectors Indicator (UUI) */
+                    skip_bits1(&s->gb);
+            }
+            if(s->h263_slice_structured){
+                if (get_bits1(&s->gb) != 0) {
+                    av_log(s->avctx, AV_LOG_ERROR, "rectangular slices not supported\n");
+                }
+                if (get_bits1(&s->gb) != 0) {
+                    av_log(s->avctx, AV_LOG_ERROR, "unordered slices not supported\n");
+                }
+            }
+        }
+
+        s->qscale = get_bits(&s->gb, 5);
+    }
+
+    s->mb_width = (s->width  + 15) / 16;
+    s->mb_height = (s->height  + 15) / 16;
+    s->mb_num = s->mb_width * s->mb_height;
+
+    if (s->pb_frame) {
+        skip_bits(&s->gb, 3); /* Temporal reference for B-pictures */
+        if (s->custom_pcf)
+            skip_bits(&s->gb, 2); //extended Temporal reference
+        skip_bits(&s->gb, 2); /* Quantization information for B-pictures */
+    }
+
+    /* PEI */
+    while (get_bits1(&s->gb) != 0) {
+        skip_bits(&s->gb, 8);
+    }
+
+    if(s->h263_slice_structured){
+        if (get_bits1(&s->gb) != 1) {
+            av_log(s->avctx, AV_LOG_ERROR, "SEPB1 marker missing\n");
+            return -1;
+        }
+
+        ff_h263_decode_mba(s);
+
+        if (get_bits1(&s->gb) != 1) {
+            av_log(s->avctx, AV_LOG_ERROR, "SEPB2 marker missing\n");
+            return -1;
+        }
+    }
+    s->f_code = 1;
+
+    if(s->h263_aic){
+         s->y_dc_scale_table=
+         s->c_dc_scale_table= ff_aic_dc_scale_table;
+    }else{
+        s->y_dc_scale_table=
+        s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
+    }
+
+        ff_h263_show_pict_info(s);
+    if (s->pict_type == FF_I_TYPE && s->codec_tag == AV_RL32("ZYGO")){
+        int i,j;
+        for(i=0; i<85; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
+        av_log(s->avctx, AV_LOG_DEBUG, "\n");
+        for(i=0; i<13; i++){
+            for(j=0; j<3; j++){
+                int v= get_bits(&s->gb, 8);
+                v |= get_sbits(&s->gb, 8)<<8;
+                av_log(s->avctx, AV_LOG_DEBUG, " %5d", v);
+            }
+            av_log(s->avctx, AV_LOG_DEBUG, "\n");
+        }
+        for(i=0; i<50; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
+    }
+
+    return 0;
+}