Initial revision

Originally committed as revision 5 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 1291 insertions, 0 deletions

diff --git a/libavcodec/h263.c b/libavcodec/h263.c
new file mode 100644
index 0000000000..35ecb15c2e
--- /dev/null
+++ b/libavcodec/h263.c
@@ -0,0 +1,1291 @@
+/*
+ * H263/MPEG4 backend for ffmpeg encoder and decoder
+ * Copyright (c) 2000,2001 Gerard Lantau.
+ * H263+ support for custom picture format.
+ * Copyright (c) 2001 Juan J. Sierralta P.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "common.h"
+#include "dsputil.h"
+#include "avcodec.h"
+#include "mpegvideo.h"
+#include "h263data.h"
+#include "mpeg4data.h"
+
+#define NDEBUG
+#include <assert.h>
+
+static void h263_encode_block(MpegEncContext * s, DCTELEM * block,
+			      int n);
+static void h263_encode_motion(MpegEncContext * s, int val);
+static void mpeg4_encode_block(MpegEncContext * s, DCTELEM * block,
+			       int n);
+static int h263_decode_motion(MpegEncContext * s, int pred);
+static int h263_decode_block(MpegEncContext * s, DCTELEM * block,
+                             int n, int coded);
+static int mpeg4_decode_block(MpegEncContext * s, DCTELEM * block,
+                              int n, int coded);
+
+int h263_get_picture_format(int width, int height)
+{
+    int format;
+
+    if (width == 128 && height == 96)
+	format = 1;
+    else if (width == 176 && height == 144)
+	format = 2;
+    else if (width == 352 && height == 288)
+	format = 3;
+    else if (width == 704 && height == 576)
+	format = 4;
+    else if (width == 1408 && height == 1152)
+	format = 5;
+    else
+        format = 7;
+    return format;
+}
+
+void h263_encode_picture_header(MpegEncContext * s, int picture_number)
+{
+    int format, umvplus;
+
+    align_put_bits(&s->pb);
+    put_bits(&s->pb, 22, 0x20);
+    put_bits(&s->pb, 8, ((s->picture_number * 30 * FRAME_RATE_BASE) / 
+                         s->frame_rate) & 0xff);
+
+    put_bits(&s->pb, 1, 1);	/* marker */
+    put_bits(&s->pb, 1, 0);	/* h263 id */
+    put_bits(&s->pb, 1, 0);	/* split screen off */
+    put_bits(&s->pb, 1, 0);	/* camera  off */
+    put_bits(&s->pb, 1, 0);	/* freeze picture release off */
+
+    if (!s->h263_plus) {
+        /* H.263v1 */
+        format = h263_get_picture_format(s->width, s->height);
+        put_bits(&s->pb, 3, format);
+        put_bits(&s->pb, 1, (s->pict_type == P_TYPE));
+        /* By now UMV IS DISABLED ON H.263v1, since the restrictions
+        of H.263v1 UMV implies to check the predicted MV after
+        calculation of the current MB to see if we're on the limits */
+        put_bits(&s->pb, 1, 0);	/* unrestricted motion vector: off */
+        put_bits(&s->pb, 1, 0);	/* SAC: off */
+        put_bits(&s->pb, 1, 0);	/* advanced prediction mode: off */
+        put_bits(&s->pb, 1, 0);	/* not PB frame */
+        put_bits(&s->pb, 5, s->qscale);
+        put_bits(&s->pb, 1, 0);	/* Continuous Presence Multipoint mode: off */
+    } else {
+        /* H.263v2 */
+        /* H.263 Plus PTYPE */
+        put_bits(&s->pb, 3, 7);
+        put_bits(&s->pb,3,1); /* Update Full Extended PTYPE */
+        put_bits(&s->pb,3,6); /* Custom Source Format */
+        put_bits(&s->pb,1,0); /* Custom PCF: off */
+        umvplus = (s->pict_type == P_TYPE) && s->unrestricted_mv;
+        put_bits(&s->pb, 1, umvplus); /* Unrestricted Motion Vector */
+        put_bits(&s->pb,1,0); /* SAC: off */
+        put_bits(&s->pb,1,0); /* Advanced Prediction Mode: off */
+        put_bits(&s->pb,1,0); /* Advanced Intra Coding: off */
+        put_bits(&s->pb,1,0); /* Deblocking Filter: off */
+        put_bits(&s->pb,1,0); /* Slice Structured: off */
+        put_bits(&s->pb,1,0); /* Reference Picture Selection: off */
+        put_bits(&s->pb,1,0); /* Independent Segment Decoding: off */
+        put_bits(&s->pb,1,0); /* Alternative Inter VLC: off */
+        put_bits(&s->pb,1,0); /* Modified Quantization: off */
+        put_bits(&s->pb,1,1); /* "1" to prevent start code emulation */
+        put_bits(&s->pb,3,0); /* Reserved */
+		
+        put_bits(&s->pb, 3, s->pict_type == P_TYPE);
+		
+        put_bits(&s->pb,1,0); /* Reference Picture Resampling: off */
+        put_bits(&s->pb,1,0); /* Reduced-Resolution Update: off */
+        put_bits(&s->pb,1,0); /* Rounding Type */
+        put_bits(&s->pb,2,0); /* Reserved */
+        put_bits(&s->pb,1,1); /* "1" to prevent start code emulation */
+		
+        /* This should be here if PLUSPTYPE */
+        put_bits(&s->pb, 1, 0);	/* Continuous Presence Multipoint mode: off */
+		
+        /* Custom Picture Format (CPFMT) */
+		
+        put_bits(&s->pb,4,2); /* Aspect ratio: CIF 12:11 (4:3) picture */
+        put_bits(&s->pb,9,(s->width >> 2) - 1);
+        put_bits(&s->pb,1,1); /* "1" to prevent start code emulation */
+        put_bits(&s->pb,9,(s->height >> 2));
+        /* Unlimited Unrestricted Motion Vectors Indicator (UUI) */
+        if (umvplus)
+            put_bits(&s->pb,1,1); /* Limited according tables of Annex D */
+        put_bits(&s->pb, 5, s->qscale);
+    }
+
+    put_bits(&s->pb, 1, 0);	/* no PEI */
+}
+
+void h263_encode_mb(MpegEncContext * s,
+		    DCTELEM block[6][64],
+		    int motion_x, int motion_y)
+{
+    int cbpc, cbpy, i, cbp, pred_x, pred_y;
+
+    //    printf("**mb x=%d y=%d\n", s->mb_x, s->mb_y);
+    if (!s->mb_intra) {
+	/* compute cbp */
+	cbp = 0;
+	for (i = 0; i < 6; i++) {
+	    if (s->block_last_index[i] >= 0)
+		cbp |= 1 << (5 - i);
+	}
+	if ((cbp | motion_x | motion_y) == 0) {
+	    /* skip macroblock */
+	    put_bits(&s->pb, 1, 1);
+	    return;
+	}
+	put_bits(&s->pb, 1, 0);	/* mb coded */
+	cbpc = cbp & 3;
+	put_bits(&s->pb,
+		 inter_MCBPC_bits[cbpc],
+		 inter_MCBPC_code[cbpc]);
+	cbpy = cbp >> 2;
+	cbpy ^= 0xf;
+	put_bits(&s->pb, cbpy_tab[cbpy][1], cbpy_tab[cbpy][0]);
+
+	/* motion vectors: 16x16 mode only now */
+        h263_pred_motion(s, 0, &pred_x, &pred_y);
+        
+        h263_encode_motion(s, motion_x - pred_x);
+        h263_encode_motion(s, motion_y - pred_y);
+    } else {
+	/* compute cbp */
+	cbp = 0;
+	for (i = 0; i < 6; i++) {
+	    if (s->block_last_index[i] >= 1)
+		cbp |= 1 << (5 - i);
+	}
+
+	cbpc = cbp & 3;
+	if (s->pict_type == I_TYPE) {
+	    put_bits(&s->pb,
+		     intra_MCBPC_bits[cbpc],
+		     intra_MCBPC_code[cbpc]);
+	} else {
+	    put_bits(&s->pb, 1, 0);	/* mb coded */
+	    put_bits(&s->pb,
+		     inter_MCBPC_bits[cbpc + 4],
+		     inter_MCBPC_code[cbpc + 4]);
+	}
+	if (s->h263_pred) {
+	    /* XXX: currently, we do not try to use ac prediction */
+	    put_bits(&s->pb, 1, 0);	/* no ac prediction */
+	}
+	cbpy = cbp >> 2;
+	put_bits(&s->pb, cbpy_tab[cbpy][1], cbpy_tab[cbpy][0]);
+    }
+
+    /* encode each block */
+    if (s->h263_pred) {
+	for (i = 0; i < 6; i++) {
+	    mpeg4_encode_block(s, block[i], i);
+	}
+    } else {
+	for (i = 0; i < 6; i++) {
+	    h263_encode_block(s, block[i], i);
+	}
+    }
+}
+
+static inline int mid_pred(int a, int b, int c)
+{
+    int vmin, vmax;
+    vmin = a;
+    if (b < vmin)
+        vmin = b;
+    if (c < vmin)
+        vmin = c;
+
+    vmax = a;
+    if (b > vmax)
+        vmax = b;
+    if (c > vmax)
+        vmax = c;
+
+    return a + b + c - vmin - vmax;
+}
+
+INT16 *h263_pred_motion(MpegEncContext * s, int block, 
+                        int *px, int *py)
+{
+    int x, y, wrap;
+    INT16 *A, *B, *C, *mot_val;
+
+    x = 2 * s->mb_x + 1 + (block & 1);
+    y = 2 * s->mb_y + 1 + ((block >> 1) & 1);
+    wrap = 2 * s->mb_width + 2;
+
+    mot_val = s->motion_val[(x) + (y) * wrap];
+
+    /* special case for first line */
+    if (y == 1 || s->first_slice_line) {
+        A = s->motion_val[(x-1) + (y) * wrap];
+        *px = A[0];
+        *py = A[1];
+    } else {
+        switch(block) {
+        default:
+        case 0:
+            A = s->motion_val[(x-1) + (y) * wrap];
+            B = s->motion_val[(x) + (y-1) * wrap];
+            C = s->motion_val[(x+2) + (y-1) * wrap];
+            break;
+        case 1:
+        case 2:
+            A = s->motion_val[(x-1) + (y) * wrap];
+            B = s->motion_val[(x) + (y-1) * wrap];
+            C = s->motion_val[(x+1) + (y-1) * wrap];
+            break;
+        case 3:
+            A = s->motion_val[(x-1) + (y) * wrap];
+            B = s->motion_val[(x-1) + (y-1) * wrap];
+            C = s->motion_val[(x) + (y-1) * wrap];
+            break;
+        }
+        *px = mid_pred(A[0], B[0], C[0]);
+        *py = mid_pred(A[1], B[1], C[1]);
+    }
+    return mot_val;
+}
+
+
+static void h263_encode_motion(MpegEncContext * s, int val)
+{
+    int range, l, m, bit_size, sign, code, bits;
+
+    if (val == 0) {
+        /* zero vector */
+        code = 0;
+        put_bits(&s->pb, mvtab[code][1], mvtab[code][0]);
+    } else {
+        bit_size = s->f_code - 1;
+        range = 1 << bit_size;
+        /* modulo encoding */
+        l = range * 32;
+        m = 2 * l;
+        if (val < -l) {
+            val += m;
+        } else if (val >= l) {
+            val -= m;
+        }
+
+        if (val >= 0) {
+            val--;
+            code = (val >> bit_size) + 1;
+            bits = val & (range - 1);
+            sign = 0;
+        } else {
+            val = -val;
+            val--;
+            code = (val >> bit_size) + 1;
+            bits = val & (range - 1);
+            sign = 1;
+        }
+
+        put_bits(&s->pb, mvtab[code][1] + 1, (mvtab[code][0] << 1) | sign); 
+        if (bit_size > 0) {
+            put_bits(&s->pb, bit_size, bits);
+        }
+    }
+}
+
+void h263_encode_init_vlc(MpegEncContext *s)
+{
+    static int done = 0;
+
+    if (!done) {
+        done = 1;
+        init_rl(&rl_inter);
+        init_rl(&rl_intra);
+    }
+}
+
+static void h263_encode_block(MpegEncContext * s, DCTELEM * block, int n)
+{
+    int level, run, last, i, j, last_index, last_non_zero, sign, slevel;
+    int code;
+    RLTable *rl = &rl_inter;
+
+    if (s->mb_intra) {
+	/* DC coef */
+	level = block[0];
+        /* 255 cannot be represented, so we clamp */
+        if (level > 254) {
+            level = 254;
+            block[0] = 254;
+        }
+	if (level == 128)
+	    put_bits(&s->pb, 8, 0xff);
+	else
+	    put_bits(&s->pb, 8, level & 0xff);
+	i = 1;
+    } else {
+	i = 0;
+    }
+
+    /* AC coefs */
+    last_index = s->block_last_index[n];
+    last_non_zero = i - 1;
+    for (; i <= last_index; i++) {
+	j = zigzag_direct[i];
+	level = block[j];
+	if (level) {
+	    run = i - last_non_zero - 1;
+	    last = (i == last_index);
+	    sign = 0;
+	    slevel = level;
+	    if (level < 0) {
+		sign = 1;
+		level = -level;
+	    }
+            code = get_rl_index(rl, last, run, level);
+            put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
+            if (code == rl->n) {
+                put_bits(&s->pb, 1, last);
+                put_bits(&s->pb, 6, run);
+                put_bits(&s->pb, 8, slevel & 0xff);
+            } else {
+                put_bits(&s->pb, 1, sign);
+            }
+	    last_non_zero = i;
+	}
+    }
+}
+
+/***************************************************/
+
+/* write mpeg4 VOP header */
+void mpeg4_encode_picture_header(MpegEncContext * s, int picture_number)
+{
+    align_put_bits(&s->pb);
+
+    put_bits(&s->pb, 32, 0x1B6);	/* vop header */
+    put_bits(&s->pb, 2, s->pict_type - 1);	/* pict type: I = 0 , P = 1 */
+    /* XXX: time base + 1 not always correct */
+    put_bits(&s->pb, 1, 1);
+    put_bits(&s->pb, 1, 0);
+
+    put_bits(&s->pb, 1, 1);	/* marker */
+    put_bits(&s->pb, 4, 1);	/* XXX: correct time increment */
+    put_bits(&s->pb, 1, 1);	/* marker */
+    put_bits(&s->pb, 1, 1);	/* vop coded */
+    if (s->pict_type == P_TYPE) {
+        s->no_rounding = 0;
+	put_bits(&s->pb, 1, s->no_rounding);	/* rounding type */
+    }
+    put_bits(&s->pb, 3, 0);	/* intra dc VLC threshold */
+
+    put_bits(&s->pb, 5, s->qscale);
+
+    if (s->pict_type != I_TYPE)
+	put_bits(&s->pb, 3, s->f_code);	/* fcode_for */
+    //    printf("****frame %d\n", picture_number);
+}
+
+void h263_dc_scale(MpegEncContext * s)
+{
+    int quant;
+
+    quant = s->qscale;
+    /* luminance */
+    if (quant < 5)
+	s->y_dc_scale = 8;
+    else if (quant > 4 && quant < 9)
+	s->y_dc_scale = (2 * quant);
+    else if (quant > 8 && quant < 25)
+	s->y_dc_scale = (quant + 8);
+    else
+	s->y_dc_scale = (2 * quant - 16);
+    /* chrominance */
+    if (quant < 5)
+	s->c_dc_scale = 8;
+    else if (quant > 4 && quant < 25)
+	s->c_dc_scale = ((quant + 13) / 2);
+    else
+	s->c_dc_scale = (quant - 6);
+}
+
+static int mpeg4_pred_dc(MpegEncContext * s, int n, UINT16 **dc_val_ptr, int *dir_ptr)
+{
+    int a, b, c, x, y, wrap, pred, scale;
+    UINT16 *dc_val;
+
+    /* find prediction */
+    if (n < 4) {
+	x = 2 * s->mb_x + 1 + (n & 1);
+	y = 2 * s->mb_y + 1 + ((n & 2) >> 1);
+	wrap = s->mb_width * 2 + 2;
+	dc_val = s->dc_val[0];
+	scale = s->y_dc_scale;
+    } else {
+	x = s->mb_x + 1;
+	y = s->mb_y + 1;
+	wrap = s->mb_width + 2;
+	dc_val = s->dc_val[n - 4 + 1];
+	scale = s->c_dc_scale;
+    }
+
+    /* B C
+     * A X 
+     */
+    a = dc_val[(x - 1) + (y) * wrap];
+    b = dc_val[(x - 1) + (y - 1) * wrap];
+    c = dc_val[(x) + (y - 1) * wrap];
+
+    if (abs(a - b) < abs(b - c)) {
+	pred = c;
+        *dir_ptr = 1; /* top */
+    } else {
+	pred = a;
+        *dir_ptr = 0; /* left */
+    }
+    /* we assume pred is positive */
+    pred = (pred + (scale >> 1)) / scale;
+
+    /* prepare address for prediction update */
+    *dc_val_ptr = &dc_val[(x) + (y) * wrap];
+
+    return pred;
+}
+
+void mpeg4_pred_ac(MpegEncContext * s, INT16 *block, int n, 
+                   int dir)
+{
+    int x, y, wrap, i;
+    INT16 *ac_val, *ac_val1;
+
+    /* find prediction */
+    if (n < 4) {
+	x = 2 * s->mb_x + 1 + (n & 1);
+	y = 2 * s->mb_y + 1 + ((n & 2) >> 1);
+	wrap = s->mb_width * 2 + 2;
+	ac_val = s->ac_val[0][0];
+    } else {
+	x = s->mb_x + 1;
+	y = s->mb_y + 1;
+	wrap = s->mb_width + 2;
+	ac_val = s->ac_val[n - 4 + 1][0];
+    }
+    ac_val += ((y) * wrap + (x)) * 16;
+    ac_val1 = ac_val;
+    if (s->ac_pred) {
+        if (dir == 0) {
+            /* left prediction */
+            ac_val -= 16;
+            for(i=1;i<8;i++) {
+                block[i*8] += ac_val[i];
+            }
+        } else {
+            /* top prediction */
+            ac_val -= 16 * wrap;
+            for(i=1;i<8;i++) {
+                block[i] += ac_val[i + 8];
+            }
+        }
+    }
+    /* left copy */
+    for(i=1;i<8;i++)
+        ac_val1[i] = block[i * 8];
+    /* top copy */
+    for(i=1;i<8;i++)
+        ac_val1[8 + i] = block[i];
+}
+
+static inline void mpeg4_encode_dc(MpegEncContext * s, int level, int n, int *dir_ptr)
+{
+    int size, v, pred;
+    UINT16 *dc_val;
+
+    pred = mpeg4_pred_dc(s, n, &dc_val, dir_ptr);
+    if (n < 4) {
+        *dc_val = level * s->y_dc_scale;
+    } else {
+        *dc_val = level * s->c_dc_scale;
+    }
+
+    /* do the prediction */
+    level -= pred;
+    /* find number of bits */
+    size = 0;
+    v = abs(level);
+    while (v) {
+	v >>= 1;
+	size++;
+    }
+
+    if (n < 4) {
+	/* luminance */
+	put_bits(&s->pb, DCtab_lum[size][1], DCtab_lum[size][0]);
+    } else {
+	/* chrominance */
+	put_bits(&s->pb, DCtab_chrom[size][1], DCtab_chrom[size][0]);
+    }
+
+    /* encode remaining bits */
+    if (size > 0) {
+	if (level < 0)
+	    level = (-level) ^ ((1 << size) - 1);
+	put_bits(&s->pb, size, level);
+	if (size > 8)
+	    put_bits(&s->pb, 1, 1);
+    }
+}
+
+static void mpeg4_encode_block(MpegEncContext * s, DCTELEM * block, int n)
+{
+    int level, run, last, i, j, last_index, last_non_zero, sign, slevel;
+    int code, dc_pred_dir;
+    const RLTable *rl;
+
+    if (s->mb_intra) {
+	/* mpeg4 based DC predictor */
+	mpeg4_encode_dc(s, block[0], n, &dc_pred_dir);
+	i = 1;
+        rl = &rl_intra;
+    } else {
+	i = 0;
+        rl = &rl_inter;
+    }
+
+    /* AC coefs */
+    last_index = s->block_last_index[n];
+    last_non_zero = i - 1;
+    for (; i <= last_index; i++) {
+	j = zigzag_direct[i];
+	level = block[j];
+	if (level) {
+	    run = i - last_non_zero - 1;
+	    last = (i == last_index);
+	    sign = 0;
+	    slevel = level;
+	    if (level < 0) {
+		sign = 1;
+		level = -level;
+	    }
+            code = get_rl_index(rl, last, run, level);
+            put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
+            if (code == rl->n) {
+                int level1, run1;
+                level1 = level - rl->max_level[last][run];
+                if (level1 < 1) 
+                    goto esc2;
+                code = get_rl_index(rl, last, run, level1);
+                if (code == rl->n) {
+                esc2:
+                    put_bits(&s->pb, 1, 1);
+                    if (level > MAX_LEVEL)
+                        goto esc3;
+                    run1 = run - rl->max_run[last][level] - 1;
+                    if (run1 < 0)
+                        goto esc3;
+                    code = get_rl_index(rl, last, run1, level);
+                    if (code == rl->n) {
+                    esc3:
+                        /* third escape */
+                        put_bits(&s->pb, 1, 1);
+                        put_bits(&s->pb, 1, last);
+                        put_bits(&s->pb, 6, run);
+                        put_bits(&s->pb, 1, 1);
+                        put_bits(&s->pb, 12, slevel & 0xfff);
+                        put_bits(&s->pb, 1, 1);
+                    } else {
+                        /* second escape */
+                        put_bits(&s->pb, 1, 0);
+                        put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
+                        put_bits(&s->pb, 1, sign);
+                    }
+                } else {
+                    /* first escape */
+                    put_bits(&s->pb, 1, 0);
+                    put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
+                    put_bits(&s->pb, 1, sign);
+                }
+            } else {
+                put_bits(&s->pb, 1, sign);
+            }
+	    last_non_zero = i;
+	}
+    }
+}
+
+
+
+/***********************************************/
+/* decoding */
+
+static VLC intra_MCBPC_vlc;
+static VLC inter_MCBPC_vlc;
+static VLC cbpy_vlc;
+static VLC mv_vlc;
+static VLC dc_lum, dc_chrom;
+
+void init_rl(RLTable *rl)
+{
+    INT8 max_level[MAX_RUN+1], max_run[MAX_LEVEL+1];
+    UINT8 index_run[MAX_RUN+1];
+    int last, run, level, start, end, i;
+
+    /* compute max_level[], max_run[] and index_run[] */
+    for(last=0;last<2;last++) {
+        if (last == 0) {
+            start = 0;
+            end = rl->last;
+        } else {
+            start = rl->last;
+            end = rl->n;
+        }
+
+        memset(max_level, 0, MAX_RUN + 1);
+        memset(max_run, 0, MAX_LEVEL + 1);
+        memset(index_run, rl->n, MAX_RUN + 1);
+        for(i=start;i<end;i++) {
+            run = rl->table_run[i];
+            level = rl->table_level[i];
+            if (index_run[run] == rl->n)
+                index_run[run] = i;
+            if (level > max_level[run])
+                max_level[run] = level;
+            if (run > max_run[level])
+                max_run[level] = run;
+        }
+        rl->max_level[last] = malloc(MAX_RUN + 1);
+        memcpy(rl->max_level[last], max_level, MAX_RUN + 1);
+        rl->max_run[last] = malloc(MAX_LEVEL + 1);
+        memcpy(rl->max_run[last], max_run, MAX_LEVEL + 1);
+        rl->index_run[last] = malloc(MAX_RUN + 1);
+        memcpy(rl->index_run[last], index_run, MAX_RUN + 1);
+    }
+}
+
+void init_vlc_rl(RLTable *rl)
+{
+    init_vlc(&rl->vlc, 9, rl->n + 1, 
+             &rl->table_vlc[0][1], 4, 2,
+             &rl->table_vlc[0][0], 4, 2);
+}
+
+/* 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(&intra_MCBPC_vlc, 6, 8, 
+                 intra_MCBPC_bits, 1, 1,
+                 intra_MCBPC_code, 1, 1);
+        init_vlc(&inter_MCBPC_vlc, 9, 20, 
+                 inter_MCBPC_bits, 1, 1,
+                 inter_MCBPC_code, 1, 1);
+        init_vlc(&cbpy_vlc, 6, 16,
+                 &cbpy_tab[0][1], 2, 1,
+                 &cbpy_tab[0][0], 2, 1);
+        init_vlc(&mv_vlc, 9, 33,
+                 &mvtab[0][1], 2, 1,
+                 &mvtab[0][0], 2, 1);
+        init_rl(&rl_inter);
+        init_rl(&rl_intra);
+        init_vlc_rl(&rl_inter);
+        init_vlc_rl(&rl_intra);
+        init_vlc(&dc_lum, 9, 13,
+                 &DCtab_lum[0][1], 2, 1,
+                 &DCtab_lum[0][0], 2, 1);
+        init_vlc(&dc_chrom, 9, 13,
+                 &DCtab_chrom[0][1], 2, 1,
+                 &DCtab_chrom[0][0], 2, 1);
+    }
+}
+
+int h263_decode_mb(MpegEncContext *s,
+                   DCTELEM block[6][64])
+{
+    int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
+    INT16 *mot_val;
+    static UINT8 quant_tab[4] = { -1, -2, 1, 2 };
+
+    if (s->pict_type == P_TYPE) {
+        if (get_bits(&s->gb, 1)) {
+            /* 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->mv[0][0][0] = 0;
+            s->mv[0][0][1] = 0;
+            return 0;
+        }
+        cbpc = get_vlc(&s->gb, &inter_MCBPC_vlc);
+        if (cbpc < 0)
+            return -1;
+        dquant = cbpc & 8;
+        s->mb_intra = ((cbpc & 4) != 0);
+    } else {
+        cbpc = get_vlc(&s->gb, &intra_MCBPC_vlc);
+        if (cbpc < 0)
+            return -1;
+        dquant = cbpc & 4;
+        s->mb_intra = 1;
+    }
+
+    if (!s->mb_intra) {
+        cbpy = get_vlc(&s->gb, &cbpy_vlc);
+        cbp = (cbpc & 3) | ((cbpy ^ 0xf) << 2);
+        if (dquant) {
+            s->qscale += quant_tab[get_bits(&s->gb, 2)];
+            if (s->qscale < 1)
+                s->qscale = 1;
+            else if (s->qscale > 31)
+                s->qscale = 31;
+        }
+        s->mv_dir = MV_DIR_FORWARD;
+        if ((cbpc & 16) == 0) {
+            /* 16x16 motion prediction */
+            s->mv_type = MV_TYPE_16X16;
+            h263_pred_motion(s, 0, &pred_x, &pred_y);
+            mx = h263_decode_motion(s, pred_x);
+            if (mx >= 0xffff)
+                return -1;
+            my = h263_decode_motion(s, pred_y);
+            if (my >= 0xffff)
+                return -1;
+            s->mv[0][0][0] = mx;
+            s->mv[0][0][1] = my;
+        } else {
+            s->mv_type = MV_TYPE_8X8;
+            for(i=0;i<4;i++) {
+                mot_val = h263_pred_motion(s, i, &pred_x, &pred_y);
+                mx = h263_decode_motion(s, pred_x);
+                if (mx >= 0xffff)
+                    return -1;
+                my = h263_decode_motion(s, pred_y);
+                if (my >= 0xffff)
+                    return -1;
+                s->mv[0][i][0] = mx;
+                s->mv[0][i][1] = my;
+                mot_val[0] = mx;
+                mot_val[1] = my;
+            }
+        }
+    } else {
+        s->ac_pred = 0;
+	if (s->h263_pred) {
+            s->ac_pred = get_bits(&s->gb, 1);
+        }
+        cbpy = get_vlc(&s->gb, &cbpy_vlc);
+        cbp = (cbpc & 3) | (cbpy << 2);
+        if (dquant) {
+            s->qscale += quant_tab[get_bits(&s->gb, 2)];
+            if (s->qscale < 1)
+                s->qscale = 1;
+            else if (s->qscale > 31)
+                s->qscale = 31;
+        }
+    }
+
+    /* decode each block */
+    if (s->h263_pred) {
+	for (i = 0; i < 6; i++) {
+	    if (mpeg4_decode_block(s, block[i], i, (cbp >> (5 - i)) & 1) < 0)
+                return -1;
+	}
+    } else {
+	for (i = 0; i < 6; i++) {
+	    if (h263_decode_block(s, block[i], i, (cbp >> (5 - i)) & 1) < 0)
+                return -1;
+	}
+    }
+    return 0;
+}
+
+static int h263_decode_motion(MpegEncContext * s, int pred)
+{
+    int code, val, sign, shift, l, m;
+
+    code = get_vlc(&s->gb, &mv_vlc);
+    if (code < 0)
+        return 0xffff;
+
+    if (code == 0)
+        return pred;
+    sign = get_bits(&s->gb, 1);
+    shift = s->f_code - 1;
+    val = (code - 1) << shift;
+    if (shift > 0)
+        val |= get_bits(&s->gb, shift);
+    val++;
+    if (sign)
+        val = -val;
+    val += pred;
+    
+    /* modulo decoding */
+    if (!s->h263_long_vectors) {
+        l = (1 << (s->f_code - 1)) * 32;
+        m = 2 * l;
+        if (val < -l) {
+            val += m;
+        } else if (val >= l) {
+            val -= m;
+        }
+    } else {
+        /* horrible h263 long vector mode */
+        if (pred < -31 && val < -63)
+            val += 64;
+        if (pred > 32 && val > 63)
+            val -= 64;
+    }
+    return val;
+}
+
+static int h263_decode_block(MpegEncContext * s, DCTELEM * block,
+                             int n, int coded)
+{
+    int code, level, i, j, last, run;
+    RLTable *rl = &rl_inter;
+
+    if (s->mb_intra) {
+	/* DC coef */
+        if (s->h263_rv10 && s->rv10_version == 3 && s->pict_type == 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;
+        }
+        block[0] = level;
+	i = 1;
+    } else {
+	i = 0;
+    }
+    if (!coded) {
+        s->block_last_index[n] = i - 1;
+        return 0;
+    }
+
+    for(;;) {
+        code = get_vlc(&s->gb, &rl->vlc);
+        if (code < 0)
+            return -1;
+        if (code == rl->n) {
+            /* escape */
+            last = get_bits(&s->gb, 1);
+            run = get_bits(&s->gb, 6);
+            level = (INT8)get_bits(&s->gb, 8);
+            if (s->h263_rv10 && level == -128) {
+                /* XXX: should patch encoder too */
+                level = get_bits(&s->gb, 12);
+                level = (level << 20) >> 20;
+            }
+        } else {
+            run = rl->table_run[code];
+            level = rl->table_level[code];
+            last = code >= rl->last;
+            if (get_bits(&s->gb, 1))
+                level = -level;
+        }
+        i += run;
+        if (i >= 64)
+            return -1;
+	j = zigzag_direct[i];
+        block[j] = level;
+        if (last)
+            break;
+        i++;
+    }
+    s->block_last_index[n] = i;
+    return 0;
+}
+
+static int mpeg4_decode_dc(MpegEncContext * s, int n, int *dir_ptr)
+{
+    int level, pred, code;
+    UINT16 *dc_val;
+
+    if (n < 4) 
+        code = get_vlc(&s->gb, &dc_lum);
+    else 
+        code = get_vlc(&s->gb, &dc_chrom);
+    if (code < 0)
+        return -1;
+    if (code == 0) {
+        level = 0;
+    } else {
+        level = get_bits(&s->gb, code);
+        if ((level >> (code - 1)) == 0) /* if MSB not set it is negative*/
+            level = - (level ^ ((1 << code) - 1));
+        if (code > 8)
+            get_bits(&s->gb, 1); /* marker */
+    }
+
+    pred = mpeg4_pred_dc(s, n, &dc_val, dir_ptr);
+    level += pred;
+    if (level < 0)
+        level = 0;
+    if (n < 4) {
+        *dc_val = level * s->y_dc_scale;
+    } else {
+        *dc_val = level * s->c_dc_scale;
+    }
+    return level;
+}
+
+static int mpeg4_decode_block(MpegEncContext * s, DCTELEM * block,
+                              int n, int coded)
+{
+    int code, level, i, j, last, run;
+    int dc_pred_dir;
+    RLTable *rl;
+    const UINT8 *scan_table;
+
+    if (s->mb_intra) {
+	/* DC coef */
+        level = mpeg4_decode_dc(s, n, &dc_pred_dir);
+        if (level < 0)
+            return -1;
+        block[0] = level;
+	i = 1;
+        if (!coded) 
+            goto not_coded;
+        rl = &rl_intra;
+        if (s->ac_pred) {
+            if (dc_pred_dir == 0) 
+                scan_table = ff_alternate_vertical_scan; /* left */
+            else
+                scan_table = ff_alternate_horizontal_scan; /* top */
+        } else {
+            scan_table = zigzag_direct;
+        }
+    } else {
+	i = 0;
+        if (!coded) {
+            s->block_last_index[n] = i - 1;
+            return 0;
+        }
+        rl = &rl_inter;
+        scan_table = zigzag_direct;
+    }
+
+    for(;;) {
+        code = get_vlc(&s->gb, &rl->vlc);
+        if (code < 0)
+            return -1;
+        if (code == rl->n) {
+            /* escape */
+            if (get_bits(&s->gb, 1) != 0) {
+                if (get_bits(&s->gb, 1) != 0) {
+                    /* third escape */
+                    last = get_bits(&s->gb, 1);
+                    run = get_bits(&s->gb, 6);
+                    get_bits(&s->gb, 1); /* marker */
+                    level = get_bits(&s->gb, 12);
+                    level = (level << 20) >> 20; /* sign extend */
+                    get_bits(&s->gb, 1); /* marker */
+                } else {
+                    /* second escape */
+                    code = get_vlc(&s->gb, &rl->vlc);
+                    if (code < 0 || code >= rl->n)
+                        return -1;
+                    run = rl->table_run[code];
+                    level = rl->table_level[code];
+                    last = code >= rl->last;
+                    run += rl->max_run[last][level] + 1;
+                    if (get_bits(&s->gb, 1))
+                        level = -level;
+                }
+            } else {
+                /* first escape */
+                code = get_vlc(&s->gb, &rl->vlc);
+                if (code < 0 || code >= rl->n)
+                    return -1;
+                run = rl->table_run[code];
+                level = rl->table_level[code];
+                last = code >= rl->last;
+                level += rl->max_level[last][run];
+                if (get_bits(&s->gb, 1))
+                    level = -level;
+            }
+        } else {
+            run = rl->table_run[code];
+            level = rl->table_level[code];
+            last = code >= rl->last;
+            if (get_bits(&s->gb, 1))
+                level = -level;
+        }
+        i += run;
+        if (i >= 64)
+            return -1;
+	j = scan_table[i];
+        block[j] = level;
+        i++;
+        if (last)
+            break;
+    }
+ not_coded:
+    if (s->mb_intra) {
+        mpeg4_pred_ac(s, block, n, dc_pred_dir);
+        if (s->ac_pred) {
+            i = 64; /* XXX: not optimal */
+        }
+    }
+    s->block_last_index[n] = i - 1;
+    return 0;
+}
+
+/* most is hardcoded. should extend to handle all h263 streams */
+int h263_decode_picture_header(MpegEncContext *s)
+{
+    int format, width, height;
+
+    /* picture header */
+    if (get_bits(&s->gb, 22) != 0x20)
+        return -1;
+    get_bits(&s->gb, 8); /* picture timestamp */
+
+    if (get_bits(&s->gb, 1) != 1)
+        return -1;	/* marker */
+    if (get_bits(&s->gb, 1) != 0)
+        return -1;	/* h263 id */
+    get_bits(&s->gb, 1);	/* split screen off */
+    get_bits(&s->gb, 1);	/* camera  off */
+    get_bits(&s->gb, 1);	/* freeze picture release off */
+
+    format = get_bits(&s->gb, 3);
+
+    if (format != 7) {
+        s->h263_plus = 0;
+        /* H.263v1 */
+        width = h263_format[format][0];
+        height = h263_format[format][1];
+        if (!width)
+            return -1;
+
+        s->pict_type = I_TYPE + get_bits(&s->gb, 1);
+
+        s->unrestricted_mv = get_bits(&s->gb, 1); 
+        s->h263_long_vectors = s->unrestricted_mv;
+
+        if (get_bits(&s->gb, 1) != 0)
+            return -1;	/* SAC: off */
+        if (get_bits(&s->gb, 1) != 0)
+            return -1;	/* advanced prediction mode: off */
+        if (get_bits(&s->gb, 1) != 0)
+            return -1;	/* not PB frame */
+
+        s->qscale = get_bits(&s->gb, 5);
+        get_bits(&s->gb, 1);	/* Continuous Presence Multipoint mode: off */
+    } else {
+        s->h263_plus = 1;
+        /* H.263v2 */
+        if (get_bits(&s->gb, 3) != 1)
+            return -1;
+        if (get_bits(&s->gb, 3) != 6) /* custom source format */
+            return -1;
+        get_bits(&s->gb, 12);
+        get_bits(&s->gb, 3);
+        s->pict_type = get_bits(&s->gb, 3) + 1;
+        if (s->pict_type != I_TYPE &&
+            s->pict_type != P_TYPE)
+            return -1;
+        get_bits(&s->gb, 7);
+        get_bits(&s->gb, 4); /* aspect ratio */
+        width = (get_bits(&s->gb, 9) + 1) * 4;
+        get_bits(&s->gb, 1);
+        height = get_bits(&s->gb, 9) * 4;
+        if (height == 0)
+            return -1;
+        s->qscale = get_bits(&s->gb, 5);
+    }
+    /* PEI */
+    while (get_bits(&s->gb, 1) != 0) {
+        get_bits(&s->gb, 8);
+    }
+    s->f_code = 1;
+    s->width = width;
+    s->height = height;
+    return 0;
+}
+
+/* decode mpeg4 VOP header */
+int mpeg4_decode_picture_header(MpegEncContext * s)
+{
+    int time_incr, startcode, state, v;
+
+ redo:
+    /* search next start code */
+    align_get_bits(&s->gb);
+    state = 0xff;
+    for(;;) {
+        v = get_bits(&s->gb, 8);
+        if (state == 0x000001) {
+            state = ((state << 8) | v) & 0xffffff;
+            startcode = state;
+            break;
+        }
+        state = ((state << 8) | v) & 0xffffff;
+        /* XXX: really detect end of frame */
+        if (state == 0)
+            return -1;
+    }
+
+    if (startcode == 0x120) {
+        int time_increment_resolution, width, height;
+
+        /* vol header */
+        get_bits(&s->gb, 1); /* random access */
+        get_bits(&s->gb, 8); /* vo_type */
+        get_bits(&s->gb, 1); /* is_ol_id */
+        get_bits(&s->gb, 4); /* vo_ver_id */
+        get_bits(&s->gb, 3); /* vo_priority */
+        
+        get_bits(&s->gb, 4); /* aspect_ratio_info */
+        get_bits(&s->gb, 1); /* vol control parameter */
+        get_bits(&s->gb, 2); /* vol shape */
+        get_bits(&s->gb, 1); /* marker */
+        
+        time_increment_resolution = get_bits(&s->gb, 16);
+        s->time_increment_bits = log2(time_increment_resolution - 1) + 1;
+        get_bits(&s->gb, 1); /* marker */
+
+        get_bits(&s->gb, 1); /* vop rate  */
+        get_bits(&s->gb, s->time_increment_bits);
+        get_bits(&s->gb, 1); /* marker */
+        
+        width = get_bits(&s->gb, 13);
+        get_bits(&s->gb, 1); /* marker */
+        height = get_bits(&s->gb, 13);
+        get_bits(&s->gb, 1); /* marker */
+        
+        get_bits(&s->gb, 1); /* interfaced */
+        get_bits(&s->gb, 1); /* OBMC */
+        get_bits(&s->gb, 2); /* vol_sprite_usage */
+        get_bits(&s->gb, 1); /* not_8_bit */
+
+        get_bits(&s->gb, 1); /* vol_quant_type */
+        get_bits(&s->gb, 1); /* vol_quarter_pixel */
+        get_bits(&s->gb, 1); /* complexity_estimation_disabled */
+        get_bits(&s->gb, 1); /* resync_marker_disabled */
+        get_bits(&s->gb, 1); /* data_partioning_enabled */
+        goto redo;
+    } else if (startcode != 0x1b6) {
+        goto redo;
+    }
+
+    s->pict_type = get_bits(&s->gb, 2) + 1;	/* pict type: I = 0 , P = 1 */
+    if (s->pict_type != I_TYPE &&
+        s->pict_type != P_TYPE)
+        return -1;
+    
+    /* XXX: parse time base */
+    time_incr = 0;
+    while (get_bits(&s->gb, 1) != 0) 
+        time_incr++;
+
+    get_bits(&s->gb, 1);	/* marker */
+    get_bits(&s->gb, s->time_increment_bits);
+    get_bits(&s->gb, 1);	/* marker */
+    /* vop coded */
+    if (get_bits(&s->gb, 1) != 1)
+	return -1; 
+    
+    if (s->pict_type == P_TYPE) {
+        /* rounding type for motion estimation */
+	s->no_rounding = get_bits(&s->gb, 1);
+    }
+        
+    if (get_bits(&s->gb, 3) != 0)
+	return -1; /* intra dc VLC threshold */
+
+    s->qscale = get_bits(&s->gb, 5);
+
+    if (s->pict_type != I_TYPE) {
+	s->f_code = get_bits(&s->gb, 3);	/* fcode_for */
+    }
+    return 0;
+}
+
+/* don't understand why they choose a different header ! */
+int intel_h263_decode_picture_header(MpegEncContext *s)
+{
+    int format;
+
+    /* picture header */
+    if (get_bits(&s->gb, 22) != 0x20)
+        return -1;
+    get_bits(&s->gb, 8); /* picture timestamp */
+
+    if (get_bits(&s->gb, 1) != 1)
+        return -1;	/* marker */
+    if (get_bits(&s->gb, 1) != 0)
+        return -1;	/* h263 id */
+    get_bits(&s->gb, 1);	/* split screen off */
+    get_bits(&s->gb, 1);	/* camera  off */
+    get_bits(&s->gb, 1);	/* freeze picture release off */
+
+    format = get_bits(&s->gb, 3);
+    if (format != 7)
+        return -1;
+
+    s->h263_plus = 0;
+
+    s->pict_type = I_TYPE + get_bits(&s->gb, 1);
+    
+    s->unrestricted_mv = get_bits(&s->gb, 1); 
+    s->h263_long_vectors = s->unrestricted_mv;
+
+    if (get_bits(&s->gb, 1) != 0)
+        return -1;	/* SAC: off */
+    if (get_bits(&s->gb, 1) != 0)
+        return -1;	/* advanced prediction mode: off */
+    if (get_bits(&s->gb, 1) != 0)
+        return -1;	/* not PB frame */
+
+    /* skip unknown header garbage */
+    get_bits(&s->gb, 41);
+
+    s->qscale = get_bits(&s->gb, 5);
+    get_bits(&s->gb, 1);	/* Continuous Presence Multipoint mode: off */
+
+    /* PEI */
+    while (get_bits(&s->gb, 1) != 0) {
+        get_bits(&s->gb, 8);
+    }
+    s->f_code = 1;
+    return 0;
+}