VP5 and VP6 video decoder

Originally committed as revision 6213 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 662 insertions, 0 deletions

diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c
new file mode 100644
index 0000000000..4a13adadaf
--- /dev/null
+++ b/libavcodec/vp56.c
@@ -0,0 +1,662 @@
+/**
+ * @file vp56.c
+ * VP5 and VP6 compatible video decoder (common features)
+ *
+ * Copyright (C) 2006  Aurelien Jacobs <aurel@gnuage.org>
+ *
+ * This library 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.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "avcodec.h"
+
+#include "vp56.h"
+#include "vp56data.h"
+
+
+void vp56_init_dequant(vp56_context_t *s, int quantizer)
+{
+    s->quantizer = quantizer;
+    s->dequant_dc = vp56_dc_dequant[quantizer] << 2;
+    s->dequant_ac = vp56_ac_dequant[quantizer] << 2;
+}
+
+static int vp56_get_vectors_predictors(vp56_context_t *s, int row, int col,
+                                       vp56_frame_t ref_frame)
+{
+    int nb_pred = 0;
+    vp56_mv_t vector[2] = {{0,0}, {0,0}};
+    int pos, offset;
+    vp56_mv_t mvp;
+
+    for (pos=0; pos<12; pos++) {
+        mvp.x = col + vp56_candidate_predictor_pos[pos][0];
+        mvp.y = row + vp56_candidate_predictor_pos[pos][1];
+        if (mvp.x < 0 || mvp.x >= s->mb_width ||
+            mvp.y < 0 || mvp.y >= s->mb_height)
+            continue;
+        offset = mvp.x + s->mb_width*mvp.y;
+
+        if (vp56_reference_frame[s->macroblocks[offset].type] != ref_frame)
+            continue;
+        if ((s->macroblocks[offset].mv.x == vector[0].x &&
+             s->macroblocks[offset].mv.y == vector[0].y) ||
+            (s->macroblocks[offset].mv.x == 0 &&
+             s->macroblocks[offset].mv.y == 0))
+            continue;
+
+        vector[nb_pred++] = s->macroblocks[offset].mv;
+        if (nb_pred > 1) {
+            nb_pred = -1;
+            break;
+        }
+        s->vector_candidate_pos = pos;
+    }
+
+    s->vector_candidate[0] = vector[0];
+    s->vector_candidate[1] = vector[1];
+
+    return nb_pred+1;
+}
+
+static void vp56_parse_mb_type_models(vp56_context_t *s)
+{
+    vp56_range_coder_t *c = &s->c;
+    int i, ctx, type;
+
+    for (ctx=0; ctx<3; ctx++) {
+        if (vp56_rac_get_prob(c, 174)) {
+            int idx = vp56_rac_gets(c, 4);
+            memcpy(s->mb_types_stats[ctx],vp56_pre_def_mb_type_stats[idx][ctx],
+                   sizeof(s->mb_types_stats[ctx]));
+        }
+        if (vp56_rac_get_prob(c, 254)) {
+            for (type=0; type<10; type++) {
+                for(i=0; i<2; i++) {
+                    if (vp56_rac_get_prob(c, 205)) {
+                        int delta, sign = vp56_rac_get(c);
+
+                        delta = vp56_rac_get_tree(c, vp56_pmbtm_tree,
+                                                  vp56_mb_type_model_model);
+                        if (!delta)
+                            delta = 4 * vp56_rac_gets(c, 7);
+                        s->mb_types_stats[ctx][type][i] += (delta ^ -sign) + sign;
+                    }
+                }
+            }
+        }
+    }
+
+    /* compute MB type probability tables based on previous MB type */
+    for (ctx=0; ctx<3; ctx++) {
+        int p[10];
+
+        for (type=0; type<10; type++)
+            p[type] = 100 * s->mb_types_stats[ctx][type][1];
+
+        for (type=0; type<10; type++) {
+            int p02, p34, p0234, p17, p56, p89, p5689, p156789;
+
+            /* conservative MB type probability */
+            s->mb_type_model[ctx][type][0] = 255 - (255 * s->mb_types_stats[ctx][type][0]) / (1 + s->mb_types_stats[ctx][type][0] + s->mb_types_stats[ctx][type][1]);
+
+            p[type] = 0;    /* same MB type => weight is null */
+
+            /* binary tree parsing probabilities */
+            p02 = p[0] + p[2];
+            p34 = p[3] + p[4];
+            p0234 = p02 + p34;
+            p17 = p[1] + p[7];
+            p56 = p[5] + p[6];
+            p89 = p[8] + p[9];
+            p5689 = p56 + p89;
+            p156789 = p17 + p5689;
+
+            s->mb_type_model[ctx][type][1] = 1 + 255 * p0234/(1+p0234+p156789);
+            s->mb_type_model[ctx][type][2] = 1 + 255 * p02  / (1+p0234);
+            s->mb_type_model[ctx][type][3] = 1 + 255 * p17  / (1+p156789);
+            s->mb_type_model[ctx][type][4] = 1 + 255 * p[0] / (1+p02);
+            s->mb_type_model[ctx][type][5] = 1 + 255 * p[3] / (1+p34);
+            s->mb_type_model[ctx][type][6] = 1 + 255 * p[1] / (1+p17);
+            s->mb_type_model[ctx][type][7] = 1 + 255 * p56  / (1+p5689);
+            s->mb_type_model[ctx][type][8] = 1 + 255 * p[5] / (1+p56);
+            s->mb_type_model[ctx][type][9] = 1 + 255 * p[8] / (1+p89);
+
+            /* restore initial value */
+            p[type] = 100 * s->mb_types_stats[ctx][type][1];
+        }
+    }
+}
+
+static vp56_mb_t vp56_parse_mb_type(vp56_context_t *s,
+                                    vp56_mb_t prev_type, int ctx)
+{
+    uint8_t *mb_type_model = s->mb_type_model[ctx][prev_type];
+    vp56_range_coder_t *c = &s->c;
+
+    if (vp56_rac_get_prob(c, mb_type_model[0]))
+        return prev_type;
+    else
+        return vp56_rac_get_tree(c, vp56_pmbt_tree, mb_type_model);
+}
+
+static void vp56_decode_4mv(vp56_context_t *s, int row, int col)
+{
+    vp56_mv_t mv = {0,0};
+    int type[4];
+    int b;
+
+    /* parse each block type */
+    for (b=0; b<4; b++) {
+        type[b] = vp56_rac_gets(&s->c, 2);
+        if (type[b])
+            type[b]++;  /* only returns 0, 2, 3 or 4 (all INTER_PF) */
+    }
+
+    /* get vectors */
+    for (b=0; b<4; b++) {
+        switch (type[b]) {
+            case VP56_MB_INTER_NOVEC_PF:
+                s->mv[b] = (vp56_mv_t) {0,0};
+                break;
+            case VP56_MB_INTER_DELTA_PF:
+                s->parse_vector_adjustment(s, &s->mv[b]);
+                break;
+            case VP56_MB_INTER_V1_PF:
+                s->mv[b] = s->vector_candidate[0];
+                break;
+            case VP56_MB_INTER_V2_PF:
+                s->mv[b] = s->vector_candidate[1];
+                break;
+        }
+        mv.x += s->mv[b].x;
+        mv.y += s->mv[b].y;
+    }
+
+    /* this is the one selected for the whole MB for prediction */
+    s->macroblocks[row * s->mb_width + col].mv = s->mv[3];
+
+    /* chroma vectors are average luma vectors */
+    if (s->avctx->codec->id == CODEC_ID_VP5) {
+        s->mv[4].x = s->mv[5].x = RSHIFT(mv.x,2);
+        s->mv[4].y = s->mv[5].y = RSHIFT(mv.y,2);
+    } else {
+        s->mv[4] = s->mv[5] = (vp56_mv_t) {mv.x/4, mv.y/4};
+    }
+}
+
+static vp56_mb_t vp56_decode_mv(vp56_context_t *s, int row, int col)
+{
+    vp56_mv_t *mv, vector = {0,0};
+    int ctx, b;
+
+    ctx = vp56_get_vectors_predictors(s, row, col, VP56_FRAME_PREVIOUS);
+    s->mb_type = vp56_parse_mb_type(s, s->mb_type, ctx);
+    s->macroblocks[row * s->mb_width + col].type = s->mb_type;
+
+    switch (s->mb_type) {
+        case VP56_MB_INTER_V1_PF:
+            mv = &s->vector_candidate[0];
+            break;
+
+        case VP56_MB_INTER_V2_PF:
+            mv = &s->vector_candidate[1];
+            break;
+
+        case VP56_MB_INTER_V1_GF:
+            vp56_get_vectors_predictors(s, row, col, VP56_FRAME_GOLDEN);
+            mv = &s->vector_candidate[0];
+            break;
+
+        case VP56_MB_INTER_V2_GF:
+            vp56_get_vectors_predictors(s, row, col, VP56_FRAME_GOLDEN);
+            mv = &s->vector_candidate[1];
+            break;
+
+        case VP56_MB_INTER_DELTA_PF:
+            s->parse_vector_adjustment(s, &vector);
+            mv = &vector;
+            break;
+
+        case VP56_MB_INTER_DELTA_GF:
+            vp56_get_vectors_predictors(s, row, col, VP56_FRAME_GOLDEN);
+            s->parse_vector_adjustment(s, &vector);
+            mv = &vector;
+            break;
+
+        case VP56_MB_INTER_4V:
+            vp56_decode_4mv(s, row, col);
+            return s->mb_type;
+
+        default:
+            mv = &vector;
+            break;
+    }
+
+    s->macroblocks[row*s->mb_width + col].mv = *mv;
+
+    /* same vector for all blocks */
+    for (b=0; b<6; b++)
+        s->mv[b] = *mv;
+
+    return s->mb_type;
+}
+
+static void vp56_add_predictors_dc(vp56_context_t *s, vp56_frame_t ref_frame)
+{
+    int idx = s->scantable.permutated[0];
+    int i;
+
+    for (i=0; i<6; i++) {
+        vp56_ref_dc_t *ab = &s->above_blocks[s->above_block_idx[i]];
+        vp56_ref_dc_t *lb = &s->left_block[vp56_b6to4[i]];
+        int count = 0;
+        int dc = 0;
+
+        if (ref_frame == lb->ref_frame) {
+            dc += lb->dc_coeff;
+            count++;
+        }
+        if (ref_frame == ab->ref_frame) {
+            dc += ab->dc_coeff;
+            count++;
+        }
+        if (s->avctx->codec->id == CODEC_ID_VP5) {
+            if (count < 2 && ref_frame == ab[-1].ref_frame) {
+                dc += ab[-1].dc_coeff;
+                count++;
+            }
+            if (count < 2 && ref_frame == ab[1].ref_frame) {
+                dc += ab[1].dc_coeff;
+                count++;
+            }
+        }
+        if (count == 0)
+            dc = s->prev_dc[vp56_b6to3[i]][ref_frame];
+        else if (count == 2)
+            dc /= 2;
+
+        s->block_coeff[i][idx] += dc;
+        s->prev_dc[vp56_b6to3[i]][ref_frame] = s->block_coeff[i][idx];
+        ab->dc_coeff = s->block_coeff[i][idx];
+        ab->ref_frame = ref_frame;
+        lb->dc_coeff = s->block_coeff[i][idx];
+        lb->ref_frame = ref_frame;
+        s->block_coeff[i][idx] *= s->dequant_dc;
+    }
+}
+
+static void vp56_edge_filter(vp56_context_t *s, uint8_t *yuv,
+                             int pix_inc, int line_inc, int t)
+{
+    int pix2_inc = 2 * pix_inc;
+    int i, v;
+
+    for (i=0; i<12; i++) {
+        v = (yuv[-pix2_inc] + 3*(yuv[0]-yuv[-pix_inc]) - yuv[pix_inc] + 4) >>3;
+        v = s->adjust(v, t);
+        yuv[-pix_inc] = clip_uint8(yuv[-pix_inc] + v);
+        yuv[0] = clip_uint8(yuv[0] - v);
+        yuv += line_inc;
+    }
+}
+
+static void vp56_deblock_filter(vp56_context_t *s, uint8_t *yuv,
+                                int stride, int dx, int dy)
+{
+    int t = vp56_filter_threshold[s->quantizer];
+    if (dx)  vp56_edge_filter(s, yuv +         10-dx ,      1, stride, t);
+    if (dy)  vp56_edge_filter(s, yuv + stride*(10-dy), stride,      1, t);
+}
+
+static void vp56_mc(vp56_context_t *s, int b, uint8_t *src,
+                    int stride, int x, int y)
+{
+    int plane = vp56_b6to3[b];
+    uint8_t *dst= s->frames[VP56_FRAME_CURRENT].data[plane]+s->block_offset[b];
+    uint8_t *src_block;
+    int src_offset;
+    int overlap_offset = 0;
+    int mask = s->vp56_coord_div[b] - 1;
+    int deblock_filtering = s->deblock_filtering;
+    int dx;
+    int dy;
+
+    if (s->avctx->skip_loop_filter >= AVDISCARD_ALL ||
+        (s->avctx->skip_loop_filter >= AVDISCARD_NONKEY
+         && !s->frames[VP56_FRAME_CURRENT].key_frame))
+        deblock_filtering = 0;
+
+    dx = s->mv[b].x / s->vp56_coord_div[b];
+    dy = s->mv[b].y / s->vp56_coord_div[b];
+
+    if (b >= 4) {
+        x /= 2;
+        y /= 2;
+    }
+    x += dx - 2;
+    y += dy - 2;
+
+    if (x<0 || x+12>=s->plane_width[plane] ||
+        y<0 || y+12>=s->plane_height[plane]) {
+        ff_emulated_edge_mc(s->edge_emu_buffer,
+                            src + s->block_offset[b] + (dy-2)*stride + (dx-2),
+                            stride, 12, 12, x, y,
+                            s->plane_width[plane],
+                            s->plane_height[plane]);
+        src_block = s->edge_emu_buffer;
+        src_offset = 2 + 2*stride;
+    } else if (deblock_filtering) {
+        /* only need a 12x12 block, but there is no such dsp function, */
+        /* so copy a 16x12 block */
+        s->dsp.put_pixels_tab[0][0](s->edge_emu_buffer,
+                                    src + s->block_offset[b] + (dy-2)*stride + (dx-2),
+                                    stride, 12);
+        src_block = s->edge_emu_buffer;
+        src_offset = 2 + 2*stride;
+    } else {
+        src_block = src;
+        src_offset = s->block_offset[b] + dy*stride + dx;
+    }
+
+    if (deblock_filtering)
+        vp56_deblock_filter(s, src_block, stride, dx&7, dy&7);
+
+    if (s->mv[b].x & mask)
+        overlap_offset += (s->mv[b].x > 0) ? 1 : -1;
+    if (s->mv[b].y & mask)
+        overlap_offset += (s->mv[b].y > 0) ? stride : -stride;
+
+    if (overlap_offset) {
+        if (s->filter)
+            s->filter(s, dst, src_block, src_offset, src_offset+overlap_offset,
+                      stride, s->mv[b], mask, s->filter_selection, b<4);
+        else
+            s->dsp.put_no_rnd_pixels_l2[1](dst, src_block+src_offset,
+                                           src_block+src_offset+overlap_offset,
+                                           stride, 8);
+    } else {
+        s->dsp.put_pixels_tab[1][0](dst, src_block+src_offset, stride, 8);
+    }
+}
+
+static void vp56_decode_mb(vp56_context_t *s, int row, int col)
+{
+    AVFrame *frame_current, *frame_ref;
+    vp56_mb_t mb_type;
+    vp56_frame_t ref_frame;
+    int b, plan, off;
+
+    if (s->frames[VP56_FRAME_CURRENT].key_frame)
+        mb_type = VP56_MB_INTRA;
+    else
+        mb_type = vp56_decode_mv(s, row, col);
+    ref_frame = vp56_reference_frame[mb_type];
+
+    memset(s->block_coeff, 0, sizeof(s->block_coeff));
+
+    s->parse_coeff(s);
+
+    vp56_add_predictors_dc(s, ref_frame);
+
+    frame_current = &s->frames[VP56_FRAME_CURRENT];
+    frame_ref = &s->frames[ref_frame];
+
+    switch (mb_type) {
+        case VP56_MB_INTRA:
+            for (b=0; b<6; b++) {
+                plan = vp56_b6to3[b];
+                s->dsp.idct_put(frame_current->data[plan] + s->block_offset[b],
+                                s->stride[plan], s->block_coeff[b]);
+            }
+            break;
+
+        case VP56_MB_INTER_NOVEC_PF:
+        case VP56_MB_INTER_NOVEC_GF:
+            for (b=0; b<6; b++) {
+                plan = vp56_b6to3[b];
+                off = s->block_offset[b];
+                s->dsp.put_pixels_tab[1][0](frame_current->data[plan] + off,
+                                            frame_ref->data[plan] + off,
+                                            s->stride[plan], 8);
+                s->dsp.idct_add(frame_current->data[plan] + off,
+                                s->stride[plan], s->block_coeff[b]);
+            }
+            break;
+
+        case VP56_MB_INTER_DELTA_PF:
+        case VP56_MB_INTER_V1_PF:
+        case VP56_MB_INTER_V2_PF:
+        case VP56_MB_INTER_DELTA_GF:
+        case VP56_MB_INTER_4V:
+        case VP56_MB_INTER_V1_GF:
+        case VP56_MB_INTER_V2_GF:
+            for (b=0; b<6; b++) {
+                int x_off = b==1 || b==3 ? 8 : 0;
+                int y_off = b==2 || b==3 ? 8 : 0;
+                plan = vp56_b6to3[b];
+                vp56_mc(s, b, frame_ref->data[plan], s->stride[plan],
+                        16*col+x_off, 16*row+y_off);
+                s->dsp.idct_add(frame_current->data[plan] + s->block_offset[b],
+                                s->stride[plan], s->block_coeff[b]);
+            }
+            break;
+    }
+}
+
+static int vp56_size_changed(AVCodecContext *avctx, vp56_context_t *s)
+{
+    int stride = s->frames[VP56_FRAME_CURRENT].linesize[0];
+    int i;
+
+    s->plane_width[0] = s->avctx->width;
+    s->plane_width[1] = s->plane_width[2] = s->avctx->width/2;
+    s->plane_height[0] = s->avctx->height;
+    s->plane_height[1] = s->plane_height[2] = s->avctx->height/2;
+
+    for (i=0; i<3; i++)
+        s->stride[i] = s->flip * s->frames[VP56_FRAME_CURRENT].linesize[i];
+
+    s->mb_width = (s->avctx->width+15) / 16;
+    s->mb_height = (s->avctx->height+15) / 16;
+
+    if (s->mb_width > 1000 || s->mb_height > 1000) {
+        av_log(avctx, AV_LOG_ERROR, "picture too big\n");
+        return -1;
+    }
+
+    s->above_blocks = av_realloc(s->above_blocks,
+                                 (4*s->mb_width+6) * sizeof(*s->above_blocks));
+    s->macroblocks = av_realloc(s->macroblocks,
+                                s->mb_width*s->mb_height*sizeof(*s->macroblocks));
+    s->edge_emu_buffer_alloc = av_realloc(s->edge_emu_buffer_alloc, 16*stride);
+    s->edge_emu_buffer = s->edge_emu_buffer_alloc;
+    if (s->flip < 0)
+        s->edge_emu_buffer += 15 * stride;
+
+    return 0;
+}
+
+int vp56_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
+                      uint8_t *buf, int buf_size)
+{
+    vp56_context_t *s = avctx->priv_data;
+    AVFrame *const p = &s->frames[VP56_FRAME_CURRENT];
+    AVFrame *picture = data;
+    int mb_row, mb_col, mb_row_flip, mb_offset = 0;
+    int block, y, uv, stride_y, stride_uv;
+    int golden_frame = 0;
+    int res;
+
+    res = s->parse_header(s, buf, buf_size, &golden_frame);
+    if (!res)
+        return -1;
+
+    p->reference = 1;
+    if (avctx->get_buffer(avctx, p) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
+        return -1;
+    }
+
+    if (res == 2)
+        if (vp56_size_changed(avctx, s)) {
+            avctx->release_buffer(avctx, p);
+            return -1;
+        }
+
+    if (p->key_frame) {
+        p->pict_type = FF_I_TYPE;
+        s->default_models_init(s);
+        for (block=0; block<s->mb_height*s->mb_width; block++)
+            s->macroblocks[block].type = VP56_MB_INTRA;
+    } else {
+        p->pict_type = FF_P_TYPE;
+        vp56_parse_mb_type_models(s);
+        s->parse_vector_models(s);
+        s->mb_type = VP56_MB_INTER_NOVEC_PF;
+    }
+
+    s->parse_coeff_models(s);
+
+    memset(s->prev_dc, 0, sizeof(s->prev_dc));
+    s->prev_dc[1][VP56_FRAME_CURRENT] = 128;
+    s->prev_dc[2][VP56_FRAME_CURRENT] = 128;
+
+    for (block=0; block < 4*s->mb_width+6; block++) {
+        s->above_blocks[block].ref_frame = -1;
+        s->above_blocks[block].dc_coeff = 0;
+        s->above_blocks[block].not_null_dc = 0;
+    }
+    s->above_blocks[2*s->mb_width + 2].ref_frame = 0;
+    s->above_blocks[3*s->mb_width + 4].ref_frame = 0;
+
+    stride_y  = p->linesize[0];
+    stride_uv = p->linesize[1];
+
+    if (s->flip < 0)
+        mb_offset = 7;
+
+    /* main macroblocks loop */
+    for (mb_row=0; mb_row<s->mb_height; mb_row++) {
+        if (s->flip < 0)
+            mb_row_flip = s->mb_height - mb_row - 1;
+        else
+            mb_row_flip = mb_row;
+
+        for (block=0; block<4; block++) {
+            s->left_block[block].ref_frame = -1;
+            s->left_block[block].dc_coeff = 0;
+            s->left_block[block].not_null_dc = 0;
+            memset(s->coeff_ctx[block], 0, 64*sizeof(s->coeff_ctx[block][0]));
+        }
+        memset(s->coeff_ctx_last, 24, sizeof(s->coeff_ctx_last));
+
+        s->above_block_idx[0] = 1;
+        s->above_block_idx[1] = 2;
+        s->above_block_idx[2] = 1;
+        s->above_block_idx[3] = 2;
+        s->above_block_idx[4] = 2*s->mb_width + 2 + 1;
+        s->above_block_idx[5] = 3*s->mb_width + 4 + 1;
+
+        s->block_offset[s->frbi] = (mb_row_flip*16 + mb_offset) * stride_y;
+        s->block_offset[s->srbi] = s->block_offset[s->frbi] + 8*stride_y;
+        s->block_offset[1] = s->block_offset[0] + 8;
+        s->block_offset[3] = s->block_offset[2] + 8;
+        s->block_offset[4] = (mb_row_flip*8 + mb_offset) * stride_uv;
+        s->block_offset[5] = s->block_offset[4];
+
+        for (mb_col=0; mb_col<s->mb_width; mb_col++) {
+            vp56_decode_mb(s, mb_row, mb_col);
+
+            for (y=0; y<4; y++) {
+                s->above_block_idx[y] += 2;
+                s->block_offset[y] += 16;
+            }
+
+            for (uv=4; uv<6; uv++) {
+                s->above_block_idx[uv] += 1;
+                s->block_offset[uv] += 8;
+            }
+        }
+    }
+
+    if (s->frames[VP56_FRAME_PREVIOUS].data[0]
+        && (s->frames[VP56_FRAME_PREVIOUS].data[0]
+            != s->frames[VP56_FRAME_GOLDEN].data[0])) {
+        avctx->release_buffer(avctx, &s->frames[VP56_FRAME_PREVIOUS]);
+    }
+    if (p->key_frame || golden_frame) {
+        if (s->frames[VP56_FRAME_GOLDEN].data[0])
+            avctx->release_buffer(avctx, &s->frames[VP56_FRAME_GOLDEN]);
+        s->frames[VP56_FRAME_GOLDEN] = *p;
+    }
+    s->frames[VP56_FRAME_PREVIOUS] = *p;
+
+    *picture = *p;
+    *data_size = sizeof(AVPicture);
+
+    return buf_size;
+}
+
+void vp56_init(vp56_context_t *s, AVCodecContext *avctx, int flip)
+{
+    int i;
+
+    s->avctx = avctx;
+    avctx->pix_fmt = PIX_FMT_YUV420P;
+
+    if (s->avctx->idct_algo == FF_IDCT_AUTO)
+        s->avctx->idct_algo = FF_IDCT_VP3;
+    dsputil_init(&s->dsp, s->avctx);
+    ff_init_scantable(s->dsp.idct_permutation, &s->scantable,ff_zigzag_direct);
+
+    avcodec_set_dimensions(s->avctx, 0, 0);
+
+    for (i=0; i<3; i++)
+        s->frames[i].data[0] = NULL;
+    s->edge_emu_buffer_alloc = NULL;
+
+    s->above_blocks = NULL;
+    s->macroblocks = NULL;
+    s->quantizer = -1;
+    s->deblock_filtering = 1;
+
+    s->filter = NULL;
+
+    if (flip) {
+        s->flip = -1;
+        s->frbi = 2;
+        s->srbi = 0;
+    } else {
+        s->flip = 1;
+        s->frbi = 0;
+        s->srbi = 2;
+    }
+}
+
+int vp56_free(AVCodecContext *avctx)
+{
+    vp56_context_t *s = avctx->priv_data;
+
+    av_free(s->above_blocks);
+    av_free(s->macroblocks);
+    av_free(s->edge_emu_buffer_alloc);
+    if (s->frames[VP56_FRAME_GOLDEN].data[0]
+        && (s->frames[VP56_FRAME_PREVIOUS].data[0]
+            != s->frames[VP56_FRAME_GOLDEN].data[0]))
+        avctx->release_buffer(avctx, &s->frames[VP56_FRAME_GOLDEN]);
+    if (s->frames[VP56_FRAME_PREVIOUS].data[0])
+        avctx->release_buffer(avctx, &s->frames[VP56_FRAME_PREVIOUS]);
+    return 0;
+}