/*
  * Microsoft Screen 2 (aka Windows Media Video V9 Screen) decoder
  *

  * 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
  * Microsoft Screen 2 (aka Windows Media Video V9 Screen) decoder
  */
 
 #include "libavutil/avassert.h"

 #include "error_resilience.h"

 #include "internal.h"

 #include "mpeg_er.h"

 #include "msmpeg4.h"

 #include "qpeldsp.h"

 #include "vc1.h"

 #include "wmv2data.h"

 #include "mss12.h"
 #include "mss2dsp.h"
 
 typedef struct MSS2Context {
     VC1Context     v;
     int            split_position;

     AVFrame       *last_pic;

     MSS12Context   c;
     MSS2DSPContext dsp;

     QpelDSPContext qdsp;

     SliceContext   sc[2];
 } MSS2Context;
 
 static void arith2_normalise(ArithCoder *c)
 {
     while ((c->high >> 15) - (c->low >> 15) < 2) {
         if ((c->low ^ c->high) & 0x10000) {
             c->high  ^= 0x8000;
             c->value ^= 0x8000;
             c->low   ^= 0x8000;
         }

         c->high  = (uint16_t)c->high  << 8  | 0xFF;
         c->value = (uint16_t)c->value << 8  | bytestream2_get_byte(c->gbc.gB);
         c->low   = (uint16_t)c->low   << 8;

     }
 }
 

 ARITH_GET_BIT(arith2)

 
 /* L. Stuiver and A. Moffat: "Piecewise Integer Mapping for Arithmetic Coding."
  * In Proc. 8th Data Compression Conference (DCC '98), pp. 3-12, Mar. 1998 */
 
 static int arith2_get_scaled_value(int value, int n, int range)
 {
     int split = (n << 1) - range;
 
     if (value > split)
         return split + (value - split >> 1);
     else
         return value;
 }
 
 static void arith2_rescale_interval(ArithCoder *c, int range,
                                     int low, int high, int n)
 {
     int split = (n << 1) - range;
 
     if (high > split)
         c->high = split + (high - split << 1);
     else
         c->high = high;
 
     c->high += c->low - 1;
 
     if (low > split)
         c->low += split + (low - split << 1);
     else
         c->low += low;
 }
 
 static int arith2_get_number(ArithCoder *c, int n)
 {
     int range = c->high - c->low + 1;
     int scale = av_log2(range) - av_log2(n);
     int val;
 
     if (n << scale > range)
         scale--;
 
     n <<= scale;
 
     val = arith2_get_scaled_value(c->value - c->low, n, range) >> scale;
 
     arith2_rescale_interval(c, range, val << scale, (val + 1) << scale, n);
 
     arith2_normalise(c);
 
     return val;
 }
 

 static int arith2_get_prob(ArithCoder *c, int16_t *probs)

 {
     int range = c->high - c->low + 1, n = *probs;
     int scale = av_log2(range) - av_log2(n);
     int i     = 0, val;
 
     if (n << scale > range)
         scale--;
 
     n <<= scale;
 
     val = arith2_get_scaled_value(c->value - c->low, n, range) >> scale;
     while (probs[++i] > val) ;
 
     arith2_rescale_interval(c, range,
                             probs[i] << scale, probs[i - 1] << scale, n);
 
     return i;
 }
 

 ARITH_GET_MODEL_SYM(arith2)

 
 static int arith2_get_consumed_bytes(ArithCoder *c)
 {
     int diff = (c->high >> 16) - (c->low >> 16);
     int bp   = bytestream2_tell(c->gbc.gB) - 3 << 3;
     int bits = 1;
 
     while (!(diff & 0x80)) {
         bits++;
         diff <<= 1;
     }
 
     return (bits + bp + 7 >> 3) + ((c->low >> 16) + 1 == c->high >> 16);
 }
 
 static void arith2_init(ArithCoder *c, GetByteContext *gB)
 {
     c->low           = 0;
     c->high          = 0xFFFFFF;
     c->value         = bytestream2_get_be24(gB);
     c->gbc.gB        = gB;
     c->get_model_sym = arith2_get_model_sym;
     c->get_number    = arith2_get_number;
 }
 
 static int decode_pal_v2(MSS12Context *ctx, const uint8_t *buf, int buf_size)
 {
     int i, ncol;
     uint32_t *pal = ctx->pal + 256 - ctx->free_colours;
 
     if (!ctx->free_colours)
         return 0;
 
     ncol = *buf++;

     if (ncol > ctx->free_colours || buf_size < 2 + ncol * 3)

         return AVERROR_INVALIDDATA;

     for (i = 0; i < ncol; i++)
         *pal++ = AV_RB24(buf + 3 * i);
 
     return 1 + ncol * 3;
 }
 

 static int decode_555(GetByteContext *gB, uint16_t *dst, ptrdiff_t stride,

                       int keyframe, int w, int h)
 {
     int last_symbol = 0, repeat = 0, prev_avail = 0;
 
     if (!keyframe) {
         int x, y, endx, endy, t;
 
 #define READ_PAIR(a, b)                 \
     a  = bytestream2_get_byte(gB) << 4; \
     t  = bytestream2_get_byte(gB);      \
     a |= t >> 4;                        \
     b  = (t & 0xF) << 8;                \
     b |= bytestream2_get_byte(gB);      \
 
         READ_PAIR(x, endx)
         READ_PAIR(y, endy)
 
         if (endx >= w || endy >= h || x > endx || y > endy)

             return AVERROR_INVALIDDATA;

         dst += x + stride * y;
         w    = endx - x + 1;
         h    = endy - y + 1;
         if (y)
             prev_avail = 1;
     }
 
     do {
         uint16_t *p = dst;
         do {
             if (repeat-- < 1) {
                 int b = bytestream2_get_byte(gB);
                 if (b < 128)
                     last_symbol = b << 8 | bytestream2_get_byte(gB);
                 else if (b > 129) {
                     repeat = 0;

                     while (b-- > 130) {
                         if (repeat >= (INT_MAX >> 8) - 1) {
                             av_log(NULL, AV_LOG_ERROR, "repeat overflow\n");
                             return AVERROR_INVALIDDATA;
                         }

                         repeat = (repeat << 8) + bytestream2_get_byte(gB) + 1;

                     }

                     if (last_symbol == -2) {
                         int skip = FFMIN((unsigned)repeat, dst + w - p);
                         repeat -= skip;
                         p      += skip;
                     }
                 } else
                     last_symbol = 127 - b;
             }
             if (last_symbol >= 0)
                 *p = last_symbol;
             else if (last_symbol == -1 && prev_avail)
                 *p = *(p - stride);
         } while (++p < dst + w);
         dst       += stride;
         prev_avail = 1;
     } while (--h);
 
     return 0;
 }
 

 static int decode_rle(GetBitContext *gb, uint8_t *pal_dst, ptrdiff_t pal_stride,
                       uint8_t *rgb_dst, ptrdiff_t rgb_stride, uint32_t *pal,

                       int keyframe, int kf_slipt, int slice, int w, int h)
 {
     uint8_t bits[270] = { 0 };
     uint32_t codes[270];
     VLC vlc;
 
     int current_length = 0, read_codes = 0, next_code = 0, current_codes = 0;
     int remaining_codes, surplus_codes, i;
 
     const int alphabet_size = 270 - keyframe;
 
     int last_symbol = 0, repeat = 0, prev_avail = 0;
 
     if (!keyframe) {
         int x, y, clipw, cliph;
 
         x     = get_bits(gb, 12);
         y     = get_bits(gb, 12);
         clipw = get_bits(gb, 12) + 1;
         cliph = get_bits(gb, 12) + 1;
 
         if (x + clipw > w || y + cliph > h)
             return AVERROR_INVALIDDATA;
         pal_dst += pal_stride * y + x;
         rgb_dst += rgb_stride * y + x * 3;
         w        = clipw;
         h        = cliph;
         if (y)
             prev_avail = 1;
     } else {
         if (slice > 0) {
             pal_dst   += pal_stride * kf_slipt;
             rgb_dst   += rgb_stride * kf_slipt;
             prev_avail = 1;
             h         -= kf_slipt;
         } else
             h = kf_slipt;
     }
 
     /* read explicit codes */
     do {
         while (current_codes--) {
             int symbol = get_bits(gb, 8);
             if (symbol >= 204 - keyframe)
                 symbol += 14 - keyframe;
             else if (symbol > 189)
                 symbol = get_bits1(gb) + (symbol << 1) - 190;
             if (bits[symbol])
                 return AVERROR_INVALIDDATA;
             bits[symbol]  = current_length;
             codes[symbol] = next_code++;
             read_codes++;
         }
         current_length++;
         next_code     <<= 1;
         remaining_codes = (1 << current_length) - next_code;
         current_codes   = get_bits(gb, av_ceil_log2(remaining_codes + 1));
         if (current_length > 22 || current_codes > remaining_codes)
             return AVERROR_INVALIDDATA;
     } while (current_codes != remaining_codes);
 
     remaining_codes = alphabet_size - read_codes;
 
     /* determine the minimum length to fit the rest of the alphabet */
     while ((surplus_codes = (2 << current_length) -
                             (next_code << 1) - remaining_codes) < 0) {
         current_length++;
         next_code <<= 1;
     }
 
     /* add the rest of the symbols lexicographically */
     for (i = 0; i < alphabet_size; i++)
         if (!bits[i]) {
             if (surplus_codes-- == 0) {
                 current_length++;
                 next_code <<= 1;
             }
             bits[i]  = current_length;
             codes[i] = next_code++;
         }
 
     if (next_code != 1 << current_length)
         return AVERROR_INVALIDDATA;
 

     if ((i = init_vlc(&vlc, 9, alphabet_size, bits, 1, 1, codes, 4, 4, 0)) < 0)

         return i;
 
     /* frame decode */
     do {
         uint8_t *pp = pal_dst;
         uint8_t *rp = rgb_dst;
         do {
             if (repeat-- < 1) {
                 int b = get_vlc2(gb, vlc.table, 9, 3);
                 if (b < 256)
                     last_symbol = b;
                 else if (b < 268) {
                     b -= 256;
                     if (b == 11)
                         b = get_bits(gb, 4) + 10;
 
                     if (!b)
                         repeat = 0;
                     else
                         repeat = get_bits(gb, b);
 

                     repeat += (1 << b) - 1;

 
                     if (last_symbol == -2) {
                         int skip = FFMIN(repeat, pal_dst + w - pp);
                         repeat -= skip;
                         pp     += skip;
                         rp     += skip * 3;
                     }
                 } else
                     last_symbol = 267 - b;
             }
             if (last_symbol >= 0) {
                 *pp = last_symbol;
                 AV_WB24(rp, pal[last_symbol]);
             } else if (last_symbol == -1 && prev_avail) {
                 *pp = *(pp - pal_stride);
                 memcpy(rp, rp - rgb_stride, 3);
             }
             rp += 3;
         } while (++pp < pal_dst + w);
         pal_dst   += pal_stride;
         rgb_dst   += rgb_stride;
         prev_avail = 1;
     } while (--h);
 
     ff_free_vlc(&vlc);
     return 0;
 }
 
 static int decode_wmv9(AVCodecContext *avctx, const uint8_t *buf, int buf_size,
                        int x, int y, int w, int h, int wmv9_mask)
 {
     MSS2Context *ctx  = avctx->priv_data;
     MSS12Context *c   = &ctx->c;
     VC1Context *v     = avctx->priv_data;
     MpegEncContext *s = &v->s;
     AVFrame *f;

     int ret;

 
     ff_mpeg_flush(avctx);
 

     if ((ret = init_get_bits8(&s->gb, buf, buf_size)) < 0)
         return ret;

 
     s->loop_filter = avctx->skip_loop_filter < AVDISCARD_ALL;
 

     if (ff_vc1_parse_frame_header(v, &s->gb) < 0) {

         av_log(v->s.avctx, AV_LOG_ERROR, "header error\n");
         return AVERROR_INVALIDDATA;
     }
 
     if (s->pict_type != AV_PICTURE_TYPE_I) {
         av_log(v->s.avctx, AV_LOG_ERROR, "expected I-frame\n");
         return AVERROR_INVALIDDATA;
     }
 

     avctx->pix_fmt = AV_PIX_FMT_YUV420P;

     if ((ret = ff_mpv_frame_start(s, avctx)) < 0) {
         av_log(v->s.avctx, AV_LOG_ERROR, "ff_mpv_frame_start error\n");

         avctx->pix_fmt = AV_PIX_FMT_RGB24;

         return ret;

     }
 

     ff_mpeg_er_frame_start(s);

 
     v->bits = buf_size * 8;
 
     v->end_mb_x = (w + 15) >> 4;
     s->end_mb_y = (h + 15) >> 4;
     if (v->respic & 1)
         v->end_mb_x = v->end_mb_x + 1 >> 1;
     if (v->respic & 2)
         s->end_mb_y = s->end_mb_y + 1 >> 1;
 
     ff_vc1_decode_blocks(v);
 

     if (v->end_mb_x == s->mb_width && s->end_mb_y == s->mb_height) {
         ff_er_frame_end(&s->er);
     } else {
         av_log(v->s.avctx, AV_LOG_WARNING,
                "disabling error correction due to block count mismatch %dx%d != %dx%d\n",
                v->end_mb_x, s->end_mb_y, s->mb_width, s->mb_height);
     }

     ff_mpv_frame_end(s);

     f = s->current_picture.f;

 
     if (v->respic == 3) {
         ctx->dsp.upsample_plane(f->data[0], f->linesize[0], w,      h);

         ctx->dsp.upsample_plane(f->data[1], f->linesize[1], w+1 >> 1, h+1 >> 1);
         ctx->dsp.upsample_plane(f->data[2], f->linesize[2], w+1 >> 1, h+1 >> 1);

     } else if (v->respic)

         avpriv_request_sample(v->s.avctx,
                               "Asymmetric WMV9 rectangle subsampling");

 
     av_assert0(f->linesize[1] == f->linesize[2]);
 
     if (wmv9_mask != -1)
         ctx->dsp.mss2_blit_wmv9_masked(c->rgb_pic + y * c->rgb_stride + x * 3,
                                        c->rgb_stride, wmv9_mask,
                                        c->pal_pic + y * c->pal_stride + x,
                                        c->pal_stride,
                                        f->data[0], f->linesize[0],
                                        f->data[1], f->data[2], f->linesize[1],
                                        w, h);
     else
         ctx->dsp.mss2_blit_wmv9(c->rgb_pic + y * c->rgb_stride + x * 3,
                                 c->rgb_stride,
                                 f->data[0], f->linesize[0],
                                 f->data[1], f->data[2], f->linesize[1],
                                 w, h);
 

     avctx->pix_fmt = AV_PIX_FMT_RGB24;

 
     return 0;
 }
 
 typedef struct Rectangle {
     int coded, x, y, w, h;
 } Rectangle;
 
 #define MAX_WMV9_RECTANGLES 20
 #define ARITH2_PADDING 2
 

 static int mss2_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,

                              AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;
     MSS2Context *ctx = avctx->priv_data;
     MSS12Context *c  = &ctx->c;

     AVFrame *frame   = data;

     GetBitContext gb;
     GetByteContext gB;
     ArithCoder acoder;
 
     int keyframe, has_wmv9, has_mv, is_rle, is_555, ret;
 
     Rectangle wmv9rects[MAX_WMV9_RECTANGLES], *r;

     int used_rects = 0, i, implicit_rect = 0, av_uninit(wmv9_mask);

     if ((ret = init_get_bits8(&gb, buf, buf_size)) < 0)
         return ret;

 
     if (keyframe = get_bits1(&gb))
         skip_bits(&gb, 7);
     has_wmv9 = get_bits1(&gb);
     has_mv   = keyframe ? 0 : get_bits1(&gb);
     is_rle   = get_bits1(&gb);
     is_555   = is_rle && get_bits1(&gb);
     if (c->slice_split > 0)
         ctx->split_position = c->slice_split;
     else if (c->slice_split < 0) {
         if (get_bits1(&gb)) {
             if (get_bits1(&gb)) {
                 if (get_bits1(&gb))
                     ctx->split_position = get_bits(&gb, 16);
                 else
                     ctx->split_position = get_bits(&gb, 12);
             } else
                 ctx->split_position = get_bits(&gb, 8) << 4;
         } else {
             if (keyframe)
                 ctx->split_position = avctx->height / 2;
         }
     } else
         ctx->split_position = avctx->height;
 
     if (c->slice_split && (ctx->split_position < 1 - is_555 ||
                            ctx->split_position > avctx->height - 1))
         return AVERROR_INVALIDDATA;
 
     align_get_bits(&gb);
     buf      += get_bits_count(&gb) >> 3;
     buf_size -= get_bits_count(&gb) >> 3;
 
     if (buf_size < 1)
         return AVERROR_INVALIDDATA;
 
     if (is_555 && (has_wmv9 || has_mv || c->slice_split && ctx->split_position))
         return AVERROR_INVALIDDATA;
 

     avctx->pix_fmt = is_555 ? AV_PIX_FMT_RGB555 : AV_PIX_FMT_RGB24;

     if (ctx->last_pic->format != avctx->pix_fmt)
         av_frame_unref(ctx->last_pic);

 
     if (has_wmv9) {
         bytestream2_init(&gB, buf, buf_size + ARITH2_PADDING);
         arith2_init(&acoder, &gB);
 
         implicit_rect = !arith2_get_bit(&acoder);
 
         while (arith2_get_bit(&acoder)) {
             if (used_rects == MAX_WMV9_RECTANGLES)
                 return AVERROR_INVALIDDATA;
             r = &wmv9rects[used_rects];
             if (!used_rects)
                 r->x = arith2_get_number(&acoder, avctx->width);
             else
                 r->x = arith2_get_number(&acoder, avctx->width -
                                          wmv9rects[used_rects - 1].x) +
                        wmv9rects[used_rects - 1].x;
             r->y = arith2_get_number(&acoder, avctx->height);
             r->w = arith2_get_number(&acoder, avctx->width  - r->x) + 1;
             r->h = arith2_get_number(&acoder, avctx->height - r->y) + 1;
             used_rects++;
         }
 
         if (implicit_rect && used_rects) {
             av_log(avctx, AV_LOG_ERROR, "implicit_rect && used_rects > 0\n");
             return AVERROR_INVALIDDATA;
         }
 
         if (implicit_rect) {
             wmv9rects[0].x = 0;
             wmv9rects[0].y = 0;
             wmv9rects[0].w = avctx->width;
             wmv9rects[0].h = avctx->height;
 
             used_rects = 1;
         }
         for (i = 0; i < used_rects; i++) {
             if (!implicit_rect && arith2_get_bit(&acoder)) {
                 av_log(avctx, AV_LOG_ERROR, "Unexpected grandchildren\n");
                 return AVERROR_INVALIDDATA;
             }
             if (!i) {
                 wmv9_mask = arith2_get_bit(&acoder) - 1;
                 if (!wmv9_mask)
                     wmv9_mask = arith2_get_number(&acoder, 256);
             }
             wmv9rects[i].coded = arith2_get_number(&acoder, 2);
         }
 
         buf      += arith2_get_consumed_bytes(&acoder);
         buf_size -= arith2_get_consumed_bytes(&acoder);
         if (buf_size < 1)
             return AVERROR_INVALIDDATA;
     }
 
     c->mvX = c->mvY = 0;
     if (keyframe && !is_555) {
         if ((i = decode_pal_v2(c, buf, buf_size)) < 0)
             return AVERROR_INVALIDDATA;
         buf      += i;
         buf_size -= i;
     } else if (has_mv) {
         buf      += 4;
         buf_size -= 4;
         if (buf_size < 1)
             return AVERROR_INVALIDDATA;
         c->mvX = AV_RB16(buf - 4) - avctx->width;
         c->mvY = AV_RB16(buf - 2) - avctx->height;
     }
 
     if (c->mvX < 0 || c->mvY < 0) {
         FFSWAP(uint8_t *, c->pal_pic, c->last_pal_pic);
 

         if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)

             return ret;
 

         if (ctx->last_pic->data[0]) {
             av_assert0(frame->linesize[0] == ctx->last_pic->linesize[0]);
             c->last_rgb_pic = ctx->last_pic->data[0] +
                               ctx->last_pic->linesize[0] * (avctx->height - 1);

         } else {
             av_log(avctx, AV_LOG_ERROR, "Missing keyframe\n");

             return AVERROR_INVALIDDATA;

         }
     } else {

         if ((ret = ff_reget_buffer(avctx, ctx->last_pic)) < 0)

             return ret;

         if ((ret = av_frame_ref(frame, ctx->last_pic)) < 0)

             return ret;

 
         c->last_rgb_pic = NULL;
     }

     c->rgb_pic    = frame->data[0] +
                     frame->linesize[0] * (avctx->height - 1);
     c->rgb_stride = -frame->linesize[0];

     frame->key_frame = keyframe;
     frame->pict_type = keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;

 
     if (is_555) {
         bytestream2_init(&gB, buf, buf_size);
 
         if (decode_555(&gB, (uint16_t *)c->rgb_pic, c->rgb_stride >> 1,
                        keyframe, avctx->width, avctx->height))
             return AVERROR_INVALIDDATA;
 
         buf_size -= bytestream2_tell(&gB);
     } else {

         if (keyframe) {
             c->corrupted = 0;
             ff_mss12_slicecontext_reset(&ctx->sc[0]);
             if (c->slice_split)
                 ff_mss12_slicecontext_reset(&ctx->sc[1]);
         }

         if (is_rle) {

             if ((ret = init_get_bits8(&gb, buf, buf_size)) < 0)
                 return ret;

             if (ret = decode_rle(&gb, c->pal_pic, c->pal_stride,
                                  c->rgb_pic, c->rgb_stride, c->pal, keyframe,

                                  ctx->split_position, 0,

                                  avctx->width, avctx->height))
                 return ret;

             align_get_bits(&gb);

             if (c->slice_split)
                 if (ret = decode_rle(&gb, c->pal_pic, c->pal_stride,
                                      c->rgb_pic, c->rgb_stride, c->pal, keyframe,
                                      ctx->split_position, 1,
                                      avctx->width, avctx->height))
                     return ret;
 
             align_get_bits(&gb);
             buf      += get_bits_count(&gb) >> 3;
             buf_size -= get_bits_count(&gb) >> 3;
         } else if (!implicit_rect || wmv9_mask != -1) {
             if (c->corrupted)

                 return AVERROR_INVALIDDATA;
             bytestream2_init(&gB, buf, buf_size + ARITH2_PADDING);
             arith2_init(&acoder, &gB);

             c->keyframe = keyframe;
             if (c->corrupted = ff_mss12_decode_rect(&ctx->sc[0], &acoder, 0, 0,

                                                     avctx->width,

                                                     ctx->split_position))

                 return AVERROR_INVALIDDATA;
 
             buf      += arith2_get_consumed_bytes(&acoder);
             buf_size -= arith2_get_consumed_bytes(&acoder);

             if (c->slice_split) {
                 if (buf_size < 1)
                     return AVERROR_INVALIDDATA;
                 bytestream2_init(&gB, buf, buf_size + ARITH2_PADDING);
                 arith2_init(&acoder, &gB);
                 if (c->corrupted = ff_mss12_decode_rect(&ctx->sc[1], &acoder, 0,
                                                         ctx->split_position,
                                                         avctx->width,
                                                         avctx->height - ctx->split_position))
                     return AVERROR_INVALIDDATA;
 
                 buf      += arith2_get_consumed_bytes(&acoder);
                 buf_size -= arith2_get_consumed_bytes(&acoder);
             }
         } else
             memset(c->pal_pic, 0, c->pal_stride * avctx->height);

     }
 
     if (has_wmv9) {
         for (i = 0; i < used_rects; i++) {
             int x = wmv9rects[i].x;
             int y = wmv9rects[i].y;
             int w = wmv9rects[i].w;
             int h = wmv9rects[i].h;
             if (wmv9rects[i].coded) {
                 int WMV9codedFrameSize;
                 if (buf_size < 4 || !(WMV9codedFrameSize = AV_RL24(buf)))
                     return AVERROR_INVALIDDATA;
                 if (ret = decode_wmv9(avctx, buf + 3, buf_size - 3,
                                       x, y, w, h, wmv9_mask))
                     return ret;
                 buf      += WMV9codedFrameSize + 3;
                 buf_size -= WMV9codedFrameSize + 3;
             } else {
                 uint8_t *dst = c->rgb_pic + y * c->rgb_stride + x * 3;
                 if (wmv9_mask != -1) {
                     ctx->dsp.mss2_gray_fill_masked(dst, c->rgb_stride,
                                                    wmv9_mask,
                                                    c->pal_pic + y * c->pal_stride + x,
                                                    c->pal_stride,
                                                    w, h);
                 } else {
                     do {
                         memset(dst, 0x80, w * 3);
                         dst += c->rgb_stride;
                     } while (--h);
                 }
             }
         }
     }
 
     if (buf_size)
         av_log(avctx, AV_LOG_WARNING, "buffer not fully consumed\n");
 

     if (c->mvX < 0 || c->mvY < 0) {

         av_frame_unref(ctx->last_pic);
         ret = av_frame_ref(ctx->last_pic, frame);

         if (ret < 0)
             return ret;
     }
 

     *got_frame       = 1;

 
     return avpkt->size;
 }
 
 static av_cold int wmv9_init(AVCodecContext *avctx)
 {
     VC1Context *v = avctx->priv_data;

     int ret;

 
     v->s.avctx    = avctx;
 

     if ((ret = ff_vc1_init_common(v)) < 0)
         return ret;

     ff_vc1dsp_init(&v->vc1dsp);
 
     v->profile = PROFILE_MAIN;
 
     v->zz_8x4     = ff_wmv2_scantableA;
     v->zz_4x8     = ff_wmv2_scantableB;
     v->res_y411   = 0;
     v->res_sprite = 0;
 
     v->frmrtq_postproc = 7;
     v->bitrtq_postproc = 31;
 
     v->res_x8          = 0;
     v->multires        = 0;
     v->res_fasttx      = 1;
 
     v->fastuvmc        = 0;
 
     v->extended_mv     = 0;
 
     v->dquant          = 1;
     v->vstransform     = 1;
 
     v->res_transtab    = 0;
 
     v->overlap         = 0;
 

     v->resync_marker   = 0;

     v->rangered        = 0;
 
     v->s.max_b_frames = avctx->max_b_frames = 0;
     v->quantizer_mode = 0;
 
     v->finterpflag = 0;
 
     v->res_rtm_flag = 1;
 
     ff_vc1_init_transposed_scantables(v);
 

     if ((ret = ff_msmpeg4_decode_init(avctx)) < 0 ||
         (ret = ff_vc1_decode_init_alloc_tables(v)) < 0)
         return ret;

 
     /* error concealment */

     v->s.me.qpel_put = v->s.qdsp.put_qpel_pixels_tab;
     v->s.me.qpel_avg = v->s.qdsp.avg_qpel_pixels_tab;

 
     return 0;
 }
 
 static av_cold int mss2_decode_end(AVCodecContext *avctx)
 {
     MSS2Context *const ctx = avctx->priv_data;
 

     av_frame_free(&ctx->last_pic);

 
     ff_mss12_decode_end(&ctx->c);
     av_freep(&ctx->c.pal_pic);
     av_freep(&ctx->c.last_pal_pic);
     ff_vc1_decode_end(avctx);
 
     return 0;
 }
 
 static av_cold int mss2_decode_init(AVCodecContext *avctx)
 {
     MSS2Context * const ctx = avctx->priv_data;
     MSS12Context *c = &ctx->c;
     int ret;
     c->avctx = avctx;

     if (ret = ff_mss12_decode_init(c, 1, &ctx->sc[0], &ctx->sc[1]))

         return ret;

     ctx->last_pic   = av_frame_alloc();

     c->pal_stride   = c->mask_stride;

     c->pal_pic      = av_mallocz(c->pal_stride * avctx->height);
     c->last_pal_pic = av_mallocz(c->pal_stride * avctx->height);

     if (!c->pal_pic || !c->last_pal_pic || !ctx->last_pic) {

         mss2_decode_end(avctx);
         return AVERROR(ENOMEM);
     }
     if (ret = wmv9_init(avctx)) {
         mss2_decode_end(avctx);
         return ret;
     }
     ff_mss2dsp_init(&ctx->dsp);

     ff_qpeldsp_init(&ctx->qdsp);

     avctx->pix_fmt = c->free_colours == 127 ? AV_PIX_FMT_RGB555
                                             : AV_PIX_FMT_RGB24;

     return 0;
 }
 
 AVCodec ff_mss2_decoder = {
     .name           = "mss2",

     .long_name      = NULL_IF_CONFIG_SMALL("MS Windows Media Video V9 Screen"),

     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_MSS2,
     .priv_data_size = sizeof(MSS2Context),
     .init           = mss2_decode_init,
     .close          = mss2_decode_end,
     .decode         = mss2_decode_frame,

     .capabilities   = AV_CODEC_CAP_DR1,

 };