ffv1: update to ffv1 version 3

Based on code from Carl Eugen Hoyos, Michael Niedermayer and Paul B Mahol.

1 files changed, 408 insertions, 129 deletions

diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c
index f8c232f9a3..f5f7a8f2f5 100644
--- a/libavcodec/ffv1dec.c
+++ b/libavcodec/ffv1dec.c
@@ -1,7 +1,7 @@
 /*
  * FFV1 decoder
  *
- * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
+ * Copyright (c) 2003-2012 Michael Niedermayer <michaelni@gmx.at>
  *
  * This file is part of Libav.
  *
@@ -26,6 +26,10 @@
  */
 
 #include "libavutil/avassert.h"
+#include "libavutil/pixdesc.h"
+#include "libavutil/crc.h"
+#include "libavutil/opt.h"
+#include "libavutil/imgutils.h"
 #include "avcodec.h"
 #include "get_bits.h"
 #include "put_bits.h"
@@ -192,86 +196,206 @@ static void decode_plane(FFV1Context *s, uint8_t *src,
         } else {
             decode_line(s, w, sample, plane_index,
                         s->avctx->bits_per_raw_sample);
-            for (x = 0; x < w; x++)
-                ((uint16_t *)(src + stride * y))[x] =
-                    sample[1][x] << (16 - s->avctx->bits_per_raw_sample);
+            if (s->packed_at_lsb) {
+                for (x = 0; x < w; x++)
+                    ((uint16_t *)(src + stride * y))[x] = sample[1][x];
+            } else {
+                for (x = 0; x < w; x++)
+                    ((uint16_t *)(src + stride * y))[x] = sample[1][x] << (16 - s->avctx->bits_per_raw_sample);
+            }
         }
 // STOP_TIMER("decode-line") }
     }
 }
 
-static void decode_rgb_frame(FFV1Context *s, uint32_t *src,
-                             int w, int h, int stride)
+static void decode_rgb_frame(FFV1Context *s, uint8_t *src[3], int w, int h,
+                             int stride[3])
 {
     int x, y, p;
-    int16_t *sample[3][2];
-    for (x = 0; x < 3; x++) {
+    int16_t *sample[4][2];
+    int lbd  = s->avctx->bits_per_raw_sample <= 8;
+    int bits = s->avctx->bits_per_raw_sample > 0
+               ? s->avctx->bits_per_raw_sample
+               : 8;
+    int offset = 1 << bits;
+
+    for (x = 0; x < 4; x++) {
         sample[x][0] = s->sample_buffer +  x * 2      * (w + 6) + 3;
         sample[x][1] = s->sample_buffer + (x * 2 + 1) * (w + 6) + 3;
     }
 
     s->run_index = 0;
 
-    memset(s->sample_buffer, 0, 6 * (w + 6) * sizeof(*s->sample_buffer));
+    memset(s->sample_buffer, 0, 8 * (w + 6) * sizeof(*s->sample_buffer));
 
     for (y = 0; y < h; y++) {
-        for (p = 0; p < 3; p++) {
-            int16_t *temp = sample[p][0]; // FIXME: try a normal buffer
+        for (p = 0; p < 3 + s->transparency; p++) {
+            int16_t *temp = sample[p][0]; //FIXME try a normal buffer
 
             sample[p][0] = sample[p][1];
             sample[p][1] = temp;
 
             sample[p][1][-1] = sample[p][0][0];
             sample[p][0][w]  = sample[p][0][w - 1];
-            decode_line(s, w, sample[p], FFMIN(p, 1), 9);
+            if (lbd)
+                decode_line(s, w, sample[p], (p + 1) / 2, 9);
+            else
+                decode_line(s, w, sample[p], (p + 1) / 2, bits + 1);
         }
         for (x = 0; x < w; x++) {
             int g = sample[0][1][x];
             int b = sample[1][1][x];
             int r = sample[2][1][x];
+            int a = sample[3][1][x];
 
-//            assert(g >= 0  && b >= 0  && r >= 0);
-//            assert(g < 256 && b < 512 && r < 512);
-
-            b -= 0x100;
-            r -= 0x100;
+            b -= offset;
+            r -= offset;
             g -= (b + r) >> 2;
             b += g;
             r += g;
 
-            src[x + stride * y] = b + (g << 8) + (r << 16) + (0xFF << 24);
+            if (lbd)
+                *((uint32_t *)(src[0] + x * 4 + stride[0] * y)) = b +
+                    (g << 8) + (r << 16) + (a << 24);
+            else {
+                *((uint16_t *)(src[0] + x * 2 + stride[0] * y)) = b;
+                *((uint16_t *)(src[1] + x * 2 + stride[1] * y)) = g;
+                *((uint16_t *)(src[2] + x * 2 + stride[2] * y)) = r;
+            }
         }
     }
 }
 
+static int decode_slice_header(FFV1Context *f, FFV1Context *fs)
+{
+    RangeCoder *c = &fs->c;
+    uint8_t state[CONTEXT_SIZE];
+    unsigned ps, i, context_count;
+    memset(state, 128, sizeof(state));
+
+    av_assert0(f->version > 2);
+
+    fs->slice_x      = get_symbol(c, state, 0) * f->width;
+    fs->slice_y      = get_symbol(c, state, 0) * f->height;
+    fs->slice_width  = (get_symbol(c, state, 0) + 1) * f->width + fs->slice_x;
+    fs->slice_height = (get_symbol(c, state, 0) + 1) * f->height + fs->slice_y;
+
+    fs->slice_x     /= f->num_h_slices;
+    fs->slice_y     /= f->num_v_slices;
+    fs->slice_width  = fs->slice_width / f->num_h_slices - fs->slice_x;
+    fs->slice_height = fs->slice_height / f->num_v_slices - fs->slice_y;
+    if ((unsigned)fs->slice_width  > f->width ||
+        (unsigned)fs->slice_height > f->height)
+        return AVERROR_INVALIDDATA;
+    if ((unsigned)fs->slice_x + (uint64_t)fs->slice_width  > f->width ||
+        (unsigned)fs->slice_y + (uint64_t)fs->slice_height > f->height)
+        return AVERROR_INVALIDDATA;
+
+    for (i = 0; i < f->plane_count; i++) {
+        PlaneContext *const p = &fs->plane[i];
+        int idx               = get_symbol(c, state, 0);
+        if (idx > (unsigned)f->quant_table_count) {
+            av_log(f->avctx, AV_LOG_ERROR, "quant_table_index out of range\n");
+            return AVERROR_INVALIDDATA;
+        }
+        p->quant_table_index = idx;
+        memcpy(p->quant_table, f->quant_tables[idx], sizeof(p->quant_table));
+        context_count = f->context_count[idx];
+
+        if (p->context_count < context_count) {
+            av_freep(&p->state);
+            av_freep(&p->vlc_state);
+        }
+        p->context_count = context_count;
+    }
+
+    ps = get_symbol(c, state, 0);
+    if (ps == 1) {
+        f->picture.interlaced_frame = 1;
+        f->picture.top_field_first  = 1;
+    } else if (ps == 2) {
+        f->picture.interlaced_frame = 1;
+        f->picture.top_field_first  = 0;
+    } else if (ps == 3) {
+        f->picture.interlaced_frame = 0;
+    }
+    f->picture.sample_aspect_ratio.num = get_symbol(c, state, 0);
+    f->picture.sample_aspect_ratio.den = get_symbol(c, state, 0);
+
+    return 0;
+}
+
 static int decode_slice(AVCodecContext *c, void *arg)
 {
-    FFV1Context *fs  = *(void **)arg;
-    FFV1Context *f   = fs->avctx->priv_data;
-    int width        = fs->slice_width;
-    int height       = fs->slice_height;
-    int x            = fs->slice_x;
-    int y            = fs->slice_y;
+    FFV1Context *fs = *(void **)arg;
+    FFV1Context *f  = fs->avctx->priv_data;
+    int width, height, x, y, ret;
+    const int ps = (av_pix_fmt_desc_get(c->pix_fmt)->flags & PIX_FMT_PLANAR)
+                   ? (c->bits_per_raw_sample > 8) + 1
+                   : 4;
     AVFrame *const p = &f->picture;
 
+    if (f->version > 2) {
+        if (decode_slice_header(f, fs) < 0) {
+            fs->slice_damaged = 1;
+            return AVERROR_INVALIDDATA;
+        }
+    }
+    if ((ret = ffv1_init_slice_state(f, fs)) < 0)
+        return ret;
+    if (f->picture.key_frame)
+        ffv1_clear_slice_state(f, fs);
+    width  = fs->slice_width;
+    height = fs->slice_height;
+    x      = fs->slice_x;
+    y      = fs->slice_y;
+
+    if (!fs->ac) {
+        if (f->version == 3 && f->minor_version > 1 || f->version > 3)
+            get_rac(&fs->c, (uint8_t[]) { 129 });
+        fs->ac_byte_count = f->version > 2 || (!x && !y) ? fs->c.bytestream - fs->c.bytestream_start - 1 : 0;
+        init_get_bits(&fs->gb, fs->c.bytestream_start + fs->ac_byte_count,
+                      (fs->c.bytestream_end - fs->c.bytestream_start -
+                       fs->ac_byte_count) * 8);
+    }
+
     av_assert1(width && height);
     if (f->colorspace == 0) {
-        const int chroma_width  = -((-width)  >> f->chroma_h_shift);
+        const int chroma_width  = -((-width) >> f->chroma_h_shift);
         const int chroma_height = -((-height) >> f->chroma_v_shift);
         const int cx            = x >> f->chroma_h_shift;
         const int cy            = y >> f->chroma_v_shift;
-
-        decode_plane(fs, p->data[0] + x + y * p->linesize[0],
-                     width, height, p->linesize[0], 0);
-
-        decode_plane(fs, p->data[1] + cx + cy * p->linesize[1],
-                     chroma_width, chroma_height, p->linesize[1], 1);
-        decode_plane(fs, p->data[2] + cx + cy * p->linesize[1],
-                     chroma_width, chroma_height, p->linesize[2], 1);
+        decode_plane(fs, p->data[0] + ps * x + y * p->linesize[0], width,
+                     height, p->linesize[0],
+                     0);
+
+        if (f->chroma_planes) {
+            decode_plane(fs, p->data[1] + ps * cx + cy * p->linesize[1],
+                         chroma_width, chroma_height, p->linesize[1],
+                         1);
+            decode_plane(fs, p->data[2] + ps * cx + cy * p->linesize[2],
+                         chroma_width, chroma_height, p->linesize[2],
+                         1);
+        }
+        if (fs->transparency)
+            decode_plane(fs, p->data[3] + ps * x + y * p->linesize[3], width,
+                         height, p->linesize[3],
+                         2);
     } else {
-        decode_rgb_frame(fs,
-                         (uint32_t *)p->data[0] + x + y * (p->linesize[0] / 4),
-                         width, height, p->linesize[0] / 4);
+        uint8_t *planes[3] = { p->data[0] + ps * x + y * p->linesize[0],
+                               p->data[1] + ps * x + y * p->linesize[1],
+                               p->data[2] + ps * x + y * p->linesize[2] };
+        decode_rgb_frame(fs, planes, width, height, p->linesize);
+    }
+    if (fs->ac && f->version > 2) {
+        int v;
+        get_rac(&fs->c, (uint8_t[]) { 129 });
+        v = fs->c.bytestream_end - fs->c.bytestream - 2 - 5 * f->ec;
+        if (v) {
+            av_log(f->avctx, AV_LOG_ERROR, "bytestream end mismatching by %d\n",
+                   v);
+            fs->slice_damaged = 1;
+        }
     }
 
     emms_c();
@@ -288,10 +412,10 @@ static int read_quant_table(RangeCoder *c, int16_t *quant_table, int scale)
     memset(state, 128, sizeof(state));
 
     for (v = 0; i < 128; v++) {
-        int len = get_symbol(c, state, 0) + 1;
+        unsigned len = get_symbol(c, state, 0) + 1;
 
-        if (len + i > 128)
-            return AVERROR_INVALIDDATA;
+        if (len > 128 - i)
+            return -1;
 
         while (len--) {
             quant_table[i] = scale * v;
@@ -315,7 +439,7 @@ static int read_quant_tables(RangeCoder *c,
     for (i = 0; i < 5; i++) {
         context_count *= read_quant_table(c, quant_table[i], context_count);
         if (context_count > 32768U) {
-            return AVERROR_INVALIDDATA;
+            return -1;
         }
     }
     return (context_count + 1) / 2;
@@ -325,7 +449,7 @@ static int read_extra_header(FFV1Context *f)
 {
     RangeCoder *const c = &f->c;
     uint8_t state[CONTEXT_SIZE];
-    int i, j, k;
+    int i, j, k, ret;
     uint8_t state2[32][CONTEXT_SIZE];
 
     memset(state2, 128, sizeof(state2));
@@ -335,19 +459,26 @@ static int read_extra_header(FFV1Context *f)
     ff_build_rac_states(c, 0.05 * (1LL << 32), 256 - 8);
 
     f->version = get_symbol(c, state, 0);
-    f->ac      = f->avctx->coder_type = get_symbol(c, state, 0);
-    if (f->ac > 1)
+    if (f->version > 2) {
+        c->bytestream_end -= 4;
+        f->minor_version   = get_symbol(c, state, 0);
+    }
+    f->ac = f->avctx->coder_type = get_symbol(c, state, 0);
+
+    if (f->ac > 1) {
         for (i = 1; i < 256; i++)
             f->state_transition[i] = get_symbol(c, state, 1) + c->one_state[i];
-    f->colorspace                 = get_symbol(c, state, 0); // YUV cs type
+    }
+
+    f->colorspace                 = get_symbol(c, state, 0); //YUV cs type
     f->avctx->bits_per_raw_sample = get_symbol(c, state, 0);
-    get_rac(c, state); // no chroma = false
-    f->chroma_h_shift = get_symbol(c, state, 0);
-    f->chroma_v_shift = get_symbol(c, state, 0);
-    get_rac(c, state); // transparency plane
-    f->plane_count  = 2;
-    f->num_h_slices = 1 + get_symbol(c, state, 0);
-    f->num_v_slices = 1 + get_symbol(c, state, 0);
+    f->chroma_planes              = get_rac(c, state);
+    f->chroma_h_shift             = get_symbol(c, state, 0);
+    f->chroma_v_shift             = get_symbol(c, state, 0);
+    f->transparency               = get_rac(c, state);
+    f->plane_count                = 2 + f->transparency;
+    f->num_h_slices               = 1 + get_symbol(c, state, 0);
+    f->num_v_slices               = 1 + get_symbol(c, state, 0);
 
     if (f->num_h_slices > (unsigned)f->width ||
         f->num_v_slices > (unsigned)f->height) {
@@ -356,62 +487,97 @@ static int read_extra_header(FFV1Context *f)
     }
 
     f->quant_table_count = get_symbol(c, state, 0);
-
     if (f->quant_table_count > (unsigned)MAX_QUANT_TABLES)
         return AVERROR_INVALIDDATA;
-
     for (i = 0; i < f->quant_table_count; i++) {
         f->context_count[i] = read_quant_tables(c, f->quant_tables[i]);
         if (f->context_count[i] < 0) {
             av_log(f->avctx, AV_LOG_ERROR, "read_quant_table error\n");
-            return f->context_count[i];
+            return AVERROR_INVALIDDATA;
         }
     }
-
-    if (ffv1_allocate_initial_states(f) < 0)
-        return AVERROR(ENOMEM);
+    if ((ret = ffv1_allocate_initial_states(f)) < 0)
+        return ret;
 
     for (i = 0; i < f->quant_table_count; i++)
-        if (get_rac(c, state))
+        if (get_rac(c, state)) {
             for (j = 0; j < f->context_count[i]; j++)
                 for (k = 0; k < CONTEXT_SIZE; k++) {
                     int pred = j ? f->initial_states[i][j - 1][k] : 128;
                     f->initial_states[i][j][k] =
                         (pred + get_symbol(c, state2[k], 1)) & 0xFF;
                 }
+        }
+
+    if (f->version > 2) {
+        f->ec = get_symbol(c, state, 0);
+    }
+
+    if (f->version > 2) {
+        unsigned v;
+        v = av_crc(av_crc_get_table(AV_CRC_32_IEEE), 0,
+                   f->avctx->extradata, f->avctx->extradata_size);
+        if (v) {
+            av_log(f->avctx, AV_LOG_ERROR, "CRC mismatch %X!\n", v);
+            return AVERROR_INVALIDDATA;
+        }
+    }
+
     return 0;
 }
 
+
 static int read_header(FFV1Context *f)
 {
     uint8_t state[CONTEXT_SIZE];
-    int i, j, context_count;
+    int i, j, context_count = -1;
     RangeCoder *const c = &f->slice_context[0]->c;
 
     memset(state, 128, sizeof(state));
 
     if (f->version < 2) {
-        f->version = get_symbol(c, state, 0);
-        f->ac      = f->avctx->coder_type = get_symbol(c, state, 0);
-        if (f->ac > 1)
+        unsigned v = get_symbol(c, state, 0);
+        if (v > 1) {
+            av_log(f->avctx, AV_LOG_ERROR,
+                   "invalid version %d in version 1 header\n", v);
+            return AVERROR_INVALIDDATA;
+        }
+        f->version = v;
+
+        f->ac = f->avctx->coder_type = get_symbol(c, state, 0);
+
+        if (f->ac > 1) {
             for (i = 1; i < 256; i++)
-                f->state_transition[i] = get_symbol(c, state, 1) + c->one_state[i];
-        f->colorspace = get_symbol(c, state, 0); // YUV cs type
+                f->state_transition[i] =
+                    get_symbol(c, state, 1) + c->one_state[i];
+        }
+
+        f->colorspace = get_symbol(c, state, 0); //YUV cs type
+
         if (f->version > 0)
             f->avctx->bits_per_raw_sample = get_symbol(c, state, 0);
-        get_rac(c, state); // no chroma = false
+
+        f->chroma_planes  = get_rac(c, state);
         f->chroma_h_shift = get_symbol(c, state, 0);
         f->chroma_v_shift = get_symbol(c, state, 0);
-        get_rac(c, state); // transparency plane
-        f->plane_count = 2;
+        f->transparency   = get_rac(c, state);
+        f->plane_count    = 2 + f->transparency;
     }
 
     if (f->colorspace == 0) {
-        if (f->avctx->bits_per_raw_sample <= 8) {
+        if (!f->transparency && !f->chroma_planes) {
+            if (f->avctx->bits_per_raw_sample <= 8)
+                f->avctx->pix_fmt = AV_PIX_FMT_GRAY8;
+            else
+                f->avctx->pix_fmt = AV_PIX_FMT_GRAY16;
+        } else if (f->avctx->bits_per_raw_sample <= 8 && !f->transparency) {
             switch (16 * f->chroma_h_shift + f->chroma_v_shift) {
             case 0x00:
                 f->avctx->pix_fmt = AV_PIX_FMT_YUV444P;
                 break;
+            case 0x01:
+                f->avctx->pix_fmt = AV_PIX_FMT_YUV440P;
+                break;
             case 0x10:
                 f->avctx->pix_fmt = AV_PIX_FMT_YUV422P;
                 break;
@@ -428,6 +594,53 @@ static int read_header(FFV1Context *f)
                 av_log(f->avctx, AV_LOG_ERROR, "format not supported\n");
                 return AVERROR(ENOSYS);
             }
+        } else if (f->avctx->bits_per_raw_sample <= 8 && f->transparency) {
+            switch (16 * f->chroma_h_shift + f->chroma_v_shift) {
+            case 0x00:
+                f->avctx->pix_fmt = AV_PIX_FMT_YUVA444P;
+                break;
+            case 0x10:
+                f->avctx->pix_fmt = AV_PIX_FMT_YUVA422P;
+                break;
+            case 0x11:
+                f->avctx->pix_fmt = AV_PIX_FMT_YUVA420P;
+                break;
+            default:
+                av_log(f->avctx, AV_LOG_ERROR, "format not supported\n");
+                return AVERROR(ENOSYS);
+            }
+        } else if (f->avctx->bits_per_raw_sample == 9) {
+            f->packed_at_lsb = 1;
+            switch (16 * f->chroma_h_shift + f->chroma_v_shift) {
+            case 0x00:
+                f->avctx->pix_fmt = AV_PIX_FMT_YUV444P9;
+                break;
+            case 0x10:
+                f->avctx->pix_fmt = AV_PIX_FMT_YUV422P9;
+                break;
+            case 0x11:
+                f->avctx->pix_fmt = AV_PIX_FMT_YUV420P9;
+                break;
+            default:
+                av_log(f->avctx, AV_LOG_ERROR, "format not supported\n");
+                return AVERROR(ENOSYS);
+            }
+        } else if (f->avctx->bits_per_raw_sample == 10) {
+            f->packed_at_lsb = 1;
+            switch (16 * f->chroma_h_shift + f->chroma_v_shift) {
+            case 0x00:
+                f->avctx->pix_fmt = AV_PIX_FMT_YUV444P10;
+                break;
+            case 0x10:
+                f->avctx->pix_fmt = AV_PIX_FMT_YUV422P10;
+                break;
+            case 0x11:
+                f->avctx->pix_fmt = AV_PIX_FMT_YUV420P10;
+                break;
+            default:
+                av_log(f->avctx, AV_LOG_ERROR, "format not supported\n");
+                return AVERROR(ENOSYS);
+            }
         } else {
             switch (16 * f->chroma_h_shift + f->chroma_v_shift) {
             case 0x00:
@@ -450,7 +663,22 @@ static int read_header(FFV1Context *f)
                    "chroma subsampling not supported in this colorspace\n");
             return AVERROR(ENOSYS);
         }
-        f->avctx->pix_fmt = AV_PIX_FMT_RGB32;
+        switch (f->avctx->bits_per_raw_sample) {
+        case 8:
+            f->avctx->pix_fmt = AV_PIX_FMT_RGB32;
+            break;
+        case 9:
+            f->avctx->pix_fmt = AV_PIX_FMT_GBRP9;
+            break;
+        case 10:
+            f->avctx->pix_fmt = AV_PIX_FMT_GBRP10;
+            break;
+        default:
+            av_log(f->avctx, AV_LOG_ERROR,
+                   "bit depth %d not supported\n",
+                   f->avctx->bits_per_raw_sample);
+            return AVERROR(ENOSYS);
+        }
     } else {
         av_log(f->avctx, AV_LOG_ERROR, "colorspace not supported\n");
         return AVERROR(ENOSYS);
@@ -458,45 +686,64 @@ static int read_header(FFV1Context *f)
 
     av_dlog(f->avctx, "%d %d %d\n",
             f->chroma_h_shift, f->chroma_v_shift, f->avctx->pix_fmt);
-
     if (f->version < 2) {
         context_count = read_quant_tables(c, f->quant_table);
         if (context_count < 0) {
             av_log(f->avctx, AV_LOG_ERROR, "read_quant_table error\n");
-            return context_count;
+            return AVERROR_INVALIDDATA;
         }
-    } else {
+    } else if (f->version < 3) {
         f->slice_count = get_symbol(c, state, 0);
-        if (f->slice_count > (unsigned)MAX_SLICES)
-            return AVERROR_INVALIDDATA;
+    } else {
+        const uint8_t *p = c->bytestream_end;
+        for (f->slice_count = 0;
+             f->slice_count < MAX_SLICES && 3 < p - c->bytestream_start;
+             f->slice_count++) {
+            int trailer = 3 + 5 * !!f->ec;
+            int size    = AV_RB24(p - trailer);
+            if (size + trailer > p - c->bytestream_start)
+                break;
+            p -= size + trailer;
+        }
+    }
+    if (f->slice_count > (unsigned)MAX_SLICES || f->slice_count <= 0) {
+        av_log(f->avctx, AV_LOG_ERROR, "slice count %d is invalid\n",
+               f->slice_count);
+        return AVERROR_INVALIDDATA;
     }
 
     for (j = 0; j < f->slice_count; j++) {
         FFV1Context *fs = f->slice_context[j];
-        fs->ac = f->ac;
-
-        if (f->version >= 2) {
-            fs->slice_x      = get_symbol(c, state, 0) * f->width;
-            fs->slice_y      = get_symbol(c, state, 0) * f->height;
-            fs->slice_width  = (get_symbol(c, state, 0) + 1) * f->width  + fs->slice_x;
-            fs->slice_height = (get_symbol(c, state, 0) + 1) * f->height + fs->slice_y;
-
-            fs->slice_x     /= f->num_h_slices;
-            fs->slice_y     /= f->num_v_slices;
-            fs->slice_width  = fs->slice_width  / f->num_h_slices - fs->slice_x;
-            fs->slice_height = fs->slice_height / f->num_v_slices - fs->slice_y;
-            if ((unsigned)fs->slice_width  > f->width ||
+        fs->ac            = f->ac;
+        fs->packed_at_lsb = f->packed_at_lsb;
+
+        fs->slice_damaged = 0;
+
+        if (f->version == 2) {
+            fs->slice_x     = get_symbol(c, state, 0) * f->width;
+            fs->slice_y     = get_symbol(c, state, 0) * f->height;
+            fs->slice_width =
+                (get_symbol(c, state, 0) + 1) * f->width + fs->slice_x;
+            fs->slice_height =
+                (get_symbol(c, state, 0) + 1) * f->height + fs->slice_y;
+
+            fs->slice_x      /= f->num_h_slices;
+            fs->slice_y      /= f->num_v_slices;
+            fs->slice_width  /= f->num_h_slices - fs->slice_x;
+            fs->slice_height /= f->num_v_slices - fs->slice_y;
+            if ((unsigned)fs->slice_width > f->width ||
                 (unsigned)fs->slice_height > f->height)
                 return AVERROR_INVALIDDATA;
-            if ((unsigned)fs->slice_x + (uint64_t)fs->slice_width  > f->width ||
-                (unsigned)fs->slice_y + (uint64_t)fs->slice_height > f->height)
+            if ((unsigned)fs->slice_x + (uint64_t)fs->slice_width > f->width
+                || (unsigned)fs->slice_y + (uint64_t)fs->slice_height >
+                f->height)
                 return AVERROR_INVALIDDATA;
         }
 
         for (i = 0; i < f->plane_count; i++) {
             PlaneContext *const p = &fs->plane[i];
 
-            if (f->version >= 2) {
+            if (f->version == 2) {
                 int idx = get_symbol(c, state, 0);
                 if (idx > (unsigned)f->quant_table_count) {
                     av_log(f->avctx, AV_LOG_ERROR,
@@ -511,14 +758,16 @@ static int read_header(FFV1Context *f)
                 memcpy(p->quant_table, f->quant_table, sizeof(p->quant_table));
             }
 
-            if (p->context_count < context_count) {
-                av_freep(&p->state);
-                av_freep(&p->vlc_state);
+            if (f->version <= 2) {
+                av_assert0(context_count >= 0);
+                if (p->context_count < context_count) {
+                    av_freep(&p->state);
+                    av_freep(&p->vlc_state);
+                }
+                p->context_count = context_count;
             }
-            p->context_count = context_count;
         }
     }
-
     return 0;
 }
 
@@ -546,7 +795,7 @@ static int ffv1_decode_frame(AVCodecContext *avctx, void *data,
     FFV1Context *f      = avctx->priv_data;
     RangeCoder *const c = &f->slice_context[0]->c;
     AVFrame *const p    = &f->picture;
-    int bytes_read, i, ret;
+    int i, ret;
     uint8_t keystate = 128;
     const uint8_t *buf_p;
 
@@ -559,67 +808,97 @@ static int ffv1_decode_frame(AVCodecContext *avctx, void *data,
     ff_init_range_decoder(c, buf, buf_size);
     ff_build_rac_states(c, 0.05 * (1LL << 32), 256 - 8);
 
-    p->pict_type = AV_PICTURE_TYPE_I; // FIXME: I vs. P
+    p->pict_type = AV_PICTURE_TYPE_I; //FIXME I vs. P
     if (get_rac(c, &keystate)) {
-        p->key_frame = 1;
+        p->key_frame    = 1;
+        f->key_frame_ok = 0;
         if ((ret = read_header(f)) < 0)
             return ret;
-        if ((ret = ffv1_init_slice_state(f)) < 0)
-            return ret;
-
-        ffv1_clear_state(f);
+        f->key_frame_ok = 1;
     } else {
-        p->key_frame = 0;
-    }
-    if (f->ac > 1) {
-        int i;
-        for (i = 1; i < 256; i++) {
-            c->one_state[i]        = f->state_transition[i];
-            c->zero_state[256 - i] = 256 - c->one_state[i];
+        if (!f->key_frame_ok) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Cant decode non keyframe without valid keyframe\n");
+            return AVERROR_INVALIDDATA;
         }
+        p->key_frame = 0;
     }
 
-    p->reference = 0;
+    p->reference = 3; //for error concealment
     if ((ret = avctx->get_buffer(avctx, p)) < 0) {
         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
         return ret;
     }
 
     if (avctx->debug & FF_DEBUG_PICT_INFO)
-        av_log(avctx, AV_LOG_ERROR, "keyframe:%d coder:%d\n", p->key_frame, f->ac);
-
-    if (!f->ac) {
-        bytes_read = c->bytestream - c->bytestream_start - 1;
-        if (bytes_read == 0)
-            av_log(avctx, AV_LOG_ERROR, "error at end of AC stream\n"); // FIXME
-        init_get_bits(&f->slice_context[0]->gb, buf + bytes_read,
-                      (buf_size - bytes_read) * 8);
-    } else {
-        bytes_read = 0; /* avoid warning */
-    }
+        av_log(avctx, AV_LOG_DEBUG,
+               "ver:%d keyframe:%d coder:%d ec:%d slices:%d bps:%d\n",
+               f->version, p->key_frame, f->ac, f->ec, f->slice_count,
+               f->avctx->bits_per_raw_sample);
 
     buf_p = buf + buf_size;
-    for (i = f->slice_count - 1; i > 0; i--) {
+    for (i = f->slice_count - 1; i >= 0; i--) {
         FFV1Context *fs = f->slice_context[i];
-        int v           = AV_RB24(buf_p - 3) + 3;
-        if (buf_p - buf <= v) {
+        int trailer     = 3 + 5 * !!f->ec;
+        int v;
+
+        if (i || f->version > 2)
+            v = AV_RB24(buf_p - trailer) + trailer;
+        else
+            v = buf_p - c->bytestream_start;
+        if (buf_p - c->bytestream_start < v) {
             av_log(avctx, AV_LOG_ERROR, "Slice pointer chain broken\n");
             return AVERROR_INVALIDDATA;
         }
         buf_p -= v;
-        if (fs->ac)
+
+        if (f->ec) {
+            unsigned crc = av_crc(av_crc_get_table(AV_CRC_32_IEEE), 0, buf_p, v);
+            if (crc) {
+                av_log(f->avctx, AV_LOG_ERROR, "CRC mismatch %X!\n", crc);
+                fs->slice_damaged = 1;
+            }
+        }
+
+        if (i) {
             ff_init_range_decoder(&fs->c, buf_p, v);
-        else
-            init_get_bits(&fs->gb, buf_p, v * 8);
+        } else
+            fs->c.bytestream_end = (uint8_t *)(buf_p + v);
+    }
+
+    avctx->execute(avctx, decode_slice, &f->slice_context[0], NULL,
+                   f->slice_count,
+                   sizeof(void *));
+
+    for (i = f->slice_count - 1; i >= 0; i--) {
+        FFV1Context *fs = f->slice_context[i];
+        int j;
+        if (fs->slice_damaged && f->last_picture.data[0]) {
+            const uint8_t *src[4];
+            uint8_t *dst[4];
+            for (j = 0; j < 4; j++) {
+                int sh = (j == 1 || j == 2) ? f->chroma_h_shift : 0;
+                int sv = (j == 1 || j == 2) ? f->chroma_v_shift : 0;
+                dst[j] = f->picture.data[j] + f->picture.linesize[j] *
+                         (fs->slice_y >> sv) + (fs->slice_x >> sh);
+                src[j] = f->last_picture.data[j] +
+                         f->last_picture.linesize[j] *
+                         (fs->slice_y >> sv) + (fs->slice_x >> sh);
+            }
+            av_image_copy(dst, f->picture.linesize, (const uint8_t **)src,
+                          f->last_picture.linesize,
+                          avctx->pix_fmt, fs->slice_width,
+                          fs->slice_height);
+        }
     }
 
-    avctx->execute(avctx, decode_slice, &f->slice_context[0],
-                   NULL, f->slice_count, sizeof(void *));
     f->picture_number++;
 
     *picture   = *p;
     *data_size = sizeof(AVFrame);
 
+    FFSWAP(AVFrame, f->picture, f->last_picture);
+
     return buf_size;
 }