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ffmpeg/libavcodec/mss1.c

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/*
* Microsoft Screen 1 (aka Windows Media Video V7 Screen) decoder
* Copyright (c) 2012 Konstantin Shishkov
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Microsoft Screen 1 (aka Windows Media Video V7 Screen) decoder
*/
#include "libavutil/intfloat.h"
#include "libavutil/intreadwrite.h"
#include "avcodec.h"
#include "get_bits.h"
enum SplitMode {
SPLIT_VERT = 0,
SPLIT_HOR,
SPLIT_NONE
};
typedef struct ArithCoder {
int low, high, value;
GetBitContext *gb;
} ArithCoder;
#define MODEL_MIN_SYMS 2
#define MODEL_MAX_SYMS 256
#define THRESH_ADAPTIVE -1
#define THRESH_LOW 15
#define THRESH_HIGH 50
typedef struct Model {
int cum_prob[MODEL_MAX_SYMS + 1];
int weights[MODEL_MAX_SYMS + 1];
int idx2sym[MODEL_MAX_SYMS + 1];
int sym2idx[MODEL_MAX_SYMS + 1];
int num_syms;
int thr_weight, threshold;
} Model;
static const int sec_order_sizes[4] = { 1, 7, 6, 1 };
enum ContextDirection {
TOP_LEFT = 0,
TOP,
TOP_RIGHT,
LEFT
};
typedef struct PixContext {
int cache_size, num_syms;
uint8_t cache[12];
Model cache_model, full_model;
Model sec_models[4][8][4];
} PixContext;
typedef struct MSS1Context {
AVCodecContext *avctx;
AVFrame pic;
uint8_t *pic_start;
int pic_stride;
uint8_t *mask;
int mask_linesize;
uint32_t pal[256];
int free_colours;
Model intra_region, inter_region;
Model pivot, edge_mode, split_mode;
PixContext intra_pix_ctx, inter_pix_ctx;
int corrupted;
} MSS1Context;
static void arith_init(ArithCoder *c, GetBitContext *gb)
{
c->low = 0;
c->high = 0xFFFF;
c->value = get_bits(gb, 16);
c->gb = gb;
}
static void arith_normalise(ArithCoder *c)
{
for (;;) {
if (c->high >= 0x8000) {
if (c->low < 0x8000) {
if (c->low >= 0x4000 && c->high < 0xC000) {
c->value -= 0x4000;
c->low -= 0x4000;
c->high -= 0x4000;
} else {
return;
}
} else {
c->value -= 0x8000;
c->low -= 0x8000;
c->high -= 0x8000;
}
}
c->value <<= 1;
c->low <<= 1;
c->high <<= 1;
c->high |= 1;
c->value |= get_bits1(c->gb);
}
}
static int arith_get_bit(ArithCoder *c)
{
int range = c->high - c->low + 1;
int bit = (((c->value - c->low) << 1) + 1) / range;
if (bit)
c->low += range >> 1;
else
c->high = c->low + (range >> 1) - 1;
arith_normalise(c);
return bit;
}
static int arith_get_bits(ArithCoder *c, int bits)
{
int range = c->high - c->low + 1;
int val = (((c->value - c->low + 1) << bits) - 1) / range;
int prob = range * val;
c->high = ((prob + range) >> bits) + c->low - 1;
c->low += prob >> bits;
arith_normalise(c);
return val;
}
static int arith_get_number(ArithCoder *c, int mod_val)
{
int range = c->high - c->low + 1;
int val = ((c->value - c->low + 1) * mod_val - 1) / range;
int prob = range * val;
c->high = (prob + range) / mod_val + c->low - 1;
c->low += prob / mod_val;
arith_normalise(c);
return val;
}
static int arith_get_prob(ArithCoder *c, int *probs)
{
int range = c->high - c->low + 1;
int val = ((c->value - c->low + 1) * probs[0] - 1) / range;
int sym = 1;
while (probs[sym] > val)
sym++;
c->high = range * probs[sym - 1] / probs[0] + c->low - 1;
c->low += range * probs[sym] / probs[0];
return sym;
}
static int model_calc_threshold(Model *m)
{
int thr;
if (m->thr_weight == -1) {
thr = 2 * m->weights[m->num_syms] - 1;
thr = ((thr >> 1) + 4 * m->cum_prob[0]) / thr;
} else {
thr = m->num_syms * m->thr_weight;
}
return FFMIN(thr, 0x3FFF);
}
static void model_reset(Model *m)
{
int i;
for (i = 0; i <= m->num_syms; i++) {
m->weights[i] = 1;
m->cum_prob[i] = m->num_syms - i;
}
m->weights[0] = -1;
m->idx2sym[0] = -1;
m->sym2idx[m->num_syms] = -1;
for (i = 0; i < m->num_syms; i++) {
m->sym2idx[i] = i + 1;
m->idx2sym[i + 1] = i;
}
}
static av_cold void model_init(Model *m, int num_syms, int thr_weight)
{
m->num_syms = num_syms;
m->thr_weight = thr_weight;
m->threshold = model_calc_threshold(m);
model_reset(m);
}
static void model_rescale_weights(Model *m)
{
int i;
int cum_prob;
if (m->thr_weight == -1)
m->threshold = model_calc_threshold(m);
while (m->cum_prob[0] > m->threshold) {
cum_prob = 0;
for (i = m->num_syms; i >= 0; i--) {
m->cum_prob[i] = cum_prob;
m->weights[i] = (m->weights[i] + 1) >> 1;
cum_prob += m->weights[i];
}
}
}
static void model_update(Model *m, int val)
{
int i;
if (m->weights[val] == m->weights[val - 1]) {
for (i = val; m->weights[i - 1] == m->weights[val]; i--);
if (i != val) {
int sym1, sym2;
sym1 = m->idx2sym[val];
sym2 = m->idx2sym[i];
m->idx2sym[val] = sym2;
m->idx2sym[i] = sym1;
m->sym2idx[sym1] = i;
m->sym2idx[sym2] = val;
val = i;
}
}
m->weights[val]++;
for (i = val - 1; i >= 0; i--)
m->cum_prob[i]++;
model_rescale_weights(m);
}
static int arith_get_model_sym(ArithCoder *c, Model *m)
{
int idx, val;
idx = arith_get_prob(c, m->cum_prob);
val = m->idx2sym[idx];
model_update(m, idx);
arith_normalise(c);
return val;
}
static void pixctx_reset(PixContext *ctx)
{
int i, j, k;
for (i = 0; i < ctx->cache_size; i++)
ctx->cache[i] = i;
model_reset(&ctx->cache_model);
model_reset(&ctx->full_model);
for (i = 0; i < 4; i++)
for (j = 0; j < sec_order_sizes[i]; j++)
for (k = 0; k < 4; k++)
model_reset(&ctx->sec_models[i][j][k]);
}
static av_cold void pixctx_init(PixContext *ctx, int cache_size)
{
int i, j, k;
ctx->cache_size = cache_size + 4;
ctx->num_syms = cache_size;
for (i = 0; i < ctx->cache_size; i++)
ctx->cache[i] = i;
model_init(&ctx->cache_model, ctx->num_syms + 1, THRESH_LOW);
model_init(&ctx->full_model, 256, THRESH_HIGH);
for (i = 0; i < 4; i++) {
for (j = 0; j < sec_order_sizes[i]; j++) {
for (k = 0; k < 4; k++) {
model_init(&ctx->sec_models[i][j][k], 2 + i,
i ? THRESH_LOW : THRESH_ADAPTIVE);
}
}
}
}
static int decode_top_left_pixel(ArithCoder *acoder, PixContext *pctx)
{
int i, val, pix;
val = arith_get_model_sym(acoder, &pctx->cache_model);
if (val < pctx->num_syms) {
pix = pctx->cache[val];
} else {
pix = arith_get_model_sym(acoder, &pctx->full_model);
for (i = 0; i < pctx->cache_size - 1; i++)
if (pctx->cache[i] == pix)
break;
val = i;
}
if (val) {
for (i = val; i > 0; i--)
pctx->cache[i] = pctx->cache[i - 1];
pctx->cache[0] = pix;
}
return pix;
}
static int decode_pixel(ArithCoder *acoder, PixContext *pctx,
uint8_t *ngb, int num_ngb)
{
int i, val, pix;
val = arith_get_model_sym(acoder, &pctx->cache_model);
if (val < pctx->num_syms) {
int idx, j;
idx = 0;
for (i = 0; i < pctx->cache_size; i++) {
for (j = 0; j < num_ngb; j++)
if (pctx->cache[i] == ngb[j])
break;
if (j == num_ngb) {
if (idx == val)
break;
idx++;
}
}
val = FFMIN(i, pctx->cache_size - 1);
pix = pctx->cache[val];
} else {
pix = arith_get_model_sym(acoder, &pctx->full_model);
for (i = 0; i < pctx->cache_size - 1; i++)
if (pctx->cache[i] == pix)
break;
val = i;
}
if (val) {
for (i = val; i > 0; i--)
pctx->cache[i] = pctx->cache[i - 1];
pctx->cache[0] = pix;
}
return pix;
}
static int decode_pixel_in_context(ArithCoder *acoder, PixContext *pctx,
uint8_t *src, int stride, int x, int y,
int has_right)
{
uint8_t neighbours[4];
uint8_t ref_pix[4];
int nlen;
int layer = 0, sub;
int pix;
int i, j;
if (!y) {
memset(neighbours, src[-1], 4);
} else {
neighbours[TOP] = src[-stride];
if (!x) {
neighbours[TOP_LEFT] = neighbours[LEFT] = neighbours[TOP];
} else {
neighbours[TOP_LEFT] = src[-stride - 1];
neighbours[ LEFT] = src[-1];
}
if (has_right)
neighbours[TOP_RIGHT] = src[-stride + 1];
else
neighbours[TOP_RIGHT] = neighbours[TOP];
}
sub = 0;
if (x >= 2 && src[-2] == neighbours[LEFT])
sub = 1;
if (y >= 2 && src[-2 * stride] == neighbours[TOP])
sub |= 2;
nlen = 1;
ref_pix[0] = neighbours[0];
for (i = 1; i < 4; i++) {
for (j = 0; j < nlen; j++)
if (ref_pix[j] == neighbours[i])
break;
if (j == nlen)
ref_pix[nlen++] = neighbours[i];
}
switch (nlen) {
case 1:
case 4:
layer = 0;
break;
case 2:
if (neighbours[TOP] == neighbours[TOP_LEFT]) {
if (neighbours[TOP_RIGHT] == neighbours[TOP_LEFT])
layer = 3;
else if (neighbours[LEFT] == neighbours[TOP_LEFT])
layer = 2;
else
layer = 4;
} else if (neighbours[TOP_RIGHT] == neighbours[TOP_LEFT]) {
if (neighbours[LEFT] == neighbours[TOP_LEFT])
layer = 1;
else
layer = 5;
} else if (neighbours[LEFT] == neighbours[TOP_LEFT]) {
layer = 6;
} else {
layer = 0;
}
break;
case 3:
if (neighbours[TOP] == neighbours[TOP_LEFT])
layer = 0;
else if (neighbours[TOP_RIGHT] == neighbours[TOP_LEFT])
layer = 1;
else if (neighbours[LEFT] == neighbours[TOP_LEFT])
layer = 2;
else if (neighbours[TOP_RIGHT] == neighbours[TOP])
layer = 3;
else if (neighbours[TOP] == neighbours[LEFT])
layer = 4;
else
layer = 5;
break;
}
pix = arith_get_model_sym(acoder, &pctx->sec_models[nlen - 1][layer][sub]);
if (pix < nlen)
return ref_pix[pix];
else
return decode_pixel(acoder, pctx, ref_pix, nlen);
}
static int decode_region(MSS1Context *ctx, ArithCoder *acoder, uint8_t *dst,
int x, int y, int width, int height, int stride,
PixContext *pctx)
{
int i, j;
dst += x + y * stride;
dst[0] = decode_top_left_pixel(acoder, pctx);
for (j = 0; j < height; j++) {
for (i = 0; i < width; i++) {
if (!i && !j)
continue;
dst[i] = decode_pixel_in_context(acoder, pctx, dst + i, stride,
i, j, width - i - 1);
}
dst += stride;
}
return 0;
}
static int decode_region_masked(MSS1Context *ctx, ArithCoder *acoder,
uint8_t *dst, int stride, uint8_t *mask,
int mask_stride, int x, int y,
int width, int height,
PixContext *pctx)
{
int i, j;
dst += x + y * stride;
mask += x + y * mask_stride;
if (mask[0] == 0xFF)
dst[0] = decode_top_left_pixel(acoder, pctx);
for (j = 0; j < height; j++) {
for (i = 0; i < width; i++) {
if (!i && !j || mask[i] != 0xFF)
continue;
dst[i] = decode_pixel_in_context(acoder, pctx, dst + i, stride,
i, j, width - i - 1);
}
dst += stride;
mask += mask_stride;
}
return 0;
}
static av_cold void codec_init(MSS1Context *ctx)
{
model_init(&ctx->intra_region, 2, THRESH_ADAPTIVE);
model_init(&ctx->inter_region, 2, THRESH_ADAPTIVE);
model_init(&ctx->split_mode, 3, THRESH_HIGH);
model_init(&ctx->edge_mode, 2, THRESH_HIGH);
model_init(&ctx->pivot, 3, THRESH_LOW);
pixctx_init(&ctx->intra_pix_ctx, 8);
pixctx_init(&ctx->inter_pix_ctx, 2);
ctx->corrupted = 1;
}
static void codec_reset(MSS1Context *ctx)
{
model_reset(&ctx->intra_region);
model_reset(&ctx->inter_region);
model_reset(&ctx->split_mode);
model_reset(&ctx->edge_mode);
model_reset(&ctx->pivot);
pixctx_reset(&ctx->intra_pix_ctx);
pixctx_reset(&ctx->inter_pix_ctx);
ctx->corrupted = 0;
}
static int decode_pal(MSS1Context *ctx, ArithCoder *acoder)
{
int i, ncol, r, g, b;
uint32_t *pal = ctx->pal + 256 - ctx->free_colours;
if (!ctx->free_colours)
return 0;
ncol = arith_get_number(acoder, ctx->free_colours + 1);
for (i = 0; i < ncol; i++) {
r = arith_get_bits(acoder, 8);
g = arith_get_bits(acoder, 8);
b = arith_get_bits(acoder, 8);
*pal++ = (r << 16) | (g << 8) | b;
}
return !!ncol;
}
static int decode_pivot(MSS1Context *ctx, ArithCoder *acoder, int base)
{
int val, inv;
inv = arith_get_model_sym(acoder, &ctx->edge_mode);
val = arith_get_model_sym(acoder, &ctx->pivot) + 1;
if (val > 2) {
if ((base + 1) / 2 - 2 <= 0) {
ctx->corrupted = 1;
return 0;
}
val = arith_get_number(acoder, (base + 1) / 2 - 2) + 3;
}
if (val == base) {
ctx->corrupted = 1;
return 0;
}
return inv ? base - val : val;
}
static int decode_region_intra(MSS1Context *ctx, ArithCoder *acoder,
int x, int y, int width, int height)
{
int mode;
mode = arith_get_model_sym(acoder, &ctx->intra_region);
if (!mode) {
int i, pix;
int stride = ctx->pic_stride;
uint8_t *dst = ctx->pic_start + x + y * stride;
pix = decode_top_left_pixel(acoder, &ctx->intra_pix_ctx);
for (i = 0; i < height; i++, dst += stride)
memset(dst, pix, width);
} else {
return decode_region(ctx, acoder, ctx->pic_start,
x, y, width, height, ctx->pic_stride,
&ctx->intra_pix_ctx);
}
return 0;
}
static int decode_intra(MSS1Context *ctx, ArithCoder *acoder,
int x, int y, int width, int height)
{
int mode, pivot;
if (ctx->corrupted)
return -1;
mode = arith_get_model_sym(acoder, &ctx->split_mode);
switch (mode) {
case SPLIT_VERT:
pivot = decode_pivot(ctx, acoder, height);
if (ctx->corrupted)
return -1;
if (decode_intra(ctx, acoder, x, y, width, pivot))
return -1;
if (decode_intra(ctx, acoder, x, y + pivot, width, height - pivot))
return -1;
break;
case SPLIT_HOR:
pivot = decode_pivot(ctx, acoder, width);
if (ctx->corrupted)
return -1;
if (decode_intra(ctx, acoder, x, y, pivot, height))
return -1;
if (decode_intra(ctx, acoder, x + pivot, y, width - pivot, height))
return -1;
break;
case SPLIT_NONE:
return decode_region_intra(ctx, acoder, x, y, width, height);
default:
return -1;
}
return 0;
}
static int decode_region_inter(MSS1Context *ctx, ArithCoder *acoder,
int x, int y, int width, int height)
{
int mode;
mode = arith_get_model_sym(acoder, &ctx->inter_region);
if (!mode) {
mode = decode_top_left_pixel(acoder, &ctx->inter_pix_ctx);
if (mode != 0xFF) {
return 0;
} else {
return decode_region_intra(ctx, acoder, x, y, width, height);
}
} else {
if (decode_region(ctx, acoder, ctx->mask,
x, y, width, height, ctx->mask_linesize,
&ctx->inter_pix_ctx) < 0)
return -1;
return decode_region_masked(ctx, acoder, ctx->pic_start,
-ctx->pic.linesize[0], ctx->mask,
ctx->mask_linesize,
x, y, width, height,
&ctx->intra_pix_ctx);
}
return 0;
}
static int decode_inter(MSS1Context *ctx, ArithCoder *acoder,
int x, int y, int width, int height)
{
int mode, pivot;
if (ctx->corrupted)
return -1;
mode = arith_get_model_sym(acoder, &ctx->split_mode);
switch (mode) {
case SPLIT_VERT:
pivot = decode_pivot(ctx, acoder, height);
if (decode_inter(ctx, acoder, x, y, width, pivot))
return -1;
if (decode_inter(ctx, acoder, x, y + pivot, width, height - pivot))
return -1;
break;
case SPLIT_HOR:
pivot = decode_pivot(ctx, acoder, width);
if (decode_inter(ctx, acoder, x, y, pivot, height))
return -1;
if (decode_inter(ctx, acoder, x + pivot, y, width - pivot, height))
return -1;
break;
case SPLIT_NONE:
return decode_region_inter(ctx, acoder, x, y, width, height);
default:
return -1;
}
return 0;
}
static int mss1_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
MSS1Context *c = avctx->priv_data;
GetBitContext gb;
ArithCoder acoder;
int pal_changed = 0;
int ret;
init_get_bits(&gb, buf, buf_size * 8);
arith_init(&acoder, &gb);
c->pic.reference = 3;
c->pic.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
FF_BUFFER_HINTS_REUSABLE;
if ((ret = avctx->reget_buffer(avctx, &c->pic)) < 0) {
av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
return ret;
}
c->pic_start = c->pic.data[0] + c->pic.linesize[0] * (avctx->height - 1);
c->pic_stride = -c->pic.linesize[0];
if (!arith_get_bit(&acoder)) {
codec_reset(c);
pal_changed = decode_pal(c, &acoder);
c->corrupted = decode_intra(c, &acoder, 0, 0,
avctx->width, avctx->height);
c->pic.key_frame = 1;
c->pic.pict_type = AV_PICTURE_TYPE_I;
} else {
if (c->corrupted)
return AVERROR_INVALIDDATA;
c->corrupted = decode_inter(c, &acoder, 0, 0,
avctx->width, avctx->height);
c->pic.key_frame = 0;
c->pic.pict_type = AV_PICTURE_TYPE_P;
}
if (c->corrupted)
return AVERROR_INVALIDDATA;
memcpy(c->pic.data[1], c->pal, AVPALETTE_SIZE);
c->pic.palette_has_changed = pal_changed;
*data_size = sizeof(AVFrame);
*(AVFrame*)data = c->pic;
/* always report that the buffer was completely consumed */
return buf_size;
}
static av_cold int mss1_decode_init(AVCodecContext *avctx)
{
MSS1Context * const c = avctx->priv_data;
int i;
c->avctx = avctx;
if (avctx->extradata_size < 52 + 256 * 3) {
av_log(avctx, AV_LOG_ERROR, "Insufficient extradata size %d\n",
avctx->extradata_size);
return AVERROR_INVALIDDATA;
}
if (AV_RB32(avctx->extradata) < avctx->extradata_size) {
av_log(avctx, AV_LOG_ERROR,
"Insufficient extradata size: expected %d got %d\n",
AV_RB32(avctx->extradata),
avctx->extradata_size);
return AVERROR_INVALIDDATA;
}
av_log(avctx, AV_LOG_DEBUG, "Encoder version %d.%d\n",
AV_RB32(avctx->extradata + 4), AV_RB32(avctx->extradata + 8));
c->free_colours = AV_RB32(avctx->extradata + 48);
if ((unsigned)c->free_colours > 256) {
av_log(avctx, AV_LOG_ERROR,
"Incorrect number of changeable palette entries: %d\n",
c->free_colours);
return AVERROR_INVALIDDATA;
}
av_log(avctx, AV_LOG_DEBUG, "%d free colour(s)\n", c->free_colours);
avctx->coded_width = AV_RB32(avctx->extradata + 20);
avctx->coded_height = AV_RB32(avctx->extradata + 24);
av_log(avctx, AV_LOG_DEBUG, "Display dimensions %dx%d\n",
AV_RB32(avctx->extradata + 12), AV_RB32(avctx->extradata + 16));
av_log(avctx, AV_LOG_DEBUG, "Coded dimensions %dx%d\n",
avctx->coded_width, avctx->coded_height);
av_log(avctx, AV_LOG_DEBUG, "%g frames per second\n",
av_int2float(AV_RB32(avctx->extradata + 28)));
av_log(avctx, AV_LOG_DEBUG, "Bitrate %d bps\n",
AV_RB32(avctx->extradata + 32));
av_log(avctx, AV_LOG_DEBUG, "Max. lead time %g ms\n",
av_int2float(AV_RB32(avctx->extradata + 36)));
av_log(avctx, AV_LOG_DEBUG, "Max. lag time %g ms\n",
av_int2float(AV_RB32(avctx->extradata + 40)));
av_log(avctx, AV_LOG_DEBUG, "Max. seek time %g ms\n",
av_int2float(AV_RB32(avctx->extradata + 44)));
for (i = 0; i < 256; i++)
c->pal[i] = AV_RB24(avctx->extradata + 52 + i * 3);
avctx->pix_fmt = PIX_FMT_PAL8;
c->mask_linesize = FFALIGN(avctx->width, 16);
c->mask = av_malloc(c->mask_linesize * avctx->height);
if (!c->mask) {
av_log(avctx, AV_LOG_ERROR, "Cannot allocate mask plane\n");
return AVERROR(ENOMEM);
}
avctx->coded_frame = &c->pic;
codec_init(c);
return 0;
}
static av_cold int mss1_decode_end(AVCodecContext *avctx)
{
MSS1Context * const c = avctx->priv_data;
if (c->pic.data[0])
avctx->release_buffer(avctx, &c->pic);
av_freep(&c->mask);
return 0;
}
AVCodec ff_mss1_decoder = {
.name = "mss1",
.type = AVMEDIA_TYPE_VIDEO,
.id = CODEC_ID_MSS1,
.priv_data_size = sizeof(MSS1Context),
.init = mss1_decode_init,
.close = mss1_decode_end,
.decode = mss1_decode_frame,
.capabilities = CODEC_CAP_DR1,
.long_name = NULL_IF_CONFIG_SMALL("MS Screen 1"),
};
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