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ffmpeg/libavcodec/mss4.c

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/*
* Microsoft Screen 4 (aka Microsoft Expression Encoder Screen) decoder
* Copyright (c) 2012 Konstantin Shishkov
*
* 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 4 (aka Microsoft Titanium Screen 2,
* aka Microsoft Expression Encoder Screen) decoder
*/
#include "libavutil/thread.h"
#include "avcodec.h"
#include "bytestream.h"
#include "get_bits.h"
#include "internal.h"
#include "jpegtables.h"
#include "mss34dsp.h"
#include "unary.h"
#define HEADER_SIZE 8
enum FrameType {
INTRA_FRAME = 0,
INTER_FRAME,
SKIP_FRAME
};
enum BlockType {
SKIP_BLOCK = 0,
DCT_BLOCK,
IMAGE_BLOCK,
};
enum CachePos {
LEFT = 0,
TOP_LEFT,
TOP,
};
static const uint8_t mss4_dc_vlc_lens[2][16] = {
{ 0, 1, 5, 1, 1, 1, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0 },
{ 0, 3, 1, 1, 1, 1, 1, 1, 1, 2, 0, 0, 0, 0, 0, 0 }
};
static const uint8_t vec_len_syms[2][4] = {
{ 4, 2, 3, 1 },
{ 4, 1, 2, 3 }
};
static const uint8_t mss4_vec_entry_vlc_lens[2][16] = {
{ 0, 2, 2, 3, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
{ 0, 1, 5, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
};
static const uint8_t mss4_vec_entry_vlc_syms[2][9] = {
{ 0, 7, 6, 5, 8, 4, 3, 1, 2 },
{ 0, 2, 3, 4, 5, 6, 7, 1, 8 }
};
#define MAX_ENTRIES 162
typedef struct MSS4Context {
AVFrame *pic;
int block[64];
uint8_t imgbuf[3][16 * 16];
int quality;
uint16_t quant_mat[2][64];
int *prev_dc[3];
ptrdiff_t dc_stride[3];
int dc_cache[4][4];
int prev_vec[3][4];
} MSS4Context;
static VLC dc_vlc[2], ac_vlc[2];
static VLC vec_entry_vlc[2];
static av_cold void mss4_init_vlc(VLC *vlc, unsigned *offset,
const uint8_t *lens, const uint8_t *syms)
{
static VLC_TYPE vlc_buf[2146][2];
uint8_t bits[MAX_ENTRIES];
int i, j;
int idx = 0;
for (i = 0; i < 16; i++) {
for (j = 0; j < lens[i]; j++) {
bits[idx] = i + 1;
idx++;
}
}
vlc->table = &vlc_buf[*offset];
vlc->table_allocated = FF_ARRAY_ELEMS(vlc_buf) - *offset;
ff_init_vlc_from_lengths(vlc, FFMIN(bits[idx - 1], 9), idx,
bits, 1, syms, 1, 1,
0, INIT_VLC_STATIC_OVERLONG, NULL);
*offset += vlc->table_size;
}
static av_cold void mss4_init_vlcs(void)
{
for (unsigned i = 0, offset = 0; i < 2; i++) {
mss4_init_vlc(&dc_vlc[i], &offset, mss4_dc_vlc_lens[i], NULL);
mss4_init_vlc(&ac_vlc[i], &offset,
i ? ff_mjpeg_bits_ac_chrominance + 1
: ff_mjpeg_bits_ac_luminance + 1,
i ? ff_mjpeg_val_ac_chrominance
: ff_mjpeg_val_ac_luminance);
mss4_init_vlc(&vec_entry_vlc[i], &offset, mss4_vec_entry_vlc_lens[i],
mss4_vec_entry_vlc_syms[i]);
}
}
/* This function returns values in the range
* (-range + 1; -range/2] U [range/2; range - 1)
* i.e.
* nbits = 0 -> 0
* nbits = 1 -> -1, 1
* nbits = 2 -> -3, -2, 2, 3
*/
static av_always_inline int get_coeff_bits(GetBitContext *gb, int nbits)
{
int val;
if (!nbits)
return 0;
val = get_bits(gb, nbits);
if (val < (1 << (nbits - 1)))
val -= (1 << nbits) - 1;
return val;
}
static inline int get_coeff(GetBitContext *gb, VLC *vlc)
{
int val = get_vlc2(gb, vlc->table, vlc->bits, 2);
return get_coeff_bits(gb, val);
}
static int mss4_decode_dct(GetBitContext *gb, VLC *dc_vlc, VLC *ac_vlc,
int *block, int *dc_cache,
int bx, int by, uint16_t *quant_mat)
{
int skip, val, pos = 1, zz_pos, dc;
memset(block, 0, sizeof(*block) * 64);
dc = get_coeff(gb, dc_vlc);
// DC prediction is the same as in MSS3
if (by) {
if (bx) {
int l, tl, t;
l = dc_cache[LEFT];
tl = dc_cache[TOP_LEFT];
t = dc_cache[TOP];
if (FFABS(t - tl) <= FFABS(l - tl))
dc += l;
else
dc += t;
} else {
dc += dc_cache[TOP];
}
} else if (bx) {
dc += dc_cache[LEFT];
}
dc_cache[LEFT] = dc;
block[0] = dc * quant_mat[0];
while (pos < 64) {
val = get_vlc2(gb, ac_vlc->table, 9, 2);
if (!val)
return 0;
if (val == -1)
return -1;
if (val == 0xF0) {
pos += 16;
continue;
}
skip = val >> 4;
val = get_coeff_bits(gb, val & 0xF);
pos += skip;
if (pos >= 64)
return -1;
zz_pos = ff_zigzag_direct[pos];
block[zz_pos] = val * quant_mat[zz_pos];
pos++;
}
return pos == 64 ? 0 : -1;
}
static int mss4_decode_dct_block(MSS4Context *c, GetBitContext *gb,
uint8_t *dst[3], int mb_x, int mb_y)
{
int i, j, k, ret;
uint8_t *out = dst[0];
for (j = 0; j < 2; j++) {
for (i = 0; i < 2; i++) {
int xpos = mb_x * 2 + i;
c->dc_cache[j][TOP_LEFT] = c->dc_cache[j][TOP];
c->dc_cache[j][TOP] = c->prev_dc[0][mb_x * 2 + i];
ret = mss4_decode_dct(gb, &dc_vlc[0], &ac_vlc[0], c->block,
c->dc_cache[j],
xpos, mb_y * 2 + j, c->quant_mat[0]);
if (ret)
return ret;
c->prev_dc[0][mb_x * 2 + i] = c->dc_cache[j][LEFT];
ff_mss34_dct_put(out + xpos * 8, c->pic->linesize[0],
c->block);
}
out += 8 * c->pic->linesize[0];
}
for (i = 1; i < 3; i++) {
c->dc_cache[i + 1][TOP_LEFT] = c->dc_cache[i + 1][TOP];
c->dc_cache[i + 1][TOP] = c->prev_dc[i][mb_x];
ret = mss4_decode_dct(gb, &dc_vlc[1], &ac_vlc[1],
c->block, c->dc_cache[i + 1], mb_x, mb_y,
c->quant_mat[1]);
if (ret)
return ret;
c->prev_dc[i][mb_x] = c->dc_cache[i + 1][LEFT];
ff_mss34_dct_put(c->imgbuf[i], 8, c->block);
out = dst[i] + mb_x * 16;
// Since the DCT block is coded as YUV420 and the whole frame as YUV444,
// we need to scale chroma.
for (j = 0; j < 16; j++) {
for (k = 0; k < 8; k++)
AV_WN16A(out + k * 2, c->imgbuf[i][k + (j & ~1) * 4] * 0x101);
out += c->pic->linesize[i];
}
}
return 0;
}
static void read_vec_pos(GetBitContext *gb, int *vec_pos, int *sel_flag,
int *sel_len, int *prev)
{
int i, y_flag = 0;
for (i = 2; i >= 0; i--) {
if (!sel_flag[i]) {
vec_pos[i] = 0;
continue;
}
if ((!i && !y_flag) || get_bits1(gb)) {
if (sel_len[i] > 0) {
int pval = prev[i];
vec_pos[i] = get_bits(gb, sel_len[i]);
if (vec_pos[i] >= pval)
vec_pos[i]++;
} else {
vec_pos[i] = !prev[i];
}
y_flag = 1;
} else {
vec_pos[i] = prev[i];
}
}
}
static int get_value_cached(GetBitContext *gb, int vec_pos, uint8_t *vec,
int vec_size, int component, int shift, int *prev)
{
if (vec_pos < vec_size)
return vec[vec_pos];
if (!get_bits1(gb))
return prev[component];
prev[component] = get_bits(gb, 8 - shift) << shift;
return prev[component];
}
#define MKVAL(vals) ((vals)[0] | ((vals)[1] << 3) | ((vals)[2] << 6))
/* Image mode - the hardest to comprehend MSS4 coding mode.
*
* In this mode all three 16x16 blocks are coded together with a method
* remotely similar to the methods employed in MSS1-MSS3.
* The idea is that every component has a vector of 1-4 most common symbols
* and an escape mode for reading new value from the bitstream. Decoding
* consists of retrieving pixel values from the vector or reading new ones
* from the bitstream; depending on flags read from the bitstream, these vector
* positions can be updated or reused from the state of the previous line
* or previous pixel.
*/
static int mss4_decode_image_block(MSS4Context *ctx, GetBitContext *gb,
uint8_t *picdst[3], int mb_x, int mb_y)
{
uint8_t vec[3][4];
int vec_len[3];
int sel_len[3], sel_flag[3];
int i, j, k, mode, split;
int prev_vec1 = 0, prev_split = 0;
int vals[3] = { 0 };
int prev_pix[3] = { 0 };
int prev_mode[16] = { 0 };
uint8_t *dst[3];
const int val_shift = ctx->quality == 100 ? 0 : 2;
for (i = 0; i < 3; i++)
dst[i] = ctx->imgbuf[i];
for (i = 0; i < 3; i++) {
vec_len[i] = vec_len_syms[!!i][get_unary(gb, 0, 3)];
for (j = 0; j < vec_len[i]; j++) {
vec[i][j] = get_coeff(gb, &vec_entry_vlc[!!i]);
vec[i][j] += ctx->prev_vec[i][j];
ctx->prev_vec[i][j] = vec[i][j];
}
sel_flag[i] = vec_len[i] > 1;
sel_len[i] = vec_len[i] > 2 ? vec_len[i] - 2 : 0;
}
for (j = 0; j < 16; j++) {
if (get_bits1(gb)) {
split = 0;
if (get_bits1(gb)) {
prev_mode[0] = 0;
vals[0] = vals[1] = vals[2] = 0;
mode = 2;
} else {
mode = get_bits1(gb);
if (mode)
split = get_bits(gb, 4);
}
for (i = 0; i < 16; i++) {
if (mode <= 1) {
vals[0] = prev_mode[i] & 7;
vals[1] = (prev_mode[i] >> 3) & 7;
vals[2] = prev_mode[i] >> 6;
if (mode == 1 && i == split) {
read_vec_pos(gb, vals, sel_flag, sel_len, vals);
}
} else if (mode == 2) {
if (get_bits1(gb))
read_vec_pos(gb, vals, sel_flag, sel_len, vals);
}
for (k = 0; k < 3; k++)
*dst[k]++ = get_value_cached(gb, vals[k], vec[k],
vec_len[k], k,
val_shift, prev_pix);
prev_mode[i] = MKVAL(vals);
}
} else {
if (get_bits1(gb)) {
split = get_bits(gb, 4);
if (split >= prev_split)
split++;
prev_split = split;
} else {
split = prev_split;
}
if (split) {
vals[0] = prev_mode[0] & 7;
vals[1] = (prev_mode[0] >> 3) & 7;
vals[2] = prev_mode[0] >> 6;
for (i = 0; i < 3; i++) {
for (k = 0; k < split; k++) {
*dst[i]++ = get_value_cached(gb, vals[i], vec[i],
vec_len[i], i, val_shift,
prev_pix);
prev_mode[k] = MKVAL(vals);
}
}
}
if (split != 16) {
vals[0] = prev_vec1 & 7;
vals[1] = (prev_vec1 >> 3) & 7;
vals[2] = prev_vec1 >> 6;
if (get_bits1(gb)) {
read_vec_pos(gb, vals, sel_flag, sel_len, vals);
prev_vec1 = MKVAL(vals);
}
for (i = 0; i < 3; i++) {
for (k = 0; k < 16 - split; k++) {
*dst[i]++ = get_value_cached(gb, vals[i], vec[i],
vec_len[i], i, val_shift,
prev_pix);
prev_mode[split + k] = MKVAL(vals);
}
}
}
}
}
for (i = 0; i < 3; i++)
for (j = 0; j < 16; j++)
memcpy(picdst[i] + mb_x * 16 + j * ctx->pic->linesize[i],
ctx->imgbuf[i] + j * 16, 16);
return 0;
}
static inline void mss4_update_dc_cache(MSS4Context *c, int mb_x)
{
int i;
c->dc_cache[0][TOP] = c->prev_dc[0][mb_x * 2 + 1];
c->dc_cache[0][LEFT] = 0;
c->dc_cache[1][TOP] = 0;
c->dc_cache[1][LEFT] = 0;
for (i = 0; i < 2; i++)
c->prev_dc[0][mb_x * 2 + i] = 0;
for (i = 1; i < 3; i++) {
c->dc_cache[i + 1][TOP] = c->prev_dc[i][mb_x];
c->dc_cache[i + 1][LEFT] = 0;
c->prev_dc[i][mb_x] = 0;
}
}
static int mss4_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
MSS4Context *c = avctx->priv_data;
GetBitContext gb;
GetByteContext bc;
uint8_t *dst[3];
int width, height, quality, frame_type;
int x, y, i, mb_width, mb_height, blk_type;
int ret;
if (buf_size < HEADER_SIZE) {
av_log(avctx, AV_LOG_ERROR,
"Frame should have at least %d bytes, got %d instead\n",
HEADER_SIZE, buf_size);
return AVERROR_INVALIDDATA;
}
bytestream2_init(&bc, buf, buf_size);
width = bytestream2_get_be16(&bc);
height = bytestream2_get_be16(&bc);
bytestream2_skip(&bc, 2);
quality = bytestream2_get_byte(&bc);
frame_type = bytestream2_get_byte(&bc);
if (width > avctx->width ||
height != avctx->height) {
av_log(avctx, AV_LOG_ERROR, "Invalid frame dimensions %dx%d\n",
width, height);
return AVERROR_INVALIDDATA;
}
if (quality < 1 || quality > 100) {
av_log(avctx, AV_LOG_ERROR, "Invalid quality setting %d\n", quality);
return AVERROR_INVALIDDATA;
}
if ((frame_type & ~3) || frame_type == 3) {
av_log(avctx, AV_LOG_ERROR, "Invalid frame type %d\n", frame_type);
return AVERROR_INVALIDDATA;
}
if (frame_type != SKIP_FRAME && !bytestream2_get_bytes_left(&bc)) {
av_log(avctx, AV_LOG_ERROR,
"Empty frame found but it is not a skip frame.\n");
return AVERROR_INVALIDDATA;
}
mb_width = FFALIGN(width, 16) >> 4;
mb_height = FFALIGN(height, 16) >> 4;
if (frame_type != SKIP_FRAME && 8*buf_size < 8*HEADER_SIZE + mb_width*mb_height)
return AVERROR_INVALIDDATA;
if ((ret = ff_reget_buffer(avctx, c->pic, 0)) < 0)
return ret;
c->pic->key_frame = (frame_type == INTRA_FRAME);
c->pic->pict_type = (frame_type == INTRA_FRAME) ? AV_PICTURE_TYPE_I
: AV_PICTURE_TYPE_P;
if (frame_type == SKIP_FRAME) {
*got_frame = 1;
if ((ret = av_frame_ref(data, c->pic)) < 0)
return ret;
return buf_size;
}
if (c->quality != quality) {
c->quality = quality;
for (i = 0; i < 2; i++)
ff_mss34_gen_quant_mat(c->quant_mat[i], quality, !i);
}
if ((ret = init_get_bits8(&gb, buf + HEADER_SIZE, buf_size - HEADER_SIZE)) < 0)
return ret;
dst[0] = c->pic->data[0];
dst[1] = c->pic->data[1];
dst[2] = c->pic->data[2];
memset(c->prev_vec, 0, sizeof(c->prev_vec));
for (y = 0; y < mb_height; y++) {
memset(c->dc_cache, 0, sizeof(c->dc_cache));
for (x = 0; x < mb_width; x++) {
blk_type = decode012(&gb);
switch (blk_type) {
case DCT_BLOCK:
if (mss4_decode_dct_block(c, &gb, dst, x, y) < 0) {
av_log(avctx, AV_LOG_ERROR,
"Error decoding DCT block %d,%d\n",
x, y);
return AVERROR_INVALIDDATA;
}
break;
case IMAGE_BLOCK:
if (mss4_decode_image_block(c, &gb, dst, x, y) < 0) {
av_log(avctx, AV_LOG_ERROR,
"Error decoding VQ block %d,%d\n",
x, y);
return AVERROR_INVALIDDATA;
}
break;
case SKIP_BLOCK:
if (frame_type == INTRA_FRAME) {
av_log(avctx, AV_LOG_ERROR, "Skip block in intra frame\n");
return AVERROR_INVALIDDATA;
}
break;
}
if (blk_type != DCT_BLOCK)
mss4_update_dc_cache(c, x);
}
dst[0] += c->pic->linesize[0] * 16;
dst[1] += c->pic->linesize[1] * 16;
dst[2] += c->pic->linesize[2] * 16;
}
if ((ret = av_frame_ref(data, c->pic)) < 0)
return ret;
*got_frame = 1;
return buf_size;
}
static av_cold int mss4_decode_end(AVCodecContext *avctx)
{
MSS4Context * const c = avctx->priv_data;
int i;
av_frame_free(&c->pic);
for (i = 0; i < 3; i++)
av_freep(&c->prev_dc[i]);
return 0;
}
static av_cold int mss4_decode_init(AVCodecContext *avctx)
{
static AVOnce init_static_once = AV_ONCE_INIT;
MSS4Context * const c = avctx->priv_data;
int i;
for (i = 0; i < 3; i++) {
c->dc_stride[i] = FFALIGN(avctx->width, 16) >> (2 + !!i);
c->prev_dc[i] = av_malloc_array(c->dc_stride[i], sizeof(**c->prev_dc));
if (!c->prev_dc[i]) {
av_log(avctx, AV_LOG_ERROR, "Cannot allocate buffer\n");
return AVERROR(ENOMEM);
}
}
c->pic = av_frame_alloc();
if (!c->pic)
return AVERROR(ENOMEM);
avctx->pix_fmt = AV_PIX_FMT_YUV444P;
ff_thread_once(&init_static_once, mss4_init_vlcs);
return 0;
}
const AVCodec ff_mts2_decoder = {
.name = "mts2",
.long_name = NULL_IF_CONFIG_SMALL("MS Expression Encoder Screen"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_MTS2,
.priv_data_size = sizeof(MSS4Context),
.init = mss4_decode_init,
.close = mss4_decode_end,
.decode = mss4_decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
.caps_internal = FF_CODEC_CAP_INIT_CLEANUP | FF_CODEC_CAP_INIT_THREADSAFE,
};
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