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third_party_ffmpeg/libavcodec/mss3.c
James Almer 9ea6d2149e avcodec/decode: add a flags parameter to ff_reget_buffer() 
Some decoders may not need a writable buffer in some specific cases, but only
a reference to the existing buffer with updated frame properties instead, for
the purpose of returning duplicate frames. For this, the
FF_REGET_BUFFER_FLAG_READONLY flag is added, which will prevent potential
allocations and buffer copies when they are not needed.

Signed-off-by: James Almer <jamrial@gmail.com>
2019-09-04 10:07:12 -03:00

880 lines
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/*
* Microsoft Screen 3 (aka Microsoft ATC 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 3 (aka Microsoft ATC Screen) decoder
*/
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#include "mathops.h"
#include "mss34dsp.h"
#define HEADER_SIZE 27
#define MODEL2_SCALE 13
#define MODEL_SCALE 15
#define MODEL256_SEC_SCALE 9
typedef struct Model2 {
int upd_val, till_rescale;
unsigned zero_freq, zero_weight;
unsigned total_freq, total_weight;
} Model2;
typedef struct Model {
int weights[16], freqs[16];
int num_syms;
int tot_weight;
int upd_val, max_upd_val, till_rescale;
} Model;
typedef struct Model256 {
int weights[256], freqs[256];
int tot_weight;
int secondary[68];
int sec_size;
int upd_val, max_upd_val, till_rescale;
} Model256;
#define RAC_BOTTOM 0x01000000
typedef struct RangeCoder {
const uint8_t *src, *src_end;
uint32_t range, low;
int got_error;
} RangeCoder;
enum BlockType {
FILL_BLOCK = 0,
IMAGE_BLOCK,
DCT_BLOCK,
HAAR_BLOCK,
SKIP_BLOCK
};
typedef struct BlockTypeContext {
int last_type;
Model bt_model[5];
} BlockTypeContext;
typedef struct FillBlockCoder {
int fill_val;
Model coef_model;
} FillBlockCoder;
typedef struct ImageBlockCoder {
Model256 esc_model, vec_entry_model;
Model vec_size_model;
Model vq_model[125];
} ImageBlockCoder;
typedef struct DCTBlockCoder {
int *prev_dc;
ptrdiff_t prev_dc_stride;
int prev_dc_height;
int quality;
uint16_t qmat[64];
Model dc_model;
Model2 sign_model;
Model256 ac_model;
} DCTBlockCoder;
typedef struct HaarBlockCoder {
int quality, scale;
Model256 coef_model;
Model coef_hi_model;
} HaarBlockCoder;
typedef struct MSS3Context {
AVCodecContext *avctx;
AVFrame *pic;
int got_error;
RangeCoder coder;
BlockTypeContext btype[3];
FillBlockCoder fill_coder[3];
ImageBlockCoder image_coder[3];
DCTBlockCoder dct_coder[3];
HaarBlockCoder haar_coder[3];
int dctblock[64];
int hblock[16 * 16];
} MSS3Context;
static void model2_reset(Model2 *m)
{
m->zero_weight = 1;
m->total_weight = 2;
m->zero_freq = 0x1000;
m->total_freq = 0x2000;
m->upd_val = 4;
m->till_rescale = 4;
}
static void model2_update(Model2 *m, int bit)
{
unsigned scale;
if (!bit)
m->zero_weight++;
m->till_rescale--;
if (m->till_rescale)
return;
m->total_weight += m->upd_val;
if (m->total_weight > 0x2000) {
m->total_weight = (m->total_weight + 1) >> 1;
m->zero_weight = (m->zero_weight + 1) >> 1;
if (m->total_weight == m->zero_weight)
m->total_weight = m->zero_weight + 1;
}
m->upd_val = m->upd_val * 5 >> 2;
if (m->upd_val > 64)
m->upd_val = 64;
scale = 0x80000000u / m->total_weight;
m->zero_freq = m->zero_weight * scale >> 18;
m->total_freq = m->total_weight * scale >> 18;
m->till_rescale = m->upd_val;
}
static void model_update(Model *m, int val)
{
int i, sum = 0;
unsigned scale;
m->weights[val]++;
m->till_rescale--;
if (m->till_rescale)
return;
m->tot_weight += m->upd_val;
if (m->tot_weight > 0x8000) {
m->tot_weight = 0;
for (i = 0; i < m->num_syms; i++) {
m->weights[i] = (m->weights[i] + 1) >> 1;
m->tot_weight += m->weights[i];
}
}
scale = 0x80000000u / m->tot_weight;
for (i = 0; i < m->num_syms; i++) {
m->freqs[i] = sum * scale >> 16;
sum += m->weights[i];
}
m->upd_val = m->upd_val * 5 >> 2;
if (m->upd_val > m->max_upd_val)
m->upd_val = m->max_upd_val;
m->till_rescale = m->upd_val;
}
static void model_reset(Model *m)
{
int i;
m->tot_weight = 0;
for (i = 0; i < m->num_syms - 1; i++)
m->weights[i] = 1;
m->weights[m->num_syms - 1] = 0;
m->upd_val = m->num_syms;
m->till_rescale = 1;
model_update(m, m->num_syms - 1);
m->till_rescale =
m->upd_val = (m->num_syms + 6) >> 1;
}
static av_cold void model_init(Model *m, int num_syms)
{
m->num_syms = num_syms;
m->max_upd_val = 8 * num_syms + 48;
model_reset(m);
}
static void model256_update(Model256 *m, int val)
{
int i, sum = 0;
unsigned scale;
int send, sidx = 1;
m->weights[val]++;
m->till_rescale--;
if (m->till_rescale)
return;
m->tot_weight += m->upd_val;
if (m->tot_weight > 0x8000) {
m->tot_weight = 0;
for (i = 0; i < 256; i++) {
m->weights[i] = (m->weights[i] + 1) >> 1;
m->tot_weight += m->weights[i];
}
}
scale = 0x80000000u / m->tot_weight;
m->secondary[0] = 0;
for (i = 0; i < 256; i++) {
m->freqs[i] = sum * scale >> 16;
sum += m->weights[i];
send = m->freqs[i] >> MODEL256_SEC_SCALE;
while (sidx <= send)
m->secondary[sidx++] = i - 1;
}
while (sidx < m->sec_size)
m->secondary[sidx++] = 255;
m->upd_val = m->upd_val * 5 >> 2;
if (m->upd_val > m->max_upd_val)
m->upd_val = m->max_upd_val;
m->till_rescale = m->upd_val;
}
static void model256_reset(Model256 *m)
{
int i;
for (i = 0; i < 255; i++)
m->weights[i] = 1;
m->weights[255] = 0;
m->tot_weight = 0;
m->upd_val = 256;
m->till_rescale = 1;
model256_update(m, 255);
m->till_rescale =
m->upd_val = (256 + 6) >> 1;
}
static av_cold void model256_init(Model256 *m)
{
m->max_upd_val = 8 * 256 + 48;
m->sec_size = (1 << 6) + 2;
model256_reset(m);
}
static void rac_init(RangeCoder *c, const uint8_t *src, int size)
{
int i;
c->src = src;
c->src_end = src + size;
c->low = 0;
for (i = 0; i < FFMIN(size, 4); i++)
c->low = (c->low << 8) | *c->src++;
c->range = 0xFFFFFFFF;
c->got_error = 0;
}
static void rac_normalise(RangeCoder *c)
{
for (;;) {
c->range <<= 8;
c->low <<= 8;
if (c->src < c->src_end) {
c->low |= *c->src++;
} else if (!c->low) {
c->got_error = 1;
c->low = 1;
}
if (c->low > c->range) {
c->got_error = 1;
c->low = 1;
}
if (c->range >= RAC_BOTTOM)
return;
}
}
static int rac_get_bit(RangeCoder *c)
{
int bit;
c->range >>= 1;
bit = (c->range <= c->low);
if (bit)
c->low -= c->range;
if (c->range < RAC_BOTTOM)
rac_normalise(c);
return bit;
}
static int rac_get_bits(RangeCoder *c, int nbits)
{
int val;
c->range >>= nbits;
val = c->low / c->range;
c->low -= c->range * val;
if (c->range < RAC_BOTTOM)
rac_normalise(c);
return val;
}
static int rac_get_model2_sym(RangeCoder *c, Model2 *m)
{
int bit, helper;
helper = m->zero_freq * (c->range >> MODEL2_SCALE);
bit = (c->low >= helper);
if (bit) {
c->low -= helper;
c->range -= helper;
} else {
c->range = helper;
}
if (c->range < RAC_BOTTOM)
rac_normalise(c);
model2_update(m, bit);
return bit;
}
static int rac_get_model_sym(RangeCoder *c, Model *m)
{
int val;
int end, end2;
unsigned prob, prob2, helper;
prob = 0;
prob2 = c->range;
c->range >>= MODEL_SCALE;
val = 0;
end = m->num_syms >> 1;
end2 = m->num_syms;
do {
helper = m->freqs[end] * c->range;
if (helper <= c->low) {
val = end;
prob = helper;
} else {
end2 = end;
prob2 = helper;
}
end = (end2 + val) >> 1;
} while (end != val);
c->low -= prob;
c->range = prob2 - prob;
if (c->range < RAC_BOTTOM)
rac_normalise(c);
model_update(m, val);
return val;
}
static int rac_get_model256_sym(RangeCoder *c, Model256 *m)
{
int val;
int start, end;
int ssym;
unsigned prob, prob2, helper;
prob2 = c->range;
c->range >>= MODEL_SCALE;
helper = c->low / c->range;
ssym = helper >> MODEL256_SEC_SCALE;
val = m->secondary[ssym];
end = start = m->secondary[ssym + 1] + 1;
while (end > val + 1) {
ssym = (end + val) >> 1;
if (m->freqs[ssym] <= helper) {
end = start;
val = ssym;
} else {
end = (end + val) >> 1;
start = ssym;
}
}
prob = m->freqs[val] * c->range;
if (val != 255)
prob2 = m->freqs[val + 1] * c->range;
c->low -= prob;
c->range = prob2 - prob;
if (c->range < RAC_BOTTOM)
rac_normalise(c);
model256_update(m, val);
return val;
}
static int decode_block_type(RangeCoder *c, BlockTypeContext *bt)
{
bt->last_type = rac_get_model_sym(c, &bt->bt_model[bt->last_type]);
return bt->last_type;
}
static int decode_coeff(RangeCoder *c, Model *m)
{
int val, sign;
val = rac_get_model_sym(c, m);
if (val) {
sign = rac_get_bit(c);
if (val > 1) {
val--;
val = (1 << val) + rac_get_bits(c, val);
}
if (!sign)
val = -val;
}
return val;
}
static void decode_fill_block(RangeCoder *c, FillBlockCoder *fc,
uint8_t *dst, ptrdiff_t stride, int block_size)
{
int i;
fc->fill_val += decode_coeff(c, &fc->coef_model);
for (i = 0; i < block_size; i++, dst += stride)
memset(dst, fc->fill_val, block_size);
}
static void decode_image_block(RangeCoder *c, ImageBlockCoder *ic,
uint8_t *dst, ptrdiff_t stride, int block_size)
{
int i, j;
int vec_size;
int vec[4];
int prev_line[16];
int A, B, C;
vec_size = rac_get_model_sym(c, &ic->vec_size_model) + 2;
for (i = 0; i < vec_size; i++)
vec[i] = rac_get_model256_sym(c, &ic->vec_entry_model);
for (; i < 4; i++)
vec[i] = 0;
memset(prev_line, 0, sizeof(prev_line));
for (j = 0; j < block_size; j++) {
A = 0;
B = 0;
for (i = 0; i < block_size; i++) {
C = B;
B = prev_line[i];
A = rac_get_model_sym(c, &ic->vq_model[A + B * 5 + C * 25]);
prev_line[i] = A;
if (A < 4)
dst[i] = vec[A];
else
dst[i] = rac_get_model256_sym(c, &ic->esc_model);
}
dst += stride;
}
}
static int decode_dct(RangeCoder *c, DCTBlockCoder *bc, int *block,
int bx, int by)
{
int skip, val, sign, pos = 1, zz_pos, dc;
int blk_pos = bx + by * bc->prev_dc_stride;
memset(block, 0, sizeof(*block) * 64);
dc = decode_coeff(c, &bc->dc_model);
if (by) {
if (bx) {
int l, tl, t;
l = bc->prev_dc[blk_pos - 1];
tl = bc->prev_dc[blk_pos - 1 - bc->prev_dc_stride];
t = bc->prev_dc[blk_pos - bc->prev_dc_stride];
if (FFABS(t - tl) <= FFABS(l - tl))
dc += l;
else
dc += t;
} else {
dc += bc->prev_dc[blk_pos - bc->prev_dc_stride];
}
} else if (bx) {
dc += bc->prev_dc[bx - 1];
}
bc->prev_dc[blk_pos] = dc;
block[0] = dc * bc->qmat[0];
while (pos < 64) {
val = rac_get_model256_sym(c, &bc->ac_model);
if (!val)
return 0;
if (val == 0xF0) {
pos += 16;
continue;
}
skip = val >> 4;
val = val & 0xF;
if (!val)
return -1;
pos += skip;
if (pos >= 64)
return -1;
sign = rac_get_model2_sym(c, &bc->sign_model);
if (val > 1) {
val--;
val = (1 << val) + rac_get_bits(c, val);
}
if (!sign)
val = -val;
zz_pos = ff_zigzag_direct[pos];
block[zz_pos] = val * bc->qmat[zz_pos];
pos++;
}
return pos == 64 ? 0 : -1;
}
static void decode_dct_block(RangeCoder *c, DCTBlockCoder *bc,
uint8_t *dst, ptrdiff_t stride, int block_size,
int *block, int mb_x, int mb_y)
{
int i, j;
int bx, by;
int nblocks = block_size >> 3;
bx = mb_x * nblocks;
by = mb_y * nblocks;
for (j = 0; j < nblocks; j++) {
for (i = 0; i < nblocks; i++) {
if (decode_dct(c, bc, block, bx + i, by + j)) {
c->got_error = 1;
return;
}
ff_mss34_dct_put(dst + i * 8, stride, block);
}
dst += 8 * stride;
}
}
static void decode_haar_block(RangeCoder *c, HaarBlockCoder *hc,
uint8_t *dst, ptrdiff_t stride,
int block_size, int *block)
{
const int hsize = block_size >> 1;
int A, B, C, D, t1, t2, t3, t4;
int i, j;
for (j = 0; j < block_size; j++) {
for (i = 0; i < block_size; i++) {
if (i < hsize && j < hsize)
block[i] = rac_get_model256_sym(c, &hc->coef_model);
else
block[i] = decode_coeff(c, &hc->coef_hi_model);
block[i] *= hc->scale;
}
block += block_size;
}
block -= block_size * block_size;
for (j = 0; j < hsize; j++) {
for (i = 0; i < hsize; i++) {
A = block[i];
B = block[i + hsize];
C = block[i + hsize * block_size];
D = block[i + hsize * block_size + hsize];
t1 = A - B;
t2 = C - D;
t3 = A + B;
t4 = C + D;
dst[i * 2] = av_clip_uint8(t1 - t2);
dst[i * 2 + stride] = av_clip_uint8(t1 + t2);
dst[i * 2 + 1] = av_clip_uint8(t3 - t4);
dst[i * 2 + 1 + stride] = av_clip_uint8(t3 + t4);
}
block += block_size;
dst += stride * 2;
}
}
static void reset_coders(MSS3Context *ctx, int quality)
{
int i, j;
for (i = 0; i < 3; i++) {
ctx->btype[i].last_type = SKIP_BLOCK;
for (j = 0; j < 5; j++)
model_reset(&ctx->btype[i].bt_model[j]);
ctx->fill_coder[i].fill_val = 0;
model_reset(&ctx->fill_coder[i].coef_model);
model256_reset(&ctx->image_coder[i].esc_model);
model256_reset(&ctx->image_coder[i].vec_entry_model);
model_reset(&ctx->image_coder[i].vec_size_model);
for (j = 0; j < 125; j++)
model_reset(&ctx->image_coder[i].vq_model[j]);
if (ctx->dct_coder[i].quality != quality) {
ctx->dct_coder[i].quality = quality;
ff_mss34_gen_quant_mat(ctx->dct_coder[i].qmat, quality, !i);
}
memset(ctx->dct_coder[i].prev_dc, 0,
sizeof(*ctx->dct_coder[i].prev_dc) *
ctx->dct_coder[i].prev_dc_stride *
ctx->dct_coder[i].prev_dc_height);
model_reset(&ctx->dct_coder[i].dc_model);
model2_reset(&ctx->dct_coder[i].sign_model);
model256_reset(&ctx->dct_coder[i].ac_model);
if (ctx->haar_coder[i].quality != quality) {
ctx->haar_coder[i].quality = quality;
ctx->haar_coder[i].scale = 17 - 7 * quality / 50;
}
model_reset(&ctx->haar_coder[i].coef_hi_model);
model256_reset(&ctx->haar_coder[i].coef_model);
}
}
static av_cold void init_coders(MSS3Context *ctx)
{
int i, j;
for (i = 0; i < 3; i++) {
for (j = 0; j < 5; j++)
model_init(&ctx->btype[i].bt_model[j], 5);
model_init(&ctx->fill_coder[i].coef_model, 12);
model256_init(&ctx->image_coder[i].esc_model);
model256_init(&ctx->image_coder[i].vec_entry_model);
model_init(&ctx->image_coder[i].vec_size_model, 3);
for (j = 0; j < 125; j++)
model_init(&ctx->image_coder[i].vq_model[j], 5);
model_init(&ctx->dct_coder[i].dc_model, 12);
model256_init(&ctx->dct_coder[i].ac_model);
model_init(&ctx->haar_coder[i].coef_hi_model, 12);
model256_init(&ctx->haar_coder[i].coef_model);
}
}
static int mss3_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
MSS3Context *c = avctx->priv_data;
RangeCoder *acoder = &c->coder;
GetByteContext gb;
uint8_t *dst[3];
int dec_width, dec_height, dec_x, dec_y, quality, keyframe;
int x, y, i, mb_width, mb_height, blk_size, btype;
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(&gb, buf, buf_size);
keyframe = bytestream2_get_be32(&gb);
if (keyframe & ~0x301) {
av_log(avctx, AV_LOG_ERROR, "Invalid frame type %X\n", keyframe);
return AVERROR_INVALIDDATA;
}
keyframe = !(keyframe & 1);
bytestream2_skip(&gb, 6);
dec_x = bytestream2_get_be16(&gb);
dec_y = bytestream2_get_be16(&gb);
dec_width = bytestream2_get_be16(&gb);
dec_height = bytestream2_get_be16(&gb);
if (dec_x + dec_width > avctx->width ||
dec_y + dec_height > avctx->height ||
(dec_width | dec_height) & 0xF) {
av_log(avctx, AV_LOG_ERROR, "Invalid frame dimensions %dx%d +%d,%d\n",
dec_width, dec_height, dec_x, dec_y);
return AVERROR_INVALIDDATA;
}
bytestream2_skip(&gb, 4);
quality = bytestream2_get_byte(&gb);
if (quality < 1 || quality > 100) {
av_log(avctx, AV_LOG_ERROR, "Invalid quality setting %d\n", quality);
return AVERROR_INVALIDDATA;
}
bytestream2_skip(&gb, 4);
if (keyframe && !bytestream2_get_bytes_left(&gb)) {
av_log(avctx, AV_LOG_ERROR, "Keyframe without data found\n");
return AVERROR_INVALIDDATA;
}
if (!keyframe && c->got_error)
return buf_size;
c->got_error = 0;
if ((ret = ff_reget_buffer(avctx, c->pic, 0)) < 0)
return ret;
c->pic->key_frame = keyframe;
c->pic->pict_type = keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
if (!bytestream2_get_bytes_left(&gb)) {
if ((ret = av_frame_ref(data, c->pic)) < 0)
return ret;
*got_frame = 1;
return buf_size;
}
reset_coders(c, quality);
rac_init(acoder, buf + HEADER_SIZE, buf_size - HEADER_SIZE);
mb_width = dec_width >> 4;
mb_height = dec_height >> 4;
dst[0] = c->pic->data[0] + dec_x + dec_y * c->pic->linesize[0];
dst[1] = c->pic->data[1] + dec_x / 2 + (dec_y / 2) * c->pic->linesize[1];
dst[2] = c->pic->data[2] + dec_x / 2 + (dec_y / 2) * c->pic->linesize[2];
for (y = 0; y < mb_height; y++) {
for (x = 0; x < mb_width; x++) {
for (i = 0; i < 3; i++) {
blk_size = 8 << !i;
btype = decode_block_type(acoder, c->btype + i);
switch (btype) {
case FILL_BLOCK:
decode_fill_block(acoder, c->fill_coder + i,
dst[i] + x * blk_size,
c->pic->linesize[i], blk_size);
break;
case IMAGE_BLOCK:
decode_image_block(acoder, c->image_coder + i,
dst[i] + x * blk_size,
c->pic->linesize[i], blk_size);
break;
case DCT_BLOCK:
decode_dct_block(acoder, c->dct_coder + i,
dst[i] + x * blk_size,
c->pic->linesize[i], blk_size,
c->dctblock, x, y);
break;
case HAAR_BLOCK:
decode_haar_block(acoder, c->haar_coder + i,
dst[i] + x * blk_size,
c->pic->linesize[i], blk_size,
c->hblock);
break;
}
if (c->got_error || acoder->got_error) {
av_log(avctx, AV_LOG_ERROR, "Error decoding block %d,%d\n",
x, y);
c->got_error = 1;
return AVERROR_INVALIDDATA;
}
}
}
dst[0] += c->pic->linesize[0] * 16;
dst[1] += c->pic->linesize[1] * 8;
dst[2] += c->pic->linesize[2] * 8;
}
if ((ret = av_frame_ref(data, c->pic)) < 0)
return ret;
*got_frame = 1;
return buf_size;
}
static av_cold int mss3_decode_end(AVCodecContext *avctx)
{
MSS3Context * const c = avctx->priv_data;
int i;
av_frame_free(&c->pic);
for (i = 0; i < 3; i++)
av_freep(&c->dct_coder[i].prev_dc);
return 0;
}
static av_cold int mss3_decode_init(AVCodecContext *avctx)
{
MSS3Context * const c = avctx->priv_data;
int i;
c->avctx = avctx;
if ((avctx->width & 0xF) || (avctx->height & 0xF)) {
av_log(avctx, AV_LOG_ERROR,
"Image dimensions should be a multiple of 16.\n");
return AVERROR_INVALIDDATA;
}
c->got_error = 0;
for (i = 0; i < 3; i++) {
int b_width = avctx->width >> (2 + !!i);
int b_height = avctx->height >> (2 + !!i);
c->dct_coder[i].prev_dc_stride = b_width;
c->dct_coder[i].prev_dc_height = b_height;
c->dct_coder[i].prev_dc = av_malloc(sizeof(*c->dct_coder[i].prev_dc) *
b_width * b_height);
if (!c->dct_coder[i].prev_dc) {
av_log(avctx, AV_LOG_ERROR, "Cannot allocate buffer\n");
av_frame_free(&c->pic);
while (i >= 0) {
av_freep(&c->dct_coder[i].prev_dc);
i--;
}
return AVERROR(ENOMEM);
}
}
c->pic = av_frame_alloc();
if (!c->pic) {
mss3_decode_end(avctx);
return AVERROR(ENOMEM);
}
avctx->pix_fmt = AV_PIX_FMT_YUV420P;
init_coders(c);
return 0;
}
AVCodec ff_msa1_decoder = {
.name = "msa1",
.long_name = NULL_IF_CONFIG_SMALL("MS ATC Screen"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_MSA1,
.priv_data_size = sizeof(MSS3Context),
.init = mss3_decode_init,
.close = mss3_decode_end,
.decode = mss3_decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
};
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