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FFmpeg/libavcodec/c93.c
Andreas Rheinhardt 20f9727018 avcodec/codec_internal: Add FFCodec, hide internal part of AVCodec 
Up until now, codec.h contains both public and private parts
of AVCodec. This exposes the internals of AVCodec to users
and leads them into the temptation of actually using them
and forces us to forward-declare structures and types that
users can't use at all.

This commit changes this by adding a new structure FFCodec to
codec_internal.h that extends AVCodec, i.e. contains the public
AVCodec as first member; the private fields of AVCodec are moved
to this structure, leaving codec.h clean.

Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-03-21 01:33:09 +01:00

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/*
* Interplay C93 video decoder
* Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
*
* 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
*/
#include "avcodec.h"
#include "bytestream.h"
#include "codec_internal.h"
#include "internal.h"
typedef struct C93DecoderContext {
AVFrame *pictures[2];
int currentpic;
} C93DecoderContext;
typedef enum {
C93_8X8_FROM_PREV = 0x02,
C93_4X4_FROM_PREV = 0x06,
C93_4X4_FROM_CURR = 0x07,
C93_8X8_2COLOR = 0x08,
C93_4X4_2COLOR = 0x0A,
C93_4X4_4COLOR_GRP = 0x0B,
C93_4X4_4COLOR = 0x0D,
C93_NOOP = 0x0E,
C93_8X8_INTRA = 0x0F,
} C93BlockType;
#define WIDTH 320
#define HEIGHT 192
#define C93_HAS_PALETTE 0x01
#define C93_FIRST_FRAME 0x02
static av_cold int decode_end(AVCodecContext *avctx)
{
C93DecoderContext * const c93 = avctx->priv_data;
av_frame_free(&c93->pictures[0]);
av_frame_free(&c93->pictures[1]);
return 0;
}
static av_cold int decode_init(AVCodecContext *avctx)
{
C93DecoderContext *s = avctx->priv_data;
avctx->pix_fmt = AV_PIX_FMT_PAL8;
s->pictures[0] = av_frame_alloc();
s->pictures[1] = av_frame_alloc();
if (!s->pictures[0] || !s->pictures[1])
return AVERROR(ENOMEM);
return 0;
}
static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
uint8_t *from, int offset, int height, int stride)
{
int i;
int width = height;
int from_x = offset % WIDTH;
int from_y = offset / WIDTH;
int overflow = from_x + width - WIDTH;
if (!from) {
/* silently ignoring predictive blocks in first frame */
return 0;
}
if (from_y + height > HEIGHT) {
av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
offset);
return AVERROR_INVALIDDATA;
}
if (overflow > 0) {
width -= overflow;
for (i = 0; i < height; i++) {
memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
}
}
for (i = 0; i < height; i++) {
memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
}
return 0;
}
static inline void draw_n_color(uint8_t *out, int stride, int width,
int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
{
int x, y;
for (y = 0; y < height; y++) {
if (grps)
cols[0] = grps[3 * (y >> 1)];
for (x = 0; x < width; x++) {
if (grps)
cols[1]= grps[(x >> 1) + 1];
out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
col >>= bpp;
}
}
}
static int decode_frame(AVCodecContext *avctx, void *data,
int *got_frame, AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
C93DecoderContext * const c93 = avctx->priv_data;
AVFrame * const newpic = c93->pictures[c93->currentpic];
AVFrame * const oldpic = c93->pictures[c93->currentpic^1];
GetByteContext gb;
uint8_t *out;
int stride, ret, i, x, y, b, bt = 0;
if ((ret = ff_set_dimensions(avctx, WIDTH, HEIGHT)) < 0)
return ret;
c93->currentpic ^= 1;
if ((ret = ff_reget_buffer(avctx, newpic, 0)) < 0)
return ret;
stride = newpic->linesize[0];
bytestream2_init(&gb, buf, buf_size);
b = bytestream2_get_byte(&gb);
if (b & C93_FIRST_FRAME) {
newpic->pict_type = AV_PICTURE_TYPE_I;
newpic->key_frame = 1;
} else {
newpic->pict_type = AV_PICTURE_TYPE_P;
newpic->key_frame = 0;
}
for (y = 0; y < HEIGHT; y += 8) {
out = newpic->data[0] + y * stride;
for (x = 0; x < WIDTH; x += 8) {
uint8_t *copy_from = oldpic->data[0];
unsigned int offset, j;
uint8_t cols[4], grps[4];
C93BlockType block_type;
if (!bt)
bt = bytestream2_get_byte(&gb);
block_type= bt & 0x0F;
switch (block_type) {
case C93_8X8_FROM_PREV:
offset = bytestream2_get_le16(&gb);
if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
return ret;
break;
case C93_4X4_FROM_CURR:
copy_from = newpic->data[0];
case C93_4X4_FROM_PREV:
for (j = 0; j < 8; j += 4) {
for (i = 0; i < 8; i += 4) {
int offset = bytestream2_get_le16(&gb);
int from_x = offset % WIDTH;
int from_y = offset / WIDTH;
if (block_type == C93_4X4_FROM_CURR && from_y == y+j &&
(FFABS(from_x - x-i) < 4 || FFABS(from_x - x-i) > WIDTH-4)) {
avpriv_request_sample(avctx, "block overlap %d %d %d %d", from_x, x+i, from_y, y+j);
return AVERROR_INVALIDDATA;
}
if ((ret = copy_block(avctx, &out[j*stride+i],
copy_from, offset, 4, stride)) < 0)
return ret;
}
}
break;
case C93_8X8_2COLOR:
bytestream2_get_buffer(&gb, cols, 2);
for (i = 0; i < 8; i++) {
draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
NULL, bytestream2_get_byte(&gb));
}
break;
case C93_4X4_2COLOR:
case C93_4X4_4COLOR:
case C93_4X4_4COLOR_GRP:
for (j = 0; j < 8; j += 4) {
for (i = 0; i < 8; i += 4) {
if (block_type == C93_4X4_2COLOR) {
bytestream2_get_buffer(&gb, cols, 2);
draw_n_color(out + i + j*stride, stride, 4, 4,
1, cols, NULL, bytestream2_get_le16(&gb));
} else if (block_type == C93_4X4_4COLOR) {
bytestream2_get_buffer(&gb, cols, 4);
draw_n_color(out + i + j*stride, stride, 4, 4,
2, cols, NULL, bytestream2_get_le32(&gb));
} else {
bytestream2_get_buffer(&gb, grps, 4);
draw_n_color(out + i + j*stride, stride, 4, 4,
1, cols, grps, bytestream2_get_le16(&gb));
}
}
}
break;
case C93_NOOP:
break;
case C93_8X8_INTRA:
for (j = 0; j < 8; j++)
bytestream2_get_buffer(&gb, out + j*stride, 8);
break;
default:
av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
block_type, x, y);
return AVERROR_INVALIDDATA;
}
bt >>= 4;
out += 8;
}
}
if (b & C93_HAS_PALETTE) {
uint32_t *palette = (uint32_t *) newpic->data[1];
for (i = 0; i < 256; i++) {
palette[i] = 0xFFU << 24 | bytestream2_get_be24(&gb);
}
newpic->palette_has_changed = 1;
} else {
if (oldpic->data[1])
memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
}
if ((ret = av_frame_ref(data, newpic)) < 0)
return ret;
*got_frame = 1;
return buf_size;
}
const FFCodec ff_c93_decoder = {
.p.name = "c93",
.p.long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
.p.type = AVMEDIA_TYPE_VIDEO,
.p.id = AV_CODEC_ID_C93,
.priv_data_size = sizeof(C93DecoderContext),
.init = decode_init,
.close = decode_end,
.decode = decode_frame,
.p.capabilities = AV_CODEC_CAP_DR1,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
};
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