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ffmpeg/libavcodec/c93.c

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/*
* Interplay C93 video decoder
* Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
*
* 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
*/
#include "avcodec.h"
#include "bytestream.h"
typedef struct {
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_init(AVCodecContext *avctx)
{
avctx->pix_fmt = PIX_FMT_PAL8;
return 0;
}
static av_cold int decode_end(AVCodecContext *avctx)
{
C93DecoderContext * const c93 = avctx->priv_data;
if (c93->pictures[0].data[0])
avctx->release_buffer(avctx, &c93->pictures[0]);
if (c93->pictures[1].data[0])
avctx->release_buffer(avctx, &c93->pictures[1]);
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 -1;
}
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 *data_size, 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];
AVFrame *picture = data;
uint8_t *out;
int stride, i, x, y, bt = 0;
c93->currentpic ^= 1;
newpic->reference = 1;
newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
if (avctx->reget_buffer(avctx, newpic)) {
av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
return -1;
}
stride = newpic->linesize[0];
if (buf[0] & 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;
}
if (*buf++ & C93_HAS_PALETTE) {
uint32_t *palette = (uint32_t *) newpic->data[1];
const uint8_t *palbuf = buf + buf_size - 768 - 1;
for (i = 0; i < 256; i++) {
palette[i] = bytestream_get_be24(&palbuf);
}
} else {
if (oldpic->data[1])
memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
}
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 = *buf++;
block_type= bt & 0x0F;
switch (block_type) {
case C93_8X8_FROM_PREV:
offset = bytestream_get_le16(&buf);
if (copy_block(avctx, out, copy_from, offset, 8, stride))
return -1;
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) {
offset = bytestream_get_le16(&buf);
if (copy_block(avctx, &out[j*stride+i],
copy_from, offset, 4, stride))
return -1;
}
}
break;
case C93_8X8_2COLOR:
bytestream_get_buffer(&buf, cols, 2);
for (i = 0; i < 8; i++) {
draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
NULL, *buf++);
}
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) {
bytestream_get_buffer(&buf, cols, 2);
draw_n_color(out + i + j*stride, stride, 4, 4,
1, cols, NULL, bytestream_get_le16(&buf));
} else if (block_type == C93_4X4_4COLOR) {
bytestream_get_buffer(&buf, cols, 4);
draw_n_color(out + i + j*stride, stride, 4, 4,
2, cols, NULL, bytestream_get_le32(&buf));
} else {
bytestream_get_buffer(&buf, grps, 4);
draw_n_color(out + i + j*stride, stride, 4, 4,
1, cols, grps, bytestream_get_le16(&buf));
}
}
}
break;
case C93_NOOP:
break;
case C93_8X8_INTRA:
for (j = 0; j < 8; j++)
bytestream_get_buffer(&buf, out + j*stride, 8);
break;
default:
av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
block_type, x, y);
return -1;
}
bt >>= 4;
out += 8;
}
}
*picture = *newpic;
*data_size = sizeof(AVFrame);
return buf_size;
}
AVCodec ff_c93_decoder = {
.name = "c93",
.type = AVMEDIA_TYPE_VIDEO,
.id = CODEC_ID_C93,
.priv_data_size = sizeof(C93DecoderContext),
.init = decode_init,
.close = decode_end,
.decode = decode_frame,
.capabilities = CODEC_CAP_DR1,
.long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
};
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