259 lines
7.9 KiB
C
259 lines
7.9 KiB
C
/*
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* Interplay C93 video decoder
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* Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avcodec.h"
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#include "bytestream.h"
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#include "internal.h"
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typedef struct {
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AVFrame pictures[2];
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int currentpic;
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} C93DecoderContext;
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typedef enum {
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C93_8X8_FROM_PREV = 0x02,
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C93_4X4_FROM_PREV = 0x06,
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C93_4X4_FROM_CURR = 0x07,
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C93_8X8_2COLOR = 0x08,
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C93_4X4_2COLOR = 0x0A,
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C93_4X4_4COLOR_GRP = 0x0B,
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C93_4X4_4COLOR = 0x0D,
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C93_NOOP = 0x0E,
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C93_8X8_INTRA = 0x0F,
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} C93BlockType;
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#define WIDTH 320
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#define HEIGHT 192
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#define C93_HAS_PALETTE 0x01
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#define C93_FIRST_FRAME 0x02
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static av_cold int decode_init(AVCodecContext *avctx)
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{
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C93DecoderContext *s = avctx->priv_data;
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avctx->pix_fmt = AV_PIX_FMT_PAL8;
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avcodec_get_frame_defaults(&s->pictures[0]);
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avcodec_get_frame_defaults(&s->pictures[1]);
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return 0;
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}
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static av_cold int decode_end(AVCodecContext *avctx)
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{
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C93DecoderContext * const c93 = avctx->priv_data;
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av_frame_unref(&c93->pictures[0]);
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av_frame_unref(&c93->pictures[1]);
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return 0;
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}
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static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
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uint8_t *from, int offset, int height, int stride)
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{
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int i;
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int width = height;
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int from_x = offset % WIDTH;
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int from_y = offset / WIDTH;
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int overflow = from_x + width - WIDTH;
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if (!from) {
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/* silently ignoring predictive blocks in first frame */
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return 0;
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}
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if (from_y + height > HEIGHT) {
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av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
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offset);
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return AVERROR_INVALIDDATA;
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}
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if (overflow > 0) {
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width -= overflow;
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for (i = 0; i < height; i++) {
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memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
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}
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}
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for (i = 0; i < height; i++) {
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memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
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}
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return 0;
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}
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static inline void draw_n_color(uint8_t *out, int stride, int width,
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int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
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{
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int x, y;
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for (y = 0; y < height; y++) {
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if (grps)
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cols[0] = grps[3 * (y >> 1)];
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for (x = 0; x < width; x++) {
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if (grps)
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cols[1]= grps[(x >> 1) + 1];
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out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
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col >>= bpp;
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}
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}
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}
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static int decode_frame(AVCodecContext *avctx, void *data,
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int *got_frame, AVPacket *avpkt)
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{
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const uint8_t *buf = avpkt->data;
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int buf_size = avpkt->size;
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C93DecoderContext * const c93 = avctx->priv_data;
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AVFrame * const newpic = &c93->pictures[c93->currentpic];
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AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
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GetByteContext gb;
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uint8_t *out;
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int stride, ret, i, x, y, b, bt = 0;
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c93->currentpic ^= 1;
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if ((ret = ff_reget_buffer(avctx, newpic)) < 0) {
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av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
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return ret;
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}
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stride = newpic->linesize[0];
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bytestream2_init(&gb, buf, buf_size);
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b = bytestream2_get_byte(&gb);
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if (b & C93_FIRST_FRAME) {
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newpic->pict_type = AV_PICTURE_TYPE_I;
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newpic->key_frame = 1;
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} else {
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newpic->pict_type = AV_PICTURE_TYPE_P;
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newpic->key_frame = 0;
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}
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for (y = 0; y < HEIGHT; y += 8) {
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out = newpic->data[0] + y * stride;
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for (x = 0; x < WIDTH; x += 8) {
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uint8_t *copy_from = oldpic->data[0];
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unsigned int offset, j;
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uint8_t cols[4], grps[4];
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C93BlockType block_type;
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if (!bt)
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bt = bytestream2_get_byte(&gb);
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block_type= bt & 0x0F;
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switch (block_type) {
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case C93_8X8_FROM_PREV:
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offset = bytestream2_get_le16(&gb);
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if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
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return ret;
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break;
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case C93_4X4_FROM_CURR:
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copy_from = newpic->data[0];
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case C93_4X4_FROM_PREV:
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for (j = 0; j < 8; j += 4) {
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for (i = 0; i < 8; i += 4) {
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offset = bytestream2_get_le16(&gb);
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if ((ret = copy_block(avctx, &out[j*stride+i],
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copy_from, offset, 4, stride)) < 0)
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return ret;
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}
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}
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break;
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case C93_8X8_2COLOR:
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bytestream2_get_buffer(&gb, cols, 2);
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for (i = 0; i < 8; i++) {
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draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
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NULL, bytestream2_get_byte(&gb));
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}
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break;
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case C93_4X4_2COLOR:
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case C93_4X4_4COLOR:
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case C93_4X4_4COLOR_GRP:
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for (j = 0; j < 8; j += 4) {
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for (i = 0; i < 8; i += 4) {
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if (block_type == C93_4X4_2COLOR) {
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bytestream2_get_buffer(&gb, cols, 2);
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draw_n_color(out + i + j*stride, stride, 4, 4,
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1, cols, NULL, bytestream2_get_le16(&gb));
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} else if (block_type == C93_4X4_4COLOR) {
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bytestream2_get_buffer(&gb, cols, 4);
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draw_n_color(out + i + j*stride, stride, 4, 4,
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2, cols, NULL, bytestream2_get_le32(&gb));
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} else {
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bytestream2_get_buffer(&gb, grps, 4);
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draw_n_color(out + i + j*stride, stride, 4, 4,
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1, cols, grps, bytestream2_get_le16(&gb));
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}
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}
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}
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break;
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case C93_NOOP:
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break;
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case C93_8X8_INTRA:
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for (j = 0; j < 8; j++)
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bytestream2_get_buffer(&gb, out + j*stride, 8);
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break;
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default:
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av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
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block_type, x, y);
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return AVERROR_INVALIDDATA;
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}
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bt >>= 4;
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out += 8;
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}
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}
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if (b & C93_HAS_PALETTE) {
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uint32_t *palette = (uint32_t *) newpic->data[1];
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for (i = 0; i < 256; i++) {
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palette[i] = bytestream2_get_be24(&gb);
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}
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newpic->palette_has_changed = 1;
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} else {
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if (oldpic->data[1])
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memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
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}
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if ((ret = av_frame_ref(data, newpic)) < 0)
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return ret;
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*got_frame = 1;
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return buf_size;
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}
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AVCodec ff_c93_decoder = {
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.name = "c93",
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.type = AVMEDIA_TYPE_VIDEO,
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.id = AV_CODEC_ID_C93,
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.priv_data_size = sizeof(C93DecoderContext),
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.init = decode_init,
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.close = decode_end,
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.decode = decode_frame,
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.capabilities = CODEC_CAP_DR1,
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.long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
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};
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