2 * Interplay C93 video decoder
3 * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
5 * This file is part of Libav.
7 * Libav is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * Libav is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include "bytestream.h"
26 typedef struct C93DecoderContext {
32 C93_8X8_FROM_PREV = 0x02,
33 C93_4X4_FROM_PREV = 0x06,
34 C93_4X4_FROM_CURR = 0x07,
35 C93_8X8_2COLOR = 0x08,
36 C93_4X4_2COLOR = 0x0A,
37 C93_4X4_4COLOR_GRP = 0x0B,
38 C93_4X4_4COLOR = 0x0D,
46 #define C93_HAS_PALETTE 0x01
47 #define C93_FIRST_FRAME 0x02
49 static av_cold int decode_end(AVCodecContext *avctx)
51 C93DecoderContext * const c93 = avctx->priv_data;
53 av_frame_free(&c93->pictures[0]);
54 av_frame_free(&c93->pictures[1]);
59 static av_cold int decode_init(AVCodecContext *avctx)
61 C93DecoderContext *s = avctx->priv_data;
62 avctx->pix_fmt = AV_PIX_FMT_PAL8;
64 s->pictures[0] = av_frame_alloc();
65 s->pictures[1] = av_frame_alloc();
66 if (!s->pictures[0] || !s->pictures[1]) {
68 return AVERROR(ENOMEM);
74 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
75 uint8_t *from, int offset, int height, int stride)
79 int from_x = offset % WIDTH;
80 int from_y = offset / WIDTH;
81 int overflow = from_x + width - WIDTH;
84 /* silently ignoring predictive blocks in first frame */
88 if (from_y + height > HEIGHT) {
89 av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
91 return AVERROR_INVALIDDATA;
96 for (i = 0; i < height; i++) {
97 memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
101 for (i = 0; i < height; i++) {
102 memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
108 static inline void draw_n_color(uint8_t *out, int stride, int width,
109 int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
112 for (y = 0; y < height; y++) {
114 cols[0] = grps[3 * (y >> 1)];
115 for (x = 0; x < width; x++) {
117 cols[1]= grps[(x >> 1) + 1];
118 out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
124 static int decode_frame(AVCodecContext *avctx, void *data,
125 int *got_frame, AVPacket *avpkt)
127 const uint8_t *buf = avpkt->data;
128 int buf_size = avpkt->size;
129 C93DecoderContext * const c93 = avctx->priv_data;
130 AVFrame * const newpic = c93->pictures[c93->currentpic];
131 AVFrame * const oldpic = c93->pictures[c93->currentpic^1];
134 int stride, ret, i, x, y, b, bt = 0;
136 c93->currentpic ^= 1;
138 if ((ret = ff_reget_buffer(avctx, newpic)) < 0) {
139 av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
143 stride = newpic->linesize[0];
145 bytestream2_init(&gb, buf, buf_size);
146 b = bytestream2_get_byte(&gb);
147 if (b & C93_FIRST_FRAME) {
148 newpic->pict_type = AV_PICTURE_TYPE_I;
149 newpic->key_frame = 1;
151 newpic->pict_type = AV_PICTURE_TYPE_P;
152 newpic->key_frame = 0;
155 for (y = 0; y < HEIGHT; y += 8) {
156 out = newpic->data[0] + y * stride;
157 for (x = 0; x < WIDTH; x += 8) {
158 uint8_t *copy_from = oldpic->data[0];
159 unsigned int offset, j;
160 uint8_t cols[4], grps[4];
161 C93BlockType block_type;
164 bt = bytestream2_get_byte(&gb);
166 block_type= bt & 0x0F;
167 switch (block_type) {
168 case C93_8X8_FROM_PREV:
169 offset = bytestream2_get_le16(&gb);
170 if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
174 case C93_4X4_FROM_CURR:
175 copy_from = newpic->data[0];
176 case C93_4X4_FROM_PREV:
177 for (j = 0; j < 8; j += 4) {
178 for (i = 0; i < 8; i += 4) {
179 offset = bytestream2_get_le16(&gb);
180 if ((ret = copy_block(avctx, &out[j*stride+i],
181 copy_from, offset, 4, stride)) < 0)
188 bytestream2_get_buffer(&gb, cols, 2);
189 for (i = 0; i < 8; i++) {
190 draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
191 NULL, bytestream2_get_byte(&gb));
198 case C93_4X4_4COLOR_GRP:
199 for (j = 0; j < 8; j += 4) {
200 for (i = 0; i < 8; i += 4) {
201 if (block_type == C93_4X4_2COLOR) {
202 bytestream2_get_buffer(&gb, cols, 2);
203 draw_n_color(out + i + j*stride, stride, 4, 4,
204 1, cols, NULL, bytestream2_get_le16(&gb));
205 } else if (block_type == C93_4X4_4COLOR) {
206 bytestream2_get_buffer(&gb, cols, 4);
207 draw_n_color(out + i + j*stride, stride, 4, 4,
208 2, cols, NULL, bytestream2_get_le32(&gb));
210 bytestream2_get_buffer(&gb, grps, 4);
211 draw_n_color(out + i + j*stride, stride, 4, 4,
212 1, cols, grps, bytestream2_get_le16(&gb));
222 for (j = 0; j < 8; j++)
223 bytestream2_get_buffer(&gb, out + j*stride, 8);
227 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
229 return AVERROR_INVALIDDATA;
236 if (b & C93_HAS_PALETTE) {
237 uint32_t *palette = (uint32_t *) newpic->data[1];
238 for (i = 0; i < 256; i++) {
239 palette[i] = bytestream2_get_be24(&gb);
241 newpic->palette_has_changed = 1;
244 memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
247 if ((ret = av_frame_ref(data, newpic)) < 0)
254 AVCodec ff_c93_decoder = {
256 .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
257 .type = AVMEDIA_TYPE_VIDEO,
258 .id = AV_CODEC_ID_C93,
259 .priv_data_size = sizeof(C93DecoderContext),
262 .decode = decode_frame,
263 .capabilities = AV_CODEC_CAP_DR1,