2 * Interplay C93 video decoder
3 * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
5 * This file is part of FFmpeg.
7 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include "bytestream.h"
31 C93_8X8_FROM_PREV = 0x02,
32 C93_4X4_FROM_PREV = 0x06,
33 C93_4X4_FROM_CURR = 0x07,
34 C93_8X8_2COLOR = 0x08,
35 C93_4X4_2COLOR = 0x0A,
36 C93_4X4_4COLOR_GRP = 0x0B,
37 C93_4X4_4COLOR = 0x0D,
45 #define C93_HAS_PALETTE 0x01
46 #define C93_FIRST_FRAME 0x02
48 static av_cold int decode_init(AVCodecContext *avctx)
50 C93DecoderContext * const c93 = avctx->priv_data;
52 avcodec_get_frame_defaults(&c93->pictures[0]);
53 avcodec_get_frame_defaults(&c93->pictures[1]);
54 avctx->pix_fmt = AV_PIX_FMT_PAL8;
58 static av_cold int decode_end(AVCodecContext *avctx)
60 C93DecoderContext * const c93 = avctx->priv_data;
62 if (c93->pictures[0].data[0])
63 avctx->release_buffer(avctx, &c93->pictures[0]);
64 if (c93->pictures[1].data[0])
65 avctx->release_buffer(avctx, &c93->pictures[1]);
69 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
70 uint8_t *from, int offset, int height, int stride)
74 int from_x = offset % WIDTH;
75 int from_y = offset / WIDTH;
76 int overflow = from_x + width - WIDTH;
79 /* silently ignoring predictive blocks in first frame */
83 if (from_y + height > HEIGHT) {
84 av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
86 return AVERROR_INVALIDDATA;
91 for (i = 0; i < height; i++) {
92 memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
96 for (i = 0; i < height; i++) {
97 memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
103 static inline void draw_n_color(uint8_t *out, int stride, int width,
104 int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
107 for (y = 0; y < height; y++) {
109 cols[0] = grps[3 * (y >> 1)];
110 for (x = 0; x < width; x++) {
112 cols[1]= grps[(x >> 1) + 1];
113 out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
119 static int decode_frame(AVCodecContext *avctx, void *data,
120 int *got_frame, AVPacket *avpkt)
122 const uint8_t *buf = avpkt->data;
123 int buf_size = avpkt->size;
124 C93DecoderContext * const c93 = avctx->priv_data;
125 AVFrame * const newpic = &c93->pictures[c93->currentpic];
126 AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
127 AVFrame *picture = data;
130 int stride, ret, i, x, y, b, bt = 0;
132 c93->currentpic ^= 1;
134 newpic->reference = 3;
135 newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
136 FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
137 if ((ret = avctx->reget_buffer(avctx, newpic))) {
138 av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
142 stride = newpic->linesize[0];
144 bytestream2_init(&gb, buf, buf_size);
145 b = bytestream2_get_byte(&gb);
146 if (b & C93_FIRST_FRAME) {
147 newpic->pict_type = AV_PICTURE_TYPE_I;
148 newpic->key_frame = 1;
150 newpic->pict_type = AV_PICTURE_TYPE_P;
151 newpic->key_frame = 0;
154 for (y = 0; y < HEIGHT; y += 8) {
155 out = newpic->data[0] + y * stride;
156 for (x = 0; x < WIDTH; x += 8) {
157 uint8_t *copy_from = oldpic->data[0];
158 unsigned int offset, j;
159 uint8_t cols[4], grps[4];
160 C93BlockType block_type;
163 bt = bytestream2_get_byte(&gb);
165 block_type= bt & 0x0F;
166 switch (block_type) {
167 case C93_8X8_FROM_PREV:
168 offset = bytestream2_get_le16(&gb);
169 if (copy_block(avctx, out, copy_from, offset, 8, stride))
170 return AVERROR_INVALIDDATA;
173 case C93_4X4_FROM_CURR:
174 copy_from = newpic->data[0];
175 case C93_4X4_FROM_PREV:
176 for (j = 0; j < 8; j += 4) {
177 for (i = 0; i < 8; i += 4) {
178 offset = bytestream2_get_le16(&gb);
179 if (copy_block(avctx, &out[j*stride+i],
180 copy_from, offset, 4, stride))
181 return AVERROR_INVALIDDATA;
187 bytestream2_get_buffer(&gb, cols, 2);
188 for (i = 0; i < 8; i++) {
189 draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
190 NULL, bytestream2_get_byte(&gb));
197 case C93_4X4_4COLOR_GRP:
198 for (j = 0; j < 8; j += 4) {
199 for (i = 0; i < 8; i += 4) {
200 if (block_type == C93_4X4_2COLOR) {
201 bytestream2_get_buffer(&gb, cols, 2);
202 draw_n_color(out + i + j*stride, stride, 4, 4,
203 1, cols, NULL, bytestream2_get_le16(&gb));
204 } else if (block_type == C93_4X4_4COLOR) {
205 bytestream2_get_buffer(&gb, cols, 4);
206 draw_n_color(out + i + j*stride, stride, 4, 4,
207 2, cols, NULL, bytestream2_get_le32(&gb));
209 bytestream2_get_buffer(&gb, grps, 4);
210 draw_n_color(out + i + j*stride, stride, 4, 4,
211 1, cols, grps, bytestream2_get_le16(&gb));
221 for (j = 0; j < 8; j++)
222 bytestream2_get_buffer(&gb, out + j*stride, 8);
226 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
228 return AVERROR_INVALIDDATA;
235 if (b & C93_HAS_PALETTE) {
236 uint32_t *palette = (uint32_t *) newpic->data[1];
237 for (i = 0; i < 256; i++) {
238 palette[i] = 0xFFU << 24 | bytestream2_get_be24(&gb);
242 memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
251 AVCodec ff_c93_decoder = {
253 .type = AVMEDIA_TYPE_VIDEO,
254 .id = AV_CODEC_ID_C93,
255 .priv_data_size = sizeof(C93DecoderContext),
258 .decode = decode_frame,
259 .capabilities = CODEC_CAP_DR1,
260 .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),