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libavcodec/c93.c

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00001 /*
00002  * Interplay C93 video decoder
00003  * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "avcodec.h"
00023 #include "bytestream.h"
00024 
00025 typedef struct {
00026     AVFrame pictures[2];
00027     int currentpic;
00028 } C93DecoderContext;
00029 
00030 typedef enum {
00031     C93_8X8_FROM_PREV  = 0x02,
00032     C93_4X4_FROM_PREV  = 0x06,
00033     C93_4X4_FROM_CURR  = 0x07,
00034     C93_8X8_2COLOR     = 0x08,
00035     C93_4X4_2COLOR     = 0x0A,
00036     C93_4X4_4COLOR_GRP = 0x0B,
00037     C93_4X4_4COLOR     = 0x0D,
00038     C93_NOOP           = 0x0E,
00039     C93_8X8_INTRA      = 0x0F,
00040 } C93BlockType;
00041 
00042 #define WIDTH   320
00043 #define HEIGHT  192
00044 
00045 #define C93_HAS_PALETTE 0x01
00046 #define C93_FIRST_FRAME 0x02
00047 
00048 static av_cold int decode_init(AVCodecContext *avctx)
00049 {
00050     avctx->pix_fmt = PIX_FMT_PAL8;
00051     return 0;
00052 }
00053 
00054 static av_cold int decode_end(AVCodecContext *avctx)
00055 {
00056     C93DecoderContext * const c93 = avctx->priv_data;
00057 
00058     if (c93->pictures[0].data[0])
00059         avctx->release_buffer(avctx, &c93->pictures[0]);
00060     if (c93->pictures[1].data[0])
00061         avctx->release_buffer(avctx, &c93->pictures[1]);
00062     return 0;
00063 }
00064 
00065 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
00066         uint8_t *from, int offset, int height, int stride)
00067 {
00068     int i;
00069     int width = height;
00070     int from_x = offset % WIDTH;
00071     int from_y = offset / WIDTH;
00072     int overflow = from_x + width - WIDTH;
00073 
00074     if (!from) {
00075         /* silently ignoring predictive blocks in first frame */
00076         return 0;
00077     }
00078 
00079     if (from_y + height > HEIGHT) {
00080         av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
00081                offset);
00082         return -1;
00083     }
00084 
00085     if (overflow > 0) {
00086         width -= overflow;
00087         for (i = 0; i < height; i++) {
00088             memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
00089         }
00090     }
00091 
00092     for (i = 0; i < height; i++) {
00093         memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
00094     }
00095 
00096     return 0;
00097 }
00098 
00099 static inline void draw_n_color(uint8_t *out, int stride, int width,
00100          int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
00101 {
00102     int x, y;
00103     for (y = 0; y < height; y++) {
00104         if (grps)
00105             cols[0] = grps[3 * (y >> 1)];
00106         for (x = 0; x < width; x++) {
00107             if (grps)
00108                 cols[1]= grps[(x >> 1) + 1];
00109             out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
00110             col >>= bpp;
00111         }
00112     }
00113 }
00114 
00115 static int decode_frame(AVCodecContext *avctx, void *data,
00116                             int *data_size, AVPacket *avpkt)
00117 {
00118     const uint8_t *buf = avpkt->data;
00119     int buf_size = avpkt->size;
00120     C93DecoderContext * const c93 = avctx->priv_data;
00121     AVFrame * const newpic = &c93->pictures[c93->currentpic];
00122     AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
00123     AVFrame *picture = data;
00124     uint8_t *out;
00125     int stride, i, x, y, bt = 0;
00126 
00127     c93->currentpic ^= 1;
00128 
00129     newpic->reference = 1;
00130     newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
00131                          FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
00132     if (avctx->reget_buffer(avctx, newpic)) {
00133         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
00134         return -1;
00135     }
00136 
00137     stride = newpic->linesize[0];
00138 
00139     if (buf[0] & C93_FIRST_FRAME) {
00140         newpic->pict_type = FF_I_TYPE;
00141         newpic->key_frame = 1;
00142     } else {
00143         newpic->pict_type = FF_P_TYPE;
00144         newpic->key_frame = 0;
00145     }
00146 
00147     if (*buf++ & C93_HAS_PALETTE) {
00148         uint32_t *palette = (uint32_t *) newpic->data[1];
00149         const uint8_t *palbuf = buf + buf_size - 768 - 1;
00150         for (i = 0; i < 256; i++) {
00151             palette[i] = bytestream_get_be24(&palbuf);
00152         }
00153     } else {
00154         if (oldpic->data[1])
00155             memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
00156     }
00157 
00158     for (y = 0; y < HEIGHT; y += 8) {
00159         out = newpic->data[0] + y * stride;
00160         for (x = 0; x < WIDTH; x += 8) {
00161             uint8_t *copy_from = oldpic->data[0];
00162             unsigned int offset, j;
00163             uint8_t cols[4], grps[4];
00164             C93BlockType block_type;
00165 
00166             if (!bt)
00167                 bt = *buf++;
00168 
00169             block_type= bt & 0x0F;
00170             switch (block_type) {
00171             case C93_8X8_FROM_PREV:
00172                 offset = bytestream_get_le16(&buf);
00173                 if (copy_block(avctx, out, copy_from, offset, 8, stride))
00174                     return -1;
00175                 break;
00176 
00177             case C93_4X4_FROM_CURR:
00178                 copy_from = newpic->data[0];
00179             case C93_4X4_FROM_PREV:
00180                 for (j = 0; j < 8; j += 4) {
00181                     for (i = 0; i < 8; i += 4) {
00182                         offset = bytestream_get_le16(&buf);
00183                         if (copy_block(avctx, &out[j*stride+i],
00184                                            copy_from, offset, 4, stride))
00185                             return -1;
00186                     }
00187                 }
00188                 break;
00189 
00190             case C93_8X8_2COLOR:
00191                 bytestream_get_buffer(&buf, cols, 2);
00192                 for (i = 0; i < 8; i++) {
00193                     draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
00194                                      NULL, *buf++);
00195                 }
00196 
00197                 break;
00198 
00199             case C93_4X4_2COLOR:
00200             case C93_4X4_4COLOR:
00201             case C93_4X4_4COLOR_GRP:
00202                 for (j = 0; j < 8; j += 4) {
00203                     for (i = 0; i < 8; i += 4) {
00204                         if (block_type == C93_4X4_2COLOR) {
00205                             bytestream_get_buffer(&buf, cols, 2);
00206                             draw_n_color(out + i + j*stride, stride, 4, 4,
00207                                     1, cols, NULL, bytestream_get_le16(&buf));
00208                         } else if (block_type == C93_4X4_4COLOR) {
00209                             bytestream_get_buffer(&buf, cols, 4);
00210                             draw_n_color(out + i + j*stride, stride, 4, 4,
00211                                     2, cols, NULL, bytestream_get_le32(&buf));
00212                         } else {
00213                             bytestream_get_buffer(&buf, grps, 4);
00214                             draw_n_color(out + i + j*stride, stride, 4, 4,
00215                                     1, cols, grps, bytestream_get_le16(&buf));
00216                         }
00217                     }
00218                 }
00219                 break;
00220 
00221             case C93_NOOP:
00222                 break;
00223 
00224             case C93_8X8_INTRA:
00225                 for (j = 0; j < 8; j++)
00226                     bytestream_get_buffer(&buf, out + j*stride, 8);
00227                 break;
00228 
00229             default:
00230                 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
00231                        block_type, x, y);
00232                 return -1;
00233             }
00234             bt >>= 4;
00235             out += 8;
00236         }
00237     }
00238 
00239     *picture = *newpic;
00240     *data_size = sizeof(AVFrame);
00241 
00242     return buf_size;
00243 }
00244 
00245 AVCodec c93_decoder = {
00246     "c93",
00247     AVMEDIA_TYPE_VIDEO,
00248     CODEC_ID_C93,
00249     sizeof(C93DecoderContext),
00250     decode_init,
00251     NULL,
00252     decode_end,
00253     decode_frame,
00254     CODEC_CAP_DR1,
00255     .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
00256 };

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