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ffmpeg / libavcodec / c93.c @ bee4f778

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/*
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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 FFmpeg.
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 *
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 * FFmpeg 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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 * FFmpeg 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 FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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 * 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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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 int decode_init(AVCodecContext *avctx)
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{
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    avctx->pix_fmt = PIX_FMT_PAL8;
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    return 0;
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}
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static int decode_end(AVCodecContext *avctx)
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{
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    C93DecoderContext * const c93 = avctx->priv_data;
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    if (c93->pictures[0].data[0])
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        avctx->release_buffer(avctx, &c93->pictures[0]);
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    if (c93->pictures[1].data[0])
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        avctx->release_buffer(avctx, &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 -1;
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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 *data_size, uint8_t * buf, int buf_size)
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{
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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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    AVFrame *picture = data;
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    uint8_t *out;
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    int stride, i, x, y;
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    C93BlockType bt = 0;
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    c93->currentpic ^= 1;
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    newpic->reference = 1;
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    newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
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                         FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
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    if (avctx->reget_buffer(avctx, newpic)) {
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        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
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        return -1;
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    }
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    stride = newpic->linesize[0];
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    if (buf[0] & C93_FIRST_FRAME) {
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        newpic->pict_type = FF_I_TYPE;
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        newpic->key_frame = 1;
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    } else {
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        newpic->pict_type = FF_P_TYPE;
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        newpic->key_frame = 0;
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    }
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    if (*buf++ & C93_HAS_PALETTE) {
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        uint32_t *palette = (uint32_t *) newpic->data[1];
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        uint8_t *palbuf = buf + buf_size - 768 - 1;
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        for (i = 0; i < 256; i++) {
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            palette[i] = bytestream_get_be24(&palbuf);
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        }
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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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    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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            if (!bt)
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                bt = *buf++;
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            switch (bt & 0x0F) {
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            case C93_8X8_FROM_PREV:
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                offset = bytestream_get_le16(&buf);
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                if (copy_block(avctx, out, copy_from, offset, 8, stride))
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                    return -1;
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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 = bytestream_get_le16(&buf);
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                        if (copy_block(avctx, &out[j*stride+i],
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                                           copy_from, offset, 4, stride))
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                            return -1;
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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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                bytestream_get_buffer(&buf, 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, *buf++);
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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 ((bt & 0x0F) == C93_4X4_2COLOR) {
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                            bytestream_get_buffer(&buf, cols, 2);
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                            draw_n_color(out + i + j*stride, stride, 4, 4,
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                                    1, cols, NULL, bytestream_get_le16(&buf));
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                        } else if ((bt & 0x0F) == C93_4X4_4COLOR) {
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                            bytestream_get_buffer(&buf, cols, 4);
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                            draw_n_color(out + i + j*stride, stride, 4, 4,
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                                    2, cols, NULL, bytestream_get_le32(&buf));
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                        } else {
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                            bytestream_get_buffer(&buf, grps, 4);
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                            draw_n_color(out + i + j*stride, stride, 4, 4,
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                                    1, cols, grps, bytestream_get_le16(&buf));
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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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                    bytestream_get_buffer(&buf, 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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                       bt & 0x0F, x, y);
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                return -1;
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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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    *picture = *newpic;
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    *data_size = sizeof(AVFrame);
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    return buf_size;
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}
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AVCodec c93_decoder = {
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    "c93",
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    CODEC_TYPE_VIDEO,
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    CODEC_ID_C93,
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    sizeof(C93DecoderContext),
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    decode_init,
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    NULL,
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    decode_end,
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    decode_frame,
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    CODEC_CAP_DR1,
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};