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ffmpeg / libavcodec / cdgraphics.c @ 72415b2a

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/*
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 * CD Graphics Video Decoder
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 * Copyright (c) 2009 Michael Tison
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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, 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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/**
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 * @file libavcodec/cdgraphics.c
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 * @brief CD Graphics Video Decoder
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 * @author Michael Tison
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 * @sa http://wiki.multimedia.cx/index.php?title=CD_Graphics
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 * @sa http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg
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 */
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/// default screen sizes
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#define CDG_FULL_WIDTH           300
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#define CDG_FULL_HEIGHT          216
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#define CDG_DISPLAY_WIDTH        294
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#define CDG_DISPLAY_HEIGHT       204
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#define CDG_BORDER_WIDTH           6
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#define CDG_BORDER_HEIGHT         12
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/// masks
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#define CDG_COMMAND             0x09
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#define CDG_MASK                0x3F
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/// instruction codes
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#define CDG_INST_MEMORY_PRESET     1
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#define CDG_INST_BORDER_PRESET     2
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#define CDG_INST_TILE_BLOCK        6
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#define CDG_INST_SCROLL_PRESET    20
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#define CDG_INST_SCROLL_COPY      24
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#define CDG_INST_LOAD_PAL_LO      30
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#define CDG_INST_LOAD_PAL_HIGH    31
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#define CDG_INST_TILE_BLOCK_XOR   38
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/// data sizes
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#define CDG_PACKET_SIZE           24
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#define CDG_DATA_SIZE             16
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#define CDG_TILE_HEIGHT           12
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#define CDG_TILE_WIDTH             6
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#define CDG_MINIMUM_PKT_SIZE       6
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#define CDG_MINIMUM_SCROLL_SIZE    3
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#define CDG_HEADER_SIZE            8
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#define CDG_PALETTE_SIZE          16
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typedef struct CDGraphicsContext {
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    AVFrame frame;
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    int hscroll;
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    int vscroll;
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} CDGraphicsContext;
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static void cdg_init_frame(AVFrame *frame)
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{
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    avcodec_get_frame_defaults(frame);
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    frame->reference = 3;
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    frame->buffer_hints = FF_BUFFER_HINTS_VALID    |
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                          FF_BUFFER_HINTS_READABLE |
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                          FF_BUFFER_HINTS_PRESERVE |
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                          FF_BUFFER_HINTS_REUSABLE;
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}
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static av_cold int cdg_decode_init(AVCodecContext *avctx)
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{
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    CDGraphicsContext *cc = avctx->priv_data;
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    cdg_init_frame(&cc->frame);
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    avctx->width   = CDG_FULL_WIDTH;
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    avctx->height  = CDG_FULL_HEIGHT;
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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 void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data)
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{
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    int y;
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    int lsize    = cc->frame.linesize[0];
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    uint8_t *buf = cc->frame.data[0];
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    int color    = data[0] & 0x0F;
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    if (!(data[1] & 0x0F)) {
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        /// fill the top and bottom borders
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        memset(buf, color, CDG_BORDER_HEIGHT * lsize);
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        memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,
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               color, CDG_BORDER_HEIGHT * lsize);
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        /// fill the side borders
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        for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {
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            memset(buf + y * lsize, color, CDG_BORDER_WIDTH);
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            memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,
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                   color, CDG_BORDER_WIDTH);
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        }
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    }
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}
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static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
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{
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    uint8_t r, g, b;
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    uint16_t color;
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    int i;
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    int array_offset  = low ? 0 : 8;
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    uint32_t *palette = (uint32_t *) cc->frame.data[1];
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    for (i = 0; i < 8; i++) {
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        color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);
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        r = ((color >> 8) & 0x000F) * 17;
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        g = ((color >> 4) & 0x000F) * 17;
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        b = ((color     ) & 0x000F) * 17;
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        palette[i + array_offset] = r << 16 | g << 8 | b;
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    }
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    cc->frame.palette_has_changed = 1;
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}
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static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b)
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{
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    unsigned ci, ri;
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    int color;
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    int x, y;
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    int ai;
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    int stride   = cc->frame.linesize[0];
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    uint8_t *buf = cc->frame.data[0];
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    ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
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    ci = (data[3] & 0x3F) * CDG_TILE_WIDTH  + cc->hscroll;
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    if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
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        return AVERROR(EINVAL);
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    if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
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        return AVERROR(EINVAL);
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    for (y = 0; y < CDG_TILE_HEIGHT; y++) {
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        for (x = 0; x < CDG_TILE_WIDTH; x++) {
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            if (!((data[4 + y] >> (5 - x)) & 0x01))
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                color = data[0] & 0x0F;
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            else
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                color = data[1] & 0x0F;
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            ai = ci + x + (stride * (ri + y));
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            if (b)
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                color ^= buf[ai];
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            buf[ai] = color;
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        }
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    }
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    return 0;
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}
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#define UP    2
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#define DOWN  1
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#define LEFT  2
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#define RIGHT 1
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static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
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                              int in_tl_x, int in_tl_y, uint8_t *in,
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                              int w, int h, int stride)
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{
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    int y;
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    in  += in_tl_x  + in_tl_y  * stride;
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    out += out_tl_x + out_tl_y * stride;
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    for (y = 0; y < h; y++)
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        memcpy(out + y * stride, in + y * stride, w);
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}
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static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
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                                 int color, int w, int h, int stride)
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{
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    int y;
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    for (y = tl_y; y < tl_y + h; y++)
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        memset(out + tl_x + y * stride, color, w);
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}
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static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
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                             int in_tl_x, int in_tl_y, uint8_t *in,
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                             int color, int w, int h, int stride, int roll)
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{
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    if (roll) {
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        cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
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                          in, w, h, stride);
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    } else {
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        cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
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    }
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}
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static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
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                       AVFrame *new_frame, int roll_over)
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{
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    int color;
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    int hscmd, h_off, hinc, vscmd, v_off, vinc;
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    int y;
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    int stride   = cc->frame.linesize[0];
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    uint8_t *in  = cc->frame.data[0];
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    uint8_t *out = new_frame->data[0];
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    color =  data[0] & 0x0F;
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    hscmd = (data[1] & 0x30) >> 4;
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    vscmd = (data[2] & 0x30) >> 4;
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    h_off =  FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH  - 1);
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    v_off =  FFMIN(data[2] & 0x07, CDG_BORDER_HEIGHT - 1);
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    /// find the difference and save the offset for cdg_tile_block usage
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    hinc = h_off - cc->hscroll;
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    vinc = v_off - cc->vscroll;
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    cc->hscroll = h_off;
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    cc->vscroll = v_off;
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    if (vscmd == UP)
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        vinc -= 12;
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    if (vscmd == DOWN)
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        vinc += 12;
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    if (hscmd == LEFT)
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        hinc -= 6;
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    if (hscmd == RIGHT)
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        hinc += 6;
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    if (!hinc && !vinc)
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        return;
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    memcpy(new_frame->data[1], cc->frame.data[1], CDG_PALETTE_SIZE * 4);
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    for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
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        memcpy(out + FFMAX(0, hinc) + stride * y,
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               in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
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               FFMIN(stride + hinc, stride));
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    if (vinc > 0)
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        cdg_fill_wrapper(0, 0, out,
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                         0, CDG_FULL_HEIGHT - vinc, in, color,
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                         stride, vinc, stride, roll_over);
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    else if (vinc < 0)
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        cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
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                         0, 0, in, color,
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                         stride, -1 * vinc, stride, roll_over);
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    if (hinc > 0)
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        cdg_fill_wrapper(0, 0, out,
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                         CDG_FULL_WIDTH - hinc, 0, in, color,
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                         hinc, CDG_FULL_HEIGHT, stride, roll_over);
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    else if (hinc < 0)
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        cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
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                         0, 0, in, color,
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                         -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
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}
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static int cdg_decode_frame(AVCodecContext *avctx,
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                            void *data, int *data_size, 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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    int ret;
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    uint8_t command, inst;
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    uint8_t cdg_data[CDG_DATA_SIZE];
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    AVFrame new_frame;
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    CDGraphicsContext *cc = avctx->priv_data;
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    if (buf_size < CDG_MINIMUM_PKT_SIZE) {
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        av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
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        return AVERROR(EINVAL);
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    }
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    ret = avctx->reget_buffer(avctx, &cc->frame);
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    if (ret) {
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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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    command = bytestream_get_byte(&buf);
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    inst    = bytestream_get_byte(&buf);
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    inst    &= CDG_MASK;
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    buf += 2;  /// skipping 2 unneeded bytes
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    bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);
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    if ((command & CDG_MASK) == CDG_COMMAND) {
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        switch (inst) {
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        case CDG_INST_MEMORY_PRESET:
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            if (!(cdg_data[1] & 0x0F))
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                memset(cc->frame.data[0], cdg_data[0] & 0x0F,
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                       cc->frame.linesize[0] * CDG_FULL_HEIGHT);
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            break;
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        case CDG_INST_LOAD_PAL_LO:
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        case CDG_INST_LOAD_PAL_HIGH:
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            if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
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                av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n");
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                return AVERROR(EINVAL);
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            }
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            cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);
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            break;
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        case CDG_INST_BORDER_PRESET:
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            cdg_border_preset(cc, cdg_data);
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            break;
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        case CDG_INST_TILE_BLOCK_XOR:
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        case CDG_INST_TILE_BLOCK:
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            if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
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                av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n");
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                return AVERROR(EINVAL);
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            }
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            ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);
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            if (ret) {
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                av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");
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                return ret;
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            }
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            break;
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        case CDG_INST_SCROLL_PRESET:
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        case CDG_INST_SCROLL_COPY:
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            if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) {
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                av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n");
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                return AVERROR(EINVAL);
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            }
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            cdg_init_frame(&new_frame);
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            ret = avctx->get_buffer(avctx, &new_frame);
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            if (ret) {
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                av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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                return ret;
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            }
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            cdg_scroll(cc, cdg_data, &new_frame, inst == CDG_INST_SCROLL_COPY);
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            avctx->release_buffer(avctx, &cc->frame);
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            cc->frame = new_frame;
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            break;
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        default:
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            break;
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        }
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        *data_size = sizeof(AVFrame);
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    } else {
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        *data_size = 0;
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        buf_size   = 0;
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    }
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    *(AVFrame *) data = cc->frame;
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    return buf_size;
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}
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static av_cold int cdg_decode_end(AVCodecContext *avctx)
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{
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    CDGraphicsContext *cc = avctx->priv_data;
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    if (cc->frame.data[0])
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        avctx->release_buffer(avctx, &cc->frame);
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    return 0;
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}
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AVCodec cdgraphics_decoder = {
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    "cdgraphics",
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    AVMEDIA_TYPE_VIDEO,
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    CODEC_ID_CDGRAPHICS,
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    sizeof(CDGraphicsContext),
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    cdg_decode_init,
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    NULL,
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    cdg_decode_end,
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    cdg_decode_frame,
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    CODEC_CAP_DR1,
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    .long_name = NULL_IF_CONFIG_SMALL("CD Graphics video"),
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};