PeerStreamer

/*

 * CD Graphics Video Decoder

 * Copyright (c) 2009 Michael Tison

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "avcodec.h"

#include "bytestream.h"

/**

 * @file libavcodec/cdgraphics.c

 * @brief CD Graphics Video Decoder

 * @author Michael Tison

 * @sa http://wiki.multimedia.cx/index.php?title=CD_Graphics

 * @sa http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg

 */

/// default screen sizes

#define CDG_FULL_WIDTH           300

#define CDG_FULL_HEIGHT          216

#define CDG_DISPLAY_WIDTH        294

#define CDG_DISPLAY_HEIGHT       204

#define CDG_BORDER_WIDTH           6

#define CDG_BORDER_HEIGHT         12

/// masks

#define CDG_COMMAND             0x09

#define CDG_MASK                0x3F

/// instruction codes

#define CDG_INST_MEMORY_PRESET     1

#define CDG_INST_BORDER_PRESET     2

#define CDG_INST_TILE_BLOCK        6

#define CDG_INST_SCROLL_PRESET    20

#define CDG_INST_SCROLL_COPY      24

#define CDG_INST_LOAD_PAL_LO      30

#define CDG_INST_LOAD_PAL_HIGH    31

#define CDG_INST_TILE_BLOCK_XOR   38

/// data sizes

#define CDG_PACKET_SIZE           24

#define CDG_DATA_SIZE             16

#define CDG_TILE_HEIGHT           12

#define CDG_TILE_WIDTH             6

#define CDG_MINIMUM_PKT_SIZE       6

#define CDG_MINIMUM_SCROLL_SIZE    3

#define CDG_HEADER_SIZE            8

#define CDG_PALETTE_SIZE          16

typedef struct CDGraphicsContext {

    AVFrame frame;

    int hscroll;

    int vscroll;

} CDGraphicsContext;

static void cdg_init_frame(AVFrame *frame)

{

    avcodec_get_frame_defaults(frame);

    frame->reference = 3;

    frame->buffer_hints = FF_BUFFER_HINTS_VALID    |

                          FF_BUFFER_HINTS_READABLE |

                          FF_BUFFER_HINTS_PRESERVE |

                          FF_BUFFER_HINTS_REUSABLE;

}

static av_cold int cdg_decode_init(AVCodecContext *avctx)

{

    CDGraphicsContext *cc = avctx->priv_data;

    cdg_init_frame(&cc->frame);

    avctx->width   = CDG_FULL_WIDTH;

    avctx->height  = CDG_FULL_HEIGHT;

    avctx->pix_fmt = PIX_FMT_PAL8;

    return 0;

}

static void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data)

{

    int y;

    int lsize    = cc->frame.linesize[0];

    uint8_t *buf = cc->frame.data[0];

    int color    = data[0] & 0x0F;

    if (!(data[1] & 0x0F)) {

        /// fill the top and bottom borders

        memset(buf, color, CDG_BORDER_HEIGHT * lsize);

        memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,

               color, CDG_BORDER_HEIGHT * lsize);

        /// fill the side borders

        for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {

            memset(buf + y * lsize, color, CDG_BORDER_WIDTH);

            memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,

                   color, CDG_BORDER_WIDTH);

        }

    }

}

static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)

{

    uint8_t r, g, b;

    uint16_t color;

    int i;

    int array_offset  = low ? 0 : 8;

    uint32_t *palette = (uint32_t *) cc->frame.data[1];

    for (i = 0; i < 8; i++) {

        color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);

        r = ((color >> 8) & 0x000F) * 17;

        g = ((color >> 4) & 0x000F) * 17;

        b = ((color     ) & 0x000F) * 17;

        palette[i + array_offset] = r << 16 | g << 8 | b;

    }

    cc->frame.palette_has_changed = 1;

}

static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b)

{

    unsigned ci, ri;

    int color;

    int x, y;

    int ai;

    int stride   = cc->frame.linesize[0];

    uint8_t *buf = cc->frame.data[0];

    ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;

    ci = (data[3] & 0x3F) * CDG_TILE_WIDTH  + cc->hscroll;

    if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))

        return AVERROR(EINVAL);

    if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))

        return AVERROR(EINVAL);

    for (y = 0; y < CDG_TILE_HEIGHT; y++) {

        for (x = 0; x < CDG_TILE_WIDTH; x++) {

            if (!((data[4 + y] >> (5 - x)) & 0x01))

                color = data[0] & 0x0F;

            else

                color = data[1] & 0x0F;

            ai = ci + x + (stride * (ri + y));

            if (b)

                color ^= buf[ai];

            buf[ai] = color;

        }

    }

    return 0;

}

#define UP    2

#define DOWN  1

#define LEFT  2

#define RIGHT 1

static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,

                              int in_tl_x, int in_tl_y, uint8_t *in,

                              int w, int h, int stride)

{

    int y;

    in  += in_tl_x  + in_tl_y  * stride;

    out += out_tl_x + out_tl_y * stride;

    for (y = 0; y < h; y++)

        memcpy(out + y * stride, in + y * stride, w);

}

static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,

                                 int color, int w, int h, int stride)

{

    int y;

    for (y = tl_y; y < tl_y + h; y++)

        memset(out + tl_x + y * stride, color, w);

}

static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,

                             int in_tl_x, int in_tl_y, uint8_t *in,

                             int color, int w, int h, int stride, int roll)

{

    if (roll) {

        cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,

                          in, w, h, stride);

    } else {

        cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);

    }

}

static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,

                       AVFrame *new_frame, int roll_over)

{

    int color;

    int hscmd, h_off, hinc, vscmd, v_off, vinc;

    int y;

    int stride   = cc->frame.linesize[0];

    uint8_t *in  = cc->frame.data[0];

    uint8_t *out = new_frame->data[0];

    color =  data[0] & 0x0F;

    hscmd = (data[1] & 0x30) >> 4;

    vscmd = (data[2] & 0x30) >> 4;

    h_off =  FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH  - 1);

    v_off =  FFMIN(data[2] & 0x07, CDG_BORDER_HEIGHT - 1);

    /// find the difference and save the offset for cdg_tile_block usage

    hinc = h_off - cc->hscroll;

    vinc = v_off - cc->vscroll;

    cc->hscroll = h_off;

    cc->vscroll = v_off;

    if (vscmd == UP)

        vinc -= 12;

    if (vscmd == DOWN)

        vinc += 12;

    if (hscmd == LEFT)

        hinc -= 6;

    if (hscmd == RIGHT)

        hinc += 6;

    if (!hinc && !vinc)

        return;

    memcpy(new_frame->data[1], cc->frame.data[1], CDG_PALETTE_SIZE * 4);

    for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)

        memcpy(out + FFMAX(0, hinc) + stride * y,

               in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,

               FFMIN(stride + hinc, stride));

    if (vinc > 0)

        cdg_fill_wrapper(0, 0, out,

                         0, CDG_FULL_HEIGHT - vinc, in, color,

                         stride, vinc, stride, roll_over);

    else if (vinc < 0)

        cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,

                         0, 0, in, color,

                         stride, -1 * vinc, stride, roll_over);

    if (hinc > 0)

        cdg_fill_wrapper(0, 0, out,

                         CDG_FULL_WIDTH - hinc, 0, in, color,

                         hinc, CDG_FULL_HEIGHT, stride, roll_over);

    else if (hinc < 0)

        cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,

                         0, 0, in, color,

                         -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);

}

static int cdg_decode_frame(AVCodecContext *avctx,

                            void *data, int *data_size, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size       = avpkt->size;

    int ret;

    uint8_t command, inst;

    uint8_t cdg_data[CDG_DATA_SIZE];

    AVFrame new_frame;

    CDGraphicsContext *cc = avctx->priv_data;

    if (buf_size < CDG_MINIMUM_PKT_SIZE) {

        av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");

        return AVERROR(EINVAL);

    }

    ret = avctx->reget_buffer(avctx, &cc->frame);

    if (ret) {

        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");

        return ret;

    }

    command = bytestream_get_byte(&buf);

    inst    = bytestream_get_byte(&buf);

    inst    &= CDG_MASK;

    buf += 2;  /// skipping 2 unneeded bytes

    bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);

    if ((command & CDG_MASK) == CDG_COMMAND) {

        switch (inst) {

        case CDG_INST_MEMORY_PRESET:

            if (!(cdg_data[1] & 0x0F))

                memset(cc->frame.data[0], cdg_data[0] & 0x0F,

                       cc->frame.linesize[0] * CDG_FULL_HEIGHT);

            break;

        case CDG_INST_LOAD_PAL_LO:

        case CDG_INST_LOAD_PAL_HIGH:

            if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {

                av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n");

                return AVERROR(EINVAL);

            }

            cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);

            break;

        case CDG_INST_BORDER_PRESET:

            cdg_border_preset(cc, cdg_data);

            break;

        case CDG_INST_TILE_BLOCK_XOR:

        case CDG_INST_TILE_BLOCK:

            if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {

                av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n");

                return AVERROR(EINVAL);

            }

            ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);

            if (ret) {

                av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");

                return ret;

            }

            break;

        case CDG_INST_SCROLL_PRESET:

        case CDG_INST_SCROLL_COPY:

            if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) {

                av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n");

                return AVERROR(EINVAL);

            }

            cdg_init_frame(&new_frame);

            ret = avctx->get_buffer(avctx, &new_frame);

            if (ret) {

                av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

                return ret;

            }

            cdg_scroll(cc, cdg_data, &new_frame, inst == CDG_INST_SCROLL_COPY);

            avctx->release_buffer(avctx, &cc->frame);

            cc->frame = new_frame;

            break;

        default:

            break;

        }

        *data_size = sizeof(AVFrame);

    } else {

        *data_size = 0;

        buf_size   = 0;

    }

    *(AVFrame *) data = cc->frame;

    return buf_size;

}

static av_cold int cdg_decode_end(AVCodecContext *avctx)

{

    CDGraphicsContext *cc = avctx->priv_data;

    if (cc->frame.data[0])

        avctx->release_buffer(avctx, &cc->frame);

    return 0;

}

AVCodec cdgraphics_decoder = {

    "cdgraphics",

    CODEC_TYPE_VIDEO,

    CODEC_ID_CDGRAPHICS,

    sizeof(CDGraphicsContext),

    cdg_decode_init,

    NULL,

    cdg_decode_end,

    cdg_decode_frame,

    CODEC_CAP_DR1,

    .long_name = NULL_IF_CONFIG_SMALL("CD Graphics video"),

};