PeerStreamer

/*

 * Interplay C93 video decoder

 * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>

 *

 * 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"

typedef struct {

    AVFrame pictures[2];

    int currentpic;

} C93DecoderContext;

typedef enum {

    C93_8X8_FROM_PREV  = 0x02,

    C93_4X4_FROM_PREV  = 0x06,

    C93_4X4_FROM_CURR  = 0x07,

    C93_8X8_2COLOR     = 0x08,

    C93_4X4_2COLOR     = 0x0A,

    C93_4X4_4COLOR_GRP = 0x0B,

    C93_4X4_4COLOR     = 0x0D,

    C93_NOOP           = 0x0E,

    C93_8X8_INTRA      = 0x0F,

} C93BlockType;

#define WIDTH   320

#define HEIGHT  192

#define C93_HAS_PALETTE 0x01

#define C93_FIRST_FRAME 0x02

static av_cold int decode_init(AVCodecContext *avctx)

{

    avctx->pix_fmt = PIX_FMT_PAL8;

    return 0;

}

static av_cold int decode_end(AVCodecContext *avctx)

{

    C93DecoderContext * const c93 = avctx->priv_data;

    if (c93->pictures[0].data[0])

        avctx->release_buffer(avctx, &c93->pictures[0]);

    if (c93->pictures[1].data[0])

        avctx->release_buffer(avctx, &c93->pictures[1]);

    return 0;

}

static inline int copy_block(AVCodecContext *avctx, uint8_t *to,

        uint8_t *from, int offset, int height, int stride)

{

    int i;

    int width = height;

    int from_x = offset % WIDTH;

    int from_y = offset / WIDTH;

    int overflow = from_x + width - WIDTH;

    if (!from) {

        /* silently ignoring predictive blocks in first frame */

        return 0;

    }

    if (from_y + height > HEIGHT) {

        av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",

               offset);

        return -1;

    }

    if (overflow > 0) {

        width -= overflow;

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

            memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);

        }

    }

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

        memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);

    }

    return 0;

}

static inline void draw_n_color(uint8_t *out, int stride, int width,

         int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)

{

    int x, y;

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

        if (grps)

            cols[0] = grps[3 * (y >> 1)];

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

            if (grps)

                cols[1]= grps[(x >> 1) + 1];

            out[x + y*stride] = cols[col & ((1 << bpp) - 1)];

            col >>= bpp;

        }

    }

}

static int decode_frame(AVCodecContext *avctx, void *data,

                            int *data_size, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    C93DecoderContext * const c93 = avctx->priv_data;

    AVFrame * const newpic = &c93->pictures[c93->currentpic];

    AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];

    AVFrame *picture = data;

    uint8_t *out;

    int stride, i, x, y, bt = 0;

    c93->currentpic ^= 1;

    newpic->reference = 1;

    newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |

                         FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;

    if (avctx->reget_buffer(avctx, newpic)) {

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

        return -1;

    }

    stride = newpic->linesize[0];

    if (buf[0] & C93_FIRST_FRAME) {

        newpic->pict_type = FF_I_TYPE;

        newpic->key_frame = 1;

    } else {

        newpic->pict_type = FF_P_TYPE;

        newpic->key_frame = 0;

    }

    if (*buf++ & C93_HAS_PALETTE) {

        uint32_t *palette = (uint32_t *) newpic->data[1];

        const uint8_t *palbuf = buf + buf_size - 768 - 1;

        for (i = 0; i < 256; i++) {

            palette[i] = bytestream_get_be24(&palbuf);

        }

    } else {

        if (oldpic->data[1])

            memcpy(newpic->data[1], oldpic->data[1], 256 * 4);

    }

    for (y = 0; y < HEIGHT; y += 8) {

        out = newpic->data[0] + y * stride;

        for (x = 0; x < WIDTH; x += 8) {

            uint8_t *copy_from = oldpic->data[0];

            unsigned int offset, j;

            uint8_t cols[4], grps[4];

            C93BlockType block_type;

            if (!bt)

                bt = *buf++;

            block_type= bt & 0x0F;

            switch (block_type) {

            case C93_8X8_FROM_PREV:

                offset = bytestream_get_le16(&buf);

                if (copy_block(avctx, out, copy_from, offset, 8, stride))

                    return -1;

                break;

            case C93_4X4_FROM_CURR:

                copy_from = newpic->data[0];

            case C93_4X4_FROM_PREV:

                for (j = 0; j < 8; j += 4) {

                    for (i = 0; i < 8; i += 4) {

                        offset = bytestream_get_le16(&buf);

                        if (copy_block(avctx, &out[j*stride+i],

                                           copy_from, offset, 4, stride))

                            return -1;

                    }

                }

                break;

            case C93_8X8_2COLOR:

                bytestream_get_buffer(&buf, cols, 2);

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

                    draw_n_color(out + i*stride, stride, 8, 1, 1, cols,

                                     NULL, *buf++);

                }

                break;

            case C93_4X4_2COLOR:

            case C93_4X4_4COLOR:

            case C93_4X4_4COLOR_GRP:

                for (j = 0; j < 8; j += 4) {

                    for (i = 0; i < 8; i += 4) {

                        if (block_type == C93_4X4_2COLOR) {

                            bytestream_get_buffer(&buf, cols, 2);

                            draw_n_color(out + i + j*stride, stride, 4, 4,

                                    1, cols, NULL, bytestream_get_le16(&buf));

                        } else if (block_type == C93_4X4_4COLOR) {

                            bytestream_get_buffer(&buf, cols, 4);

                            draw_n_color(out + i + j*stride, stride, 4, 4,

                                    2, cols, NULL, bytestream_get_le32(&buf));

                        } else {

                            bytestream_get_buffer(&buf, grps, 4);

                            draw_n_color(out + i + j*stride, stride, 4, 4,

                                    1, cols, grps, bytestream_get_le16(&buf));

                        }

                    }

                }

                break;

            case C93_NOOP:

                break;

            case C93_8X8_INTRA:

                for (j = 0; j < 8; j++)

                    bytestream_get_buffer(&buf, out + j*stride, 8);

                break;

            default:

                av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",

                       block_type, x, y);

                return -1;

            }

            bt >>= 4;

            out += 8;

        }

    }

    *picture = *newpic;

    *data_size = sizeof(AVFrame);

    return buf_size;

}

AVCodec ff_c93_decoder = {

    "c93",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_C93,

    sizeof(C93DecoderContext),

    decode_init,

    NULL,

    decode_end,

    decode_frame,

    CODEC_CAP_DR1,

    .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),

};