avs.c 5.19 KB
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/*
 * AVS video decoder.
 * Copyright (c) 2006  Aurelien Jacobs <aurel@gnuage.org>
 *
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 * This file is part of FFmpeg.
 *
 * 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
 * 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
 * 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
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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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 */

#include "avcodec.h"
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#include "get_bits.h"
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typedef struct {
    AVFrame picture;
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} AvsContext;
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typedef enum {
    AVS_VIDEO     = 0x01,
    AVS_AUDIO     = 0x02,
    AVS_PALETTE   = 0x03,
    AVS_GAME_DATA = 0x04,
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} AvsBlockType;
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typedef enum {
    AVS_I_FRAME     = 0x00,
    AVS_P_FRAME_3X3 = 0x01,
    AVS_P_FRAME_2X2 = 0x02,
    AVS_P_FRAME_2X3 = 0x03,
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} AvsVideoSubType;
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static int
avs_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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    const uint8_t *buf_end = avpkt->data + avpkt->size;
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    int buf_size = avpkt->size;
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    AvsContext *const avs = avctx->priv_data;
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    AVFrame *picture = data;
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    AVFrame *const p =  &avs->picture;
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    const uint8_t *table, *vect;
    uint8_t *out;
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    int i, j, x, y, stride, vect_w = 3, vect_h = 3;
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    AvsVideoSubType sub_type;
    AvsBlockType type;
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    GetBitContext change_map;

    if (avctx->reget_buffer(avctx, p)) {
        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
        return -1;
    }
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    p->reference = 3;
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    p->pict_type = AV_PICTURE_TYPE_P;
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    p->key_frame = 0;

    out = avs->picture.data[0];
    stride = avs->picture.linesize[0];

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    if (buf_end - buf < 4)
        return AVERROR_INVALIDDATA;
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    sub_type = buf[0];
    type = buf[1];
    buf += 4;

    if (type == AVS_PALETTE) {
        int first, last;
        uint32_t *pal = (uint32_t *) avs->picture.data[1];

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        first = AV_RL16(buf);
        last = first + AV_RL16(buf + 2);
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        if (first >= 256 || last > 256 || buf_end - buf < 4 + 4 + 3 * (last - first))
            return AVERROR_INVALIDDATA;
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        buf += 4;
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        for (i=first; i<last; i++, buf+=3) {
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            pal[i] = (buf[0] << 18) | (buf[1] << 10) | (buf[2] << 2);
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            pal[i] |= 0xFF << 24 | (pal[i] >> 6) & 0x30303;
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        }
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        sub_type = buf[0];
        type = buf[1];
        buf += 4;
    }

    if (type != AVS_VIDEO)
        return -1;

    switch (sub_type) {
    case AVS_I_FRAME:
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        p->pict_type = AV_PICTURE_TYPE_I;
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        p->key_frame = 1;
    case AVS_P_FRAME_3X3:
        vect_w = 3;
        vect_h = 3;
        break;

    case AVS_P_FRAME_2X2:
        vect_w = 2;
        vect_h = 2;
        break;

    case AVS_P_FRAME_2X3:
        vect_w = 2;
        vect_h = 3;
        break;

    default:
      return -1;
    }

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    if (buf_end - buf < 256 * vect_w * vect_h)
        return AVERROR_INVALIDDATA;
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    table = buf + (256 * vect_w * vect_h);
    if (sub_type != AVS_I_FRAME) {
        int map_size = ((318 / vect_w + 7) / 8) * (198 / vect_h);
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        if (buf_end - table < map_size)
            return AVERROR_INVALIDDATA;
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        init_get_bits(&change_map, table, map_size * 8);
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        table += map_size;
    }

    for (y=0; y<198; y+=vect_h) {
        for (x=0; x<318; x+=vect_w) {
            if (sub_type == AVS_I_FRAME || get_bits1(&change_map)) {
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                if (buf_end - table < 1)
                    return AVERROR_INVALIDDATA;
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                vect = &buf[*table++ * (vect_w * vect_h)];
                for (j=0; j<vect_w; j++) {
                    out[(y + 0) * stride + x + j] = vect[(0 * vect_w) + j];
                    out[(y + 1) * stride + x + j] = vect[(1 * vect_w) + j];
                    if (vect_h == 3)
                        out[(y + 2) * stride + x + j] =
                            vect[(2 * vect_w) + j];
                }
            }
        }
        if (sub_type != AVS_I_FRAME)
            align_get_bits(&change_map);
    }

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    *picture   = avs->picture;
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    *data_size = sizeof(AVPicture);

    return buf_size;
}

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static av_cold int avs_decode_init(AVCodecContext * avctx)
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{
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    AvsContext *const avs = avctx->priv_data;
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    avctx->pix_fmt = PIX_FMT_PAL8;
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    avcodec_get_frame_defaults(&avs->picture);
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    avcodec_set_dimensions(avctx, 318, 198);
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    return 0;
}

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static av_cold int avs_decode_end(AVCodecContext *avctx)
{
    AvsContext *s = avctx->priv_data;
    if (s->picture.data[0])
        avctx->release_buffer(avctx, &s->picture);
    return 0;
}


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AVCodec ff_avs_decoder = {
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    .name           = "avs",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = CODEC_ID_AVS,
    .priv_data_size = sizeof(AvsContext),
    .init           = avs_decode_init,
    .decode         = avs_decode_frame,
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    .close          = avs_decode_end,
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    .capabilities   = CODEC_CAP_DR1,
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    .long_name      = NULL_IF_CONFIG_SMALL("AVS (Audio Video Standard) video"),
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};