vcr1.c 4.44 KB
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/*
 * ATI VCR1 codec
 * Copyright (c) 2003 Michael Niedermayer
 *
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 * This file is part of Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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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/**
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 * @file
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 * ATI VCR1 codec
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 */
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#include "avcodec.h"
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#include "internal.h"
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#include "libavutil/internal.h"
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typedef struct VCR1Context {
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    int delta[16];
    int offset[4];
} VCR1Context;

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static av_cold int vcr1_decode_init(AVCodecContext *avctx)
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{
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    avctx->pix_fmt = AV_PIX_FMT_YUV410P;
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    if (avctx->width & 7) {
        av_log(avctx, AV_LOG_ERROR, "Width %d is not divisble by 8.\n", avctx->width);
        return AVERROR_INVALIDDATA;
    }

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    return 0;
}

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static int vcr1_decode_frame(AVCodecContext *avctx, void *data,
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                             int *got_frame, AVPacket *avpkt)
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{
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    const uint8_t *buf        = avpkt->data;
    int buf_size              = avpkt->size;
    VCR1Context *const a      = avctx->priv_data;
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    AVFrame *const p          = data;
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    const uint8_t *bytestream = buf;
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    int i, x, y, ret;
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    if ((ret = ff_get_buffer(avctx, p, 0)) < 0) {
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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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    p->pict_type = AV_PICTURE_TYPE_I;
    p->key_frame = 1;
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    if (buf_size < 32)
        goto packet_small;

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    for (i = 0; i < 16; i++) {
        a->delta[i] = *bytestream++;
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        bytestream++;
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        buf_size--;
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    }
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    for (y = 0; y < avctx->height; y++) {
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        int offset;
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        uint8_t *luma = &p->data[0][y * p->linesize[0]];
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        if ((y & 3) == 0) {
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            uint8_t *cb = &p->data[1][(y >> 2) * p->linesize[1]];
            uint8_t *cr = &p->data[2][(y >> 2) * p->linesize[2]];
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            if (buf_size < 4 + avctx->width)
                goto packet_small;

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            for (i = 0; i < 4; i++)
                a->offset[i] = *bytestream++;
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            buf_size -= 4;
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            offset = a->offset[0] - a->delta[bytestream[2] & 0xF];
            for (x = 0; x < avctx->width; x += 4) {
                luma[0]     = offset += a->delta[bytestream[2] & 0xF];
                luma[1]     = offset += a->delta[bytestream[2] >>  4];
                luma[2]     = offset += a->delta[bytestream[0] & 0xF];
                luma[3]     = offset += a->delta[bytestream[0] >>  4];
                luma       += 4;
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                *cb++       = bytestream[3];
                *cr++       = bytestream[1];
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                bytestream += 4;
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                buf_size   -= 4;
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            }
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        } else {
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            if (buf_size < avctx->width / 2)
                goto packet_small;

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            offset = a->offset[y & 3] - a->delta[bytestream[2] & 0xF];

            for (x = 0; x < avctx->width; x += 8) {
                luma[0]     = offset += a->delta[bytestream[2] & 0xF];
                luma[1]     = offset += a->delta[bytestream[2] >>  4];
                luma[2]     = offset += a->delta[bytestream[3] & 0xF];
                luma[3]     = offset += a->delta[bytestream[3] >>  4];
                luma[4]     = offset += a->delta[bytestream[0] & 0xF];
                luma[5]     = offset += a->delta[bytestream[0] >>  4];
                luma[6]     = offset += a->delta[bytestream[1] & 0xF];
                luma[7]     = offset += a->delta[bytestream[1] >>  4];
                luma       += 8;
                bytestream += 4;
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                buf_size   -= 4;
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            }
        }
    }

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    *got_frame = 1;
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    return buf_size;
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packet_small:
    av_log(avctx, AV_LOG_ERROR, "Input packet too small.\n");
    return AVERROR_INVALIDDATA;
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}

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AVCodec ff_vcr1_decoder = {
    .name           = "vcr1",
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    .long_name      = NULL_IF_CONFIG_SMALL("ATI VCR1"),
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    .type           = AVMEDIA_TYPE_VIDEO,
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    .id             = AV_CODEC_ID_VCR1,
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    .priv_data_size = sizeof(VCR1Context),
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    .init           = vcr1_decode_init,
    .decode         = vcr1_decode_frame,
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    .capabilities   = CODEC_CAP_DR1,
};