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ffmpeg / libavcodec / qpeg.c @ 01791786

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/*
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 * QPEG codec
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 * Copyright (c) 2004 Konstantin Shishkov
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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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/**
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 * @file qpeg.c
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 * QPEG codec.
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 */
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#include "avcodec.h"
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#include "mpegvideo.h"
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typedef struct QpegContext{
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    AVCodecContext *avctx;
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    AVFrame pic;
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    uint8_t *refdata;
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} QpegContext;
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static void qpeg_decode_intra(const uint8_t *src, uint8_t *dst, int size,
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                            int stride, int width, int height)
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{
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    int i;
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    int code;
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    int c0, c1;
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    int run, copy;
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    int filled = 0;
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    int rows_to_go;
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    rows_to_go = height;
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    height--;
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    dst = dst + height * stride;
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    while((size > 0) && (rows_to_go > 0)) {
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        code = *src++;
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        size--;
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        run = copy = 0;
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        if(code == 0xFC) /* end-of-picture code */
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            break;
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        if(code >= 0xF8) { /* very long run */
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            c0 = *src++;
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            c1 = *src++;
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            size -= 2;
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            run = ((code & 0x7) << 16) + (c0 << 8) + c1 + 2;
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        } else if (code >= 0xF0) { /* long run */
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            c0 = *src++;
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            size--;
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            run = ((code & 0xF) << 8) + c0 + 2;
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        } else if (code >= 0xE0) { /* short run */
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            run = (code & 0x1F) + 2;
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        } else if (code >= 0xC0) { /* very long copy */
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            c0 = *src++;
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            c1 = *src++;
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            size -= 2;
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            copy = ((code & 0x3F) << 16) + (c0 << 8) + c1 + 1;
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        } else if (code >= 0x80) { /* long copy */
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            c0 = *src++;
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            size--;
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            copy = ((code & 0x7F) << 8) + c0 + 1;
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        } else { /* short copy */
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            copy = code + 1;
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        }
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        /* perform actual run or copy */
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        if(run) {
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            int p;
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            p = *src++;
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            size--;
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            for(i = 0; i < run; i++) {
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                dst[filled++] = p;
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                if (filled >= width) {
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                    filled = 0;
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                    dst -= stride;
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                    rows_to_go--;
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                    if(rows_to_go <= 0)
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                        break;
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                }
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            }
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        } else {
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            size -= copy;
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            for(i = 0; i < copy; i++) {
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                dst[filled++] = *src++;
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                if (filled >= width) {
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                    filled = 0;
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                    dst -= stride;
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                    rows_to_go--;
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                    if(rows_to_go <= 0)
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                        break;
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                }
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            }
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        }
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    }
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}
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static int qpeg_table_h[16] =
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 { 0x00, 0x20, 0x20, 0x20, 0x18, 0x10, 0x10, 0x20, 0x10, 0x08, 0x18, 0x08, 0x08, 0x18, 0x10, 0x04};
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static int qpeg_table_w[16] =
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 { 0x00, 0x20, 0x18, 0x08, 0x18, 0x10, 0x20, 0x10, 0x08, 0x10, 0x20, 0x20, 0x08, 0x10, 0x18, 0x04};
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/* Decodes delta frames */
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static void qpeg_decode_inter(const uint8_t *src, uint8_t *dst, int size,
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                            int stride, int width, int height,
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                            int delta, const uint8_t *ctable, uint8_t *refdata)
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{
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    int i, j;
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    int code;
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    int filled = 0;
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    int orig_height;
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    /* copy prev frame */
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    for(i = 0; i < height; i++)
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        memcpy(refdata + (i * width), dst + (i * stride), width);
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    orig_height = height;
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    height--;
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    dst = dst + height * stride;
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    while((size > 0) && (height >= 0)) {
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        code = *src++;
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        size--;
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        if(delta) {
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            /* motion compensation */
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            while((code & 0xF0) == 0xF0) {
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                if(delta == 1) {
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                    int me_idx;
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                    int me_w, me_h, me_x, me_y;
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                    uint8_t *me_plane;
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                    int corr, val;
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                    /* get block size by index */
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                    me_idx = code & 0xF;
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                    me_w = qpeg_table_w[me_idx];
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                    me_h = qpeg_table_h[me_idx];
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                    /* extract motion vector */
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                    corr = *src++;
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                    size--;
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                    val = corr >> 4;
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                    if(val > 7)
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                        val -= 16;
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                    me_x = val;
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                    val = corr & 0xF;
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                    if(val > 7)
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                        val -= 16;
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                    me_y = val;
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                    /* check motion vector */
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                    if ((me_x + filled < 0) || (me_x + me_w + filled > width) ||
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                       (height - me_y - me_h < 0) || (height - me_y > orig_height) ||
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                       (filled + me_w > width) || (height - me_h < 0))
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                        av_log(NULL, AV_LOG_ERROR, "Bogus motion vector (%i,%i), block size %ix%i at %i,%i\n",
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                               me_x, me_y, me_w, me_h, filled, height);
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                    else {
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                        /* do motion compensation */
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                        me_plane = refdata + (filled + me_x) + (height - me_y) * width;
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                        for(j = 0; j < me_h; j++) {
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                            for(i = 0; i < me_w; i++)
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                                dst[filled + i - (j * stride)] = me_plane[i - (j * width)];
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                        }
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                    }
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                }
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                code = *src++;
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                size--;
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            }
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        }
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        if(code == 0xE0) /* end-of-picture code */
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            break;
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        if(code > 0xE0) { /* run code: 0xE1..0xFF */
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            int p;
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            code &= 0x1F;
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            p = *src++;
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            size--;
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            for(i = 0; i <= code; i++) {
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                dst[filled++] = p;
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                if(filled >= width) {
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                    filled = 0;
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                    dst -= stride;
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                    height--;
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                }
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            }
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        } else if(code >= 0xC0) { /* copy code: 0xC0..0xDF */
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            code &= 0x1F;
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            for(i = 0; i <= code; i++) {
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                dst[filled++] = *src++;
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                if(filled >= width) {
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                    filled = 0;
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                    dst -= stride;
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                    height--;
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                }
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            }
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            size -= code + 1;
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        } else if(code >= 0x80) { /* skip code: 0x80..0xBF */
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            int skip;
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            code &= 0x3F;
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            /* codes 0x80 and 0x81 are actually escape codes,
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               skip value minus constant is in the next byte */
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            if(!code)
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                skip = (*src++) + 64;
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            else if(code == 1)
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                skip = (*src++) + 320;
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            else
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                skip = code;
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            filled += skip;
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            while( filled >= width) {
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                filled -= width;
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                dst -= stride;
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                height--;
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                if(height < 0)
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                    break;
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            }
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        } else {
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            /* zero code treated as one-pixel skip */
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            if(code)
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                dst[filled++] = ctable[code & 0x7F];
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            else
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                filled++;
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            if(filled >= width) {
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                filled = 0;
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                dst -= stride;
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                height--;
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            }
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        }
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    }
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}
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static int decode_frame(AVCodecContext *avctx,
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                        void *data, int *data_size,
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                        const uint8_t *buf, int buf_size)
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{
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    QpegContext * const a = avctx->priv_data;
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    AVFrame * const p= (AVFrame*)&a->pic;
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    uint8_t* outdata;
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    int delta;
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    if(p->data[0])
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        avctx->release_buffer(avctx, p);
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    p->reference= 0;
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    if(avctx->get_buffer(avctx, p) < 0){
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        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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        return -1;
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    }
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    outdata = a->pic.data[0];
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    if(buf[0x85] == 0x10) {
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        qpeg_decode_intra(buf+0x86, outdata, buf_size - 0x86, a->pic.linesize[0], avctx->width, avctx->height);
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    } else {
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        delta = buf[0x85];
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        qpeg_decode_inter(buf+0x86, outdata, buf_size - 0x86, a->pic.linesize[0], avctx->width, avctx->height, delta, buf + 4, a->refdata);
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    }
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    /* make the palette available on the way out */
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    memcpy(a->pic.data[1], a->avctx->palctrl->palette, AVPALETTE_SIZE);
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    if (a->avctx->palctrl->palette_changed) {
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        a->pic.palette_has_changed = 1;
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        a->avctx->palctrl->palette_changed = 0;
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    }
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    *data_size = sizeof(AVFrame);
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    *(AVFrame*)data = a->pic;
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    return buf_size;
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}
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static int decode_init(AVCodecContext *avctx){
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    QpegContext * const a = avctx->priv_data;
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    a->avctx = avctx;
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    avctx->pix_fmt= PIX_FMT_PAL8;
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    a->pic.data[0] = NULL;
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    a->refdata = av_malloc(avctx->width * avctx->height);
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    return 0;
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}
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static int decode_end(AVCodecContext *avctx){
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    QpegContext * const a = avctx->priv_data;
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    AVFrame * const p= (AVFrame*)&a->pic;
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    if(p->data[0])
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        avctx->release_buffer(avctx, p);
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    av_free(a->refdata);
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    return 0;
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}
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AVCodec qpeg_decoder = {
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    "qpeg",
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    CODEC_TYPE_VIDEO,
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    CODEC_ID_QPEG,
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    sizeof(QpegContext),
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    decode_init,
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    NULL,
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    decode_end,
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    decode_frame,
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    CODEC_CAP_DR1,
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};