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ffmpeg / libavcodec / yop.c @ 72415b2a

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/**
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 * @file libavcodec/yop.c
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 * Psygnosis YOP decoder
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 *
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 * Copyright (C) 2010 Mohamed Naufal Basheer <naufal11@gmail.com>
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 * derived from the code by
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 * Copyright (C) 2009 Thomas P. Higdon <thomas.p.higdon@gmail.com>
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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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#include "libavutil/intreadwrite.h"
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#include "avcodec.h"
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#include "get_bits.h"
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typedef struct YopDecContext {
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    AVFrame frame;
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    AVCodecContext *avctx;
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    int num_pal_colors;
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    int first_color[2];
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    int frame_data_length;
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    int row_pos;
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    uint8_t *low_nibble;
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    uint8_t *srcptr;
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    uint8_t *dstptr;
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    uint8_t *dstbuf;
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} YopDecContext;
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// These tables are taken directly from:
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// http://wiki.multimedia.cx/index.php?title=Psygnosis_YOP
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/**
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 * Lookup table for painting macroblocks. Bytes 0-2 of each entry contain
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 * the macroblock positions to be painted (taken as (0, B0, B1, B2)).
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 * Byte 3 contains the number of bytes consumed on the input,
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 * equal to max(bytes 0-2) + 1.
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 */
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static const uint8_t paint_lut[15][4] =
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    {{1, 2, 3, 4}, {1, 2, 0, 3},
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     {1, 2, 1, 3}, {1, 2, 2, 3},
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     {1, 0, 2, 3}, {1, 0, 0, 2},
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     {1, 0, 1, 2}, {1, 1, 2, 3},
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     {0, 1, 2, 3}, {0, 1, 0, 2},
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     {1, 1, 0, 2}, {0, 1, 1, 2},
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     {0, 0, 1, 2}, {0, 0, 0, 1},
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     {1, 1, 1, 2},
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    };
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/**
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 * Lookup table for copying macroblocks. Each entry contains the respective
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 * x and y pixel offset for the copy source.
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 */
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static const int8_t motion_vector[16][2] =
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    {{-4, -4}, {-2, -4},
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     { 0, -4}, { 2, -4},
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     {-4, -2}, {-4,  0},
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     {-3, -3}, {-1, -3},
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     { 1, -3}, { 3, -3},
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     {-3, -1}, {-2, -2},
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     { 0, -2}, { 2, -2},
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     { 4, -2}, {-2,  0},
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    };
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static av_cold int yop_decode_init(AVCodecContext *avctx)
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{
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    YopDecContext *s = avctx->priv_data;
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    s->avctx = avctx;
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    if (avctx->width & 1 || avctx->height & 1 ||
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        avcodec_check_dimensions(avctx, avctx->width, avctx->height) < 0) {
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        av_log(avctx, AV_LOG_ERROR, "YOP has invalid dimensions\n");
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        return -1;
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    }
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    avctx->pix_fmt = PIX_FMT_PAL8;
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    s->num_pal_colors = avctx->extradata[0];
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    s->first_color[0] = avctx->extradata[1];
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    s->first_color[1] = avctx->extradata[2];
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    if (s->num_pal_colors + s->first_color[0] > 256 ||
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        s->num_pal_colors + s->first_color[1] > 256) {
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        av_log(avctx, AV_LOG_ERROR,
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               "YOP: palette parameters invalid, header probably corrupt\n");
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        return AVERROR_INVALIDDATA;
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    }
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    return 0;
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}
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static av_cold int yop_decode_close(AVCodecContext *avctx)
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{
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    YopDecContext *s = avctx->priv_data;
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    if (s->frame.data[0])
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        avctx->release_buffer(avctx, &s->frame);
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    return 0;
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}
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/**
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 * Paints a macroblock using the pattern in paint_lut.
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 * @param s codec context
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 * @param tag the tag that was in the nibble
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 */
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static void yop_paint_block(YopDecContext *s, int tag)
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{
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    s->dstptr[0]                        = s->srcptr[0];
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    s->dstptr[1]                        = s->srcptr[paint_lut[tag][0]];
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    s->dstptr[s->frame.linesize[0]]     = s->srcptr[paint_lut[tag][1]];
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    s->dstptr[s->frame.linesize[0] + 1] = s->srcptr[paint_lut[tag][2]];
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    // The number of src bytes consumed is in the last part of the lut entry.
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    s->srcptr += paint_lut[tag][3];
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}
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/**
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 * Copies a previously painted macroblock to the current_block.
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 * @param copy_tag the tag that was in the nibble
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 */
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static int yop_copy_previous_block(YopDecContext *s, int copy_tag)
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{
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    uint8_t *bufptr;
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    // Calculate position for the copy source
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    bufptr = s->dstptr + motion_vector[copy_tag][0] +
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             s->frame.linesize[0] * motion_vector[copy_tag][1];
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    if (bufptr < s->dstbuf) {
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        av_log(s->avctx, AV_LOG_ERROR,
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               "YOP: cannot decode, file probably corrupt\n");
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        return AVERROR_INVALIDDATA;
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    }
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    s->dstptr[0]                        = bufptr[0];
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    s->dstptr[1]                        = bufptr[1];
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    s->dstptr[s->frame.linesize[0]]     = bufptr[s->frame.linesize[0]];
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    s->dstptr[s->frame.linesize[0] + 1] = bufptr[s->frame.linesize[0] + 1];
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    return 0;
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}
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/**
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 * Returns the next nibble in sequence, consuming a new byte on the input
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 * only if necessary.
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 */
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static uint8_t yop_get_next_nibble(YopDecContext *s)
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{
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    int ret;
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    if (s->low_nibble) {
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        ret           = *s->low_nibble & 0xf;
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        s->low_nibble = NULL;
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    }else {
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        s->low_nibble = s->srcptr++;
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        ret           = *s->low_nibble >> 4;
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    }
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    return ret;
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}
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/**
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 * Takes s->dstptr to the next macroblock in sequence.
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 */
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static void yop_next_macroblock(YopDecContext *s)
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{
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    // If we are advancing to the next row of macroblocks
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    if (s->row_pos == s->frame.linesize[0] - 2) {
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        s->dstptr  += s->frame.linesize[0];
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        s->row_pos =  0;
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    }else {
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        s->row_pos += 2;
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    }
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    s->dstptr += 2;
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}
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static int yop_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
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                            AVPacket *avpkt)
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{
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    YopDecContext *s = avctx->priv_data;
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    int tag, firstcolor, is_odd_frame;
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    int ret, i;
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    uint32_t *palette;
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    if (s->frame.data[0])
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        avctx->release_buffer(avctx, &s->frame);
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    ret = avctx->get_buffer(avctx, &s->frame);
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    if (ret < 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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    s->frame.linesize[0] = avctx->width;
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    s->dstbuf     = s->frame.data[0];
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    s->dstptr     = s->frame.data[0];
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    s->srcptr     = avpkt->data + 4;
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    s->row_pos    = 0;
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    s->low_nibble = NULL;
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    is_odd_frame = avpkt->data[0];
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    firstcolor   = s->first_color[is_odd_frame];
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    palette      = (uint32_t *)s->frame.data[1];
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    for (i = 0; i < s->num_pal_colors; i++, s->srcptr += 3)
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        palette[i + firstcolor] = (s->srcptr[0] << 18) |
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                                  (s->srcptr[1] << 10) |
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                                  (s->srcptr[2] << 2);
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    s->frame.palette_has_changed = 1;
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    while (s->dstptr - s->dstbuf <
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           avctx->width * avctx->height &&
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           s->srcptr - avpkt->data < avpkt->size) {
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        tag = yop_get_next_nibble(s);
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        if (tag != 0xf) {
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            yop_paint_block(s, tag);
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        }else {
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            tag = yop_get_next_nibble(s);
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            ret = yop_copy_previous_block(s, tag);
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            if (ret < 0) {
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                avctx->release_buffer(avctx, &s->frame);
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                return ret;
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            }
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        }
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        yop_next_macroblock(s);
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    }
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    *data_size        = sizeof(AVFrame);
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    *(AVFrame *) data = s->frame;
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    return avpkt->size;
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}
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AVCodec yop_decoder = {
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    "yop",
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    AVMEDIA_TYPE_VIDEO,
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    CODEC_ID_YOP,
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    sizeof(YopDecContext),
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    yop_decode_init,
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    NULL,
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    yop_decode_close,
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    yop_decode_frame,
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    .long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP Video"),
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};