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ffmpeg / libavcodec / sgidec.c @ 2912e87a

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/*
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 * SGI image decoder
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 * Todd Kirby <doubleshot@pacbell.net>
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 *
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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
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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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 * 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
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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 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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#include "libavutil/imgutils.h"
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#include "avcodec.h"
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#include "bytestream.h"
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#include "sgi.h"
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typedef struct SgiState {
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    AVFrame picture;
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    unsigned int width;
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    unsigned int height;
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    unsigned int depth;
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    unsigned int bytes_per_channel;
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    int linesize;
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} SgiState;
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/**
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 * Expand an RLE row into a channel.
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 * @param in_buf input buffer
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 * @param in_end end of input buffer
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 * @param out_buf Points to one line after the output buffer.
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 * @param out_end end of line in output buffer
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 * @param pixelstride pixel stride of input buffer
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 * @return size of output in bytes, -1 if buffer overflows
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 */
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static int expand_rle_row(const uint8_t *in_buf, const uint8_t* in_end,
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            unsigned char *out_buf, uint8_t* out_end, int pixelstride)
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{
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    unsigned char pixel, count;
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    unsigned char *orig = out_buf;
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    while (1) {
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        if(in_buf + 1 > in_end) return -1;
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        pixel = bytestream_get_byte(&in_buf);
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        if (!(count = (pixel & 0x7f))) {
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            return (out_buf - orig) / pixelstride;
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        }
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        /* Check for buffer overflow. */
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        if(out_buf + pixelstride * count >= out_end) return -1;
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        if (pixel & 0x80) {
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            while (count--) {
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                *out_buf = bytestream_get_byte(&in_buf);
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                out_buf += pixelstride;
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            }
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        } else {
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            pixel = bytestream_get_byte(&in_buf);
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            while (count--) {
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                *out_buf = pixel;
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                out_buf += pixelstride;
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            }
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        }
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    }
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}
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/**
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 * Read a run length encoded SGI image.
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 * @param out_buf output buffer
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 * @param in_buf input buffer
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 * @param in_end end of input buffer
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 * @param s the current image state
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 * @return 0 if no error, else return error number.
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 */
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static int read_rle_sgi(unsigned char* out_buf, const uint8_t *in_buf,
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                        const uint8_t *in_end, SgiState* s)
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{
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    uint8_t *dest_row;
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    unsigned int len = s->height * s->depth * 4;
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    const uint8_t *start_table = in_buf;
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    unsigned int y, z;
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    unsigned int start_offset;
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    /* size of  RLE offset and length tables */
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    if(len * 2  > in_end - in_buf) {
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        return AVERROR_INVALIDDATA;
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    }
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    in_buf -= SGI_HEADER_SIZE;
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    for (z = 0; z < s->depth; z++) {
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        dest_row = out_buf;
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        for (y = 0; y < s->height; y++) {
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            dest_row -= s->linesize;
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            start_offset = bytestream_get_be32(&start_table);
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            if(start_offset > in_end - in_buf) {
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                return AVERROR_INVALIDDATA;
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            }
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            if (expand_rle_row(in_buf + start_offset, in_end, dest_row + z,
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                dest_row + FFABS(s->linesize), s->depth) != s->width)
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                return AVERROR_INVALIDDATA;
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        }
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    }
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    return 0;
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}
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/**
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 * Read an uncompressed SGI image.
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 * @param out_buf output buffer
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 * @param out_end end ofoutput buffer
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 * @param in_buf input buffer
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 * @param in_end end of input buffer
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 * @param s the current image state
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 * @return 0 if read success, otherwise return -1.
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 */
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static int read_uncompressed_sgi(unsigned char* out_buf, uint8_t* out_end,
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                const uint8_t *in_buf, const uint8_t *in_end, SgiState* s)
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{
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    int x, y, z;
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    const uint8_t *ptr;
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    unsigned int offset = s->height * s->width * s->bytes_per_channel;
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    /* Test buffer size. */
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    if (offset * s->depth > in_end - in_buf) {
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       return -1;
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    }
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    for (y = s->height - 1; y >= 0; y--) {
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        out_end = out_buf + (y * s->linesize);
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        for (x = s->width; x > 0; x--) {
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            ptr = in_buf += s->bytes_per_channel;
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            for(z = 0; z < s->depth; z ++) {
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                memcpy(out_end, ptr, s->bytes_per_channel);
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                out_end += s->bytes_per_channel;
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                ptr += offset;
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            }
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        }
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    }
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    return 0;
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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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                        AVPacket *avpkt)
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{
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    const uint8_t *in_buf = avpkt->data;
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    int buf_size = avpkt->size;
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    SgiState *s = avctx->priv_data;
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    AVFrame *picture = data;
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    AVFrame *p = &s->picture;
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    const uint8_t *in_end = in_buf + buf_size;
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    unsigned int dimension, rle;
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    int ret = 0;
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    uint8_t *out_buf, *out_end;
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    if (buf_size < SGI_HEADER_SIZE){
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        av_log(avctx, AV_LOG_ERROR, "buf_size too small (%d)\n", buf_size);
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        return -1;
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    }
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    /* Test for SGI magic. */
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    if (bytestream_get_be16(&in_buf) != SGI_MAGIC) {
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        av_log(avctx, AV_LOG_ERROR, "bad magic number\n");
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        return -1;
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    }
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    rle = bytestream_get_byte(&in_buf);
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    s->bytes_per_channel = bytestream_get_byte(&in_buf);
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    dimension = bytestream_get_be16(&in_buf);
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    s->width  = bytestream_get_be16(&in_buf);
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    s->height = bytestream_get_be16(&in_buf);
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    s->depth  = bytestream_get_be16(&in_buf);
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    if (s->bytes_per_channel != 1 && (s->bytes_per_channel != 2 || rle)) {
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        av_log(avctx, AV_LOG_ERROR, "wrong channel number\n");
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        return -1;
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    }
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    /* Check for supported image dimensions. */
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    if (dimension != 2 && dimension != 3) {
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        av_log(avctx, AV_LOG_ERROR, "wrong dimension number\n");
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        return -1;
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    }
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    if (s->depth == SGI_GRAYSCALE) {
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        avctx->pix_fmt = s->bytes_per_channel == 2 ? PIX_FMT_GRAY16BE : PIX_FMT_GRAY8;
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    } else if (s->depth == SGI_RGB) {
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        avctx->pix_fmt = s->bytes_per_channel == 2 ? PIX_FMT_RGB48BE : PIX_FMT_RGB24;
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    } else if (s->depth == SGI_RGBA && s->bytes_per_channel == 1) {
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        avctx->pix_fmt = PIX_FMT_RGBA;
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    } else {
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        av_log(avctx, AV_LOG_ERROR, "wrong picture format\n");
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        return -1;
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    }
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    if (av_image_check_size(s->width, s->height, 0, avctx))
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        return -1;
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    avcodec_set_dimensions(avctx, s->width, s->height);
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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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    p->pict_type = FF_I_TYPE;
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    p->key_frame = 1;
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    out_buf = p->data[0];
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    out_end = out_buf + p->linesize[0] * s->height;
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    s->linesize = p->linesize[0];
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    /* Skip header. */
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    in_buf += SGI_HEADER_SIZE - 12;
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    if (rle) {
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        ret = read_rle_sgi(out_end, in_buf, in_end, s);
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    } else {
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        ret = read_uncompressed_sgi(out_buf, out_end, in_buf, in_end, s);
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    }
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    if (ret == 0) {
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        *picture   = s->picture;
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        *data_size = sizeof(AVPicture);
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        return buf_size;
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    } else {
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        return -1;
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    }
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}
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static av_cold int sgi_init(AVCodecContext *avctx){
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    SgiState *s = avctx->priv_data;
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    avcodec_get_frame_defaults(&s->picture);
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    avctx->coded_frame = &s->picture;
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    return 0;
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}
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static av_cold int sgi_end(AVCodecContext *avctx)
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{
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    SgiState * const s = avctx->priv_data;
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    if (s->picture.data[0])
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        avctx->release_buffer(avctx, &s->picture);
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    return 0;
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}
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AVCodec ff_sgi_decoder = {
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    "sgi",
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    AVMEDIA_TYPE_VIDEO,
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    CODEC_ID_SGI,
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    sizeof(SgiState),
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    sgi_init,
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    NULL,
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    sgi_end,
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    decode_frame,
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    .long_name = NULL_IF_CONFIG_SMALL("SGI image"),
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};
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