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* Todd Kirby <doubleshot@pacbell.net>
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* This file is part of FFmpeg.
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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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* 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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* 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 "bytestream.h"
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typedef struct SgiState {
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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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static int expand_rle_row(uint8_t *in_buf, uint8_t* in_end,
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unsigned char *out_buf, uint8_t* out_end, int pixelstride)
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unsigned char pixel, count;
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unsigned char *orig = out_buf;
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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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/* Check for buffer overflow. */
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if(out_buf + pixelstride * count >= out_end) return -1;
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*out_buf = bytestream_get_byte(&in_buf);
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out_buf += pixelstride;
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pixel = bytestream_get_byte(&in_buf);
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out_buf += pixelstride;
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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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static int read_rle_sgi(unsigned char* out_buf, uint8_t *in_buf,
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uint8_t *in_end, SgiState* s)
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unsigned int len = s->height * s->depth * 4;
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uint8_t *start_table = in_buf;
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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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in_buf -= SGI_HEADER_SIZE;
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for (z = 0; z < s->depth; z++) {
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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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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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* 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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static int read_uncompressed_sgi(unsigned char* out_buf, uint8_t* out_end,
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uint8_t *in_buf, uint8_t *in_end, SgiState* s)
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unsigned int offset = s->height * s->width;
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/* Test buffer size. */
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if (offset * s->depth > in_end - in_buf) {
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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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for(z = 0; z < s->depth; z ++) {
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bytestream_put_byte(&out_end, *ptr);
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static int decode_frame(AVCodecContext *avctx,
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void *data, int *data_size,
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uint8_t *in_buf, int buf_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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uint8_t *in_end = in_buf + buf_size;
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unsigned int dimension, bytes_per_channel, rle;
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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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/* 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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rle = bytestream_get_byte(&in_buf);
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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 (bytes_per_channel != 1) {
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av_log(avctx, AV_LOG_ERROR, "wrong channel number\n");
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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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if (s->depth == SGI_GRAYSCALE) {
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avctx->pix_fmt = PIX_FMT_GRAY8;
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} else if (s->depth == SGI_RGB) {
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avctx->pix_fmt = PIX_FMT_RGB24;
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} else if (s->depth == SGI_RGBA) {
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avctx->pix_fmt = PIX_FMT_RGBA;
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av_log(avctx, AV_LOG_ERROR, "wrong picture format\n");
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if (avcodec_check_dimensions(avctx, s->width, s->height))
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avcodec_set_dimensions(avctx, s->width, s->height);
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avctx->release_buffer(avctx, p);
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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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p->pict_type = FF_I_TYPE;
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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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in_buf += SGI_HEADER_SIZE - 12;
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ret = read_rle_sgi(out_end, in_buf, in_end, s);
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ret = read_uncompressed_sgi(out_buf, out_end, in_buf, in_end, s);
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*picture = s->picture;
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*data_size = sizeof(AVPicture);
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static 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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static int sgi_end(AVCodecContext *avctx)
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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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AVCodec sgi_decoder = {