Libav 0.7.1
libavcodec/sgidec.c
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00001 /*
00002  * SGI image decoder
00003  * Todd Kirby <doubleshot@pacbell.net>
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "libavutil/imgutils.h"
00023 #include "avcodec.h"
00024 #include "bytestream.h"
00025 #include "sgi.h"
00026 
00027 typedef struct SgiState {
00028     AVFrame picture;
00029     unsigned int width;
00030     unsigned int height;
00031     unsigned int depth;
00032     unsigned int bytes_per_channel;
00033     int linesize;
00034 } SgiState;
00035 
00045 static int expand_rle_row(const uint8_t *in_buf, const uint8_t* in_end,
00046             unsigned char *out_buf, uint8_t* out_end, int pixelstride)
00047 {
00048     unsigned char pixel, count;
00049     unsigned char *orig = out_buf;
00050 
00051     while (1) {
00052         if(in_buf + 1 > in_end) return -1;
00053         pixel = bytestream_get_byte(&in_buf);
00054         if (!(count = (pixel & 0x7f))) {
00055             return (out_buf - orig) / pixelstride;
00056         }
00057 
00058         /* Check for buffer overflow. */
00059         if(out_buf + pixelstride * count >= out_end) return -1;
00060 
00061         if (pixel & 0x80) {
00062             while (count--) {
00063                 *out_buf = bytestream_get_byte(&in_buf);
00064                 out_buf += pixelstride;
00065             }
00066         } else {
00067             pixel = bytestream_get_byte(&in_buf);
00068 
00069             while (count--) {
00070                 *out_buf = pixel;
00071                 out_buf += pixelstride;
00072             }
00073         }
00074     }
00075 }
00076 
00085 static int read_rle_sgi(unsigned char* out_buf, const uint8_t *in_buf,
00086                         const uint8_t *in_end, SgiState* s)
00087 {
00088     uint8_t *dest_row;
00089     unsigned int len = s->height * s->depth * 4;
00090     const uint8_t *start_table = in_buf;
00091     unsigned int y, z;
00092     unsigned int start_offset;
00093 
00094     /* size of  RLE offset and length tables */
00095     if(len * 2  > in_end - in_buf) {
00096         return AVERROR_INVALIDDATA;
00097     }
00098 
00099     in_buf -= SGI_HEADER_SIZE;
00100     for (z = 0; z < s->depth; z++) {
00101         dest_row = out_buf;
00102         for (y = 0; y < s->height; y++) {
00103             dest_row -= s->linesize;
00104             start_offset = bytestream_get_be32(&start_table);
00105             if(start_offset > in_end - in_buf) {
00106                 return AVERROR_INVALIDDATA;
00107             }
00108             if (expand_rle_row(in_buf + start_offset, in_end, dest_row + z,
00109                 dest_row + FFABS(s->linesize), s->depth) != s->width)
00110                 return AVERROR_INVALIDDATA;
00111         }
00112     }
00113     return 0;
00114 }
00115 
00125 static int read_uncompressed_sgi(unsigned char* out_buf, uint8_t* out_end,
00126                 const uint8_t *in_buf, const uint8_t *in_end, SgiState* s)
00127 {
00128     int x, y, z;
00129     const uint8_t *ptr;
00130     unsigned int offset = s->height * s->width * s->bytes_per_channel;
00131 
00132     /* Test buffer size. */
00133     if (offset * s->depth > in_end - in_buf) {
00134        return -1;
00135     }
00136 
00137     for (y = s->height - 1; y >= 0; y--) {
00138         out_end = out_buf + (y * s->linesize);
00139         for (x = s->width; x > 0; x--) {
00140             ptr = in_buf += s->bytes_per_channel;
00141             for(z = 0; z < s->depth; z ++) {
00142                 memcpy(out_end, ptr, s->bytes_per_channel);
00143                 out_end += s->bytes_per_channel;
00144                 ptr += offset;
00145             }
00146         }
00147     }
00148     return 0;
00149 }
00150 
00151 static int decode_frame(AVCodecContext *avctx,
00152                         void *data, int *data_size,
00153                         AVPacket *avpkt)
00154 {
00155     const uint8_t *in_buf = avpkt->data;
00156     int buf_size = avpkt->size;
00157     SgiState *s = avctx->priv_data;
00158     AVFrame *picture = data;
00159     AVFrame *p = &s->picture;
00160     const uint8_t *in_end = in_buf + buf_size;
00161     unsigned int dimension, rle;
00162     int ret = 0;
00163     uint8_t *out_buf, *out_end;
00164 
00165     if (buf_size < SGI_HEADER_SIZE){
00166         av_log(avctx, AV_LOG_ERROR, "buf_size too small (%d)\n", buf_size);
00167         return -1;
00168     }
00169 
00170     /* Test for SGI magic. */
00171     if (bytestream_get_be16(&in_buf) != SGI_MAGIC) {
00172         av_log(avctx, AV_LOG_ERROR, "bad magic number\n");
00173         return -1;
00174     }
00175 
00176     rle = bytestream_get_byte(&in_buf);
00177     s->bytes_per_channel = bytestream_get_byte(&in_buf);
00178     dimension = bytestream_get_be16(&in_buf);
00179     s->width  = bytestream_get_be16(&in_buf);
00180     s->height = bytestream_get_be16(&in_buf);
00181     s->depth  = bytestream_get_be16(&in_buf);
00182 
00183     if (s->bytes_per_channel != 1 && (s->bytes_per_channel != 2 || rle)) {
00184         av_log(avctx, AV_LOG_ERROR, "wrong channel number\n");
00185         return -1;
00186     }
00187 
00188     /* Check for supported image dimensions. */
00189     if (dimension != 2 && dimension != 3) {
00190         av_log(avctx, AV_LOG_ERROR, "wrong dimension number\n");
00191         return -1;
00192     }
00193 
00194     if (s->depth == SGI_GRAYSCALE) {
00195         avctx->pix_fmt = s->bytes_per_channel == 2 ? PIX_FMT_GRAY16BE : PIX_FMT_GRAY8;
00196     } else if (s->depth == SGI_RGB) {
00197         avctx->pix_fmt = s->bytes_per_channel == 2 ? PIX_FMT_RGB48BE : PIX_FMT_RGB24;
00198     } else if (s->depth == SGI_RGBA && s->bytes_per_channel == 1) {
00199         avctx->pix_fmt = PIX_FMT_RGBA;
00200     } else {
00201         av_log(avctx, AV_LOG_ERROR, "wrong picture format\n");
00202         return -1;
00203     }
00204 
00205     if (av_image_check_size(s->width, s->height, 0, avctx))
00206         return -1;
00207     avcodec_set_dimensions(avctx, s->width, s->height);
00208 
00209     if (p->data[0])
00210         avctx->release_buffer(avctx, p);
00211 
00212     p->reference = 0;
00213     if (avctx->get_buffer(avctx, p) < 0) {
00214         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed.\n");
00215         return -1;
00216     }
00217 
00218     p->pict_type = AV_PICTURE_TYPE_I;
00219     p->key_frame = 1;
00220     out_buf = p->data[0];
00221 
00222     out_end = out_buf + p->linesize[0] * s->height;
00223 
00224     s->linesize = p->linesize[0];
00225 
00226     /* Skip header. */
00227     in_buf += SGI_HEADER_SIZE - 12;
00228     if (rle) {
00229         ret = read_rle_sgi(out_end, in_buf, in_end, s);
00230     } else {
00231         ret = read_uncompressed_sgi(out_buf, out_end, in_buf, in_end, s);
00232     }
00233 
00234     if (ret == 0) {
00235         *picture   = s->picture;
00236         *data_size = sizeof(AVPicture);
00237         return buf_size;
00238     } else {
00239         return -1;
00240     }
00241 }
00242 
00243 static av_cold int sgi_init(AVCodecContext *avctx){
00244     SgiState *s = avctx->priv_data;
00245 
00246     avcodec_get_frame_defaults(&s->picture);
00247     avctx->coded_frame = &s->picture;
00248 
00249     return 0;
00250 }
00251 
00252 static av_cold int sgi_end(AVCodecContext *avctx)
00253 {
00254     SgiState * const s = avctx->priv_data;
00255 
00256     if (s->picture.data[0])
00257         avctx->release_buffer(avctx, &s->picture);
00258 
00259     return 0;
00260 }
00261 
00262 AVCodec ff_sgi_decoder = {
00263     "sgi",
00264     AVMEDIA_TYPE_VIDEO,
00265     CODEC_ID_SGI,
00266     sizeof(SgiState),
00267     sgi_init,
00268     NULL,
00269     sgi_end,
00270     decode_frame,
00271     .long_name = NULL_IF_CONFIG_SMALL("SGI image"),
00272 };
00273