ffmpeg/libavcodec/aliaspixdec.c

   1 /*
   2  * Alias PIX image decoder
   3  * Copyright (C) 2014 Vittorio Giovara <vittorio.giovara@gmail.com>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "libavutil/intreadwrite.h"
  23
  24 #include "avcodec.h"
  25 #include "bytestream.h"
  26 #include "internal.h"
  27
  28 #define ALIAS_HEADER_SIZE 10
  29
  30 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
  31                         AVPacket *avpkt)
  32 {
  33     AVFrame *f = data;
  34     GetByteContext gb;
  35     int width, height, ret, bits_pixel, pixel;
  36     uint8_t *out_buf;
  37     uint8_t count;
  38     int x, y;
  39
  40     bytestream2_init(&gb, avpkt->data, avpkt->size);
  41
  42     if (bytestream2_get_bytes_left(&gb) < ALIAS_HEADER_SIZE) {
  43         av_log(avctx, AV_LOG_ERROR, "Header too small %d.\n", avpkt->size);
  44         return AVERROR_INVALIDDATA;
  45     }
  46
  47     width  = bytestream2_get_be16u(&gb);
  48     height = bytestream2_get_be16u(&gb);
  49     bytestream2_skipu(&gb, 4); // obsolete X, Y offset
  50     bits_pixel = bytestream2_get_be16u(&gb);
  51
  52     if (bits_pixel == 24)
  53         avctx->pix_fmt = AV_PIX_FMT_BGR24;
  54     else if (bits_pixel == 8)
  55         avctx->pix_fmt = AV_PIX_FMT_GRAY8;
  56     else {
  57         av_log(avctx, AV_LOG_ERROR, "Invalid pixel format.\n");
  58         return AVERROR_INVALIDDATA;
  59     }
  60
  61     ret = ff_set_dimensions(avctx, width, height);
  62     if (ret < 0)
  63         return ret;
  64
  65     ret = ff_get_buffer(avctx, f, 0);
  66     if (ret < 0)
  67         return ret;
  68
  69     f->pict_type = AV_PICTURE_TYPE_I;
  70     f->key_frame = 1;
  71
  72     x = 0;
  73     y = 1;
  74     out_buf = f->data[0];
  75     while (bytestream2_get_bytes_left(&gb) > 0) {
  76         int i;
  77
  78         /* set buffer at the right position at every new line */
  79         if (x == avctx->width) {
  80             x = 0;
  81             out_buf = f->data[0] + f->linesize[0] * y++;
  82             if (y > avctx->height) {
  83                 av_log(avctx, AV_LOG_ERROR,
  84                        "Ended frame decoding with %d bytes left.\n",
  85                        bytestream2_get_bytes_left(&gb));
  86                 return AVERROR_INVALIDDATA;
  87             }
  88         }
  89
  90         /* read packet and copy data */
  91         count = bytestream2_get_byteu(&gb);
  92         if (!count || x + count > avctx->width) {
  93             av_log(avctx, AV_LOG_ERROR, "Invalid run length %d.\n", count);
  94             return AVERROR_INVALIDDATA;
  95         }
  96
  97         if (avctx->pix_fmt == AV_PIX_FMT_BGR24) {
  98             pixel = bytestream2_get_be24(&gb);
  99             for (i = 0; i < count; i++) {
 100                 AV_WB24(out_buf, pixel);
 101                 out_buf += 3;
 102             }
 103         } else { // AV_PIX_FMT_GRAY8
 104             pixel = bytestream2_get_byte(&gb);
 105             for (i = 0; i < count; i++)
 106                 *out_buf++ = pixel;
 107         }
 108
 109         x += i;
 110     }
 111
 112     if (x != width || y != height) {
 113         av_log(avctx, AV_LOG_ERROR, "Picture stopped at %d,%d.\n", x, y);
 114         return AVERROR_INVALIDDATA;
 115     }
 116
 117     *got_frame = 1;
 118     return avpkt->size;
 119 }
 120
 121 AVCodec ff_alias_pix_decoder = {
 122     .name         = "alias_pix",
 123     .long_name    = NULL_IF_CONFIG_SMALL("Alias/Wavefront PIX image"),
 124     .type         = AVMEDIA_TYPE_VIDEO,
 125     .id           = AV_CODEC_ID_ALIAS_PIX,
 126     .decode       = decode_frame,
 127     .capabilities = CODEC_CAP_DR1,
 128 };