libavcodec/mjpegbdec.c

   1 /*
   2  * Apple MJPEG-B decoder
   3  * Copyright (c) 2002 Alex Beregszaszi
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * Apple MJPEG-B decoder.
  25  */
  26
  27 #include <inttypes.h>
  28
  29 #include "avcodec.h"
  30 #include "internal.h"
  31 #include "mjpeg.h"
  32 #include "mjpegdec.h"
  33
  34 static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
  35     uint32_t offs= get_bits_long(gb, 32);
  36     if(offs >= size){
  37         av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
  38         return 0;
  39     }
  40     return offs;
  41 }
  42
  43 static int mjpegb_decode_frame(AVCodecContext *avctx,
  44                               void *data, int *got_frame,
  45                               AVPacket *avpkt)
  46 {
  47     const uint8_t *buf = avpkt->data;
  48     int buf_size = avpkt->size;
  49     MJpegDecodeContext *s = avctx->priv_data;
  50     const uint8_t *buf_end, *buf_ptr;
  51     GetBitContext hgb; /* for the header */
  52     uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
  53     uint32_t field_size, sod_offs;
  54     int ret;
  55
  56     buf_ptr = buf;
  57     buf_end = buf + buf_size;
  58
  59 read_header:
  60     /* reset on every SOI */
  61     s->restart_interval = 0;
  62     s->restart_count = 0;
  63     s->mjpb_skiptosod = 0;
  64
  65     if (buf_end - buf_ptr >= 1 << 28)
  66         return AVERROR_INVALIDDATA;
  67
  68     init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
  69
  70     skip_bits(&hgb, 32); /* reserved zeros */
  71
  72     if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
  73     {
  74         av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
  75         return AVERROR_INVALIDDATA;
  76     }
  77
  78     field_size = get_bits_long(&hgb, 32); /* field size */
  79     av_log(avctx, AV_LOG_DEBUG, "field size: 0x%"PRIx32"\n", field_size);
  80     skip_bits(&hgb, 32); /* padded field size */
  81     second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");
  82     av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%"PRIx32"\n",
  83            second_field_offs);
  84
  85     dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");
  86     av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%"PRIx32"\n", dqt_offs);
  87     if (dqt_offs)
  88     {
  89         init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
  90         s->start_code = DQT;
  91         if (ff_mjpeg_decode_dqt(s) < 0 &&
  92             (avctx->err_recognition & AV_EF_EXPLODE))
  93           return AVERROR_INVALIDDATA;
  94     }
  95
  96     dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");
  97     av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%"PRIx32"\n", dht_offs);
  98     if (dht_offs)
  99     {
 100         init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
 101         s->start_code = DHT;
 102         ff_mjpeg_decode_dht(s);
 103     }
 104
 105     sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
 106     av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%"PRIx32"\n", sof_offs);
 107     if (sof_offs)
 108     {
 109         init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
 110         s->start_code = SOF0;
 111         if (ff_mjpeg_decode_sof(s) < 0)
 112             return -1;
 113     }
 114
 115     sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");
 116     av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%"PRIx32"\n", sos_offs);
 117     sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
 118     av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%"PRIx32"\n", sod_offs);
 119     if (sos_offs)
 120     {
 121         init_get_bits(&s->gb, buf_ptr + sos_offs,
 122                       8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs));
 123         s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
 124         s->start_code = SOS;
 125         if (ff_mjpeg_decode_sos(s, NULL, NULL) < 0 &&
 126             (avctx->err_recognition & AV_EF_EXPLODE))
 127           return AVERROR_INVALIDDATA;
 128     }
 129
 130     if (s->interlaced) {
 131         s->bottom_field ^= 1;
 132         /* if not bottom field, do not output image yet */
 133         if (s->bottom_field != s->interlace_polarity && second_field_offs)
 134         {
 135             buf_ptr = buf + second_field_offs;
 136             second_field_offs = 0;
 137             goto read_header;
 138             }
 139     }
 140
 141     //XXX FIXME factorize, this looks very similar to the EOI code
 142
 143     if ((ret = av_frame_ref(data, s->picture_ptr)) < 0)
 144         return ret;
 145     *got_frame = 1;
 146
 147     if (!s->lossless && avctx->debug & FF_DEBUG_QP) {
 148         av_log(avctx, AV_LOG_DEBUG, "QP: %d\n",
 149                FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]));
 150     }
 151
 152     return buf_size;
 153 }
 154
 155 AVCodec ff_mjpegb_decoder = {
 156     .name           = "mjpegb",
 157     .long_name      = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),
 158     .type           = AVMEDIA_TYPE_VIDEO,
 159     .id             = AV_CODEC_ID_MJPEGB,
 160     .priv_data_size = sizeof(MJpegDecodeContext),
 161     .init           = ff_mjpeg_decode_init,
 162     .close          = ff_mjpeg_decode_end,
 163     .decode         = mjpegb_decode_frame,
 164     .capabilities   = AV_CODEC_CAP_DR1,
 165     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 166 };