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 "avcodec.h"
  28 #include "mjpeg.h"
  29 #include "mjpegdec.h"
  30
  31 static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
  32     uint32_t offs= get_bits_long(gb, 32);
  33     if(offs >= size){
  34         av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
  35         return 0;
  36     }
  37     return offs;
  38 }
  39
  40 static int mjpegb_decode_frame(AVCodecContext *avctx,
  41                               void *data, int *got_frame,
  42                               AVPacket *avpkt)
  43 {
  44     const uint8_t *buf = avpkt->data;
  45     int buf_size = avpkt->size;
  46     MJpegDecodeContext *s = avctx->priv_data;
  47     const uint8_t *buf_end, *buf_ptr;
  48     GetBitContext hgb; /* for the header */
  49     uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
  50     uint32_t field_size, sod_offs;
  51     int ret;
  52
  53     buf_ptr = buf;
  54     buf_end = buf + buf_size;
  55
  56 read_header:
  57     /* reset on every SOI */
  58     s->restart_interval = 0;
  59     s->restart_count = 0;
  60     s->mjpb_skiptosod = 0;
  61
  62     if (buf_end - buf_ptr >= 1 << 28)
  63         return AVERROR_INVALIDDATA;
  64
  65     init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
  66
  67     skip_bits(&hgb, 32); /* reserved zeros */
  68
  69     if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
  70     {
  71         av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
  72         return AVERROR_INVALIDDATA;
  73     }
  74
  75     field_size = get_bits_long(&hgb, 32); /* field size */
  76     av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);
  77     skip_bits(&hgb, 32); /* padded field size */
  78     second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");
  79     av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
  80
  81     dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");
  82     av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
  83     if (dqt_offs)
  84     {
  85         init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
  86         s->start_code = DQT;
  87         if (ff_mjpeg_decode_dqt(s) < 0 &&
  88             (avctx->err_recognition & AV_EF_EXPLODE))
  89           return AVERROR_INVALIDDATA;
  90     }
  91
  92     dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");
  93     av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
  94     if (dht_offs)
  95     {
  96         init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
  97         s->start_code = DHT;
  98         ff_mjpeg_decode_dht(s);
  99     }
 100
 101     sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
 102     av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
 103     if (sof_offs)
 104     {
 105         init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
 106         s->start_code = SOF0;
 107         if (ff_mjpeg_decode_sof(s) < 0)
 108             return -1;
 109     }
 110
 111     sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");
 112     av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);
 113     sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
 114     av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
 115     if (sos_offs)
 116     {
 117         init_get_bits(&s->gb, buf_ptr + sos_offs,
 118                       8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs));
 119         s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
 120         s->start_code = SOS;
 121         if (ff_mjpeg_decode_sos(s, NULL, NULL) < 0 &&
 122             (avctx->err_recognition & AV_EF_EXPLODE))
 123           return AVERROR_INVALIDDATA;
 124     }
 125
 126     if (s->interlaced) {
 127         s->bottom_field ^= 1;
 128         /* if not bottom field, do not output image yet */
 129         if (s->bottom_field != s->interlace_polarity && second_field_offs)
 130         {
 131             buf_ptr = buf + second_field_offs;
 132             second_field_offs = 0;
 133             goto read_header;
 134             }
 135     }
 136
 137     //XXX FIXME factorize, this looks very similar to the EOI code
 138
 139     if ((ret = av_frame_ref(data, s->picture_ptr)) < 0)
 140         return ret;
 141     *got_frame = 1;
 142
 143     if (!s->lossless && avctx->debug & FF_DEBUG_QP) {
 144         av_log(avctx, AV_LOG_DEBUG, "QP: %d\n",
 145                FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]));
 146     }
 147
 148     return buf_size;
 149 }
 150
 151 AVCodec ff_mjpegb_decoder = {
 152     .name           = "mjpegb",
 153     .type           = AVMEDIA_TYPE_VIDEO,
 154     .id             = AV_CODEC_ID_MJPEGB,
 155     .priv_data_size = sizeof(MJpegDecodeContext),
 156     .init           = ff_mjpeg_decode_init,
 157     .close          = ff_mjpeg_decode_end,
 158     .decode         = mjpegb_decode_frame,
 159     .capabilities   = CODEC_CAP_DR1,
 160     .long_name      = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),
 161 };