/*
  * Apple MJPEG-B decoder
  * Copyright (c) 2002 Alex Beregszaszi
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**

  * @file

  * Apple MJPEG-B decoder.
  */
 

 #include <inttypes.h>
 

 #include "avcodec.h"
 #include "mjpeg.h"
 #include "mjpegdec.h"
 

 static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
     uint32_t offs= get_bits_long(gb, 32);
     if(offs >= size){
         av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
         return 0;
     }
     return offs;
 }

 
 static int mjpegb_decode_frame(AVCodecContext *avctx,

                               void *data, int *got_frame,

                               AVPacket *avpkt)

 {

     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;

     MJpegDecodeContext *s = avctx->priv_data;

     const uint8_t *buf_end, *buf_ptr;

     GetBitContext hgb; /* for the header */
     uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
     uint32_t field_size, sod_offs;

     int ret;

 
     buf_ptr = buf;
     buf_end = buf + buf_size;

     s->got_picture = 0;

 
 read_header:
     /* reset on every SOI */
     s->restart_interval = 0;
     s->restart_count = 0;
     s->mjpb_skiptosod = 0;
 

     if (buf_end - buf_ptr >= 1 << 28)
         return AVERROR_INVALIDDATA;
 

     init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
 
     skip_bits(&hgb, 32); /* reserved zeros */
 
     if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
     {
         av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");

         return AVERROR_INVALIDDATA;

     }
 
     field_size = get_bits_long(&hgb, 32); /* field size */

     av_log(avctx, AV_LOG_DEBUG, "field size: 0x%"PRIx32"\n", field_size);

     skip_bits(&hgb, 32); /* padded field size */

     second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");

     av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%"PRIx32"\n",
            second_field_offs);

     dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");

     av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%"PRIx32"\n", dqt_offs);

     if (dqt_offs)
     {

         init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);

         s->start_code = DQT;

         if (ff_mjpeg_decode_dqt(s) < 0 &&

             (avctx->err_recognition & AV_EF_EXPLODE))

           return AVERROR_INVALIDDATA;

     }
 

     dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");

     av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%"PRIx32"\n", dht_offs);

     if (dht_offs)
     {

         init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);

         s->start_code = DHT;
         ff_mjpeg_decode_dht(s);
     }
 

     sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");

     av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%"PRIx32"\n", sof_offs);

     if (sof_offs)
     {

         init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);

         s->start_code = SOF0;
         if (ff_mjpeg_decode_sof(s) < 0)
             return -1;
     }
 

     sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");

     av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%"PRIx32"\n", sos_offs);

     sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");

     av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%"PRIx32"\n", sod_offs);

     if (sos_offs)
     {

         init_get_bits(&s->gb, buf_ptr + sos_offs,
                       8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs));

         s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
         s->start_code = SOS;

         if (ff_mjpeg_decode_sos(s, NULL, 0, NULL) < 0 &&

             (avctx->err_recognition & AV_EF_EXPLODE))

           return AVERROR_INVALIDDATA;

     }
 
     if (s->interlaced) {
         s->bottom_field ^= 1;
         /* if not bottom field, do not output image yet */

         if (s->bottom_field != s->interlace_polarity && second_field_offs)

         {
             buf_ptr = buf + second_field_offs;
             goto read_header;
             }
     }
 
     //XXX FIXME factorize, this looks very similar to the EOI code
 

     if(!s->got_picture) {
         av_log(avctx, AV_LOG_WARNING, "no picture\n");
         return buf_size;
     }
 

     if ((ret = av_frame_ref(data, s->picture_ptr)) < 0)
         return ret;

     *got_frame = 1;

     if (!s->lossless && avctx->debug & FF_DEBUG_QP) {
         av_log(avctx, AV_LOG_DEBUG, "QP: %d\n",
                FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]));

     }
 

     return buf_size;

 }
 

 AVCodec ff_mjpegb_decoder = {

     .name           = "mjpegb",

     .long_name      = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),

     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_MJPEGB,

     .priv_data_size = sizeof(MJpegDecodeContext),
     .init           = ff_mjpeg_decode_init,
     .close          = ff_mjpeg_decode_end,
     .decode         = mjpegb_decode_frame,
     .capabilities   = CODEC_CAP_DR1,

     .max_lowres     = 3,

 };