/*
  * MJPEG A dump header bitstream filter

  * Copyright (c) 2006 Baptiste Coudurier

  *
  * 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

  * MJPEG A dump header bitstream filter
  * modifies bitstream to be decoded by quicktime
  */
 
 #include "avcodec.h"
 #include "bytestream.h"
 #include "mjpeg.h"
 
 
 static int mjpega_dump_header(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args,
                               uint8_t **poutbuf, int *poutbuf_size,
                               const uint8_t *buf, int buf_size, int keyframe)
 {
     uint8_t *poutbufp;

     unsigned dqt = 0, dht = 0, sof0 = 0;

     int i;
 

     if (avctx->codec_id != AV_CODEC_ID_MJPEG) {

         av_log(avctx, AV_LOG_ERROR, "mjpega bitstream filter only applies to mjpeg codec\n");
         return 0;
     }
 
     *poutbuf_size = 0;
     *poutbuf = av_malloc(buf_size + 44 + FF_INPUT_BUFFER_PADDING_SIZE);
     poutbufp = *poutbuf;
     bytestream_put_byte(&poutbufp, 0xff);
     bytestream_put_byte(&poutbufp, SOI);
     bytestream_put_byte(&poutbufp, 0xff);
     bytestream_put_byte(&poutbufp, APP1);
     bytestream_put_be16(&poutbufp, 42); /* size */
     bytestream_put_be32(&poutbufp, 0);
     bytestream_put_buffer(&poutbufp, "mjpg", 4);
     bytestream_put_be32(&poutbufp, buf_size + 44); /* field size */
     bytestream_put_be32(&poutbufp, buf_size + 44); /* pad field size */
     bytestream_put_be32(&poutbufp, 0);             /* next ptr */
 
     for (i = 0; i < buf_size - 1; i++) {
         if (buf[i] == 0xff) {
             switch (buf[i + 1]) {

             case DQT:  dqt  = i + 46; break;
             case DHT:  dht  = i + 46; break;
             case SOF0: sof0 = i + 46; break;

             case SOS:

                 bytestream_put_be32(&poutbufp, dqt); /* quant off */
                 bytestream_put_be32(&poutbufp, dht); /* huff off */
                 bytestream_put_be32(&poutbufp, sof0); /* image off */

                 bytestream_put_be32(&poutbufp, i + 46); /* scan off */
                 bytestream_put_be32(&poutbufp, i + 46 + AV_RB16(buf + i + 2)); /* data off */
                 bytestream_put_buffer(&poutbufp, buf + 2, buf_size - 2); /* skip already written SOI */
                 *poutbuf_size = poutbufp - *poutbuf;
                 return 1;
             case APP1:

                 if (i + 8 < buf_size && AV_RL32(buf + i + 8) == AV_RL32("mjpg")) {

                     av_log(avctx, AV_LOG_ERROR, "bitstream already formatted\n");
                     memcpy(*poutbuf, buf, buf_size);
                     *poutbuf_size = buf_size;
                     return 1;
                 }
             }
         }
     }
     av_freep(poutbuf);
     av_log(avctx, AV_LOG_ERROR, "could not find SOS marker in bitstream\n");
     return 0;
 }
 

 AVBitStreamFilter ff_mjpega_dump_header_bsf = {

     "mjpegadump",
     0,
     mjpega_dump_header,
 };