/*
  * 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 "bsf.h"

 #include "bytestream.h"
 #include "mjpeg.h"
 
 

 static int mjpega_dump_header(AVBSFContext *ctx, AVPacket *out)

 {

     AVPacket *in;
     uint8_t *out_buf;

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

     int ret = 0, i;

     ret = ff_bsf_get_packet(ctx, &in);
     if (ret < 0)
         return ret;
 
     ret = av_new_packet(out, in->size + 44);
     if (ret < 0)
         goto fail;
 
     ret = av_packet_copy_props(out, in);
     if (ret < 0)
         goto fail;

     out_buf = out->data;
     bytestream_put_byte(&out_buf, 0xff);
     bytestream_put_byte(&out_buf, SOI);
     bytestream_put_byte(&out_buf, 0xff);
     bytestream_put_byte(&out_buf, APP1);
     bytestream_put_be16(&out_buf, 42); /* size */
     bytestream_put_be32(&out_buf, 0);
     bytestream_put_buffer(&out_buf, "mjpg", 4);
     bytestream_put_be32(&out_buf, in->size + 44); /* field size */
     bytestream_put_be32(&out_buf, in->size + 44); /* pad field size */
     bytestream_put_be32(&out_buf, 0);             /* next ptr */

     for (i = 0; i < in->size - 1; i++) {
         if (in->data[i] == 0xff) {
             switch (in->data[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(&out_buf, dqt); /* quant off */
                 bytestream_put_be32(&out_buf, dht); /* huff off */
                 bytestream_put_be32(&out_buf, sof0); /* image off */
                 bytestream_put_be32(&out_buf, i + 46); /* scan off */
                 bytestream_put_be32(&out_buf, i + 46 + AV_RB16(in->data + i + 2)); /* data off */
                 bytestream_put_buffer(&out_buf, in->data + 2, in->size - 2); /* skip already written SOI */
 
                 out->size = out_buf - out->data;
                 av_packet_free(&in);
                 return 0;

             case APP1:

                 if (i + 8 < in->size && AV_RL32(in->data + i + 8) == AV_RL32("mjpg")) {
                     av_log(ctx, AV_LOG_ERROR, "bitstream already formatted\n");
                     av_packet_unref(out);
                     av_packet_move_ref(out, in);
                     av_packet_free(&in);
                     return 0;

                 }
             }
         }
     }

     av_log(ctx, AV_LOG_ERROR, "could not find SOS marker in bitstream\n");
 fail:
     av_packet_unref(out);
     av_packet_free(&in);
     return AVERROR_INVALIDDATA;

 }
 

 static const enum AVCodecID codec_ids[] = {
     AV_CODEC_ID_MJPEG, AV_CODEC_ID_NONE,
 };
 
 const AVBitStreamFilter ff_mjpega_dump_header_bsf = {
     .name      = "mjpegadump",
     .filter    = mjpega_dump_header,
     .codec_ids = codec_ids,

 };