/*
  * MJPEG/AVI1 to JPEG/JFIF bitstream format filter
  * Copyright (c) 2010 Adrian Daerr and Nicolas George
  *
  * 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
  */
 
 /*
  * Adapted from mjpeg2jpeg.c, with original copyright:
  * Paris 2010 Adrian Daerr, public domain
  */
 
 #include <string.h>

 
 #include "libavutil/error.h"
 #include "libavutil/mem.h"

 #include "libavutil/intreadwrite.h"

 #include "avcodec.h"

 #include "bsf.h"

 #include "jpegtables.h"

 #include "mjpeg.h"

 
 static const uint8_t jpeg_header[] = {
     0xff, 0xd8,                     // SOI
     0xff, 0xe0,                     // APP0
     0x00, 0x10,                     // APP0 header size (including
                                     // this field, but excluding preceding)
     0x4a, 0x46, 0x49, 0x46, 0x00,   // ID string 'JFIF\0'
     0x01, 0x01,                     // version
     0x00,                           // bits per type
     0x00, 0x00,                     // X density
     0x00, 0x00,                     // Y density
     0x00,                           // X thumbnail size
     0x00,                           // Y thumbnail size
 };
 
 static const int dht_segment_size = 420;
 static const uint8_t dht_segment_head[] = { 0xFF, 0xC4, 0x01, 0xA2, 0x00 };
 static const uint8_t dht_segment_frag[] = {
     0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
     0x0a, 0x0b, 0x01, 0x00, 0x03, 0x01, 0x01, 0x01, 0x01, 0x01,
     0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
 };
 
 static uint8_t *append(uint8_t *buf, const uint8_t *src, int size)
 {
     memcpy(buf, src, size);
     return buf + size;
 }
 
 static uint8_t *append_dht_segment(uint8_t *buf)
 {
     buf = append(buf, dht_segment_head, sizeof(dht_segment_head));

     buf = append(buf, avpriv_mjpeg_bits_dc_luminance + 1, 16);

     buf = append(buf, dht_segment_frag, sizeof(dht_segment_frag));

     buf = append(buf, avpriv_mjpeg_val_dc, 12);

     *(buf++) = 0x10;

     buf = append(buf, avpriv_mjpeg_bits_ac_luminance + 1, 16);
     buf = append(buf, avpriv_mjpeg_val_ac_luminance, 162);

     *(buf++) = 0x11;

     buf = append(buf, avpriv_mjpeg_bits_ac_chrominance + 1, 16);
     buf = append(buf, avpriv_mjpeg_val_ac_chrominance, 162);

     return buf;
 }
 

 static int mjpeg2jpeg_filter(AVBSFContext *ctx, AVPacket *out)

 {

     AVPacket *in;
     int ret = 0;

     int input_skip, output_size;

     uint8_t *output;

     ret = ff_bsf_get_packet(ctx, &in);

     if (ret < 0)
         return ret;

 
     if (in->size < 12) {
         av_log(ctx, AV_LOG_ERROR, "input is truncated\n");
         ret = AVERROR_INVALIDDATA;
         goto fail;

     }

     if (AV_RB16(in->data) != 0xffd8) {
         av_log(ctx, AV_LOG_ERROR, "input is not MJPEG\n");

         ret = AVERROR_INVALIDDATA;
         goto fail;

     }

     if (in->data[2] == 0xff && in->data[3] == APP0) {
         input_skip = (in->data[4] << 8) + in->data[5] + 4;

     } else {
         input_skip = 2;

     }

     if (in->size < input_skip) {
         av_log(ctx, AV_LOG_ERROR, "input is truncated\n");
         ret = AVERROR_INVALIDDATA;
         goto fail;

     }

     output_size = in->size - input_skip +

                   sizeof(jpeg_header) + dht_segment_size;

     ret = av_new_packet(out, output_size);
     if (ret < 0)
         goto fail;
 
     output = out->data;
 
     output = append(output, jpeg_header, sizeof(jpeg_header));
     output = append_dht_segment(output);
     output = append(output, in->data + input_skip, in->size - input_skip);
 
     ret = av_packet_copy_props(out, in);
     if (ret < 0)
         goto fail;
 
 fail:
     if (ret < 0)
         av_packet_unref(out);
     av_packet_free(&in);
     return ret;

 }
 

 static const enum AVCodecID codec_ids[] = {
     AV_CODEC_ID_MJPEG, AV_CODEC_ID_NONE,
 };
 

 const AVBitStreamFilter ff_mjpeg2jpeg_bsf = {

     .name           = "mjpeg2jpeg",
     .filter         = mjpeg2jpeg_filter,

     .codec_ids      = codec_ids,

 };