/*
  * 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 "avcodec.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(AVBitStreamFilterContext *bsfc,
                              AVCodecContext *avctx, const char *args,
                              uint8_t **poutbuf, int *poutbuf_size,
                              const uint8_t *buf, int buf_size,
                              int keyframe)
 {
     int input_skip, output_size;
     uint8_t *output, *out;
 
     if (buf_size < 12) {
         av_log(avctx, AV_LOG_ERROR, "input is truncated\n");
         return AVERROR_INVALIDDATA;
     }
     if (memcmp("AVI1", buf + 6, 4)) {
         av_log(avctx, AV_LOG_ERROR, "input is not MJPEG/AVI1\n");
         return AVERROR_INVALIDDATA;
     }
     input_skip = (buf[4] << 8) + buf[5] + 4;
     if (buf_size < input_skip) {
         av_log(avctx, AV_LOG_ERROR, "input is truncated\n");
         return AVERROR_INVALIDDATA;
     }
     output_size = buf_size - input_skip +
                   sizeof(jpeg_header) + dht_segment_size;
     output = out = av_malloc(output_size);
     if (!output)
         return AVERROR(ENOMEM);
     out = append(out, jpeg_header, sizeof(jpeg_header));
     out = append_dht_segment(out);
     out = append(out, buf + input_skip, buf_size - input_skip);
     *poutbuf = output;
     *poutbuf_size = output_size;
     return 1;
 }
 

 AVBitStreamFilter ff_mjpeg2jpeg_bsf = {

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