/*
  * RTP JPEG-compressed video Packetizer, RFC 2435
  * Copyright (c) 2012 Samuel Pitoiset
  *

  * 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
  */
 
 #include "libavcodec/bytestream.h"
 #include "libavcodec/mjpeg.h"

 #include "libavcodec/jpegtables.h"

 #include "libavutil/intreadwrite.h"
 #include "rtpenc.h"
 
 void ff_rtp_send_jpeg(AVFormatContext *s1, const uint8_t *buf, int size)
 {
     RTPMuxContext *s = s1->priv_data;

     const uint8_t *qtables[4] = { NULL };

     int nb_qtables = 0;

     uint8_t type;

     uint8_t w, h;
     uint8_t *p;
     int off = 0; /* fragment offset of the current JPEG frame */
     int len;
     int i;

     int default_huffman_tables = 0;

 
     s->buf_ptr   = s->buf;
     s->timestamp = s->cur_timestamp;
 
     /* convert video pixel dimensions from pixels to blocks */

     w = AV_CEIL_RSHIFT(s1->streams[0]->codecpar->width, 3);
     h = AV_CEIL_RSHIFT(s1->streams[0]->codecpar->height, 3);

     /* get the pixel format type or fail */

     if (s1->streams[0]->codecpar->format == AV_PIX_FMT_YUVJ422P ||
         (s1->streams[0]->codecpar->color_range == AVCOL_RANGE_JPEG &&
          s1->streams[0]->codecpar->format == AV_PIX_FMT_YUV422P)) {

         type = 0;

     } else if (s1->streams[0]->codecpar->format == AV_PIX_FMT_YUVJ420P ||
                (s1->streams[0]->codecpar->color_range == AVCOL_RANGE_JPEG &&
                 s1->streams[0]->codecpar->format == AV_PIX_FMT_YUV420P)) {

         type = 1;
     } else {
         av_log(s1, AV_LOG_ERROR, "Unsupported pixel format\n");
         return;
     }
 

     /* preparse the header for getting some info */

     for (i = 0; i < size; i++) {
         if (buf[i] != 0xff)
             continue;
 
         if (buf[i + 1] == DQT) {

             int tables, j;

             if (buf[i + 4] & 0xF0)

                 av_log(s1, AV_LOG_WARNING,
                        "Only 8-bit precision is supported.\n");
 
             /* a quantization table is 64 bytes long */

             tables = AV_RB16(&buf[i + 2]) / 65;
             if (i + 5 + tables * 65 > size) {

                 av_log(s1, AV_LOG_ERROR, "Too short JPEG header. Aborted!\n");
                 return;
             }

             if (nb_qtables + tables > 4) {
                 av_log(s1, AV_LOG_ERROR, "Invalid number of quantisation tables\n");
                 return;
             }

             for (j = 0; j < tables; j++)
                 qtables[nb_qtables + j] = buf + i + 5 + j * 65;
             nb_qtables += tables;

         } else if (buf[i + 1] == SOF0) {
             if (buf[i + 14] != 17 || buf[i + 17] != 17) {
                 av_log(s1, AV_LOG_ERROR,
                        "Only 1x1 chroma blocks are supported. Aborted!\n");
                 return;
             }

         } else if (buf[i + 1] == DHT) {

             int dht_size = AV_RB16(&buf[i + 2]);
             default_huffman_tables |= 1 << 4;
             i += 3;
             dht_size -= 2;
             if (i + dht_size >= size)
                 continue;
             while (dht_size > 0)
                 switch (buf[i + 1]) {
                 case 0x00:
                     if (   dht_size >= 29
                         && !memcmp(buf + i +  2, avpriv_mjpeg_bits_dc_luminance + 1, 16)
                         && !memcmp(buf + i + 18, avpriv_mjpeg_val_dc, 12)) {
                         default_huffman_tables |= 1;
                         i += 29;
                         dht_size -= 29;
                     } else {
                         i += dht_size;
                         dht_size = 0;
                     }
                     break;
                 case 0x01:
                     if (   dht_size >= 29
                         && !memcmp(buf + i +  2, avpriv_mjpeg_bits_dc_chrominance + 1, 16)
                         && !memcmp(buf + i + 18, avpriv_mjpeg_val_dc, 12)) {
                         default_huffman_tables |= 1 << 1;
                         i += 29;
                         dht_size -= 29;
                     } else {
                         i += dht_size;
                         dht_size = 0;
                     }
                     break;
                 case 0x10:
                     if (   dht_size >= 179
                         && !memcmp(buf + i +  2, avpriv_mjpeg_bits_ac_luminance   + 1, 16)
                         && !memcmp(buf + i + 18, avpriv_mjpeg_val_ac_luminance, 162)) {
                         default_huffman_tables |= 1 << 2;
                         i += 179;
                         dht_size -= 179;
                     } else {
                         i += dht_size;
                         dht_size = 0;
                     }
                     break;
                 case 0x11:
                     if (   dht_size >= 179
                         && !memcmp(buf + i +  2, avpriv_mjpeg_bits_ac_chrominance + 1, 16)
                         && !memcmp(buf + i + 18, avpriv_mjpeg_val_ac_chrominance, 162)) {
                         default_huffman_tables |= 1 << 3;
                         i += 179;
                         dht_size -= 179;
                     } else {
                         i += dht_size;
                         dht_size = 0;
                     }
                     break;
                 default:
                     i += dht_size;
                     dht_size = 0;
                     continue;

             }

         } else if (buf[i + 1] == SOS) {
             /* SOS is last marker in the header */
             i += AV_RB16(&buf[i + 2]) + 2;

             if (i > size) {
                 av_log(s1, AV_LOG_ERROR,
                        "Insufficient data. Aborted!\n");
                 return;
             }

             break;
         }
     }

     if (default_huffman_tables && default_huffman_tables != 31) {
         av_log(s1, AV_LOG_ERROR,
                "RFC 2435 requires standard Huffman tables for jpeg\n");
         return;
     }

     if (nb_qtables && nb_qtables != 2)
         av_log(s1, AV_LOG_WARNING,
                "RFC 2435 suggests two quantization tables, %d provided\n",
                nb_qtables);

 
     /* skip JPEG header */
     buf  += i;
     size -= i;
 
     for (i = size - 2; i >= 0; i--) {
         if (buf[i] == 0xff && buf[i + 1] == EOI) {
             /* Remove the EOI marker */
             size = i;
             break;
         }
     }
 
     p = s->buf_ptr;
     while (size > 0) {
         int hdr_size = 8;
 
         if (off == 0 && nb_qtables)
             hdr_size += 4 + 64 * nb_qtables;
 
         /* payload max in one packet */
         len = FFMIN(size, s->max_payload_size - hdr_size);
 
         /* set main header */
         bytestream_put_byte(&p, 0);
         bytestream_put_be24(&p, off);
         bytestream_put_byte(&p, type);
         bytestream_put_byte(&p, 255);
         bytestream_put_byte(&p, w);
         bytestream_put_byte(&p, h);
 
         if (off == 0 && nb_qtables) {
             /* set quantization tables header */
             bytestream_put_byte(&p, 0);
             bytestream_put_byte(&p, 0);
             bytestream_put_be16(&p, 64 * nb_qtables);
 
             for (i = 0; i < nb_qtables; i++)

                 bytestream_put_buffer(&p, qtables[i], 64);

         }
 
         /* copy payload data */
         memcpy(p, buf, len);
 
         /* marker bit is last packet in frame */
         ff_rtp_send_data(s1, s->buf, len + hdr_size, size == len);
 
         buf  += len;
         size -= len;
         off  += len;
         p     = s->buf;
     }
 }