/*
  * RTP packetization for H.264 (RFC3984)
  * RTP packetizer for HEVC/H.265 payload format (draft version 6)
  * Copyright (c) 2008 Luca Abeni
  * Copyright (c) 2014 Thomas Volkert <thomas@homer-conferencing.com>
  *

  * 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
  * @brief H.264/HEVC packetization
  * @author Luca Abeni <lucabe72@email.it>
  */
 
 #include "libavutil/intreadwrite.h"
 
 #include "avformat.h"
 #include "avc.h"
 #include "rtpenc.h"
 
 static void flush_buffered(AVFormatContext *s1, int last)
 {
     RTPMuxContext *s = s1->priv_data;
     if (s->buf_ptr != s->buf) {
         // If we're only sending one single NAL unit, send it as such, skip
         // the STAP-A/AP framing
         if (s->buffered_nals == 1) {

             enum AVCodecID codec = s1->streams[0]->codecpar->codec_id;

             if (codec == AV_CODEC_ID_H264)
                 ff_rtp_send_data(s1, s->buf + 3, s->buf_ptr - s->buf - 3, last);
             else
                 ff_rtp_send_data(s1, s->buf + 4, s->buf_ptr - s->buf - 4, last);
         } else
             ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, last);
     }
     s->buf_ptr = s->buf;
     s->buffered_nals = 0;
 }
 
 static void nal_send(AVFormatContext *s1, const uint8_t *buf, int size, int last)
 {
     RTPMuxContext *s = s1->priv_data;

     enum AVCodecID codec = s1->streams[0]->codecpar->codec_id;

 
     av_log(s1, AV_LOG_DEBUG, "Sending NAL %x of len %d M=%d\n", buf[0] & 0x1F, size, last);
     if (size <= s->max_payload_size) {
         int buffered_size = s->buf_ptr - s->buf;
         int header_size;
         int skip_aggregate = 0;
 
         if (codec == AV_CODEC_ID_H264) {
             header_size = 1;
             skip_aggregate = s->flags & FF_RTP_FLAG_H264_MODE0;
         } else {
             header_size = 2;
         }
 
         // Flush buffered NAL units if the current unit doesn't fit
         if (buffered_size + 2 + size > s->max_payload_size) {
             flush_buffered(s1, 0);
             buffered_size = 0;
         }
         // If we aren't using mode 0, and the NAL unit fits including the
         // framing (2 bytes length, plus 1/2 bytes for the STAP-A/AP marker),
         // write the unit to the buffer as a STAP-A/AP packet, otherwise flush
         // and send as single NAL.
         if (buffered_size + 2 + header_size + size <= s->max_payload_size &&
             !skip_aggregate) {
             if (buffered_size == 0) {
                 if (codec == AV_CODEC_ID_H264) {
                     *s->buf_ptr++ = 24;
                 } else {
                     *s->buf_ptr++ = 48 << 1;
                     *s->buf_ptr++ = 1;
                 }
             }
             AV_WB16(s->buf_ptr, size);
             s->buf_ptr += 2;
             memcpy(s->buf_ptr, buf, size);
             s->buf_ptr += size;
             s->buffered_nals++;
         } else {
             flush_buffered(s1, 0);
             ff_rtp_send_data(s1, buf, size, last);
         }
     } else {
         int flag_byte, header_size;
         flush_buffered(s1, 0);
         if (codec == AV_CODEC_ID_H264 && (s->flags & FF_RTP_FLAG_H264_MODE0)) {
             av_log(s1, AV_LOG_ERROR,
                    "NAL size %d > %d, try -slice-max-size %d\n", size,
                    s->max_payload_size, s->max_payload_size);
             return;
         }
         av_log(s1, AV_LOG_DEBUG, "NAL size %d > %d\n", size, s->max_payload_size);
         if (codec == AV_CODEC_ID_H264) {
             uint8_t type = buf[0] & 0x1F;
             uint8_t nri = buf[0] & 0x60;
 
             s->buf[0] = 28;        /* FU Indicator; Type = 28 ---> FU-A */
             s->buf[0] |= nri;
             s->buf[1] = type;
             s->buf[1] |= 1 << 7;
             buf  += 1;
             size -= 1;
 
             flag_byte   = 1;
             header_size = 2;
         } else {
             uint8_t nal_type = (buf[0] >> 1) & 0x3F;
             /*
              * create the HEVC payload header and transmit the buffer as fragmentation units (FU)
              *
              *    0                   1
              *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
              *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              *   |F|   Type    |  LayerId  | TID |
              *   +-------------+-----------------+
              *
              *      F       = 0
              *      Type    = 49 (fragmentation unit (FU))
              *      LayerId = 0
              *      TID     = 1
              */
             s->buf[0] = 49 << 1;
             s->buf[1] = 1;
 
             /*
              *     create the FU header
              *
              *     0 1 2 3 4 5 6 7
              *    +-+-+-+-+-+-+-+-+
              *    |S|E|  FuType   |
              *    +---------------+
              *
              *       S       = variable
              *       E       = variable
              *       FuType  = NAL unit type
              */
             s->buf[2]  = nal_type;
             /* set the S bit: mark as start fragment */
             s->buf[2] |= 1 << 7;
 
             /* pass the original NAL header */
             buf  += 2;
             size -= 2;
 
             flag_byte   = 2;
             header_size = 3;
         }
 
         while (size + header_size > s->max_payload_size) {
             memcpy(&s->buf[header_size], buf, s->max_payload_size - header_size);
             ff_rtp_send_data(s1, s->buf, s->max_payload_size, 0);
             buf  += s->max_payload_size - header_size;
             size -= s->max_payload_size - header_size;
             s->buf[flag_byte] &= ~(1 << 7);
         }
         s->buf[flag_byte] |= 1 << 6;
         memcpy(&s->buf[header_size], buf, size);
         ff_rtp_send_data(s1, s->buf, size + header_size, last);
     }
 }
 
 void ff_rtp_send_h264_hevc(AVFormatContext *s1, const uint8_t *buf1, int size)
 {
     const uint8_t *r, *end = buf1 + size;
     RTPMuxContext *s = s1->priv_data;
 
     s->timestamp = s->cur_timestamp;
     s->buf_ptr   = s->buf;
     if (s->nal_length_size)
         r = ff_avc_mp4_find_startcode(buf1, end, s->nal_length_size) ? buf1 : end;
     else
         r = ff_avc_find_startcode(buf1, end);
     while (r < end) {
         const uint8_t *r1;
 
         if (s->nal_length_size) {
             r1 = ff_avc_mp4_find_startcode(r, end, s->nal_length_size);
             if (!r1)
                 r1 = end;
             r += s->nal_length_size;
         } else {
             while (!*(r++));
             r1 = ff_avc_find_startcode(r, end);
         }
         nal_send(s1, r, r1 - r, r1 == end);
         r = r1;
     }
     flush_buffered(s1, 1);
 }