/*
  * RTP parser for HEVC/H.265 payload format (draft version 6)
  * 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
  */
 

 #include "libavutil/avassert.h"

 #include "libavutil/avstring.h"

 #include "libavutil/base64.h"

 #include "libavcodec/get_bits.h"

 #include "avformat.h"

 #include "internal.h"

 #include "rtpdec.h"

 #include "rtpdec_formats.h"

 #define RTP_HEVC_PAYLOAD_HEADER_SIZE       2
 #define RTP_HEVC_FU_HEADER_SIZE            1
 #define RTP_HEVC_DONL_FIELD_SIZE           2
 #define RTP_HEVC_DOND_FIELD_SIZE           1
 #define RTP_HEVC_AP_NALU_LENGTH_FIELD_SIZE 2
 #define HEVC_SPECIFIED_NAL_UNIT_TYPES      48

 /* SDP out-of-band signaling data */

 struct PayloadContext {
     int using_donl_field;
     int profile_id;

     uint8_t *sps, *pps, *vps, *sei;
     int sps_size, pps_size, vps_size, sei_size;

 };
 
 static const uint8_t start_sequence[] = { 0x00, 0x00, 0x00, 0x01 };
 
 static av_cold int hevc_sdp_parse_fmtp_config(AVFormatContext *s,

                                               AVStream *stream,
                                               PayloadContext *hevc_data,

                                               const char *attr, const char *value)

 {
     /* profile-space: 0-3 */
     /* profile-id: 0-31 */
     if (!strcmp(attr, "profile-id")) {
         hevc_data->profile_id = atoi(value);

         av_log(s, AV_LOG_TRACE, "SDP: found profile-id: %d\n", hevc_data->profile_id);

     }
 
     /* tier-flag: 0-1 */
     /* level-id: 0-255 */
     /* interop-constraints: [base16] */
     /* profile-compatibility-indicator: [base16] */
     /* sprop-sub-layer-id: 0-6, defines highest possible value for TID, default: 6 */
     /* recv-sub-layer-id: 0-6 */
     /* max-recv-level-id: 0-255 */
     /* tx-mode: MSM,SSM */
     /* sprop-vps: [base64] */
     /* sprop-sps: [base64] */
     /* sprop-pps: [base64] */
     /* sprop-sei: [base64] */

     if (!strcmp(attr, "sprop-vps") || !strcmp(attr, "sprop-sps") ||
         !strcmp(attr, "sprop-pps") || !strcmp(attr, "sprop-sei")) {

         uint8_t **data_ptr = NULL;
         int *size_ptr = NULL;

         if (!strcmp(attr, "sprop-vps")) {
             data_ptr = &hevc_data->vps;
             size_ptr = &hevc_data->vps_size;
         } else if (!strcmp(attr, "sprop-sps")) {
             data_ptr = &hevc_data->sps;
             size_ptr = &hevc_data->sps_size;
         } else if (!strcmp(attr, "sprop-pps")) {
             data_ptr = &hevc_data->pps;
             size_ptr = &hevc_data->pps_size;
         } else if (!strcmp(attr, "sprop-sei")) {
             data_ptr = &hevc_data->sei;
             size_ptr = &hevc_data->sei_size;

         } else
             av_assert0(0);

         ff_h264_parse_sprop_parameter_sets(s, data_ptr,
                                            size_ptr, value);

     }
 

     /* max-lsr, max-lps, max-cpb, max-dpb, max-br, max-tr, max-tc */
     /* max-fps */
 
     /* sprop-max-don-diff: 0-32767
 
          When the RTP stream depends on one or more other RTP
          streams (in this case tx-mode MUST be equal to "MSM" and
          MSM is in use), this parameter MUST be present and the
          value MUST be greater than 0.
     */
     if (!strcmp(attr, "sprop-max-don-diff")) {

         if (atoi(value) > 0)

             hevc_data->using_donl_field = 1;

         av_log(s, AV_LOG_TRACE, "Found sprop-max-don-diff in SDP, DON field usage is: %d\n",

                 hevc_data->using_donl_field);

     }
 
     /* sprop-depack-buf-nalus: 0-32767 */
     if (!strcmp(attr, "sprop-depack-buf-nalus")) {

         if (atoi(value) > 0)

             hevc_data->using_donl_field = 1;

         av_log(s, AV_LOG_TRACE, "Found sprop-depack-buf-nalus in SDP, DON field usage is: %d\n",

                 hevc_data->using_donl_field);

     }
 
     /* sprop-depack-buf-bytes: 0-4294967295 */
     /* depack-buf-cap */
     /* sprop-segmentation-id: 0-3 */
     /* sprop-spatial-segmentation-idc: [base16] */
     /* dec-parallel-ca: */
     /* include-dph */
 
     return 0;
 }
 
 static av_cold int hevc_parse_sdp_line(AVFormatContext *ctx, int st_index,

                                        PayloadContext *hevc_data, const char *line)

 {
     AVStream *current_stream;

     AVCodecParameters *par;

     const char *sdp_line_ptr = line;
 
     if (st_index < 0)
         return 0;
 
     current_stream = ctx->streams[st_index];

     par  = current_stream->codecpar;

 
     if (av_strstart(sdp_line_ptr, "framesize:", &sdp_line_ptr)) {

         ff_h264_parse_framesize(par, sdp_line_ptr);

     } else if (av_strstart(sdp_line_ptr, "fmtp:", &sdp_line_ptr)) {

         int ret = ff_parse_fmtp(ctx, current_stream, hevc_data, sdp_line_ptr,
                                 hevc_sdp_parse_fmtp_config);
         if (hevc_data->vps_size || hevc_data->sps_size ||
             hevc_data->pps_size || hevc_data->sei_size) {

             par->extradata_size = hevc_data->vps_size + hevc_data->sps_size +
                                   hevc_data->pps_size + hevc_data->sei_size;

             if ((ret = ff_alloc_extradata(par, par->extradata_size)) >= 0) {

                 int pos = 0;

                 memcpy(par->extradata + pos, hevc_data->vps, hevc_data->vps_size);

                 pos += hevc_data->vps_size;

                 memcpy(par->extradata + pos, hevc_data->sps, hevc_data->sps_size);

                 pos += hevc_data->sps_size;

                 memcpy(par->extradata + pos, hevc_data->pps, hevc_data->pps_size);

                 pos += hevc_data->pps_size;

                 memcpy(par->extradata + pos, hevc_data->sei, hevc_data->sei_size);

             }
 
             av_freep(&hevc_data->vps);
             av_freep(&hevc_data->sps);
             av_freep(&hevc_data->pps);
             av_freep(&hevc_data->sei);
             hevc_data->vps_size = 0;
             hevc_data->sps_size = 0;
             hevc_data->pps_size = 0;
             hevc_data->sei_size = 0;
         }
         return ret;

     }
 
     return 0;
 }
 
 static int hevc_handle_packet(AVFormatContext *ctx, PayloadContext *rtp_hevc_ctx,
                               AVStream *st, AVPacket *pkt, uint32_t *timestamp,
                               const uint8_t *buf, int len, uint16_t seq,
                               int flags)
 {
     const uint8_t *rtp_pl = buf;
     int tid, lid, nal_type;
     int first_fragment, last_fragment, fu_type;
     uint8_t new_nal_header[2];

     int res = 0;

     /* sanity check for size of input packet: 1 byte payload at least */
     if (len < RTP_HEVC_PAYLOAD_HEADER_SIZE + 1) {

         av_log(ctx, AV_LOG_ERROR, "Too short RTP/HEVC packet, got %d bytes\n", len);
         return AVERROR_INVALIDDATA;
     }
 
     /*

      * decode the HEVC payload header according to section 4 of draft version 6:
      *
      *    0                   1
      *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      *   |F|   Type    |  LayerId  | TID |
      *   +-------------+-----------------+
      *
      *      Forbidden zero (F): 1 bit
      *      NAL unit type (Type): 6 bits
      *      NUH layer ID (LayerId): 6 bits
      *      NUH temporal ID plus 1 (TID): 3 bits
      */

     nal_type =  (buf[0] >> 1) & 0x3f;
     lid  = ((buf[0] << 5) & 0x20) | ((buf[1] >> 3) & 0x1f);
     tid  =   buf[1] & 0x07;
 
     /* sanity check for correct layer ID */

     if (lid) {

         /* future scalable or 3D video coding extensions */

         avpriv_report_missing_feature(ctx, "Multi-layer HEVC coding");

         return AVERROR_PATCHWELCOME;
     }
 
     /* sanity check for correct temporal ID */

     if (!tid) {

         av_log(ctx, AV_LOG_ERROR, "Illegal temporal ID in RTP/HEVC packet\n");
         return AVERROR_INVALIDDATA;
     }
 
     /* sanity check for correct NAL unit type */

     if (nal_type > 50) {

         av_log(ctx, AV_LOG_ERROR, "Unsupported (HEVC) NAL type (%d)\n", nal_type);
         return AVERROR_INVALIDDATA;
     }
 

     switch (nal_type) {

     /* video parameter set (VPS) */
     case 32:
     /* sequence parameter set (SPS) */
     case 33:
     /* picture parameter set (PPS) */
     case 34:
     /*  supplemental enhancement information (SEI) */
     case 39:
     /* single NAL unit packet */
     default:
         /* create A/V packet */
         if ((res = av_new_packet(pkt, sizeof(start_sequence) + len)) < 0)
             return res;
         /* A/V packet: copy start sequence */
         memcpy(pkt->data, start_sequence, sizeof(start_sequence));
         /* A/V packet: copy NAL unit data */
         memcpy(pkt->data + sizeof(start_sequence), buf, len);
 
         break;

     /* aggregated packet (AP) - with two or more NAL units */
     case 48:
         /* pass the HEVC payload header */
         buf += RTP_HEVC_PAYLOAD_HEADER_SIZE;
         len -= RTP_HEVC_PAYLOAD_HEADER_SIZE;
 

         /* pass the HEVC DONL field */
         if (rtp_hevc_ctx->using_donl_field) {
             buf += RTP_HEVC_DONL_FIELD_SIZE;
             len -= RTP_HEVC_DONL_FIELD_SIZE;
         }
 

         res = ff_h264_handle_aggregated_packet(ctx, rtp_hevc_ctx, pkt, buf, len,

                                                rtp_hevc_ctx->using_donl_field ?

                                                RTP_HEVC_DOND_FIELD_SIZE : 0,

                                                NULL, 0);
         if (res < 0)
             return res;

         break;

     /* fragmentation unit (FU) */
     case 49:
         /* pass the HEVC payload header */
         buf += RTP_HEVC_PAYLOAD_HEADER_SIZE;
         len -= RTP_HEVC_PAYLOAD_HEADER_SIZE;
 

         /*

          *    decode the FU header
          *
          *     0 1 2 3 4 5 6 7
          *    +-+-+-+-+-+-+-+-+
          *    |S|E|  FuType   |
          *    +---------------+
          *
          *       Start fragment (S): 1 bit
          *       End fragment (E): 1 bit
          *       FuType: 6 bits
          */

         first_fragment = buf[0] & 0x80;

         last_fragment  = buf[0] & 0x40;
         fu_type        = buf[0] & 0x3f;

 
         /* pass the HEVC FU header */
         buf += RTP_HEVC_FU_HEADER_SIZE;
         len -= RTP_HEVC_FU_HEADER_SIZE;
 

         /* pass the HEVC DONL field */
         if (rtp_hevc_ctx->using_donl_field) {
             buf += RTP_HEVC_DONL_FIELD_SIZE;
             len -= RTP_HEVC_DONL_FIELD_SIZE;

         }
 

         av_log(ctx, AV_LOG_TRACE, " FU type %d with %d bytes\n", fu_type, len);

         /* sanity check for size of input packet: 1 byte payload at least */

         if (len <= 0) {

             if (len < 0) {
                 av_log(ctx, AV_LOG_ERROR,
                        "Too short RTP/HEVC packet, got %d bytes of NAL unit type %d\n",
                        len, nal_type);

                 return AVERROR_INVALIDDATA;

             } else {

                 return AVERROR(EAGAIN);

             }

         }
 

         if (first_fragment && last_fragment) {
             av_log(ctx, AV_LOG_ERROR, "Illegal combination of S and E bit in RTP/HEVC packet\n");
             return AVERROR_INVALIDDATA;
         }
 
         new_nal_header[0] = (rtp_pl[0] & 0x81) | (fu_type << 1);
         new_nal_header[1] = rtp_pl[1];
 

         res = ff_h264_handle_frag_packet(pkt, buf, len, first_fragment,
                                          new_nal_header, sizeof(new_nal_header));

         break;
     /* PACI packet */
     case 50:
         /* Temporal scalability control information (TSCI) */

         avpriv_report_missing_feature(ctx, "PACI packets for RTP/HEVC");

         res = AVERROR_PATCHWELCOME;
         break;
     }
 
     pkt->stream_index = st->index;
 
     return res;
 }
 

 const RTPDynamicProtocolHandler ff_hevc_dynamic_handler = {

     .enc_name         = "H265",
     .codec_type       = AVMEDIA_TYPE_VIDEO,

     .codec_id         = AV_CODEC_ID_HEVC,

     .need_parsing     = AVSTREAM_PARSE_FULL,

     .priv_data_size   = sizeof(PayloadContext),

     .parse_sdp_a_line = hevc_parse_sdp_line,

     .parse_packet     = hevc_handle_packet,

 };