/*
  * RTP H264 Protocol (RFC3984)

  * Copyright (c) 2006 Ryan Martell

  *
  * 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 / RTP Code (RFC3984)
  * @author Ryan Martell <rdm4@martellventures.com>
  *
  * @note Notes:
  * Notes:
  * This currently supports packetization mode:
  * Single Nal Unit Mode (0), or
  * Non-Interleaved Mode (1).  It currently does not support

  * Interleaved Mode (2). (This requires implementing STAP-B, MTAP16, MTAP24,
  *                        FU-B packet types)

  */
 

 #include "libavutil/base64.h"
 #include "libavutil/avstring.h"

 #include "libavcodec/get_bits.h"

 #include "avformat.h"
 

 #include "network.h"

 #include <assert.h>
 

 #include "rtpdec.h"

 #include "rtpdec_formats.h"

 struct PayloadContext {

     // sdp setup parameters

     uint8_t profile_idc;
     uint8_t profile_iop;
     uint8_t level_idc;
     int packetization_mode;

 #ifdef DEBUG
     int packet_types_received[32];
 #endif

 };

 #ifdef DEBUG
 #define COUNT_NAL_TYPE(data, nal) data->packet_types_received[(nal) & 0x1f]++
 #else
 #define COUNT_NAL_TYPE(data, nal) do { } while (0)
 #endif
 

 static const uint8_t start_sequence[] = { 0, 0, 0, 1 };
 

 static int sdp_parse_fmtp_config_h264(AVStream *stream,
                                       PayloadContext *h264_data,

                                       char *attr, char *value)

 {
     AVCodecContext *codec = stream->codec;

     assert(codec->codec_id == AV_CODEC_ID_H264);

     assert(h264_data != NULL);
 
     if (!strcmp(attr, "packetization-mode")) {

         av_log(codec, AV_LOG_DEBUG, "RTP Packetization Mode: %d\n", atoi(value));

         h264_data->packetization_mode = atoi(value);

         /*

          * Packetization Mode:
          * 0 or not present: Single NAL mode (Only nals from 1-23 are allowed)
          * 1: Non-interleaved Mode: 1-23, 24 (STAP-A), 28 (FU-A) are allowed.
          * 2: Interleaved Mode: 25 (STAP-B), 26 (MTAP16), 27 (MTAP24), 28 (FU-A),
          *                      and 29 (FU-B) are allowed.

          */
         if (h264_data->packetization_mode > 1)

             av_log(codec, AV_LOG_ERROR,

                    "Interleaved RTP mode is not supported yet.\n");

     } else if (!strcmp(attr, "profile-level-id")) {
         if (strlen(value) == 6) {
             char buffer[3];
             // 6 characters=3 bytes, in hex.
             uint8_t profile_idc;
             uint8_t profile_iop;
             uint8_t level_idc;
 

             buffer[0]   = value[0];
             buffer[1]   = value[1];
             buffer[2]   = '\0';

             profile_idc = strtol(buffer, NULL, 16);

             buffer[0]   = value[2];
             buffer[1]   = value[3];

             profile_iop = strtol(buffer, NULL, 16);

             buffer[0]   = value[4];
             buffer[1]   = value[5];
             level_idc   = strtol(buffer, NULL, 16);

             av_log(codec, AV_LOG_DEBUG,
                    "RTP Profile IDC: %x Profile IOP: %x Level: %x\n",

                    profile_idc, profile_iop, level_idc);
             h264_data->profile_idc = profile_idc;
             h264_data->profile_iop = profile_iop;

             h264_data->level_idc   = level_idc;

         }

     } else if (!strcmp(attr, "sprop-parameter-sets")) {
         codec->extradata_size = 0;

         av_freep(&codec->extradata);

 
         while (*value) {
             char base64packet[1024];
             uint8_t decoded_packet[1024];

             int packet_size;

             char *dst = base64packet;
 
             while (*value && *value != ','
                    && (dst - base64packet) < sizeof(base64packet) - 1) {
                 *dst++ = *value++;
             }
             *dst++ = '\0';
 
             if (*value == ',')
                 value++;
 

             packet_size = av_base64_decode(decoded_packet, base64packet,
                                            sizeof(decoded_packet));

             if (packet_size > 0) {

                 uint8_t *dest = av_malloc(packet_size + sizeof(start_sequence) +

                                           codec->extradata_size +
                                           FF_INPUT_BUFFER_PADDING_SIZE);

                 if (!dest) {

                     av_log(codec, AV_LOG_ERROR,

                            "Unable to allocate memory for extradata!\n");

                     return AVERROR(ENOMEM);

                 }

                 if (codec->extradata_size) {
                     memcpy(dest, codec->extradata, codec->extradata_size);
                     av_free(codec->extradata);
                 }
 
                 memcpy(dest + codec->extradata_size, start_sequence,
                        sizeof(start_sequence));
                 memcpy(dest + codec->extradata_size + sizeof(start_sequence),
                        decoded_packet, packet_size);
                 memset(dest + codec->extradata_size + sizeof(start_sequence) +
                        packet_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
 
                 codec->extradata       = dest;
                 codec->extradata_size += sizeof(start_sequence) + packet_size;

             }
         }

         av_log(codec, AV_LOG_DEBUG, "Extradata set to %p (size: %d)!\n",

                codec->extradata, codec->extradata_size);

     }

     return 0;

 }
 

 // return 0 on packet, no more left, 1 on packet, 1 on partial packet

 static int h264_handle_packet(AVFormatContext *ctx, PayloadContext *data,
                               AVStream *st, AVPacket *pkt, uint32_t *timestamp,

                               const uint8_t *buf, int len, uint16_t seq,
                               int flags)

 {

     uint8_t nal;
     uint8_t type;

     int result = 0;

     if (!len) {
         av_log(ctx, AV_LOG_ERROR, "Empty H264 RTP packet\n");
         return AVERROR_INVALIDDATA;
     }
     nal  = buf[0];
     type = nal & 0x1f;
 

     assert(data);
     assert(buf);
 

     /* Simplify the case (these are all the nal types used internally by
      * the h264 codec). */

     if (type >= 1 && type <= 23)

         type = 1;

     switch (type) {

     case 0:                    // undefined, but pass them through

     case 1:

         av_new_packet(pkt, len + sizeof(start_sequence));

         memcpy(pkt->data, start_sequence, sizeof(start_sequence));

         memcpy(pkt->data + sizeof(start_sequence), buf, len);

         COUNT_NAL_TYPE(data, nal);

         break;
 
     case 24:                   // STAP-A (one packet, multiple nals)
         // consume the STAP-A NAL
         buf++;
         len--;

         // first we are going to figure out the total size

         {

             int pass         = 0;
             int total_length = 0;
             uint8_t *dst     = NULL;

             for (pass = 0; pass < 2; pass++) {
                 const uint8_t *src = buf;
                 int src_len        = len;

                 while (src_len > 2) {

                     uint16_t nal_size = AV_RB16(src);

                     // consume the length of the aggregate

                     src     += 2;

                     src_len -= 2;
 
                     if (nal_size <= src_len) {

                         if (pass == 0) {

                             // counting

                             total_length += sizeof(start_sequence) + nal_size;

                         } else {
                             // copying
                             assert(dst);
                             memcpy(dst, start_sequence, sizeof(start_sequence));

                             dst += sizeof(start_sequence);

                             memcpy(dst, src, nal_size);

                             COUNT_NAL_TYPE(data, *src);

                             dst += nal_size;

                         }
                     } else {

                         av_log(ctx, AV_LOG_ERROR,

                                "nal size exceeds length: %d %d\n", nal_size, src_len);
                     }
 

                     // eat what we handled

                     src     += nal_size;

                     src_len -= nal_size;
 
                     if (src_len < 0)

                         av_log(ctx, AV_LOG_ERROR,

                                "Consumed more bytes than we got! (%d)\n", src_len);

                 }

                 if (pass == 0) {

                     /* now we know the total size of the packet (with the
                      * start sequences added) */

                     av_new_packet(pkt, total_length);

                     dst = pkt->data;

                 } else {

                     assert(dst - pkt->data == total_length);

                 }
             }
         }
         break;
 
     case 25:                   // STAP-B
     case 26:                   // MTAP-16
     case 27:                   // MTAP-24
     case 29:                   // FU-B

         av_log(ctx, AV_LOG_ERROR,

                "Unhandled type (%d) (See RFC for implementation details\n",
                type);

         result = AVERROR(ENOSYS);

         break;
 
     case 28:                   // FU-A (fragmented nal)
         buf++;

         len--;                 // skip the fu_indicator

         if (len > 1) {

             // these are the same as above, we just redo them here for clarity

             uint8_t fu_indicator      = nal;
             uint8_t fu_header         = *buf;
             uint8_t start_bit         = fu_header >> 7;

             uint8_t av_unused end_bit = (fu_header & 0x40) >> 6;

             uint8_t nal_type          = fu_header & 0x1f;

             uint8_t reconstructed_nal;
 

             // Reconstruct this packet's true nal; only the data follows.
             /* The original nal forbidden bit and NRI are stored in this
              * packet's nal. */

             reconstructed_nal  = fu_indicator & 0xe0;

             reconstructed_nal |= nal_type;

             // skip the fu_header

             buf++;
             len--;
 
             if (start_bit)

                 COUNT_NAL_TYPE(data, nal_type);

             if (start_bit) {

                 /* copy in the start sequence, and the reconstructed nal */

                 av_new_packet(pkt, sizeof(start_sequence) + sizeof(nal) + len);

                 memcpy(pkt->data, start_sequence, sizeof(start_sequence));

                 pkt->data[sizeof(start_sequence)] = reconstructed_nal;
                 memcpy(pkt->data + sizeof(start_sequence) + sizeof(nal), buf, len);

             } else {
                 av_new_packet(pkt, len);
                 memcpy(pkt->data, buf, len);
             }

         } else {
             av_log(ctx, AV_LOG_ERROR, "Too short data for FU-A H264 RTP packet\n");
             result = AVERROR_INVALIDDATA;

         }
         break;
 
     case 30:                   // undefined
     case 31:                   // undefined
     default:

         av_log(ctx, AV_LOG_ERROR, "Undefined type (%d)\n", type);

         result = AVERROR_INVALIDDATA;

         break;
     }
 

     pkt->stream_index = st->index;
 

     return result;
 }
 

 static PayloadContext *h264_new_context(void)

 {

     return av_mallocz(sizeof(PayloadContext) + FF_INPUT_BUFFER_PADDING_SIZE);

 }
 

 static void h264_free_context(PayloadContext *data)

 {
 #ifdef DEBUG
     int ii;
 
     for (ii = 0; ii < 32; ii++) {
         if (data->packet_types_received[ii])
             av_log(NULL, AV_LOG_DEBUG, "Received %d packets of type %d\n",
                    data->packet_types_received[ii], ii);
     }
 #endif
 
     av_free(data);
 }
 

 static int parse_h264_sdp_line(AVFormatContext *s, int st_index,
                                PayloadContext *h264_data, const char *line)

 {

     AVStream *stream;
     AVCodecContext *codec;

     const char *p = line;
 

     if (st_index < 0)
         return 0;
 
     stream = s->streams[st_index];

     codec  = stream->codec;

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

         char buf1[50];
         char *dst = buf1;
 

         // remove the protocol identifier

         while (*p && *p == ' ')
             p++;                     // strip spaces.
         while (*p && *p != ' ')
             p++;                     // eat protocol identifier
         while (*p && *p == ' ')
             p++;                     // strip trailing spaces.
         while (*p && *p != '-' && (dst - buf1) < sizeof(buf1) - 1)

             *dst++ = *p++;
         *dst = '\0';
 
         // a='framesize:96 320-240'

         // set our parameters

         codec->width   = atoi(buf1);
         codec->height  = atoi(p + 1); // skip the -

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

         return ff_parse_fmtp(stream, h264_data, p, sdp_parse_fmtp_config_h264);

     } else if (av_strstart(p, "cliprect:", &p)) {

         // could use this if we wanted.
     }
 

     return 0;

 }
 
 RTPDynamicProtocolHandler ff_h264_dynamic_handler = {

     .enc_name         = "H264",

     .codec_type       = AVMEDIA_TYPE_VIDEO,

     .codec_id         = AV_CODEC_ID_H264,

     .parse_sdp_a_line = parse_h264_sdp_line,

     .alloc            = h264_new_context,
     .free             = h264_free_context,

     .parse_packet     = h264_handle_packet

 };