/*
  * RTP/Quicktime support.
  * Copyright (c) 2009 Ronald S. Bultje
  *
  * 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 Quicktime-style RTP support
  * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
  */
 
 #include "avformat.h"

 #include "internal.h"

 #include "avio_internal.h"

 #include "rtp.h"
 #include "rtpdec.h"
 #include "isom.h"
 #include "libavcodec/get_bits.h"
 
 struct PayloadContext {
     AVPacket pkt;
     int bytes_per_frame, remaining;
     uint32_t timestamp;
 };
 
 static int qt_rtp_parse_packet(AVFormatContext *s, PayloadContext *qt,
                                AVStream *st, AVPacket *pkt,
                                uint32_t *timestamp, const uint8_t *buf,

                                int len, uint16_t seq, int flags)

 {

     AVIOContext pb;

     GetBitContext gb;
     int packing_scheme, has_payload_desc, has_packet_info, alen,
         has_marker_bit = flags & RTP_FLAG_MARKER;
 
     if (qt->remaining) {
         int num = qt->pkt.size / qt->bytes_per_frame;
 
         if (av_new_packet(pkt, qt->bytes_per_frame))
             return AVERROR(ENOMEM);
         pkt->stream_index = st->index;
         pkt->flags        = qt->pkt.flags;
         memcpy(pkt->data,
                &qt->pkt.data[(num - qt->remaining) * qt->bytes_per_frame],
                qt->bytes_per_frame);
         if (--qt->remaining == 0) {
             av_freep(&qt->pkt.data);
             qt->pkt.size = 0;
         }
         return qt->remaining > 0;
     }
 
     /**
      * The RTP payload is described in:
      * http://developer.apple.com/quicktime/icefloe/dispatch026.html
      */
     init_get_bits(&gb, buf, len << 3);

     ffio_init_context(&pb, buf, len, 0, NULL, NULL, NULL, NULL);

 
     if (len < 4)
         return AVERROR_INVALIDDATA;
 
     skip_bits(&gb, 4); // version
     if ((packing_scheme = get_bits(&gb, 2)) == 0)
         return AVERROR_INVALIDDATA;
     if (get_bits1(&gb))
         flags          |= RTP_FLAG_KEY;
     has_payload_desc    = get_bits1(&gb);
     has_packet_info     = get_bits1(&gb);
     skip_bits(&gb, 23); // reserved:7, cache payload info:1, payload ID:15
 
     if (has_payload_desc) {
         int data_len, pos, is_start, is_finish;
         uint32_t tag;
 
         pos = get_bits_count(&gb) >> 3;
         if (pos + 12 > len)
             return AVERROR_INVALIDDATA;
 
         skip_bits(&gb, 2); // has non-I frames:1, is sparse:1
         is_start  = get_bits1(&gb);
         is_finish = get_bits1(&gb);
         if (!is_start || !is_finish) {
             av_log_missing_feature(s, "RTP-X-QT with payload description "
                                       "split over several packets", 1);

             return AVERROR_PATCHWELCOME;

         }
         skip_bits(&gb, 12); // reserved
         data_len = get_bits(&gb, 16);
 

         avio_seek(&pb, pos + 4, SEEK_SET);

         tag = avio_rl32(&pb);

         if ((st->codec->codec_type == AVMEDIA_TYPE_VIDEO &&

                  tag != MKTAG('v','i','d','e')) ||

             (st->codec->codec_type == AVMEDIA_TYPE_AUDIO &&

                  tag != MKTAG('s','o','u','n')))
             return AVERROR_INVALIDDATA;

         avpriv_set_pts_info(st, 32, 1, avio_rb32(&pb));

 
         if (pos + data_len > len)
             return AVERROR_INVALIDDATA;
         /* TLVs */

         while (avio_tell(&pb) + 4 < pos + data_len) {

             int tlv_len = avio_rb16(&pb);
             tag = avio_rl16(&pb);

             if (avio_tell(&pb) + tlv_len > pos + data_len)

                 return AVERROR_INVALIDDATA;
 
 #define MKTAG16(a,b) MKTAG(a,b,0,0)
             switch (tag) {
             case MKTAG16('s','d'): {
                 MOVStreamContext *msc;
                 void *priv_data = st->priv_data;
                 int nb_streams = s->nb_streams;
                 MOVContext *mc = av_mallocz(sizeof(*mc));
                 if (!mc)
                     return AVERROR(ENOMEM);
                 mc->fc = s;
                 st->priv_data = msc = av_mallocz(sizeof(MOVStreamContext));
                 if (!msc) {
                     av_free(mc);
                     st->priv_data = priv_data;
                     return AVERROR(ENOMEM);
                 }
                 /* ff_mov_read_stsd_entries updates stream s->nb_streams-1,
                  * so set it temporarily to indicate which stream to update. */
                 s->nb_streams = st->index + 1;
                 ff_mov_read_stsd_entries(mc, &pb, 1);
                 qt->bytes_per_frame = msc->bytes_per_frame;
                 av_free(msc);
                 av_free(mc);
                 st->priv_data = priv_data;
                 s->nb_streams = nb_streams;
                 break;
             }
             default:

                 avio_skip(&pb, tlv_len);

                 break;
             }
         }
 
         /* 32-bit alignment */

         avio_skip(&pb, ((avio_tell(&pb) + 3) & ~3) - avio_tell(&pb));

     } else

         avio_seek(&pb, 4, SEEK_SET);

 
     if (has_packet_info) {
         av_log_missing_feature(s, "RTP-X-QT with packet specific info", 1);

         return AVERROR_PATCHWELCOME;

     }
 

     alen = len - avio_tell(&pb);

     if (alen <= 0)
         return AVERROR_INVALIDDATA;
 
     switch (packing_scheme) {
     case 3: /* one data packet spread over 1 or multiple RTP packets */
         if (qt->pkt.size > 0 && qt->timestamp == *timestamp) {
             qt->pkt.data = av_realloc(qt->pkt.data, qt->pkt.size + alen +
                                       FF_INPUT_BUFFER_PADDING_SIZE);
         } else {
             av_freep(&qt->pkt.data);
             av_init_packet(&qt->pkt);
             qt->pkt.data = av_malloc(alen + FF_INPUT_BUFFER_PADDING_SIZE);
             qt->pkt.size = 0;
             qt->timestamp = *timestamp;
         }
         if (!qt->pkt.data)
             return AVERROR(ENOMEM);

         memcpy(qt->pkt.data + qt->pkt.size, buf + avio_tell(&pb), alen);

         qt->pkt.size += alen;
         if (has_marker_bit) {
             *pkt = qt->pkt;
             qt->pkt.size = 0;
             qt->pkt.data = NULL;
             pkt->flags        = flags & RTP_FLAG_KEY ? AV_PKT_FLAG_KEY : 0;
             pkt->stream_index = st->index;
             pkt->destruct     = av_destruct_packet;
             memset(pkt->data + pkt->size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
             return 0;
         }
         return AVERROR(EAGAIN);
 
     case 1: /* constant packet size, multiple packets per RTP packet */
         if (qt->bytes_per_frame == 0 ||
             alen % qt->bytes_per_frame != 0)
             return AVERROR_INVALIDDATA; /* wrongly padded */
         qt->remaining = (alen / qt->bytes_per_frame) - 1;
         if (av_new_packet(pkt, qt->bytes_per_frame))
             return AVERROR(ENOMEM);

         memcpy(pkt->data, buf + avio_tell(&pb), qt->bytes_per_frame);

         pkt->flags = flags & RTP_FLAG_KEY ? AV_PKT_FLAG_KEY : 0;
         pkt->stream_index = st->index;
         if (qt->remaining > 0) {
             av_freep(&qt->pkt.data);
             qt->pkt.data = av_malloc(qt->remaining * qt->bytes_per_frame);
             if (!qt->pkt.data) {
                 av_free_packet(pkt);
                 return AVERROR(ENOMEM);
             }
             qt->pkt.size = qt->remaining * qt->bytes_per_frame;
             memcpy(qt->pkt.data,

                    buf + avio_tell(&pb) + qt->bytes_per_frame,

                    qt->remaining * qt->bytes_per_frame);
             qt->pkt.flags = pkt->flags;
             return 1;
         }
         return 0;
 
     default:  /* unimplemented */
         av_log_missing_feature(NULL, "RTP-X-QT with packing scheme 2", 1);

         return AVERROR_PATCHWELCOME;

     }
 }
 
 static PayloadContext *qt_rtp_new(void)
 {
     return av_mallocz(sizeof(PayloadContext));
 }
 
 static void qt_rtp_free(PayloadContext *qt)
 {
     av_freep(&qt->pkt.data);
     av_free(qt);
 }
 
 #define RTP_QT_HANDLER(m, n, s, t) \
 RTPDynamicProtocolHandler ff_ ## m ## _rtp_ ## n ## _handler = { \

     .enc_name         = s, \
     .codec_type       = t, \

     .codec_id         = AV_CODEC_ID_NONE, \

     .alloc            = qt_rtp_new,    \
     .free             = qt_rtp_free,   \

     .parse_packet     = qt_rtp_parse_packet, \

 }

 RTP_QT_HANDLER(qt,        vid, "X-QT",        AVMEDIA_TYPE_VIDEO);
 RTP_QT_HANDLER(qt,        aud, "X-QT",        AVMEDIA_TYPE_AUDIO);
 RTP_QT_HANDLER(quicktime, vid, "X-QUICKTIME", AVMEDIA_TYPE_VIDEO);
 RTP_QT_HANDLER(quicktime, aud, "X-QUICKTIME", AVMEDIA_TYPE_AUDIO);