/*

  * RTP Depacketization of MP4A-LATM, RFC 3016
  * Copyright (c) 2010 Martin Storsjo
  *
  * 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 "rtpdec_formats.h"
 #include "internal.h"
 #include "libavutil/avstring.h"
 #include "libavcodec/get_bits.h"
 
 struct PayloadContext {

     AVIOContext *dyn_buf;

     uint8_t *buf;
     int pos, len;
     uint32_t timestamp;
 };
 
 static PayloadContext *latm_new_context(void)
 {
     return av_mallocz(sizeof(PayloadContext));
 }
 
 static void latm_free_context(PayloadContext *data)
 {
     if (!data)
         return;
     if (data->dyn_buf) {
         uint8_t *p;

         avio_close_dyn_buf(data->dyn_buf, &p);

         av_free(p);
     }
     av_free(data->buf);
     av_free(data);
 }
 
 static int latm_parse_packet(AVFormatContext *ctx, PayloadContext *data,
                              AVStream *st, AVPacket *pkt, uint32_t *timestamp,

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

 {
     int ret, cur_len;
 
     if (buf) {
         if (!data->dyn_buf || data->timestamp != *timestamp) {
             av_freep(&data->buf);
             if (data->dyn_buf)

                 avio_close_dyn_buf(data->dyn_buf, &data->buf);

             data->dyn_buf = NULL;
             av_freep(&data->buf);
 
             data->timestamp = *timestamp;

             if ((ret = avio_open_dyn_buf(&data->dyn_buf)) < 0)

                 return ret;
         }

         avio_write(data->dyn_buf, buf, len);

 
         if (!(flags & RTP_FLAG_MARKER))
             return AVERROR(EAGAIN);
         av_free(data->buf);

         data->len = avio_close_dyn_buf(data->dyn_buf, &data->buf);

         data->dyn_buf = NULL;
         data->pos = 0;
     }
 
     if (!data->buf) {
         av_log(ctx, AV_LOG_ERROR, "No data available yet\n");
         return AVERROR(EIO);
     }
 
     cur_len = 0;
     while (data->pos < data->len) {
         uint8_t val = data->buf[data->pos++];
         cur_len += val;
         if (val != 0xff)
             break;
     }
     if (data->pos + cur_len > data->len) {
         av_log(ctx, AV_LOG_ERROR, "Malformed LATM packet\n");
         return AVERROR(EIO);
     }
 
     if ((ret = av_new_packet(pkt, cur_len)) < 0)
         return ret;
     memcpy(pkt->data, data->buf + data->pos, cur_len);
     data->pos += cur_len;
     pkt->stream_index = st->index;
     return data->pos < data->len;
 }
 
 static int parse_fmtp_config(AVStream *st, char *value)
 {
     int len = ff_hex_to_data(NULL, value), i, ret = 0;
     GetBitContext gb;
     uint8_t *config;

     int audio_mux_version, same_time_framing, num_programs, num_layers;

 
     /* Pad this buffer, too, to avoid out of bounds reads with get_bits below */
     config = av_mallocz(len + FF_INPUT_BUFFER_PADDING_SIZE);
     if (!config)
         return AVERROR(ENOMEM);
     ff_hex_to_data(config, value);
     init_get_bits(&gb, config, len*8);
     audio_mux_version = get_bits(&gb, 1);
     same_time_framing = get_bits(&gb, 1);

     skip_bits(&gb, 6); /* num_sub_frames */

     num_programs      = get_bits(&gb, 4);
     num_layers        = get_bits(&gb, 3);
     if (audio_mux_version != 0 || same_time_framing != 1 || num_programs != 0 ||
         num_layers != 0) {
         av_log(NULL, AV_LOG_WARNING, "Unsupported LATM config (%d,%d,%d,%d)\n",
                                      audio_mux_version, same_time_framing,
                                      num_programs, num_layers);
         ret = AVERROR_PATCHWELCOME;
         goto end;
     }
     av_freep(&st->codec->extradata);

     if (ff_alloc_extradata(st->codec, (get_bits_left(&gb) + 7)/8)) {

         ret = AVERROR(ENOMEM);
         goto end;
     }
     for (i = 0; i < st->codec->extradata_size; i++)
         st->codec->extradata[i] = get_bits(&gb, 8);
 
 end:
     av_free(config);
     return ret;
 }
 
 static int parse_fmtp(AVStream *stream, PayloadContext *data,
                       char *attr, char *value)
 {
     int res;
 
     if (!strcmp(attr, "config")) {
         res = parse_fmtp_config(stream, value);
         if (res < 0)
             return res;
     } else if (!strcmp(attr, "cpresent")) {
         int cpresent = atoi(value);
         if (cpresent != 0)

             avpriv_request_sample(NULL,
                                   "RTP MP4A-LATM with in-band configuration");

     }
 
     return 0;
 }
 
 static int latm_parse_sdp_line(AVFormatContext *s, int st_index,
                                PayloadContext *data, const char *line)
 {
     const char *p;
 

     if (st_index < 0)
         return 0;
 

     if (av_strstart(line, "fmtp:", &p))
         return ff_parse_fmtp(s->streams[st_index], data, p, parse_fmtp);
 
     return 0;
 }
 
 RTPDynamicProtocolHandler ff_mp4a_latm_dynamic_handler = {
     .enc_name           = "MP4A-LATM",
     .codec_type         = AVMEDIA_TYPE_AUDIO,

     .codec_id           = AV_CODEC_ID_AAC,

     .parse_sdp_a_line   = latm_parse_sdp_line,

     .alloc              = latm_new_context,
     .free               = latm_free_context,

     .parse_packet       = latm_parse_packet
 };