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  1. /*
  2.  * RTP Depacketization of MP4A-LATM, RFC 3016
  3.  * Copyright (c) 2010 Martin Storsjo
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. #include "avio_internal.h"
  23. #include "rtpdec_formats.h"
  24. #include "internal.h"
  25. #include "libavutil/avstring.h"
  26. #include "libavcodec/get_bits.h"
  27.  
  28. struct PayloadContext {
  29.     AVIOContext *dyn_buf;
  30.     uint8_t *buf;
  31.     int pos, len;
  32.     uint32_t timestamp;
  33. };
  34.  
  35. static void latm_close_context(PayloadContext *data)
  36. {
  37.     ffio_free_dyn_buf(&data->dyn_buf);
  38.     av_freep(&data->buf);
  39. }
  40.  
  41. static int latm_parse_packet(AVFormatContext *ctx, PayloadContext *data,
  42.                              AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  43.                              const uint8_t *buf, int len, uint16_t seq,
  44.                              int flags)
  45. {
  46.     int ret, cur_len;
  47.  
  48.     if (buf) {
  49.         if (!data->dyn_buf || data->timestamp != *timestamp) {
  50.             av_freep(&data->buf);
  51.             ffio_free_dyn_buf(&data->dyn_buf);
  52.  
  53.             data->timestamp = *timestamp;
  54.             if ((ret = avio_open_dyn_buf(&data->dyn_buf)) < 0)
  55.                 return ret;
  56.         }
  57.         avio_write(data->dyn_buf, buf, len);
  58.  
  59.         if (!(flags & RTP_FLAG_MARKER))
  60.             return AVERROR(EAGAIN);
  61.         av_freep(&data->buf);
  62.         data->len = avio_close_dyn_buf(data->dyn_buf, &data->buf);
  63.         data->dyn_buf = NULL;
  64.         data->pos = 0;
  65.     }
  66.  
  67.     if (!data->buf) {
  68.         av_log(ctx, AV_LOG_ERROR, "No data available yet\n");
  69.         return AVERROR(EIO);
  70.     }
  71.  
  72.     cur_len = 0;
  73.     while (data->pos < data->len) {
  74.         uint8_t val = data->buf[data->pos++];
  75.         cur_len += val;
  76.         if (val != 0xff)
  77.             break;
  78.     }
  79.     if (data->pos + cur_len > data->len) {
  80.         av_log(ctx, AV_LOG_ERROR, "Malformed LATM packet\n");
  81.         return AVERROR(EIO);
  82.     }
  83.  
  84.     if ((ret = av_new_packet(pkt, cur_len)) < 0)
  85.         return ret;
  86.     memcpy(pkt->data, data->buf + data->pos, cur_len);
  87.     data->pos += cur_len;
  88.     pkt->stream_index = st->index;
  89.     return data->pos < data->len;
  90. }
  91.  
  92. static int parse_fmtp_config(AVStream *st, const char *value)
  93. {
  94.     int len = ff_hex_to_data(NULL, value), i, ret = 0;
  95.     GetBitContext gb;
  96.     uint8_t *config;
  97.     int audio_mux_version, same_time_framing, num_programs, num_layers;
  98.  
  99.     /* Pad this buffer, too, to avoid out of bounds reads with get_bits below */
  100.     config = av_mallocz(len + AV_INPUT_BUFFER_PADDING_SIZE);
  101.     if (!config)
  102.         return AVERROR(ENOMEM);
  103.     ff_hex_to_data(config, value);
  104.     init_get_bits(&gb, config, len*8);
  105.     audio_mux_version = get_bits(&gb, 1);
  106.     same_time_framing = get_bits(&gb, 1);
  107.     skip_bits(&gb, 6); /* num_sub_frames */
  108.     num_programs      = get_bits(&gb, 4);
  109.     num_layers        = get_bits(&gb, 3);
  110.     if (audio_mux_version != 0 || same_time_framing != 1 || num_programs != 0 ||
  111.         num_layers != 0) {
  112.         av_log(NULL, AV_LOG_WARNING, "Unsupported LATM config (%d,%d,%d,%d)\n",
  113.                                      audio_mux_version, same_time_framing,
  114.                                      num_programs, num_layers);
  115.         ret = AVERROR_PATCHWELCOME;
  116.         goto end;
  117.     }
  118.     av_freep(&st->codec->extradata);
  119.     if (ff_alloc_extradata(st->codec, (get_bits_left(&gb) + 7)/8)) {
  120.         ret = AVERROR(ENOMEM);
  121.         goto end;
  122.     }
  123.     for (i = 0; i < st->codec->extradata_size; i++)
  124.         st->codec->extradata[i] = get_bits(&gb, 8);
  125.  
  126. end:
  127.     av_free(config);
  128.     return ret;
  129. }
  130.  
  131. static int parse_fmtp(AVFormatContext *s,
  132.                       AVStream *stream, PayloadContext *data,
  133.                       const char *attr, const char *value)
  134. {
  135.     int res;
  136.  
  137.     if (!strcmp(attr, "config")) {
  138.         res = parse_fmtp_config(stream, value);
  139.         if (res < 0)
  140.             return res;
  141.     } else if (!strcmp(attr, "cpresent")) {
  142.         int cpresent = atoi(value);
  143.         if (cpresent != 0)
  144.             avpriv_request_sample(s,
  145.                                   "RTP MP4A-LATM with in-band configuration");
  146.     }
  147.  
  148.     return 0;
  149. }
  150.  
  151. static int latm_parse_sdp_line(AVFormatContext *s, int st_index,
  152.                                PayloadContext *data, const char *line)
  153. {
  154.     const char *p;
  155.  
  156.     if (st_index < 0)
  157.         return 0;
  158.  
  159.     if (av_strstart(line, "fmtp:", &p))
  160.         return ff_parse_fmtp(s, s->streams[st_index], data, p, parse_fmtp);
  161.  
  162.     return 0;
  163. }
  164.  
  165. RTPDynamicProtocolHandler ff_mp4a_latm_dynamic_handler = {
  166.     .enc_name           = "MP4A-LATM",
  167.     .codec_type         = AVMEDIA_TYPE_AUDIO,
  168.     .codec_id           = AV_CODEC_ID_AAC,
  169.     .priv_data_size     = sizeof(PayloadContext),
  170.     .parse_sdp_a_line   = latm_parse_sdp_line,
  171.     .close              = latm_close_context,
  172.     .parse_packet       = latm_parse_packet,
  173. };
  174.