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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 "rtpdec_formats.h"
  23. #include "internal.h"
  24. #include "libavutil/avstring.h"
  25. #include "libavcodec/get_bits.h"
  26.  
  27. struct PayloadContext {
  28.     AVIOContext *dyn_buf;
  29.     uint8_t *buf;
  30.     int pos, len;
  31.     uint32_t timestamp;
  32. };
  33.  
  34. static PayloadContext *latm_new_context(void)
  35. {
  36.     return av_mallocz(sizeof(PayloadContext));
  37. }
  38.  
  39. static void latm_free_context(PayloadContext *data)
  40. {
  41.     if (!data)
  42.         return;
  43.     if (data->dyn_buf) {
  44.         uint8_t *p;
  45.         avio_close_dyn_buf(data->dyn_buf, &p);
  46.         av_free(p);
  47.     }
  48.     av_free(data->buf);
  49.     av_free(data);
  50. }
  51.  
  52. static int latm_parse_packet(AVFormatContext *ctx, PayloadContext *data,
  53.                              AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  54.                              const uint8_t *buf, int len, uint16_t seq,
  55.                              int flags)
  56. {
  57.     int ret, cur_len;
  58.  
  59.     if (buf) {
  60.         if (!data->dyn_buf || data->timestamp != *timestamp) {
  61.             av_freep(&data->buf);
  62.             if (data->dyn_buf)
  63.                 avio_close_dyn_buf(data->dyn_buf, &data->buf);
  64.             data->dyn_buf = NULL;
  65.             av_freep(&data->buf);
  66.  
  67.             data->timestamp = *timestamp;
  68.             if ((ret = avio_open_dyn_buf(&data->dyn_buf)) < 0)
  69.                 return ret;
  70.         }
  71.         avio_write(data->dyn_buf, buf, len);
  72.  
  73.         if (!(flags & RTP_FLAG_MARKER))
  74.             return AVERROR(EAGAIN);
  75.         av_free(data->buf);
  76.         data->len = avio_close_dyn_buf(data->dyn_buf, &data->buf);
  77.         data->dyn_buf = NULL;
  78.         data->pos = 0;
  79.     }
  80.  
  81.     if (!data->buf) {
  82.         av_log(ctx, AV_LOG_ERROR, "No data available yet\n");
  83.         return AVERROR(EIO);
  84.     }
  85.  
  86.     cur_len = 0;
  87.     while (data->pos < data->len) {
  88.         uint8_t val = data->buf[data->pos++];
  89.         cur_len += val;
  90.         if (val != 0xff)
  91.             break;
  92.     }
  93.     if (data->pos + cur_len > data->len) {
  94.         av_log(ctx, AV_LOG_ERROR, "Malformed LATM packet\n");
  95.         return AVERROR(EIO);
  96.     }
  97.  
  98.     if ((ret = av_new_packet(pkt, cur_len)) < 0)
  99.         return ret;
  100.     memcpy(pkt->data, data->buf + data->pos, cur_len);
  101.     data->pos += cur_len;
  102.     pkt->stream_index = st->index;
  103.     return data->pos < data->len;
  104. }
  105.  
  106. static int parse_fmtp_config(AVStream *st, char *value)
  107. {
  108.     int len = ff_hex_to_data(NULL, value), i, ret = 0;
  109.     GetBitContext gb;
  110.     uint8_t *config;
  111.     int audio_mux_version, same_time_framing, num_programs, num_layers;
  112.  
  113.     /* Pad this buffer, too, to avoid out of bounds reads with get_bits below */
  114.     config = av_mallocz(len + FF_INPUT_BUFFER_PADDING_SIZE);
  115.     if (!config)
  116.         return AVERROR(ENOMEM);
  117.     ff_hex_to_data(config, value);
  118.     init_get_bits(&gb, config, len*8);
  119.     audio_mux_version = get_bits(&gb, 1);
  120.     same_time_framing = get_bits(&gb, 1);
  121.     skip_bits(&gb, 6); /* num_sub_frames */
  122.     num_programs      = get_bits(&gb, 4);
  123.     num_layers        = get_bits(&gb, 3);
  124.     if (audio_mux_version != 0 || same_time_framing != 1 || num_programs != 0 ||
  125.         num_layers != 0) {
  126.         av_log(NULL, AV_LOG_WARNING, "Unsupported LATM config (%d,%d,%d,%d)\n",
  127.                                      audio_mux_version, same_time_framing,
  128.                                      num_programs, num_layers);
  129.         ret = AVERROR_PATCHWELCOME;
  130.         goto end;
  131.     }
  132.     av_freep(&st->codec->extradata);
  133.     if (ff_alloc_extradata(st->codec, (get_bits_left(&gb) + 7)/8)) {
  134.         ret = AVERROR(ENOMEM);
  135.         goto end;
  136.     }
  137.     for (i = 0; i < st->codec->extradata_size; i++)
  138.         st->codec->extradata[i] = get_bits(&gb, 8);
  139.  
  140. end:
  141.     av_free(config);
  142.     return ret;
  143. }
  144.  
  145. static int parse_fmtp(AVStream *stream, PayloadContext *data,
  146.                       char *attr, char *value)
  147. {
  148.     int res;
  149.  
  150.     if (!strcmp(attr, "config")) {
  151.         res = parse_fmtp_config(stream, value);
  152.         if (res < 0)
  153.             return res;
  154.     } else if (!strcmp(attr, "cpresent")) {
  155.         int cpresent = atoi(value);
  156.         if (cpresent != 0)
  157.             avpriv_request_sample(NULL,
  158.                                   "RTP MP4A-LATM with in-band configuration");
  159.     }
  160.  
  161.     return 0;
  162. }
  163.  
  164. static int latm_parse_sdp_line(AVFormatContext *s, int st_index,
  165.                                PayloadContext *data, const char *line)
  166. {
  167.     const char *p;
  168.  
  169.     if (st_index < 0)
  170.         return 0;
  171.  
  172.     if (av_strstart(line, "fmtp:", &p))
  173.         return ff_parse_fmtp(s->streams[st_index], data, p, parse_fmtp);
  174.  
  175.     return 0;
  176. }
  177.  
  178. RTPDynamicProtocolHandler ff_mp4a_latm_dynamic_handler = {
  179.     .enc_name           = "MP4A-LATM",
  180.     .codec_type         = AVMEDIA_TYPE_AUDIO,
  181.     .codec_id           = AV_CODEC_ID_AAC,
  182.     .parse_sdp_a_line   = latm_parse_sdp_line,
  183.     .alloc              = latm_new_context,
  184.     .free               = latm_free_context,
  185.     .parse_packet       = latm_parse_packet
  186. };
  187.