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  1. /*
  2.  * Common code for the RTP depacketization of MPEG-4 formats.
  3.  * Copyright (c) 2010 Fabrice Bellard
  4.  *                    Romain Degez
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. /**
  24.  * @file
  25.  * @brief MPEG4 / RTP Code
  26.  * @author Fabrice Bellard
  27.  * @author Romain Degez
  28.  */
  29.  
  30. #include "rtpdec_formats.h"
  31. #include "internal.h"
  32. #include "libavutil/attributes.h"
  33. #include "libavutil/avstring.h"
  34. #include "libavcodec/get_bits.h"
  35.  
  36. /** Structure listing useful vars to parse RTP packet payload */
  37. struct PayloadContext {
  38.     int sizelength;
  39.     int indexlength;
  40.     int indexdeltalength;
  41.     int profile_level_id;
  42.     int streamtype;
  43.     int objecttype;
  44.     char *mode;
  45.  
  46.     /** mpeg 4 AU headers */
  47.     struct AUHeaders {
  48.         int size;
  49.         int index;
  50.         int cts_flag;
  51.         int cts;
  52.         int dts_flag;
  53.         int dts;
  54.         int rap_flag;
  55.         int streamstate;
  56.     } *au_headers;
  57.     int au_headers_allocated;
  58.     int nb_au_headers;
  59.     int au_headers_length_bytes;
  60.     int cur_au_index;
  61.  
  62.     uint8_t buf[RTP_MAX_PACKET_LENGTH];
  63.     int buf_pos, buf_size;
  64. };
  65.  
  66. typedef struct {
  67.     const char *str;
  68.     uint16_t    type;
  69.     uint32_t    offset;
  70. } AttrNameMap;
  71.  
  72. /* All known fmtp parameters and the corresponding RTPAttrTypeEnum */
  73. #define ATTR_NAME_TYPE_INT 0
  74. #define ATTR_NAME_TYPE_STR 1
  75. static const AttrNameMap attr_names[] = {
  76.     { "SizeLength",       ATTR_NAME_TYPE_INT,
  77.       offsetof(PayloadContext, sizelength) },
  78.     { "IndexLength",      ATTR_NAME_TYPE_INT,
  79.       offsetof(PayloadContext, indexlength) },
  80.     { "IndexDeltaLength", ATTR_NAME_TYPE_INT,
  81.       offsetof(PayloadContext, indexdeltalength) },
  82.     { "profile-level-id", ATTR_NAME_TYPE_INT,
  83.       offsetof(PayloadContext, profile_level_id) },
  84.     { "StreamType",       ATTR_NAME_TYPE_INT,
  85.       offsetof(PayloadContext, streamtype) },
  86.     { "mode",             ATTR_NAME_TYPE_STR,
  87.       offsetof(PayloadContext, mode) },
  88.     { NULL, -1, -1 },
  89. };
  90.  
  91. static PayloadContext *new_context(void)
  92. {
  93.     return av_mallocz(sizeof(PayloadContext));
  94. }
  95.  
  96. static void free_context(PayloadContext *data)
  97. {
  98.     av_free(data->au_headers);
  99.     av_free(data->mode);
  100.     av_free(data);
  101. }
  102.  
  103. static int parse_fmtp_config(AVCodecContext *codec, char *value)
  104. {
  105.     /* decode the hexa encoded parameter */
  106.     int len = ff_hex_to_data(NULL, value);
  107.     av_free(codec->extradata);
  108.     if (ff_alloc_extradata(codec, len))
  109.         return AVERROR(ENOMEM);
  110.     ff_hex_to_data(codec->extradata, value);
  111.     return 0;
  112. }
  113.  
  114. static int rtp_parse_mp4_au(PayloadContext *data, const uint8_t *buf, int len)
  115. {
  116.     int au_headers_length, au_header_size, i;
  117.     GetBitContext getbitcontext;
  118.  
  119.     if (len < 2)
  120.         return AVERROR_INVALIDDATA;
  121.  
  122.     /* decode the first 2 bytes where the AUHeader sections are stored
  123.        length in bits */
  124.     au_headers_length = AV_RB16(buf);
  125.  
  126.     if (au_headers_length > RTP_MAX_PACKET_LENGTH)
  127.       return -1;
  128.  
  129.     data->au_headers_length_bytes = (au_headers_length + 7) / 8;
  130.  
  131.     /* skip AU headers length section (2 bytes) */
  132.     buf += 2;
  133.     len -= 2;
  134.  
  135.     if (len < data->au_headers_length_bytes)
  136.         return AVERROR_INVALIDDATA;
  137.  
  138.     init_get_bits(&getbitcontext, buf, data->au_headers_length_bytes * 8);
  139.  
  140.     /* XXX: Wrong if optional additional sections are present (cts, dts etc...) */
  141.     au_header_size = data->sizelength + data->indexlength;
  142.     if (au_header_size <= 0 || (au_headers_length % au_header_size != 0))
  143.         return -1;
  144.  
  145.     data->nb_au_headers = au_headers_length / au_header_size;
  146.     if (!data->au_headers || data->au_headers_allocated < data->nb_au_headers) {
  147.         av_free(data->au_headers);
  148.         data->au_headers = av_malloc(sizeof(struct AUHeaders) * data->nb_au_headers);
  149.         if (!data->au_headers)
  150.             return AVERROR(ENOMEM);
  151.         data->au_headers_allocated = data->nb_au_headers;
  152.     }
  153.  
  154.     for (i = 0; i < data->nb_au_headers; ++i) {
  155.         data->au_headers[i].size  = get_bits_long(&getbitcontext, data->sizelength);
  156.         data->au_headers[i].index = get_bits_long(&getbitcontext, data->indexlength);
  157.     }
  158.  
  159.     return 0;
  160. }
  161.  
  162.  
  163. /* Follows RFC 3640 */
  164. static int aac_parse_packet(AVFormatContext *ctx, PayloadContext *data,
  165.                             AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  166.                             const uint8_t *buf, int len, uint16_t seq,
  167.                             int flags)
  168. {
  169.     int ret;
  170.  
  171.     if (!buf) {
  172.         if (data->cur_au_index > data->nb_au_headers)
  173.             return AVERROR_INVALIDDATA;
  174.         if (data->buf_size - data->buf_pos < data->au_headers[data->cur_au_index].size)
  175.             return AVERROR_INVALIDDATA;
  176.         if ((ret = av_new_packet(pkt, data->au_headers[data->cur_au_index].size)) < 0)
  177.             return ret;
  178.         memcpy(pkt->data, &data->buf[data->buf_pos], data->au_headers[data->cur_au_index].size);
  179.         data->buf_pos += data->au_headers[data->cur_au_index].size;
  180.         pkt->stream_index = st->index;
  181.         data->cur_au_index++;
  182.         return data->cur_au_index < data->nb_au_headers;
  183.     }
  184.  
  185.     if (rtp_parse_mp4_au(data, buf, len))
  186.         return -1;
  187.  
  188.     buf += data->au_headers_length_bytes + 2;
  189.     len -= data->au_headers_length_bytes + 2;
  190.  
  191.     if (len < data->au_headers[0].size)
  192.         return AVERROR_INVALIDDATA;
  193.     if ((ret = av_new_packet(pkt, data->au_headers[0].size)) < 0)
  194.         return ret;
  195.     memcpy(pkt->data, buf, data->au_headers[0].size);
  196.     len -= data->au_headers[0].size;
  197.     buf += data->au_headers[0].size;
  198.     pkt->stream_index = st->index;
  199.  
  200.     if (len > 0 && data->nb_au_headers > 1) {
  201.         data->buf_size = FFMIN(len, sizeof(data->buf));
  202.         memcpy(data->buf, buf, data->buf_size);
  203.         data->cur_au_index = 1;
  204.         data->buf_pos = 0;
  205.         return 1;
  206.     }
  207.  
  208.     return 0;
  209. }
  210.  
  211. static int parse_fmtp(AVStream *stream, PayloadContext *data,
  212.                       char *attr, char *value)
  213. {
  214.     AVCodecContext *codec = stream->codec;
  215.     int res, i;
  216.  
  217.     if (!strcmp(attr, "config")) {
  218.         res = parse_fmtp_config(codec, value);
  219.  
  220.         if (res < 0)
  221.             return res;
  222.     }
  223.  
  224.     if (codec->codec_id == AV_CODEC_ID_AAC) {
  225.         /* Looking for a known attribute */
  226.         for (i = 0; attr_names[i].str; ++i) {
  227.             if (!av_strcasecmp(attr, attr_names[i].str)) {
  228.                 if (attr_names[i].type == ATTR_NAME_TYPE_INT) {
  229.                     *(int *)((char *)data+
  230.                         attr_names[i].offset) = atoi(value);
  231.                 } else if (attr_names[i].type == ATTR_NAME_TYPE_STR)
  232.                     *(char **)((char *)data+
  233.                         attr_names[i].offset) = av_strdup(value);
  234.             }
  235.         }
  236.     }
  237.     return 0;
  238. }
  239.  
  240. static int parse_sdp_line(AVFormatContext *s, int st_index,
  241.                           PayloadContext *data, const char *line)
  242. {
  243.     const char *p;
  244.  
  245.     if (st_index < 0)
  246.         return 0;
  247.  
  248.     if (av_strstart(line, "fmtp:", &p))
  249.         return ff_parse_fmtp(s->streams[st_index], data, p, parse_fmtp);
  250.  
  251.     return 0;
  252. }
  253.  
  254. static av_cold int init_video(AVFormatContext *s, int st_index,
  255.                               PayloadContext *data)
  256. {
  257.     if (st_index < 0)
  258.         return 0;
  259.     s->streams[st_index]->need_parsing = AVSTREAM_PARSE_FULL;
  260.     return 0;
  261. }
  262.  
  263. RTPDynamicProtocolHandler ff_mp4v_es_dynamic_handler = {
  264.     .enc_name           = "MP4V-ES",
  265.     .codec_type         = AVMEDIA_TYPE_VIDEO,
  266.     .codec_id           = AV_CODEC_ID_MPEG4,
  267.     .init               = init_video,
  268.     .parse_sdp_a_line   = parse_sdp_line,
  269. };
  270.  
  271. RTPDynamicProtocolHandler ff_mpeg4_generic_dynamic_handler = {
  272.     .enc_name           = "mpeg4-generic",
  273.     .codec_type         = AVMEDIA_TYPE_AUDIO,
  274.     .codec_id           = AV_CODEC_ID_AAC,
  275.     .parse_sdp_a_line   = parse_sdp_line,
  276.     .alloc              = new_context,
  277.     .free               = free_context,
  278.     .parse_packet       = aac_parse_packet
  279. };
  280.