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 Libav.
7 *
8 * Libav 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 * Libav 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 Libav; 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/avstring.h"
33#include "libavcodec/get_bits.h"
34
35/** Structure listing useful vars to parse RTP packet payload*/
36struct PayloadContext
37{
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
63typedef struct {
64    const char *str;
65    uint16_t    type;
66    uint32_t    offset;
67} AttrNameMap;
68
69/* All known fmtp parameters and the corresponding RTPAttrTypeEnum */
70#define ATTR_NAME_TYPE_INT 0
71#define ATTR_NAME_TYPE_STR 1
72static const AttrNameMap attr_names[]=
73{
74    { "SizeLength",       ATTR_NAME_TYPE_INT,
75      offsetof(PayloadContext, sizelength) },
76    { "IndexLength",      ATTR_NAME_TYPE_INT,
77      offsetof(PayloadContext, indexlength) },
78    { "IndexDeltaLength", ATTR_NAME_TYPE_INT,
79      offsetof(PayloadContext, indexdeltalength) },
80    { "profile-level-id", ATTR_NAME_TYPE_INT,
81      offsetof(PayloadContext, profile_level_id) },
82    { "StreamType",       ATTR_NAME_TYPE_INT,
83      offsetof(PayloadContext, streamtype) },
84    { "mode",             ATTR_NAME_TYPE_STR,
85      offsetof(PayloadContext, mode) },
86    { NULL, -1, -1 },
87};
88
89static PayloadContext *new_context(void)
90{
91    return av_mallocz(sizeof(PayloadContext));
92}
93
94static void free_context(PayloadContext * data)
95{
96    int i;
97    for (i = 0; i < data->nb_au_headers; i++) {
98         /* according to rtp_parse_mp4_au, we treat multiple
99          * au headers as one, so nb_au_headers is always 1.
100          * loop anyway in case this changes.
101          * (note: changes done carelessly might lead to a double free)
102          */
103       av_free(&data->au_headers[i]);
104    }
105    av_free(data->mode);
106    av_free(data);
107}
108
109static int parse_fmtp_config(AVCodecContext * codec, char *value)
110{
111    /* decode the hexa encoded parameter */
112    int len = ff_hex_to_data(NULL, value);
113    av_free(codec->extradata);
114    codec->extradata = av_mallocz(len + FF_INPUT_BUFFER_PADDING_SIZE);
115    if (!codec->extradata)
116        return AVERROR(ENOMEM);
117    codec->extradata_size = len;
118    ff_hex_to_data(codec->extradata, value);
119    return 0;
120}
121
122static int rtp_parse_mp4_au(PayloadContext *data, const uint8_t *buf)
123{
124    int au_headers_length, au_header_size, i;
125    GetBitContext getbitcontext;
126
127    /* decode the first 2 bytes where the AUHeader sections are stored
128       length in bits */
129    au_headers_length = AV_RB16(buf);
130
131    if (au_headers_length > RTP_MAX_PACKET_LENGTH)
132      return -1;
133
134    data->au_headers_length_bytes = (au_headers_length + 7) / 8;
135
136    /* skip AU headers length section (2 bytes) */
137    buf += 2;
138
139    init_get_bits(&getbitcontext, buf, data->au_headers_length_bytes * 8);
140
141    /* XXX: Wrong if optionnal additional sections are present (cts, dts etc...) */
142    au_header_size = data->sizelength + data->indexlength;
143    if (au_header_size <= 0 || (au_headers_length % au_header_size != 0))
144        return -1;
145
146    data->nb_au_headers = au_headers_length / au_header_size;
147    if (!data->au_headers || data->au_headers_allocated < data->nb_au_headers) {
148        av_free(data->au_headers);
149        data->au_headers = av_malloc(sizeof(struct AUHeaders) * data->nb_au_headers);
150        data->au_headers_allocated = data->nb_au_headers;
151    }
152
153    /* XXX: We handle multiple AU Section as only one (need to fix this for interleaving)
154       In my test, the FAAD decoder does not behave correctly when sending each AU one by one
155       but does when sending the whole as one big packet...  */
156    data->au_headers[0].size = 0;
157    data->au_headers[0].index = 0;
158    for (i = 0; i < data->nb_au_headers; ++i) {
159        data->au_headers[0].size += get_bits_long(&getbitcontext, data->sizelength);
160        data->au_headers[0].index = get_bits_long(&getbitcontext, data->indexlength);
161    }
162
163    data->nb_au_headers = 1;
164
165    return 0;
166}
167
168
169/* Follows RFC 3640 */
170static int aac_parse_packet(AVFormatContext *ctx,
171                            PayloadContext *data,
172                            AVStream *st,
173                            AVPacket *pkt,
174                            uint32_t *timestamp,
175                            const uint8_t *buf, int len, int flags)
176{
177    if (rtp_parse_mp4_au(data, buf))
178        return -1;
179
180    buf += data->au_headers_length_bytes + 2;
181    len -= data->au_headers_length_bytes + 2;
182
183    /* XXX: Fixme we only handle the case where rtp_parse_mp4_au define
184                    one au_header */
185    av_new_packet(pkt, data->au_headers[0].size);
186    memcpy(pkt->data, buf, data->au_headers[0].size);
187
188    pkt->stream_index = st->index;
189    return 0;
190}
191
192static int parse_fmtp(AVStream *stream, PayloadContext *data,
193                      char *attr, char *value)
194{
195    AVCodecContext *codec = stream->codec;
196    int res, i;
197
198    if (!strcmp(attr, "config")) {
199        res = parse_fmtp_config(codec, value);
200
201        if (res < 0)
202            return res;
203    }
204
205    if (codec->codec_id == CODEC_ID_AAC) {
206        /* Looking for a known attribute */
207        for (i = 0; attr_names[i].str; ++i) {
208            if (!av_strcasecmp(attr, attr_names[i].str)) {
209                if (attr_names[i].type == ATTR_NAME_TYPE_INT) {
210                    *(int *)((char *)data+
211                        attr_names[i].offset) = atoi(value);
212                } else if (attr_names[i].type == ATTR_NAME_TYPE_STR)
213                    *(char **)((char *)data+
214                        attr_names[i].offset) = av_strdup(value);
215            }
216        }
217    }
218    return 0;
219}
220
221static int parse_sdp_line(AVFormatContext *s, int st_index,
222                          PayloadContext *data, const char *line)
223{
224    const char *p;
225
226    if (av_strstart(line, "fmtp:", &p))
227        return ff_parse_fmtp(s->streams[st_index], data, p, parse_fmtp);
228
229    return 0;
230}
231
232RTPDynamicProtocolHandler ff_mp4v_es_dynamic_handler = {
233    .enc_name           = "MP4V-ES",
234    .codec_type         = AVMEDIA_TYPE_VIDEO,
235    .codec_id           = CODEC_ID_MPEG4,
236    .parse_sdp_a_line   = parse_sdp_line,
237};
238
239RTPDynamicProtocolHandler ff_mpeg4_generic_dynamic_handler = {
240    .enc_name           = "mpeg4-generic",
241    .codec_type         = AVMEDIA_TYPE_AUDIO,
242    .codec_id           = CODEC_ID_AAC,
243    .parse_sdp_a_line   = parse_sdp_line,
244    .alloc              = new_context,
245    .free               = free_context,
246    .parse_packet       = aac_parse_packet
247};
248