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
28struct PayloadContext {
29    AVIOContext *dyn_buf;
30    uint8_t *buf;
31    int pos, len;
32    uint32_t timestamp;
33};
34
35static void latm_close_context(PayloadContext *data)
36{
37    ffio_free_dyn_buf(&data->dyn_buf);
38    av_freep(&data->buf);
39}
40
41static 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
92static 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    ret = init_get_bits(&gb, config, len*8);
105    if (ret < 0)
106        return ret;
107    audio_mux_version = get_bits(&gb, 1);
108    same_time_framing = get_bits(&gb, 1);
109    skip_bits(&gb, 6); /* num_sub_frames */
110    num_programs      = get_bits(&gb, 4);
111    num_layers        = get_bits(&gb, 3);
112    if (audio_mux_version != 0 || same_time_framing != 1 || num_programs != 0 ||
113        num_layers != 0) {
114        avpriv_report_missing_feature(NULL, "LATM config (%d,%d,%d,%d)",
115                                      audio_mux_version, same_time_framing,
116                                      num_programs, num_layers);
117        ret = AVERROR_PATCHWELCOME;
118        goto end;
119    }
120    ret = ff_alloc_extradata(st->codecpar, (get_bits_left(&gb) + 7)/8);
121    if (ret < 0) {
122        goto end;
123    }
124    for (i = 0; i < st->codecpar->extradata_size; i++)
125        st->codecpar->extradata[i] = get_bits(&gb, 8);
126
127end:
128    av_free(config);
129    return ret;
130}
131
132static int parse_fmtp(AVFormatContext *s,
133                      AVStream *stream, PayloadContext *data,
134                      const char *attr, const char *value)
135{
136    int res;
137
138    if (!strcmp(attr, "config")) {
139        res = parse_fmtp_config(stream, value);
140        if (res < 0)
141            return res;
142    } else if (!strcmp(attr, "cpresent")) {
143        int cpresent = atoi(value);
144        if (cpresent != 0)
145            avpriv_request_sample(s,
146                                  "RTP MP4A-LATM with in-band configuration");
147    }
148
149    return 0;
150}
151
152static int latm_parse_sdp_line(AVFormatContext *s, int st_index,
153                               PayloadContext *data, const char *line)
154{
155    const char *p;
156
157    if (st_index < 0)
158        return 0;
159
160    if (av_strstart(line, "fmtp:", &p))
161        return ff_parse_fmtp(s, s->streams[st_index], data, p, parse_fmtp);
162
163    return 0;
164}
165
166const RTPDynamicProtocolHandler ff_mp4a_latm_dynamic_handler = {
167    .enc_name           = "MP4A-LATM",
168    .codec_type         = AVMEDIA_TYPE_AUDIO,
169    .codec_id           = AV_CODEC_ID_AAC,
170    .priv_data_size     = sizeof(PayloadContext),
171    .parse_sdp_a_line   = latm_parse_sdp_line,
172    .close              = latm_close_context,
173    .parse_packet       = latm_parse_packet,
174};
175