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
27struct PayloadContext {
28    AVIOContext *dyn_buf;
29    uint8_t *buf;
30    int pos, len;
31    uint32_t timestamp;
32};
33
34static PayloadContext *latm_new_context(void)
35{
36    return av_mallocz(sizeof(PayloadContext));
37}
38
39static 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
52static 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
106static 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
140end:
141    av_free(config);
142    return ret;
143}
144
145static int parse_fmtp(AVFormatContext *s,
146                      AVStream *stream, PayloadContext *data,
147                      char *attr, char *value)
148{
149    int res;
150
151    if (!strcmp(attr, "config")) {
152        res = parse_fmtp_config(stream, value);
153        if (res < 0)
154            return res;
155    } else if (!strcmp(attr, "cpresent")) {
156        int cpresent = atoi(value);
157        if (cpresent != 0)
158            avpriv_request_sample(s,
159                                  "RTP MP4A-LATM with in-band configuration");
160    }
161
162    return 0;
163}
164
165static int latm_parse_sdp_line(AVFormatContext *s, int st_index,
166                               PayloadContext *data, const char *line)
167{
168    const char *p;
169
170    if (st_index < 0)
171        return 0;
172
173    if (av_strstart(line, "fmtp:", &p))
174        return ff_parse_fmtp(s, s->streams[st_index], data, p, parse_fmtp);
175
176    return 0;
177}
178
179RTPDynamicProtocolHandler ff_mp4a_latm_dynamic_handler = {
180    .enc_name           = "MP4A-LATM",
181    .codec_type         = AVMEDIA_TYPE_AUDIO,
182    .codec_id           = AV_CODEC_ID_AAC,
183    .parse_sdp_a_line   = latm_parse_sdp_line,
184    .alloc              = latm_new_context,
185    .free               = latm_free_context,
186    .parse_packet       = latm_parse_packet
187};
188