1/*
2 * RTP parser for loss tolerant payload format for MP3 audio (RFC 5219)
3 * Copyright (c) 2015 Gilles Chanteperdrix <gch@xenomai.org>
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 "libavutil/attributes.h"
23#include "libavutil/intreadwrite.h"
24
25#include "avio_internal.h"
26#include "rtpdec_formats.h"
27
28struct PayloadContext {
29    unsigned adu_size;
30    unsigned cur_size;
31    uint32_t timestamp;
32    uint8_t *split_buf;
33    int split_pos, split_buf_size, split_pkts;
34    AVIOContext *fragment;
35};
36
37static void mpa_robust_close_context(PayloadContext *data)
38{
39    ffio_free_dyn_buf(&data->fragment);
40    av_free(data->split_buf);
41}
42
43static int mpa_robust_parse_rtp_header(AVFormatContext *ctx,
44                                       const uint8_t *buf, int len,
45                                       unsigned *adu_size, unsigned *cont)
46{
47    unsigned header_size;
48
49    if (len < 2) {
50        av_log(ctx, AV_LOG_ERROR, "Invalid %d bytes packet\n", len);
51        return AVERROR_INVALIDDATA;
52    }
53
54    *cont = !!(buf[0] & 0x80);
55    if (!(buf[0] & 0x40)) {
56        header_size = 1;
57        *adu_size = buf[0] & ~0xc0;
58    } else {
59        header_size = 2;
60        *adu_size = AV_RB16(buf) & ~0xc000;
61    }
62
63    return header_size;
64}
65
66static int mpa_robust_parse_packet(AVFormatContext *ctx, PayloadContext *data,
67                                   AVStream *st, AVPacket *pkt,
68                                   uint32_t *timestamp, const uint8_t *buf,
69                                   int len, uint16_t seq, int flags)
70{
71    unsigned adu_size, continuation;
72    int err, header_size;
73
74    if (!buf) {
75        buf = &data->split_buf[data->split_pos];
76        len = data->split_buf_size - data->split_pos;
77
78        header_size = mpa_robust_parse_rtp_header(ctx, buf, len, &adu_size,
79                                                  &continuation);
80        if (header_size < 0) {
81            av_freep(&data->split_buf);
82            return header_size;
83        }
84        buf += header_size;
85        len -= header_size;
86
87        if (continuation || adu_size > len) {
88            av_freep(&data->split_buf);
89            av_log(ctx, AV_LOG_ERROR, "Invalid frame\n");
90            return AVERROR_INVALIDDATA;
91        }
92
93        if ((err = av_new_packet(pkt, adu_size)) < 0) {
94            av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
95            return err;
96        }
97
98        pkt->stream_index = st->index;
99        memcpy(pkt->data, buf, adu_size);
100
101        data->split_pos += header_size + adu_size;
102
103        if (data->split_pos == data->split_buf_size) {
104            av_freep(&data->split_buf);
105            return 0;
106        }
107
108        return 1;
109    }
110
111
112    header_size = mpa_robust_parse_rtp_header(ctx, buf, len, &adu_size,
113                                              &continuation);
114    if (header_size < 0)
115        return header_size;
116
117    buf += header_size;
118    len -= header_size;
119
120    if (!continuation && adu_size <= len) {
121        /* One or more complete frames */
122
123        if ((err = av_new_packet(pkt, adu_size)) < 0) {
124            av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
125            return err;
126        }
127
128        pkt->stream_index = st->index;
129        memcpy(pkt->data, buf, adu_size);
130
131        buf += adu_size;
132        len -= adu_size;
133        if (len) {
134            data->split_buf_size = len;
135            data->split_buf = av_malloc(data->split_buf_size);
136            data->split_pos = 0;
137            if (!data->split_buf) {
138                av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
139                av_packet_unref(pkt);
140                return AVERROR(ENOMEM);
141            }
142            memcpy(data->split_buf, buf, data->split_buf_size);
143            return 1;
144        }
145        return 0;
146    } else if (!continuation) { /* && adu_size > len */
147        /* First fragment */
148        ffio_free_dyn_buf(&data->fragment);
149
150        data->adu_size = adu_size;
151        data->cur_size = len;
152        data->timestamp = *timestamp;
153
154        err = avio_open_dyn_buf(&data->fragment);
155        if (err < 0)
156            return err;
157
158        avio_write(data->fragment, buf, len);
159        return AVERROR(EAGAIN);
160    }
161    /* else continuation == 1 */
162
163    /* Fragment other than first */
164    if (!data->fragment) {
165        av_log(ctx, AV_LOG_WARNING,
166            "Received packet without a start fragment; dropping.\n");
167        return AVERROR(EAGAIN);
168    }
169    if (adu_size != data->adu_size ||
170        data->timestamp != *timestamp) {
171        ffio_free_dyn_buf(&data->fragment);
172        av_log(ctx, AV_LOG_ERROR, "Invalid packet received\n");
173        return AVERROR_INVALIDDATA;
174    }
175
176    avio_write(data->fragment, buf, len);
177    data->cur_size += len;
178
179    if (data->cur_size < data->adu_size)
180        return AVERROR(EAGAIN);
181
182    err = ff_rtp_finalize_packet(pkt, &data->fragment, st->index);
183    if (err < 0) {
184        av_log(ctx, AV_LOG_ERROR,
185               "Error occurred when getting fragment buffer.\n");
186        return err;
187    }
188
189    return 0;
190}
191
192const RTPDynamicProtocolHandler ff_mpeg_audio_robust_dynamic_handler = {
193    .enc_name          = "mpa-robust",
194    .codec_type        = AVMEDIA_TYPE_AUDIO,
195    .codec_id          = AV_CODEC_ID_MP3ADU,
196    .need_parsing      = AVSTREAM_PARSE_HEADERS,
197    .priv_data_size    = sizeof(PayloadContext),
198    .close             = mpa_robust_close_context,
199    .parse_packet      = mpa_robust_parse_packet,
200};
201