1 /*
2 * RTP parser for AC3 payload format (RFC 4184)
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 "avformat.h"
23 #include "avio_internal.h"
24 #include "rtpdec_formats.h"
25
26 #define RTP_AC3_PAYLOAD_HEADER_SIZE 2
27
28 struct PayloadContext {
29 unsigned nr_frames;
30 unsigned last_frame;
31 uint32_t timestamp;
32 AVIOContext *fragment;
33 };
34
ac3_close_context(PayloadContext * data)35 static void ac3_close_context(PayloadContext *data)
36 {
37 ffio_free_dyn_buf(&data->fragment);
38 }
39
ac3_handle_packet(AVFormatContext * ctx,PayloadContext * data,AVStream * st,AVPacket * pkt,uint32_t * timestamp,const uint8_t * buf,int len,uint16_t seq,int flags)40 static int ac3_handle_packet(AVFormatContext *ctx, PayloadContext *data,
41 AVStream *st, AVPacket *pkt, uint32_t *timestamp,
42 const uint8_t *buf, int len, uint16_t seq,
43 int flags)
44 {
45 unsigned frame_type;
46 unsigned nr_frames;
47 int err;
48
49 if (len < RTP_AC3_PAYLOAD_HEADER_SIZE + 1) {
50 av_log(ctx, AV_LOG_ERROR, "Invalid %d bytes packet\n", len);
51 return AVERROR_INVALIDDATA;
52 }
53
54 frame_type = buf[0] & 0x3;
55 nr_frames = buf[1];
56 buf += RTP_AC3_PAYLOAD_HEADER_SIZE;
57 len -= RTP_AC3_PAYLOAD_HEADER_SIZE;
58
59 switch (frame_type) {
60 case 0: /* One or more complete frames */
61 if (!nr_frames) {
62 av_log(ctx, AV_LOG_ERROR, "Invalid AC3 packet data\n");
63 return AVERROR_INVALIDDATA;
64 }
65 if ((err = av_new_packet(pkt, len)) < 0) {
66 av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
67 return err;
68 }
69
70 pkt->stream_index = st->index;
71 memcpy(pkt->data, buf, len);
72 return 0;
73
74 case 1:
75 case 2: /* First fragment */
76 ffio_free_dyn_buf(&data->fragment);
77
78 data->last_frame = 1;
79 data->nr_frames = nr_frames;
80 err = avio_open_dyn_buf(&data->fragment);
81 if (err < 0)
82 return err;
83
84 avio_write(data->fragment, buf, len);
85 data->timestamp = *timestamp;
86 return AVERROR(EAGAIN);
87
88 case 3: /* Fragment other than first */
89 if (!data->fragment) {
90 av_log(ctx, AV_LOG_WARNING,
91 "Received packet without a start fragment; dropping.\n");
92 return AVERROR(EAGAIN);
93 }
94 if (nr_frames != data->nr_frames ||
95 data->timestamp != *timestamp) {
96 ffio_free_dyn_buf(&data->fragment);
97 av_log(ctx, AV_LOG_ERROR, "Invalid packet received\n");
98 return AVERROR_INVALIDDATA;
99 }
100
101 avio_write(data->fragment, buf, len);
102 data->last_frame++;
103 }
104
105 if (!(flags & RTP_FLAG_MARKER))
106 return AVERROR(EAGAIN);
107
108 if (data->last_frame != data->nr_frames) {
109 ffio_free_dyn_buf(&data->fragment);
110 av_log(ctx, AV_LOG_ERROR, "Missed %d packets\n",
111 data->nr_frames - data->last_frame);
112 return AVERROR_INVALIDDATA;
113 }
114
115 err = ff_rtp_finalize_packet(pkt, &data->fragment, st->index);
116 if (err < 0) {
117 av_log(ctx, AV_LOG_ERROR,
118 "Error occurred when getting fragment buffer.\n");
119 return err;
120 }
121
122 return 0;
123 }
124
125 const RTPDynamicProtocolHandler ff_ac3_dynamic_handler = {
126 .enc_name = "ac3",
127 .codec_type = AVMEDIA_TYPE_AUDIO,
128 .codec_id = AV_CODEC_ID_AC3,
129 .need_parsing = AVSTREAM_PARSE_FULL,
130 .priv_data_size = sizeof(PayloadContext),
131 .close = ac3_close_context,
132 .parse_packet = ac3_handle_packet,
133 };
134