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path: root/libavformat/rtpdec_h263_rfc2190.c (plain)
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1/*
2 * RTP H.263 Depacketizer, RFC 2190
3 * Copyright (c) 2012 Martin Storsjo
4 * Based on the GStreamer H.263 Depayloder:
5 * Copyright 2005 Wim Taymans
6 * Copyright 2007 Edward Hervey
7 * Copyright 2007 Nokia Corporation
8 * Copyright 2007 Collabora Ltd, Philippe Kalaf
9 * Copyright 2010 Mark Nauwelaerts
10 *
11 * This file is part of FFmpeg.
12 *
13 * FFmpeg is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU Lesser General Public
15 * License as published by the Free Software Foundation; either
16 * version 2.1 of the License, or (at your option) any later version.
17 *
18 * FFmpeg is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 * Lesser General Public License for more details.
22 *
23 * You should have received a copy of the GNU Lesser General Public
24 * License along with FFmpeg; if not, write to the Free Software
25 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 */
27
28#include "avformat.h"
29#include "avio_internal.h"
30#include "rtpdec_formats.h"
31#include "libavutil/attributes.h"
32#include "libavutil/intreadwrite.h"
33#include "libavcodec/get_bits.h"
34
35struct PayloadContext {
36 AVIOContext *buf;
37 uint8_t endbyte;
38 int endbyte_bits;
39 uint32_t timestamp;
40 int newformat;
41};
42
43static void h263_close_context(PayloadContext *data)
44{
45 ffio_free_dyn_buf(&data->buf);
46}
47
48static int h263_handle_packet(AVFormatContext *ctx, PayloadContext *data,
49 AVStream *st, AVPacket *pkt, uint32_t *timestamp,
50 const uint8_t *buf, int len, uint16_t seq,
51 int flags)
52{
53 /* Corresponding to header fields in the RFC */
54 int f, p, i, sbit, ebit, src, r;
55 int header_size, ret;
56
57 if (data->newformat)
58 return ff_h263_handle_packet(ctx, data, st, pkt, timestamp, buf, len,
59 seq, flags);
60
61 if (data->buf && data->timestamp != *timestamp) {
62 /* Dropping old buffered, unfinished data */
63 ffio_free_dyn_buf(&data->buf);
64 data->endbyte_bits = 0;
65 }
66
67 if (len < 4) {
68 av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet: %d\n", len);
69 return AVERROR_INVALIDDATA;
70 }
71
72 f = buf[0] & 0x80;
73 p = buf[0] & 0x40;
74 if (!f) {
75 /* Mode A */
76 header_size = 4;
77 i = buf[1] & 0x10;
78 r = ((buf[1] & 0x01) << 3) | ((buf[2] & 0xe0) >> 5);
79 } else if (!p) {
80 /* Mode B */
81 header_size = 8;
82 if (len < header_size) {
83 av_log(ctx, AV_LOG_ERROR,
84 "Too short H.263 RTP packet: %d bytes, %d header bytes\n",
85 len, header_size);
86 return AVERROR_INVALIDDATA;
87 }
88 r = buf[3] & 0x03;
89 i = buf[4] & 0x80;
90 } else {
91 /* Mode C */
92 header_size = 12;
93 if (len < header_size) {
94 av_log(ctx, AV_LOG_ERROR,
95 "Too short H.263 RTP packet: %d bytes, %d header bytes\n",
96 len, header_size);
97 return AVERROR_INVALIDDATA;
98 }
99 r = buf[3] & 0x03;
100 i = buf[4] & 0x80;
101 }
102 sbit = (buf[0] >> 3) & 0x7;
103 ebit = buf[0] & 0x7;
104 src = (buf[1] & 0xe0) >> 5;
105 if (!(buf[0] & 0xf8)) { /* Reserved bits in RFC 2429/4629 are zero */
106 if ((src == 0 || src >= 6) && r) {
107 /* Invalid src for this format, and bits that should be zero
108 * according to RFC 2190 aren't zero. */
109 av_log(ctx, AV_LOG_WARNING,
110 "Interpreting H.263 RTP data as RFC 2429/4629 even though "
111 "signalled with a static payload type.\n");
112 data->newformat = 1;
113 return ff_h263_handle_packet(ctx, data, st, pkt, timestamp, buf,
114 len, seq, flags);
115 }
116 }
117
118 buf += header_size;
119 len -= header_size;
120
121 if (!data->buf) {
122 /* Check the picture start code, only start buffering a new frame
123 * if this is correct */
124 if (len > 4 && AV_RB32(buf) >> 10 == 0x20) {
125 ret = avio_open_dyn_buf(&data->buf);
126 if (ret < 0)
127 return ret;
128 data->timestamp = *timestamp;
129 } else {
130 /* Frame not started yet, skipping */
131 return AVERROR(EAGAIN);
132 }
133 }
134
135 if (data->endbyte_bits || sbit) {
136 if (data->endbyte_bits == sbit) {
137 data->endbyte |= buf[0] & (0xff >> sbit);
138 data->endbyte_bits = 0;
139 buf++;
140 len--;
141 avio_w8(data->buf, data->endbyte);
142 } else {
143 /* Start/end skip bits not matching - missed packets? */
144 GetBitContext gb;
145 init_get_bits(&gb, buf, len*8 - ebit);
146 skip_bits(&gb, sbit);
147 if (data->endbyte_bits) {
148 data->endbyte |= get_bits(&gb, 8 - data->endbyte_bits);
149 avio_w8(data->buf, data->endbyte);
150 }
151 while (get_bits_left(&gb) >= 8)
152 avio_w8(data->buf, get_bits(&gb, 8));
153 data->endbyte_bits = get_bits_left(&gb);
154 if (data->endbyte_bits)
155 data->endbyte = get_bits(&gb, data->endbyte_bits) <<
156 (8 - data->endbyte_bits);
157 ebit = 0;
158 len = 0;
159 }
160 }
161 if (ebit) {
162 if (len > 0)
163 avio_write(data->buf, buf, len - 1);
164 data->endbyte_bits = 8 - ebit;
165 data->endbyte = buf[len - 1] & (0xff << ebit);
166 } else {
167 avio_write(data->buf, buf, len);
168 }
169
170 if (!(flags & RTP_FLAG_MARKER))
171 return AVERROR(EAGAIN);
172
173 if (data->endbyte_bits)
174 avio_w8(data->buf, data->endbyte);
175 data->endbyte_bits = 0;
176
177 ret = ff_rtp_finalize_packet(pkt, &data->buf, st->index);
178 if (ret < 0)
179 return ret;
180 if (!i)
181 pkt->flags |= AV_PKT_FLAG_KEY;
182
183 return 0;
184}
185
186RTPDynamicProtocolHandler ff_h263_rfc2190_dynamic_handler = {
187 .codec_type = AVMEDIA_TYPE_VIDEO,
188 .codec_id = AV_CODEC_ID_H263,
189 .need_parsing = AVSTREAM_PARSE_FULL,
190 .parse_packet = h263_handle_packet,
191 .priv_data_size = sizeof(PayloadContext),
192 .close = h263_close_context,
193 .static_payload_id = 34,
194};
195
generated by cgit at 2024-05-17 05:04:18 (GMT)