FFmpeg
rtpdec_h263_rfc2190.c
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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 
35 struct PayloadContext {
38  int endbyte_bits;
39  uint32_t timestamp;
40  int newformat;
41 };
42 
44 {
45  ffio_free_dyn_buf(&data->buf);
46 }
47 
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 
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 };
static int h263_handle_packet(AVFormatContext *ctx, PayloadContext *data, AVStream *st, AVPacket *pkt, uint32_t *timestamp, const uint8_t *buf, int len, uint16_t seq, int flags)
static void h263_close_context(PayloadContext *data)
AVPacket pkt
Definition: rtpdec_qt.c:37
Bytestream IO Context.
Definition: avio.h:161
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
int ff_h263_handle_packet(AVFormatContext *ctx, PayloadContext *data, AVStream *st, AVPacket *pkt, uint32_t *timestamp, const uint8_t *buf, int len, uint16_t seq, int flags)
Definition: rtpdec_h263.c:27
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
uint8_t endbyte
Definition: rtpdec_h261.c:31
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:379
const RTPDynamicProtocolHandler ff_h263_rfc2190_dynamic_handler
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
RTP/JPEG specific private data.
Definition: rdt.c:83
int index
stream index in AVFormatContext
Definition: avformat.h:882
#define src
Definition: vp8dsp.c:254
int avio_open_dyn_buf(AVIOContext **s)
Open a write only memory stream.
Definition: aviobuf.c:1430
enum AVMediaType codec_type
Definition: rtpdec.h:117
Macro definitions for various function/variable attributes.
Format I/O context.
Definition: avformat.h:1358
uint8_t
#define f(width, name)
Definition: cbs_vp9.c:255
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_RB32
Definition: bytestream.h:87
bitstream reader API header.
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:218
#define av_log(a,...)
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: avcodec.h:1509
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:849
uint32_t timestamp
current frame timestamp
Definition: rtpdec_ac3.c:31
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
#define RTP_FLAG_MARKER
RTP marker bit was set for this packet.
Definition: rtpdec.h:93
const char * r
Definition: vf_curves.c:114
int flags
A combination of AV_PKT_FLAG values.
Definition: avcodec.h:1483
AVFormatContext * ctx
Definition: movenc.c:48
void ffio_free_dyn_buf(AVIOContext **s)
Free a dynamic buffer.
Definition: aviobuf.c:1489
Stream structure.
Definition: avformat.h:881
void avio_w8(AVIOContext *s, int b)
Definition: aviobuf.c:196
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:467
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:659
uint8_t * buf
the temporary storage buffer
Definition: rtpdec_asf.c:183
#define flags(name, subs,...)
Definition: cbs_av1.c:561
full parsing and repack
Definition: avformat.h:800
Main libavformat public API header.
int ff_rtp_finalize_packet(AVPacket *pkt, AVIOContext **dyn_buf, int stream_idx)
Close the dynamic buffer and make a packet from it.
Definition: rtpdec.c:927
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
This structure stores compressed data.
Definition: avcodec.h:1454