FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
rtpdec_h263.c
Go to the documentation of this file.
1 /*
2  * RTP H.263 Depacketizer, RFC 4629
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 "avformat.h"
23 #include "rtpdec_formats.h"
24 #include "libavutil/attributes.h"
25 #include "libavutil/intreadwrite.h"
26 
28  AVStream *st, AVPacket *pkt, uint32_t *timestamp,
29  const uint8_t *buf, int len, uint16_t seq, int flags)
30 {
31  uint8_t *ptr;
32  uint16_t header;
33  int startcode, vrc, picture_header;
34 
35  if (len < 2) {
36  av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet\n");
37  return AVERROR_INVALIDDATA;
38  }
39 
40  /* Decode the 16 bit H.263+ payload header, as described in section
41  * 5.1 of RFC 4629. The fields of this header are:
42  * - 5 reserved bits, should be ignored.
43  * - One bit (P, startcode), indicating a picture start, picture segment
44  * start or video sequence end. If set, two zero bytes should be
45  * prepended to the payload.
46  * - One bit (V, vrc), indicating the presence of an 8 bit Video
47  * Redundancy Coding field after this 16 bit header.
48  * - 6 bits (PLEN, picture_header), the length (in bytes) of an extra
49  * picture header, following the VRC field.
50  * - 3 bits (PEBIT), the number of bits to ignore of the last byte
51  * of the extra picture header. (Not used at the moment.)
52  */
53  header = AV_RB16(buf);
54  startcode = (header & 0x0400) >> 9;
55  vrc = header & 0x0200;
56  picture_header = (header & 0x01f8) >> 3;
57  buf += 2;
58  len -= 2;
59 
60  if (vrc) {
61  /* Skip VRC header if present, not used at the moment. */
62  buf += 1;
63  len -= 1;
64  }
65  if (picture_header) {
66  /* Skip extra picture header if present, not used at the moment. */
67  buf += picture_header;
68  len -= picture_header;
69  }
70 
71  if (len < 0) {
72  av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet\n");
73  return AVERROR_INVALIDDATA;
74  }
75 
76  if (av_new_packet(pkt, len + startcode)) {
77  av_log(ctx, AV_LOG_ERROR, "Out of memory\n");
78  return AVERROR(ENOMEM);
79  }
80  pkt->stream_index = st->index;
81  ptr = pkt->data;
82 
83  if (startcode) {
84  *ptr++ = 0;
85  *ptr++ = 0;
86  }
87  memcpy(ptr, buf, len);
88 
89  return 0;
90 }
91 
93  .enc_name = "H263-1998",
94  .codec_type = AVMEDIA_TYPE_VIDEO,
95  .codec_id = AV_CODEC_ID_H263,
96  .need_parsing = AVSTREAM_PARSE_FULL,
97  .parse_packet = ff_h263_handle_packet,
98 };
99 
101  .enc_name = "H263-2000",
102  .codec_type = AVMEDIA_TYPE_VIDEO,
103  .codec_id = AV_CODEC_ID_H263,
104  .need_parsing = AVSTREAM_PARSE_FULL,
105  .parse_packet = ff_h263_handle_packet,
106 };
RTPDynamicProtocolHandler ff_h263_2000_dynamic_handler
Definition: rtpdec_h263.c:100
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:101
RTP/JPEG specific private data.
Definition: rdt.c:83
int index
stream index in AVFormatContext
Definition: avformat.h:843
static AVPacket pkt
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_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:87
Macro definitions for various function/variable attributes.
Format I/O context.
Definition: avformat.h:1272
uint8_t
uint8_t * data
Definition: avcodec.h:1422
static const uint8_t header[24]
Definition: sdr2.c:67
#define av_log(a,...)
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:83
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
RTPDynamicProtocolHandler ff_h263_1998_dynamic_handler
Definition: rtpdec_h263.c:92
#define AVERROR(e)
Definition: error.h:43
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
Stream structure.
Definition: avformat.h:842
void * buf
Definition: avisynth_c.h:553
const char * enc_name
Definition: rtpdec.h:116
static int flags
Definition: cpu.c:47
full parsing and repack
Definition: avformat.h:774
Main libavformat public API header.
int len
int stream_index
Definition: avcodec.h:1424
This structure stores compressed data.
Definition: avcodec.h:1399