blob: 97aa4add3685c1392eca33fd8d9bc7fdd4ca052a
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 | |
27 | int ff_h263_handle_packet(AVFormatContext *ctx, PayloadContext *data, |
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 | |
92 | RTPDynamicProtocolHandler ff_h263_1998_dynamic_handler = { |
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 | |
100 | RTPDynamicProtocolHandler ff_h263_2000_dynamic_handler = { |
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 | }; |
107 |