blob: 3567202d8d4a00112c577707e14582c1d4b16aab
1 | /* |
2 | * RTP packetization for H.263 video |
3 | * Copyright (c) 2012 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 "rtpenc.h" |
24 | #include "libavcodec/put_bits.h" |
25 | #include "libavcodec/get_bits.h" |
26 | |
27 | struct H263Info { |
28 | int src; |
29 | int i; |
30 | int u; |
31 | int s; |
32 | int a; |
33 | int pb; |
34 | int tr; |
35 | }; |
36 | |
37 | struct H263State { |
38 | int gobn; |
39 | int mba; |
40 | int hmv1, vmv1, hmv2, vmv2; |
41 | int quant; |
42 | }; |
43 | |
44 | static void send_mode_a(AVFormatContext *s1, const struct H263Info *info, |
45 | const uint8_t *buf, int len, int ebits, int m) |
46 | { |
47 | RTPMuxContext *s = s1->priv_data; |
48 | PutBitContext pb; |
49 | |
50 | init_put_bits(&pb, s->buf, 32); |
51 | put_bits(&pb, 1, 0); /* F - 0, mode A */ |
52 | put_bits(&pb, 1, 0); /* P - 0, normal I/P */ |
53 | put_bits(&pb, 3, 0); /* SBIT - 0 bits */ |
54 | put_bits(&pb, 3, ebits); /* EBIT */ |
55 | put_bits(&pb, 3, info->src); /* SRC - source format */ |
56 | put_bits(&pb, 1, info->i); /* I - inter/intra */ |
57 | put_bits(&pb, 1, info->u); /* U - unrestricted motion vector */ |
58 | put_bits(&pb, 1, info->s); /* S - syntax-baesd arithmetic coding */ |
59 | put_bits(&pb, 1, info->a); /* A - advanced prediction */ |
60 | put_bits(&pb, 4, 0); /* R - reserved */ |
61 | put_bits(&pb, 2, 0); /* DBQ - 0 */ |
62 | put_bits(&pb, 3, 0); /* TRB - 0 */ |
63 | put_bits(&pb, 8, info->tr); /* TR */ |
64 | flush_put_bits(&pb); |
65 | memcpy(s->buf + 4, buf, len); |
66 | |
67 | ff_rtp_send_data(s1, s->buf, len + 4, m); |
68 | } |
69 | |
70 | static void send_mode_b(AVFormatContext *s1, const struct H263Info *info, |
71 | const struct H263State *state, const uint8_t *buf, |
72 | int len, int sbits, int ebits, int m) |
73 | { |
74 | RTPMuxContext *s = s1->priv_data; |
75 | PutBitContext pb; |
76 | |
77 | init_put_bits(&pb, s->buf, 64); |
78 | put_bits(&pb, 1, 1); /* F - 1, mode B */ |
79 | put_bits(&pb, 1, 0); /* P - 0, mode B */ |
80 | put_bits(&pb, 3, sbits); /* SBIT - 0 bits */ |
81 | put_bits(&pb, 3, ebits); /* EBIT - 0 bits */ |
82 | put_bits(&pb, 3, info->src); /* SRC - source format */ |
83 | put_bits(&pb, 5, state->quant); /* QUANT - quantizer for the first MB */ |
84 | put_bits(&pb, 5, state->gobn); /* GOBN - GOB number */ |
85 | put_bits(&pb, 9, state->mba); /* MBA - MB address */ |
86 | put_bits(&pb, 2, 0); /* R - reserved */ |
87 | put_bits(&pb, 1, info->i); /* I - inter/intra */ |
88 | put_bits(&pb, 1, info->u); /* U - unrestricted motion vector */ |
89 | put_bits(&pb, 1, info->s); /* S - syntax-baesd arithmetic coding */ |
90 | put_bits(&pb, 1, info->a); /* A - advanced prediction */ |
91 | put_bits(&pb, 7, state->hmv1); /* HVM1 - horizontal motion vector 1 */ |
92 | put_bits(&pb, 7, state->vmv1); /* VMV1 - vertical motion vector 1 */ |
93 | put_bits(&pb, 7, state->hmv2); /* HVM2 - horizontal motion vector 2 */ |
94 | put_bits(&pb, 7, state->vmv2); /* VMV2 - vertical motion vector 2 */ |
95 | flush_put_bits(&pb); |
96 | memcpy(s->buf + 8, buf, len); |
97 | |
98 | ff_rtp_send_data(s1, s->buf, len + 8, m); |
99 | } |
100 | |
101 | void ff_rtp_send_h263_rfc2190(AVFormatContext *s1, const uint8_t *buf, int size, |
102 | const uint8_t *mb_info, int mb_info_size) |
103 | { |
104 | RTPMuxContext *s = s1->priv_data; |
105 | int len, sbits = 0, ebits = 0; |
106 | GetBitContext gb; |
107 | struct H263Info info = { 0 }; |
108 | struct H263State state = { 0 }; |
109 | int mb_info_pos = 0, mb_info_count = mb_info_size / 12; |
110 | const uint8_t *buf_base = buf; |
111 | |
112 | s->timestamp = s->cur_timestamp; |
113 | |
114 | init_get_bits(&gb, buf, size*8); |
115 | if (get_bits(&gb, 22) == 0x20) { /* Picture Start Code */ |
116 | info.tr = get_bits(&gb, 8); |
117 | skip_bits(&gb, 2); /* PTYPE start, H.261 disambiguation */ |
118 | skip_bits(&gb, 3); /* Split screen, document camera, freeze picture release */ |
119 | info.src = get_bits(&gb, 3); |
120 | info.i = get_bits(&gb, 1); |
121 | info.u = get_bits(&gb, 1); |
122 | info.s = get_bits(&gb, 1); |
123 | info.a = get_bits(&gb, 1); |
124 | info.pb = get_bits(&gb, 1); |
125 | } |
126 | |
127 | while (size > 0) { |
128 | struct H263State packet_start_state = state; |
129 | len = FFMIN(s->max_payload_size - 8, size); |
130 | |
131 | /* Look for a better place to split the frame into packets. */ |
132 | if (len < size) { |
133 | const uint8_t *end = ff_h263_find_resync_marker_reverse(buf, |
134 | buf + len); |
135 | len = end - buf; |
136 | if (len == s->max_payload_size - 8) { |
137 | /* Skip mb info prior to the start of the current ptr */ |
138 | while (mb_info_pos < mb_info_count) { |
139 | uint32_t pos = AV_RL32(&mb_info[12*mb_info_pos])/8; |
140 | if (pos >= buf - buf_base) |
141 | break; |
142 | mb_info_pos++; |
143 | } |
144 | /* Find the first mb info past the end pointer */ |
145 | while (mb_info_pos + 1 < mb_info_count) { |
146 | uint32_t pos = AV_RL32(&mb_info[12*(mb_info_pos + 1)])/8; |
147 | if (pos >= end - buf_base) |
148 | break; |
149 | mb_info_pos++; |
150 | } |
151 | if (mb_info_pos < mb_info_count) { |
152 | const uint8_t *ptr = &mb_info[12*mb_info_pos]; |
153 | /* get position in bits in the input packet at which the next info block should be used */ |
154 | uint32_t bit_pos = AV_RL32(ptr); |
155 | /* get position in bytes */ |
156 | uint32_t pos_next_mb_info = (bit_pos + 7)/8; |
157 | /* check if data from the next MB info block should be used */ |
158 | if (pos_next_mb_info <= end - buf_base) { |
159 | state.quant = ptr[4]; |
160 | state.gobn = ptr[5]; |
161 | state.mba = AV_RL16(&ptr[6]); |
162 | state.hmv1 = (int8_t) ptr[8]; |
163 | state.vmv1 = (int8_t) ptr[9]; |
164 | state.hmv2 = (int8_t) ptr[10]; |
165 | state.vmv2 = (int8_t) ptr[11]; |
166 | ebits = 8 * pos_next_mb_info - bit_pos; |
167 | len = pos_next_mb_info - (buf - buf_base); |
168 | mb_info_pos++; |
169 | } |
170 | } else { |
171 | av_log(s1, AV_LOG_ERROR, "Unable to split H.263 packet, " |
172 | "use -mb_info %d or -ps 1.\n", |
173 | s->max_payload_size - 8); |
174 | } |
175 | } |
176 | } |
177 | |
178 | if (size > 2 && !buf[0] && !buf[1]) |
179 | send_mode_a(s1, &info, buf, len, ebits, len == size); |
180 | else |
181 | send_mode_b(s1, &info, &packet_start_state, buf, len, sbits, |
182 | ebits, len == size); |
183 | |
184 | if (ebits) { |
185 | sbits = 8 - ebits; |
186 | len--; |
187 | } else { |
188 | sbits = 0; |
189 | } |
190 | buf += len; |
191 | size -= len; |
192 | ebits = 0; |
193 | } |
194 | } |
195 |