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 27struct H263Info { 28 int src; 29 int i; 30 int u; 31 int s; 32 int a; 33 int pb; 34 int tr; 35}; 36 37struct H263State { 38 int gobn; 39 int mba; 40 int hmv1, vmv1, hmv2, vmv2; 41 int quant; 42}; 43 44static 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 70static 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 101void 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, H261 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 uint32_t bit_pos = AV_RL32(ptr); 154 uint32_t pos = (bit_pos + 7)/8; 155 if (pos <= end - buf_base) { 156 state.quant = ptr[4]; 157 state.gobn = ptr[5]; 158 state.mba = AV_RL16(&ptr[6]); 159 state.hmv1 = (int8_t) ptr[8]; 160 state.vmv1 = (int8_t) ptr[9]; 161 state.hmv2 = (int8_t) ptr[10]; 162 state.vmv2 = (int8_t) ptr[11]; 163 ebits = 8 * pos - bit_pos; 164 len = pos - (buf - buf_base); 165 mb_info_pos++; 166 } else { 167 av_log(s1, AV_LOG_ERROR, 168 "Unable to split H263 packet, use -mb_info %d " 169 "or lower.\n", s->max_payload_size - 8); 170 } 171 } else { 172 av_log(s1, AV_LOG_ERROR, "Unable to split H263 packet, " 173 "use -mb_info %d or -ps 1.\n", 174 s->max_payload_size - 8); 175 } 176 } 177 } 178 179 if (size > 2 && !buf[0] && !buf[1]) 180 send_mode_a(s1, &info, buf, len, ebits, len == size); 181 else 182 send_mode_b(s1, &info, &packet_start_state, buf, len, sbits, 183 ebits, len == size); 184 185 if (ebits) { 186 sbits = 8 - ebits; 187 len--; 188 } else { 189 sbits = 0; 190 } 191 buf += len; 192 size -= len; 193 ebits = 0; 194 } 195} 196