libavformat/rtpenc_h263_rfc2190.c

   1 /*
   2  * RTP packetization for H.263 video
   3  * Copyright (c) 2012 Martin Storsjo
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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, 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 }