epan/dissectors/packet-h263.c

   1 /* packet-h263.c
   2  *
   3  * Routines for ITU-T Recommendation H.263 dissection
   4  *
   5  * Copyright 2003 Niklas Ogren <niklas.ogren@7l.se>
   6  * Seven Levels Consultants AB
   7  *
   8  * Copyright 2008 Richard van der Hoff, MX Telecom
   9  * <richardv@mxtelecom.com>
  10  *
  11  * $Id$
  12  *
  13  * Wireshark - Network traffic analyzer
  14  * By Gerald Combs <gerald@wireshark.org>
  15  * Copyright 1998 Gerald Combs
  16  *
  17  * Copied structure from packet-h261.c
  18  *
  19  * This program is free software; you can redistribute it and/or
  20  * modify it under the terms of the GNU General Public License
  21  * as published by the Free Software Foundation; either version 2
  22  * of the License, or (at your option) any later version.
  23  *
  24  * This program is distributed in the hope that it will be useful,
  25  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  26  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  27  * GNU General Public License for more details.
  28  *
  29  * You should have received a copy of the GNU General Public License
  30  * along with this program; if not, write to the Free Software
  31  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  32  */
  33
  34
  35 #ifdef HAVE_CONFIG_H
  36 # include "config.h"
  37 #endif
  38
  39 #include <glib.h>
  40 #include <epan/packet.h>
  41
  42 #include <stdio.h>
  43 #include <string.h>
  44
  45 #include "packet-h263.h"
  46
  47 static int proto_h263_data              = -1;
  48
  49 /* Fields for the data section */
  50 static int hf_h263_psc = -1;
  51 static int hf_h263_gbsc = -1;
  52 static int hf_h263_TR =-1;
  53 static int hf_h263_split_screen_indicator = -1;
  54 static int hf_h263_document_camera_indicator = -1;
  55 static int hf_h263_full_picture_freeze_release = -1;
  56 static int hf_h263_source_format = -1;
  57 static int hf_h263_payload_picture_coding_type = -1;
  58 static int hf_h263_opt_unres_motion_vector_mode = -1;
  59 static int hf_h263_syntax_based_arithmetic_coding_mode = -1;
  60 static int hf_h263_optional_advanced_prediction_mode = -1;
  61 static int hf_h263_PB_frames_mode = -1;
  62 static int hf_h263_data                 = -1;
  63 static int hf_h263_GN                   = -1;
  64 static int hf_h263_UFEP                 = -1;
  65 static int hf_h263_opptype              = -1;
  66 static int hf_h263_pquant               = -1;
  67 static int hf_h263_cpm                  = -1;
  68 static int hf_h263_psbi                 = -1;
  69 static int hf_h263_picture_type_code = -1;
  70 static int hf_h263_ext_source_format = -1;
  71 static int hf_h263_custom_pcf   = -1;
  72 static int hf_h263_pei                  = -1;
  73 static int hf_h263_psupp                = -1;
  74 static int hf_h263_trb = -1;
  75 static int hf_h263_not_dissected = -1;
  76
  77 /* H.263 fields defining a sub tree */
  78 static gint ett_h263_payload    = -1;
  79 static gint ett_h263_optype             = -1;
  80
  81
  82 /* Source format types */
  83 #define H263_SRCFORMAT_FORB             0  /* forbidden */
  84 #define H263_SRCFORMAT_SQCIF    1
  85 #define H263_SRCFORMAT_QCIF             2
  86 #define H263_SRCFORMAT_CIF              3
  87 #define H263_SRCFORMAT_4CIF             4
  88 #define H263_SRCFORMAT_16CIF    5
  89 #define H263_PLUSPTYPE                  7
  90
  91 const value_string h263_srcformat_vals[] =
  92 {
  93   { H263_SRCFORMAT_FORB,                "forbidden" },
  94   { H263_SRCFORMAT_SQCIF,               "sub-QCIF 128x96" },
  95   { H263_SRCFORMAT_QCIF,                "QCIF 176x144" },
  96   { H263_SRCFORMAT_CIF,                 "CIF 352x288" },
  97   { H263_SRCFORMAT_4CIF,                "4CIF 704x576" },
  98   { H263_SRCFORMAT_16CIF,               "16CIF 1408x1152" },
  99   { 6,                                                  "Reserved",},
 100   { H263_PLUSPTYPE,                             "extended PTYPE" },
 101   { 0,          NULL },
 102 };
 103
 104 /*
 105  * If UFEP is "001", then the following bits are present in PLUSPTYPE:
 106  *  Bits 1-3 Source Format, "000" reserved, "001" sub-QCIF, "010" QCIF, "011" CIF,
 107  * "100" 4CIF, "101" 16CIF, "110" custom source format, "111" reserved;
 108  */
 109 static const value_string ext_srcformat_vals[] =
 110 {
 111   { 0,                                                  "reserved" },
 112   { H263_SRCFORMAT_SQCIF,               "sub-QCIF 128x96" },
 113   { H263_SRCFORMAT_QCIF,                "QCIF 176x144" },
 114   { H263_SRCFORMAT_CIF,                 "CIF 352x288" },
 115   { H263_SRCFORMAT_4CIF,                "4CIF 704x576" },
 116   { H263_SRCFORMAT_16CIF,               "16CIF 1408x1152" },
 117   { 6,                                                  "Custom source format",},
 118   { 7,                                                  "Reserved" },
 119   { 0,          NULL },
 120 };
 121
 122 static const value_string h263_ufep_vals[] =
 123 {
 124   { 0,          "Only MPPTYPE included" },
 125   { 1,          "All extended PTYPE fields are included" },
 126   { 0,          NULL },
 127 };
 128
 129 static const true_false_string on_off_flg = {
 130   "On",
 131   "Off"
 132 };
 133 static const true_false_string picture_coding_type_flg = {
 134   "INTER (P-picture)",
 135   "INTRA (I-picture)"
 136 };
 137
 138 static const value_string picture_coding_type_vals[] =
 139 {
 140   { 0,          "I-Frame" },
 141   { 1,          "P-frame" },
 142   { 0,          NULL },
 143 };
 144
 145 static const true_false_string PB_frames_mode_flg = {
 146   "PB-frame",
 147   "Normal I- or P-picture"
 148 };
 149
 150 static const true_false_string cpm_flg = {
 151   "On",
 152   "Off"
 153 };
 154
 155 static const true_false_string custom_pcf_flg = {
 156   "Custom PCF",
 157   "CIF PCF"
 158 };
 159
 160 /*  Bits 1-3 Picture Type Code:*/
 161 static const value_string picture_type_code_vals[] =
 162 {
 163   { 0,          "I-picture (INTRA)" },
 164   { 1,          "P-picture (INTER)" },
 165   { 2,          "Improved PB-frame (see Annex M)" },
 166   { 3,          "B-picture (see Annex O)" },
 167   { 4,          "EI-picture (see Annex O)" },
 168   { 5,          "EP-picture (see Annex O)" },
 169   { 6,          "Reserved" },
 170   { 7,          "Reserved" },
 171   { 0,          NULL },
 172 };
 173
 174
 175 /*
 176  * 5.3 Macroblock layer
 177 static int
 178 dissect_h263_macroblock_layer( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gint offset)
 179 {
 180
 181 }
 182  */
 183
 184
 185 int
 186 dissect_h263_group_of_blocks_layer( tvbuff_t *tvb, proto_tree *tree, gint offset, gboolean is_rfc4626)
 187 {
 188
 189         unsigned int offset_in_bits             = offset << 3;
 190
 191         if(is_rfc4626){
 192                 /* GBSC 1xxx xxxx */
 193                 proto_tree_add_bits_item(tree, hf_h263_gbsc, tvb, offset_in_bits, 1, FALSE);
 194                 offset_in_bits++;
 195         }else{
 196                 /* Group of Block Start Code (GBSC) (17 bits)
 197                  * A word of 17 bits. Its value is 0000 0000 0000 0000 1.
 198                  */
 199                 proto_tree_add_bits_item(tree, hf_h263_gbsc, tvb, offset_in_bits, 17, FALSE);
 200                 offset_in_bits = offset_in_bits +17;
 201         }
 202         /*
 203          * Group Number (GN) (5 bits)
 204          */
 205         proto_tree_add_bits_item(tree, hf_h263_GN, tvb, offset_in_bits, 5, FALSE);
 206         offset_in_bits = offset_in_bits +5;
 207         /* 5.2.4 GOB Sub-Bitstream Indicator (GSBI) (2 bits)
 208          * A fixed length codeword of 2 bits that is only present if CPM is "1" in the picture header.
 209          */
 210         /*
 211          * 5.2.5 GOB Frame ID (GFID) (2 bits)
 212          */
 213         /*
 214          * 5.2.6 Quantizer Information (GQUANT) (5 bits)
 215          */
 216         /*
 217          * 5.3 Macroblock layer
 218          */
 219
 220         return offset_in_bits>>3;
 221 }
 222
 223
 224 /*
 225  * Length is used for the "Extra header" otherwise set to -1.
 226  */
 227 int
 228 dissect_h263_picture_layer( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gint offset, gint length _U_, gboolean is_rfc4626)
 229 {
 230         proto_tree *h263_opptype_tree   = NULL;
 231         proto_item *opptype_item                = NULL;
 232         unsigned int offset_in_bits             = offset << 3;
 233         unsigned int saved_bit_offset;
 234         guint64 source_format;
 235         guint64 ufep;
 236         guint64 picture_coding_type;
 237         guint64 PB_frames_mode = 0;
 238         guint64 custom_pcf = 0;
 239         guint64 picture_type_code =0;
 240         guint64 cpm;
 241         guint64 pei;
 242
 243         if(is_rfc4626){
 244                 /* PC 1000 00xx */
 245                 proto_tree_add_bits_item(tree, hf_h263_psc, tvb, offset_in_bits, 6, FALSE);
 246                 offset_in_bits = offset_in_bits +6;
 247
 248         }else{
 249         /* Check for PSC, PSC is a word of 22 bits.
 250          * Its value is 0000 0000 0000 0000' 1000 00xx xxxx xxxx.
 251          */
 252                 proto_tree_add_bits_item(tree, hf_h263_psc, tvb, offset_in_bits, 22, FALSE);
 253                 offset_in_bits = offset_in_bits +22;
 254
 255         }
 256         proto_tree_add_bits_item(tree, hf_h263_TR, tvb, offset_in_bits, 8, FALSE);
 257         offset_in_bits = offset_in_bits +8;
 258         /*
 259          * Bit 1: Always "1", in order to avoid start code emulation.
 260          * Bit 2: Always "0", for distinction with Recommendation H.261.
 261          */
 262         offset_in_bits = offset_in_bits +2;
 263         /* Bit 3: Split screen indicator, "0" off, "1" on. */
 264         proto_tree_add_bits_item( tree, hf_h263_split_screen_indicator, tvb, offset_in_bits, 1, FALSE);
 265         offset_in_bits++;
 266         /* Bit 4: Document camera indicator, */
 267         proto_tree_add_bits_item( tree, hf_h263_document_camera_indicator, tvb, offset_in_bits, 1, FALSE);
 268         offset_in_bits++;
 269         /* Bit 5: Full Picture Freeze Release, "0" off, "1" on. */
 270         proto_tree_add_bits_item( tree, hf_h263_full_picture_freeze_release, tvb, offset_in_bits, 1, FALSE);
 271         offset_in_bits++;
 272         /* Bits 6-8: Source Format, "000" forbidden, "001" sub-QCIF, "010" QCIF, "011" CIF,
 273          * "100" 4CIF, "101" 16CIF, "110" reserved, "111" extended PTYPE.
 274          */
 275         proto_tree_add_bits_ret_val( tree, hf_h263_source_format, tvb, offset_in_bits, 3 ,&source_format, FALSE);
 276         offset_in_bits = offset_in_bits +3;
 277         if (source_format != H263_PLUSPTYPE){
 278                 /* Not extended PTYPE */
 279                 /* Bit 9: Picture Coding Type, "0" INTRA (I-picture), "1" INTER (P-picture). */
 280                 proto_tree_add_bits_ret_val( tree, hf_h263_payload_picture_coding_type, tvb, offset_in_bits, 1, &picture_coding_type, FALSE);
 281                 if ( check_col( pinfo->cinfo, COL_INFO) )
 282                         col_append_str(pinfo->cinfo, COL_INFO, val_to_str((guint32)picture_coding_type, picture_coding_type_vals, "Unknown (%u)"));
 283                 offset_in_bits++;
 284                 /* Bit 10: Optional Unrestricted Motion Vector mode (see Annex D), "0" off, "1" on. */
 285                 proto_tree_add_bits_item( tree, hf_h263_opt_unres_motion_vector_mode, tvb, offset_in_bits, 1, FALSE);
 286                 offset_in_bits++;
 287                 /* Bit 11: Optional Syntax-based Arithmetic Coding mode (see Annex E), "0" off, "1" on.*/
 288                 proto_tree_add_bits_item( tree, hf_h263_syntax_based_arithmetic_coding_mode, tvb, offset_in_bits, 1, FALSE);
 289                 offset_in_bits++;
 290                 /* Bit 12: Optional Advanced Prediction mode (see Annex F), "0" off, "1" on.*/
 291                 proto_tree_add_bits_item( tree, hf_h263_optional_advanced_prediction_mode, tvb, offset_in_bits, 1, FALSE);
 292                 offset_in_bits++;
 293                 /* Bit 13: Optional PB-frames mode (see Annex G), "0" normal I- or P-picture, "1" PB-frame.*/
 294                 proto_tree_add_bits_ret_val( tree, hf_h263_PB_frames_mode, tvb, offset_in_bits, 1, &PB_frames_mode, FALSE);
 295                 offset_in_bits++;
 296         }else{
 297                 /* Extended PTYPE
 298                  * Update Full Extended PTYPE (UFEP) (3 bits)
 299                  */
 300                 /* .... ..xx x... .... */
 301                 proto_tree_add_bits_ret_val( tree, hf_h263_UFEP, tvb, offset_in_bits, 3, &ufep, FALSE);
 302                 offset_in_bits = offset_in_bits +3;
 303                 if(ufep==1){
 304                         /* The Optional Part of PLUSPTYPE (OPPTYPE) (18 bits)
 305                          */
 306                          /*  .xxx xxxx  xxxx xxxx  xxx. .... */
 307                         opptype_item = proto_tree_add_bits_item( tree, hf_h263_opptype, tvb, offset_in_bits, 18, FALSE);
 308                         h263_opptype_tree = proto_item_add_subtree( opptype_item, ett_h263_optype );
 309                         /*
 310                          * If UFEP is "001", then the following bits are present in PLUSPTYPE:
 311                          *  Bits 1-3 Source Format, "000" reserved, "001" sub-QCIF, "010" QCIF, "011" CIF,
 312                          * "100" 4CIF, "101" 16CIF, "110" custom source format, "111" reserved;
 313                          */
 314                         proto_tree_add_bits_item( h263_opptype_tree, hf_h263_ext_source_format, tvb, offset_in_bits, 3, FALSE);
 315                         offset_in_bits+=3;
 316
 317                         /*
 318                          *  Bit 4 Optional Custom PCF, "0" CIF PCF, "1" custom PCF;
 319                          */
 320                         proto_tree_add_bits_ret_val( h263_opptype_tree, hf_h263_custom_pcf, tvb, offset_in_bits, 1, &custom_pcf, FALSE);
 321                         offset_in_bits++;
 322                         saved_bit_offset=offset_in_bits;
 323                         /*
 324                          *  Bit 5 Optional Unrestricted Motion Vector (UMV) mode (see Annex D), "0" off, "1" on;
 325                          */
 326                         offset_in_bits++;
 327                         /*
 328                          *  Bit 6 Optional Syntax-based Arithmetic Coding (SAC) mode (see Annex E), "0" off, "1" on;
 329                          */
 330                         offset_in_bits++;
 331                         /*
 332                          *  Bit 7 Optional Advanced Prediction (AP) mode (see Annex F), "0" off, "1" on;
 333                          */
 334                         offset_in_bits++;
 335                         /*
 336                          *  Bit 8 Optional Advanced INTRA Coding (AIC) mode (see Annex I), "0" off, "1" on;
 337                          */
 338                         offset_in_bits++;
 339                         /*
 340                          *  Bit 9 Optional Deblocking Filter (DF) mode (see Annex J), "0" off, "1" on;
 341                          */
 342                         offset_in_bits++;
 343                         /*
 344                          *  Bit 10 Optional Slice Structured (SS) mode (see Annex K), "0" off, "1" on;
 345                          */
 346                         offset_in_bits++;
 347                         /*
 348                          *  Bit 11 Optional Reference Picture Selection (RPS) mode (see Annex N), "0" off, "1" on;
 349                          */
 350                         offset_in_bits++;
 351                         /*
 352                          *  Bit 12 Optional Independent Segment Decoding (ISD) mode (see Annex R), "0" off,"1" on;
 353                          */
 354                         offset_in_bits++;
 355                         /*
 356                          *  Bit 13 Optional Alternative INTER VLC (AIV) mode (see Annex S), "0" off, "1" on;
 357                          */
 358                         offset_in_bits++;
 359                         /*
 360                          *  Bit 14 Optional Modified Quantization (MQ) mode (see Annex T), "0" off, "1" on;
 361                          */
 362                         offset_in_bits++;
 363                         /*
 364                          *  Bit 15 Equal to "1" to prevent start code emulation;
 365                          */
 366                         offset_in_bits++;
 367                         /*
 368                          *  Bit 16 Reserved, shall be equal to "0";
 369                          */
 370                         offset_in_bits++;
 371                         /*
 372                          *  Bit 17 Reserved, shall be equal to "0";
 373                          */
 374                         offset_in_bits++;
 375                         /*
 376                          *  Bit 18 Reserved, shall be equal to "0".
 377                          */
 378                         offset_in_bits++;
 379                         proto_tree_add_bits_item( h263_opptype_tree, hf_h263_not_dissected, tvb, saved_bit_offset, offset_in_bits-saved_bit_offset, FALSE);
 380
 381                 }
 382                 /*
 383                  * 5.1.4.3 The mandatory part of PLUSPTYPE when PLUSPTYPE present (MPPTYPE) (9 bits)
 384                  * Regardless of the value of UFEP, the following 9 bits are also present in PLUSPTYPE:
 385                  * - Bits 1-3 Picture Type Code:
 386                  * "000" I-picture (INTRA);
 387                  * "001" P-picture (INTER);
 388                  * "010" Improved PB-frame (see Annex M);
 389                  * "011" B-picture (see Annex O);
 390                  * "100" EI-picture (see Annex O);
 391                  * "101" EP-picture (see Annex O);
 392                  * "110" Reserved;
 393                  * "111" Reserved;
 394                  */
 395                 proto_tree_add_bits_ret_val( tree, hf_h263_picture_type_code, tvb, offset_in_bits, 3, &picture_type_code, FALSE);
 396                 offset_in_bits+=3;
 397                 saved_bit_offset=offset_in_bits;
 398                 /*
 399                  *  Bit 4 Optional Reference Picture Resampling (RPR) mode (see Annex P), "0" off, "1" on;
 400                  */
 401                 offset_in_bits++;
 402                 /*
 403                  *  Bit 5 Optional Reduced-Resolution Update (RRU) mode (see Annex Q), "0" off, "1" on;
 404                  */
 405                 offset_in_bits++;
 406                 /*
 407                  *  Bit 6 Rounding Type (RTYPE) (see 6.1.2);
 408                  */
 409                 offset_in_bits++;
 410                 /*
 411                  *  Bit 7 Reserved, shall be equal to "0";
 412                  */
 413                 offset_in_bits++;
 414                 /*
 415                  *  Bit 8 Reserved, shall be equal to "0";
 416                  */
 417                 offset_in_bits++;
 418                 /*
 419                  *  Bit 9 Equal to "1" to prevent start code emulation.
 420                  */
 421                 offset_in_bits++;
 422                 proto_tree_add_bits_item( tree, hf_h263_not_dissected, tvb, saved_bit_offset, offset_in_bits-saved_bit_offset, FALSE);
 423                 /* The picture header location of CPM (1 bit) and PSBI (2 bits)
 424                  * the picture header depends on whether or not PLUSPTYPE is present
 425                  * (see 5.1.20 and 5.1.21). If PLUSPTYPE is present, then CPM follows
 426                  * immediately after PLUSPTYPE in the picture header.
 427                  */
 428                 proto_tree_add_bits_ret_val( tree, hf_h263_cpm, tvb, offset_in_bits, 1, &cpm, FALSE);
 429                 offset_in_bits++;
 430                 /* 5.1.21 Picture Sub-Bitstream Indicator (PSBI) (2 bits)
 431                  * only present if Continuous Presence Multipoint and Video
 432                  * Multiplex mode is indicated by CPM.
 433                  */
 434                 if(cpm==1){
 435                         proto_tree_add_bits_item( tree, hf_h263_psbi, tvb, offset_in_bits, 2, FALSE);
 436                         offset_in_bits+=2;
 437                 }
 438                 return offset_in_bits>>3;
 439                 /* TODO Add the rest of the fields */
 440                 /* 5.1.5 Custom Picture Format (CPFMT) (23 bits)
 441                  * present only if the use of a custom picture format is
 442                  * signalled in PLUSPTYPE and UFEP is '001'. When present, CPFMT consists of:
 443                  * Bits 1-4 Pixel Aspect Ratio Code: A 4-bit index to the PAR value in Table 5. For
 444                  * extended PAR, the exact pixel aspect ratio shall be specified in EPAR
 445                  * (see 5.1.6);
 446                  * Bits 5-13 Picture Width Indication: Range [0, ... , 511]; Number of pixels per
 447                  * line = (PWI + 1) * 4;
 448                  * Bit 14 Equal to "1" to prevent start code emulation;
 449                  * Bits 15-23 Picture Height Indication: Range [1, ... , 288]; Number of lines = PHI * 4.
 450                  */
 451                 /* 5.1.6 Extended Pixel Aspect Ratio (EPAR) (16 bits)
 452                  * A fixed length codeword of 16 bits that is present only if CPFMT is present and extended PAR is
 453                  * indicated therein. When present, EPAR consists of:
 454                  *  Bits 1-8 PAR Width: "0" is forbidden. The natural binary representation of the PAR
 455                  * width;
 456                  *  Bits 9-16 PAR Height: "0" is forbidden. The natural binary representation of the PAR
 457                  * height.
 458                  */
 459                 /* 5.1.7 Custom Picture Clock Frequency Code (CPCFC) (8 bits)
 460                  * A fixed length codeword of 8 bits that is present only if PLUSPTYPE is present and UFEP is 001
 461                  * and a custom picture clock frequency is signalled in PLUSPTYPE. When present, CPCFC consists of:
 462                  * Bit 1 Clock Conversion Code: "0" indicates a clock conversion factor of 1000 and
 463                  * "1" indicates 1001;
 464                  * Bits 2-8 Clock Divisor: "0" is forbidden. The natural binary representation of the value
 465                  * of the clock divisor.
 466                  */
 467                 /* 5.1.8 Extended Temporal Reference (ETR) (2 bits)
 468                  * A fixed length codeword of 2 bits which is present only if a custom picture clock frequency is in
 469                  * use (regardless of the value of UFEP). It is the two MSBs of the 10-bit number defined in 5.1.2.
 470                  */
 471                 /* 5.1.9 Unlimited Unrestricted Motion Vectors Indicator (UUI) (Variable length)
 472                  * A variable length codeword of 1 or 2 bits that is present only if the optional Unrestricted Motion
 473                  * Vector mode is indicated in PLUSPTYPE and UFEP is 001. When UUI is present it indicates the
 474                  * effective limitation of the range of the motion vectors being used.
 475                  *  UUI = "1" The motion vector range is limited according to Tables D.1 and D.2.
 476                  *  UUI = "01" The motion vector range is not limited except by the picture size.
 477                  */
 478                 /*
 479                  *  5.1.10 Slice Structured Submode bits (SSS) (2 bits)
 480                  *  A fixed length codeword of 2 bits which is present only if the optional Slice Structured mode
 481                  *  (see Annex K) is indicated in PLUSPTYPE and UFEP is 001. If the Slice Structured mode is in use
 482                  *  but UFEP is not 001, the last values sent for SSS shall remain in effect.
 483                  *  - Bit 1 Rectangular Slices, "0" indicates free-running slices, "1" indicates rectangular
 484                  *  slices;
 485                  *  - Bit 2 Arbitrary Slice Ordering, "0" indicates sequential order, "1" indicates arbitrary
 486                  *  order.
 487                  *  5.1.11 Enhancement Layer Number (ELNUM) (4 bits)
 488                  *  A fixed length codeword of 4 bits which is present only if the optional Temporal, SNR, and Spatial
 489                  *  Scalability mode is in use (regardless of the value of UFEP). The particular enhancement layer is
 490                  *  identified by an enhancement layer number, ELNUM. Picture correspondence between layers is
 491                  *  achieved via the temporal reference. Picture size is either indicated within each enhancement layer
 492                  *  using the existing source format fields or is inferred by the relationship to the reference layer. The
 493                  *  first enhancement layer above the base layer is designated as Enhancement Layer Number 2, and
 494                  *  the base layer has number 1.
 495                  *  5.1.12 Reference Layer Number (RLNUM) (4 bits)
 496                  *  A fixed length codeword of 4 bits which is present only if the optional Temporal, SNR, and Spatial
 497                  *  Scalability mode is in use (see Annex O) and UFEP is 001. The layer number for the pictures used
 498                  *  as reference anchors is identified by a Reference Layer Number (RLNUM). Time correspondence
 499                  *  between layers is achieved via the temporal reference.
 500                  *  Note that for B-pictures in an enhancement layer having temporally surrounding EI- or EP-pictures
 501                  *  which are present in the same enhancement layer, RLNUM shall be equal to ELNUM
 502                  *  (see Annex O).
 503                  *  5.1.13 Reference Picture Selection Mode Flags (RPSMF) (3 bits)
 504                  *  A fixed length codeword of 3 bits that is present only if the Reference Picture Selection mode is in
 505                  *  use and UFEP is 001. When present, RPSMF indicates which type of back-channel messages are
 506                  *  needed by the encoder. If the Reference Picture Selection mode is in use but RPSMF is not present,
 507                  *  the last value of RPSMF that was sent shall remain in effect.
 508                  *  - 100: neither ACK nor NACK signals needed;
 509                  *  - 101: need ACK signals to be returned;
 510                  *  - 110: need NACK signals to be returned;
 511                  *  - 111: need both ACK and NACK signals to be returned;
 512                  *  - 000-011: Reserved.
 513                  *  5.1.14 Temporal Reference for Prediction Indication (TRPI) (1 bit)
 514                  *  A fixed length codeword of 1 bit that is present only if the optional Reference Picture Selection
 515                  *  mode is in use (regardless of the value of UFEP). When present, TRPI indicates the presence of the
 516                  *  following TRP field:
 517                  *  - 0: TRP field is not present;
 518                  *  - 1: TRP field is present.
 519                  *  TRPI shall be 0 whenever the picture header indicates an I- or EI-picture.
 520                  *  5.1.15 Temporal Reference for Prediction (TRP) (10 bits)
 521                  *  When present (as indicated in TRPI), TRP indicates the Temporal Reference which is used for
 522                  *  prediction of the encoding, except for in the case of B-pictures. For B-pictures, the picture having
 523                  *  the temporal reference TRP is used for the prediction in the forward direction. (Prediction in the
 524                  *  reverse-temporal direction always uses the immediately temporally subsequent picture.) TRP is a
 525                  *  ten-bit number. If a custom picture clock frequency was not in use for the reference picture, the two
 526                  *  MSBs of TRP are zero and the LSBs contain the eight-bit TR found in the picture header of the
 527                  *  reference picture. If a custom picture clock frequency was in use for the reference picture, TRP is a
 528                  *  ten-bit number consisting of the concatenation of ETR and TR from the reference picture header.
 529                  *  When TRP is not present, the most recent temporally previous anchor picture shall be used for
 530                  *  prediction, as when not in the Reference Picture Selection mode. TRP is valid until the next PSC,
 531                  *  GSC, or SSC.
 532                  *  5.1.16 Back-Channel message Indication (BCI) (Variable length)
 533                  *  A variable length field of one or two bits that is present only if the optional Reference Picture
 534                  *  Selection mode is in use. When set to "1", this signals the presence of the following optional video
 535                  *  Back-Channel Message (BCM) field. "01" indicates the absence or the end of the video backchannel
 536                  *  message field. Combinations of BCM and BCI may not be present, and may be repeated
 537                  *  when present. BCI shall be set to "01" if the videomux submode of the optional Reference Picture
 538                  *  Selection mode is not in use.
 539                  *  5.1.17 Back-Channel Message (BCM) (Variable length)
 540                  *  The Back-Channel message with syntax as specified in N.4.2, which is present only if the preceding
 541                  *  BCI field is present and is set to "1".
 542                  *  5.1.18 Reference Picture Resampling Parameters (RPRP) (Variable length)
 543                  *  A variable length field that is present only if the optional Reference Picture Resampling mode bit is
 544                  *  set in PLUSPTYPE. This field carries the parameters of the Reference Picture Resampling mode
 545                  *  (see Annex P). Note that the Reference Picture Resampling mode can also be invoked implicitly by
 546                  *  the occurrence of a picture header for an INTER coded picture having a picture size which differs
 547                  *  from that of the previous encoded picture, in which case the RPRP field is not present and the
 548                  *  Reference Picture Resampling mode bit is not set.
 549                  */
 550         }
 551         /* 5.1.19 Quantizer Information (PQUANT) (5 bits) */
 552         proto_tree_add_bits_item( tree, hf_h263_pquant, tvb, offset_in_bits, 5, FALSE);
 553         offset_in_bits = offset_in_bits +5;
 554         if (source_format != H263_PLUSPTYPE){
 555                 proto_tree_add_bits_ret_val( tree, hf_h263_cpm, tvb, offset_in_bits, 1, &cpm, FALSE);
 556                 offset_in_bits++;
 557                 /* 5.1.21 Picture Sub-Bitstream Indicator (PSBI) (2 bits)
 558                  * only present if Continuous Presence Multipoint and Video
 559                  * Multiplex mode is indicated by CPM.
 560                  */
 561                 if(cpm==1){
 562                         proto_tree_add_bits_item( tree, hf_h263_psbi, tvb, offset_in_bits, 2, FALSE);
 563                         offset_in_bits = offset_in_bits +2;
 564                 }
 565         }
 566         /* 5.1.22 Temporal Reference for B-pictures in PB-frames (TRB) (3/5 bits)
 567          * TRB is present if PTYPE or PLUSPTYPE indicates "PB-frame" or "Improved PB-frame"
 568          * It is 3 bits long for standard CIF picture clock frequency and is
 569          * extended to 5 bits when a custom picture clock frequency is in use.
 570          */
 571         if((PB_frames_mode == 1)||(picture_type_code == 2 )){
 572                 if(custom_pcf == 0){
 573                         proto_tree_add_bits_item( tree, hf_h263_trb, tvb, offset_in_bits, 3, FALSE);
 574                         offset_in_bits = offset_in_bits +3;
 575                 }else{
 576                         proto_tree_add_bits_item( tree, hf_h263_trb, tvb, offset_in_bits, 5, FALSE);
 577                         offset_in_bits = offset_in_bits +5;
 578                 }
 579         }
 580         /* 5.1.23 Quantization information for B-pictures in PB-frames (DBQUANT) (2 bits)
 581          * DBQUANT is present if PTYPE or PLUSPTYPE indicates "PB-frame" or "Improved PB-frame"
 582          */
 583         if((PB_frames_mode == 1)||(picture_type_code == 2 )){
 584                 offset_in_bits = offset_in_bits +2;
 585         }
 586         /* 5.1.24 Extra Insertion Information (PEI) (1 bit)
 587          * A bit which when set to "1" signals the presence of the following optional data field.
 588          */
 589         proto_tree_add_bits_ret_val( tree, hf_h263_pei, tvb, offset_in_bits, 1, &pei, FALSE);
 590         offset_in_bits++;
 591         while(pei==1)
 592         {
 593                 /*5.1.25 Supplemental Enhancement Information (PSUPP) (0/8/16 ... bits)
 594                  * If PEI is set to "1", then 9 bits follow consisting of 8 bits of data (PSUPP) and then another PEI bit
 595                  * to indicate if a further 9 bits follow and so on. Encoders shall use PSUPP as specified in Annex L.
 596                  */
 597                 proto_tree_add_bits_item( tree, hf_h263_psupp, tvb, offset_in_bits, 8, FALSE);
 598                 offset_in_bits+=8;
 599                 proto_tree_add_bits_ret_val( tree, hf_h263_pei, tvb, offset_in_bits, 1, &pei, FALSE);
 600                 offset_in_bits++;
 601         }
 602         /* For the first GOB in each picture (with number 0), no GOB header shall be transmitted.
 603          * For all other GOBs, the GOB header may be empty, depending on the encoder strategy.
 604          */
 605
 606         /*
 607          * 5.3 Macroblock layer
 608          * dissect_h263_macroblock_layer( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gint offset)
 609          */
 610
 611         return offset_in_bits>>3;
 612
 613 }
 614
 615 /*
 616         5.1.1 Picture Start Code (PSC) (22 bits)
 617         PSC is a word of 22 bits. Its value is 0000 0000 0000 0000 1 00000. All picture start codes shall be
 618         byte aligned.
 619         ( 1000 00xx)
 620
 621         End Of Sequence (EOS) (22 bits)
 622         A codeword of 22 bits. Its value is 0000 0000 0000 0000 1 11111.
 623         ( 1111 11xx )
 624
 625         Group of Block Start Code (GBSC) (17 bits)
 626         A word of 17 bits. Its value is 0000 0000 0000 0000 1.
 627         ( 1xxx xxxx )
 628
 629         End Of Sub-Bitstream code (EOSBS) (23 bits)
 630         The EOSBS code is a codeword of 23 bits. Its value is 0000 0000 0000 0000 1 11110 0.
 631         ( 1111 100x )
 632
 633         Slice Start Code (SSC) (17 bits)
 634         A word of 17 bits. Its value is 0000 0000 0000 0000 1.
 635         ( 1xxx xxxx )
 636   */
 637 static void dissect_h263_data( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
 638 {
 639         guint offset = 0;
 640         proto_item *h263_payload_item   = NULL;
 641         proto_tree *h263_payload_tree   = NULL;
 642         guint32 data;
 643         guint8 startcode;
 644
 645         col_append_str( pinfo->cinfo, COL_INFO, "H263 payload ");
 646
 647         if( tree ) {
 648           h263_payload_item = proto_tree_add_item( tree, proto_h263_data, tvb, offset, -1, FALSE );
 649           h263_payload_tree = proto_item_add_subtree( h263_payload_item, ett_h263_payload );
 650         }
 651
 652         /* Check for PSC, PSC is a word of 22 bits. Its value is 0000 0000 0000 0000' 1000 00xx xxxx xxxx. */
 653         data = tvb_get_ntohl(tvb, offset);
 654
 655         if (( data & 0xffff8000) == 0x00008000 ) {
 656                 /* Start Code found
 657                  *
 658                  * Startc code holds bit 17 -23 of the codeword
 659                  */
 660                 startcode = tvb_get_guint8(tvb,offset+2)&0xfe;
 661                 if (startcode & 0x80){
 662                         switch(startcode){
 663                         case 0xf8:
 664                                 /* End Of Sub-Bitstream code (EOSBS)
 665                                  * ( 1111 100. )
 666                                  */
 667                                 break;
 668                         case 0x80:
 669                         case 0x82:
 670                                 /* Picture Start Code (PSC)
 671                                  * ( 1000 00x.)
 672                                  */
 673                                 col_append_str( pinfo->cinfo, COL_INFO, "(PSC) ");
 674                                 offset = dissect_h263_picture_layer( tvb, pinfo, h263_payload_tree, offset, -1, FALSE);
 675                                 break;
 676                         case 0xfc:
 677                         case 0xfe:
 678                                 /* End Of Sequence (EOS)
 679                                  * ( 1111 11x. )
 680                                  */
 681                         default:
 682                                 /* Group of Block Start Code (GBSC) or
 683                                  * Slice Start Code (SSC)
 684                                  */
 685                                 col_append_str( pinfo->cinfo, COL_INFO, "(GBSC) ");
 686                                 offset = dissect_h263_group_of_blocks_layer( tvb, h263_payload_tree, offset,FALSE);
 687                                 break;
 688                         }
 689                 }else{
 690                         /* Error */
 691                 }
 692         }
 693         if( tree )
 694                 proto_tree_add_item( h263_payload_tree, hf_h263_data, tvb, offset, -1, FALSE );
 695 }
 696
 697 void
 698 proto_register_h263_data(void)
 699 {
 700         static hf_register_info hf[] =
 701         {
 702                 {
 703                         &hf_h263_psc,
 704                         {
 705                                 "H.263 Picture start Code",
 706                                 "h263.psc",
 707                                 FT_UINT32,
 708                                 BASE_HEX,
 709                                 NULL,
 710                                 0x0,
 711                                 "Picture start Code, PSC", HFILL
 712                         }
 713                 },
 714                 { &hf_h263_gbsc,
 715                         {
 716                                 "H.263 Group of Block Start Code",
 717                                 "h263.gbsc",
 718                                 FT_UINT32,
 719                                 BASE_HEX,
 720                                 NULL,
 721                                 0x0,
 722                                 "Group of Block Start Code", HFILL
 723                         }
 724                 },
 725                 {
 726                         &hf_h263_TR,
 727                         {
 728                                 "H.263 Temporal Reference",
 729                                 "h263.tr2",
 730                                 FT_UINT32,
 731                                 BASE_DEC,
 732                                 NULL,
 733                                 0x0,
 734                                 "Temporal Reference, TR", HFILL
 735                         }
 736                 },
 737                 {
 738                         &hf_h263_trb,
 739                         {
 740                                 "Temporal Reference for B frames",
 741                                 "h263.trb",
 742                                 FT_UINT8,
 743                                 BASE_DEC,
 744                                 NULL,
 745                                 0x0,
 746                                 "Temporal Reference for the B frame as defined by H.263", HFILL
 747                         }
 748                 },
 749                 {
 750                         &hf_h263_split_screen_indicator,
 751                         {
 752                                 "H.263 Split screen indicator",
 753                                 "h263.split_screen_indicator",
 754                                 FT_BOOLEAN,
 755                                 BASE_NONE,
 756                                 TFS(&on_off_flg),
 757                                 0x0,
 758                                 "Split screen indicator", HFILL
 759                         }
 760                 },
 761                 {
 762                         &hf_h263_document_camera_indicator,
 763                         {
 764                                 "H.263 Document camera indicator",
 765                                 "h263.document_camera_indicator",
 766                                 FT_BOOLEAN,
 767                                 BASE_NONE,
 768                                 TFS(&on_off_flg),
 769                                 0x0,
 770                                 "Document camera indicator", HFILL
 771                         }
 772                 },
 773                 {
 774                         &hf_h263_full_picture_freeze_release,
 775                         {
 776                                 "H.263 Full Picture Freeze Release",
 777                                 "h263.split_screen_indicator",
 778                                 FT_BOOLEAN,
 779                                 BASE_NONE,
 780                                 TFS(&on_off_flg),
 781                                 0x0,
 782                                 "Full Picture Freeze Release", HFILL
 783                         }
 784                 },
 785                 {
 786                         &hf_h263_source_format,
 787                         {
 788                                 "H.263 Source Format",
 789                                 "h263.source_format",
 790                                 FT_UINT8,
 791                                 BASE_HEX,
 792                                 VALS(h263_srcformat_vals),
 793                                 0x0,
 794                                 "Source Format", HFILL
 795                         }
 796                 },
 797                 {
 798                         &hf_h263_ext_source_format,
 799                         {
 800                                 "H.263 Source Format",
 801                                 "h263.ext_source_format",
 802                                 FT_UINT8,
 803                                 BASE_HEX,
 804                                 VALS(ext_srcformat_vals),
 805                                 0x0,
 806                                 "Source Format", HFILL
 807                         }
 808                 },
 809                 {
 810                         &hf_h263_UFEP,
 811                         {
 812                                 "H.263 Update Full Extended PTYPE",
 813                                 "h263.ufep",
 814                                 FT_UINT16,
 815                                 BASE_DEC,
 816                                 VALS(h263_ufep_vals),
 817                                 0x0,
 818                                 "Update Full Extended PTYPE", HFILL
 819                         }
 820                 },
 821                 {
 822                         &hf_h263_opptype,
 823                         {
 824                                 "H.263 Optional Part of PLUSPTYPE",
 825                                 "h263.opptype",
 826                                 FT_UINT24,
 827                                 BASE_DEC,
 828                                 NULL,
 829                                 0x0,
 830                                 "Optional Part of PLUSPTYPE", HFILL
 831                         }
 832                 },
 833                 {
 834                         &hf_h263_payload_picture_coding_type,
 835                         {
 836                                 "H.263 Picture Coding Type",
 837                                 "h263.picture_coding_type",
 838                                 FT_BOOLEAN,
 839                                 BASE_NONE,
 840                                 TFS(&picture_coding_type_flg),
 841                                 0x0,
 842                                 "Picture Coding Type", HFILL
 843                         }
 844                 },
 845                 {
 846                         &hf_h263_opt_unres_motion_vector_mode,
 847                         {
 848                                 "H.263 Optional Unrestricted Motion Vector mode",
 849                                 "h263.opt_unres_motion_vector_mode",
 850                                 FT_BOOLEAN,
 851                                 BASE_NONE,
 852                                 TFS(&on_off_flg),
 853                                 0x0,
 854                                 "Optional Unrestricted Motion Vector mode", HFILL
 855                         }
 856                 },
 857                 {
 858                         &hf_h263_syntax_based_arithmetic_coding_mode,
 859                         {
 860                                 "H.263 Optional Syntax-based Arithmetic Coding mode",
 861                                 "h263.syntax_based_arithmetic_coding_mode",
 862                                 FT_BOOLEAN,
 863                                 BASE_NONE,
 864                                 TFS(&on_off_flg),
 865                                 0x0,
 866                                 "Optional Syntax-based Arithmetic Coding mode", HFILL
 867                         }
 868                 },
 869                 {
 870                         &hf_h263_optional_advanced_prediction_mode,
 871                         {
 872                                 "H.263 Optional Advanced Prediction mode",
 873                                 "h263.optional_advanced_prediction_mode",
 874                                 FT_BOOLEAN,
 875                                 BASE_NONE,
 876                                 TFS(&on_off_flg),
 877                                 0x0,
 878                                 "Optional Advanced Prediction mode", HFILL
 879                         }
 880                 },
 881                 {
 882                         &hf_h263_PB_frames_mode,
 883                         {
 884                                 "H.263 Optional PB-frames mode",
 885                                 "h263.PB_frames_mode",
 886                                 FT_BOOLEAN,
 887                                 BASE_NONE,
 888                                 TFS(&PB_frames_mode_flg),
 889                                 0x0,
 890                                 "Optional PB-frames mode", HFILL
 891                         }
 892                 },
 893                 {
 894                         &hf_h263_GN,
 895                         {
 896                                 "H.263 Group Number",
 897                                 "h263.gn",
 898                                 FT_UINT32,
 899                                 BASE_DEC,
 900                                 NULL,
 901                                 0x0,
 902                                 "Group Number, GN", HFILL
 903                         }
 904                 },
 905                 {
 906                         &hf_h263_pquant,
 907                         {
 908                                 "H.263 Quantizer Information (PQUANT)",
 909                                 "h263.pquant",
 910                                 FT_UINT32,
 911                                 BASE_DEC,
 912                                 NULL,
 913                                 0x0,
 914                                 "Quantizer Information (PQUANT)", HFILL
 915                         }
 916                 },
 917                 {
 918                         &hf_h263_cpm,
 919                         {
 920                                 "H.263 Continuous Presence Multipoint and Video Multiplex (CPM)",
 921                                 "h263.cpm",
 922                                 FT_BOOLEAN,
 923                                 BASE_NONE,
 924                                 TFS(&cpm_flg),
 925                                 0x0,
 926                                 "Continuous Presence Multipoint and Video Multiplex (CPM)", HFILL
 927                         }
 928                 },
 929                 {
 930                         &hf_h263_psbi,
 931                         {
 932                                 "H.263 Picture Sub-Bitstream Indicator (PSBI)",
 933                                 "h263.psbi",
 934                                 FT_UINT32,
 935                                 BASE_DEC,
 936                                 NULL,
 937                                 0x0,
 938                                 "Picture Sub-Bitstream Indicator (PSBI)", HFILL
 939                         }
 940                 },
 941                 {
 942                         &hf_h263_picture_type_code,
 943                         {
 944                                 "H.263 Picture Type Code",
 945                                 "h263.psi",
 946                                 FT_UINT32,
 947                                 BASE_DEC,
 948                                 VALS(picture_type_code_vals),
 949                                 0x0,
 950                                 "Picture Type Code", HFILL
 951                         }
 952                 },
 953                 {
 954                         &hf_h263_custom_pcf,
 955                         {
 956                                 "H.263 Custom PCF",
 957                                 "h263.custom_pcf",
 958                                 FT_BOOLEAN,
 959                                 BASE_NONE,
 960                                 TFS(&custom_pcf_flg),
 961                                 0x0,
 962                                 "Custom PCF", HFILL
 963                         }
 964                 },
 965                 {
 966                         &hf_h263_pei,
 967                         {
 968                                 "H.263 Extra Insertion Information (PEI)",
 969                                 "h263.pei",
 970                                 FT_BOOLEAN,
 971                                 BASE_NONE,
 972                                 NULL,
 973                                 0x0,
 974                                 "Extra Insertion Information (PEI)", HFILL
 975                         }
 976                 },
 977                 {
 978                         &hf_h263_psupp,
 979                         {
 980                                 "H.263 Supplemental Enhancement Information (PSUPP)",
 981                                 "h263.psupp",
 982                                 FT_UINT32,
 983                                 BASE_DEC,
 984                                 NULL,
 985                                 0x0,
 986                                 "Supplemental Enhancement Information (PSUPP)", HFILL
 987                         }
 988                 },
 989                 {
 990                         &hf_h263_data,
 991                         {
 992                                 "H.263 stream",
 993                                 "h263.stream",
 994                                 FT_BYTES,
 995                                 BASE_NONE,
 996                                 NULL,
 997                                 0x0,
 998                                 "The H.263 stream including its Picture, GOB or Macro block start code.", HFILL
 999                         }
1000                 },
1001                 {
1002                         &hf_h263_not_dissected,
1003                         {
1004                                 "H.263 Bits currently not dissected",
1005                                 "h263.not_dis",
1006                                 FT_UINT32,
1007                                 BASE_DEC,
1008                                 NULL,
1009                                 0x0,
1010                                 "These bits are not dissected(yet), displayed for clarity", HFILL
1011                         }
1012                 },
1013 };
1014
1015         static gint *ett[] =
1016         {
1017             &ett_h263_payload,
1018             &ett_h263_optype,
1019         };
1020
1021         proto_register_subtree_array(ett, array_length(ett));
1022
1023         proto_h263_data = proto_register_protocol("ITU-T Recommendation H.263",
1024             "H.263", "h263");
1025         proto_register_field_array(proto_h263_data, hf, array_length(hf));
1026         register_dissector("h263data", dissect_h263_data, proto_h263_data);
1027 }