path: root/epan/dissectors/packet-mp4ves.c

/*
 * packet-mp4ves.c
 * Routines for MPEG4 dissection
 * Copyright 2007-2008, Anders Broman <anders.broman[at]ericsson.com>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * References:
 * https://tools.ietf.org/html/rfc3016
 */

#include "config.h"


#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/asn1.h>

#include <epan/prefs.h>

#include "packet-mp4ves.h"

void proto_register_mp4ves(void);
void proto_reg_handoff_mp4ves(void);

/* Initialize the protocol and registered fields */
static int proto_mp4ves;

static int hf_mp4ves_config;
static int hf_mp4ves_start_code_prefix;
static int hf_mp4ves_start_code;
static int hf_mp4ves_vop_coding_type;
static int hf_mp4ves_profile_and_level_indication;
static int hf_mp4ves_is_visual_object_identifier;
static int hf_mp4ves_visual_object_type;
static int hf_mp4ves_video_signal_type;
static int hf_mp4ves_stuffing;
static int hf_mp4ves_video_object_type_indication;
static int hf_mp4ves_random_accessible_vol;
static int hf_mp4ves_is_object_layer_identifier;
static int hf_mp4ves_aspect_ratio_info;
static int hf_mp4ves_vol_control_parameters;
static int hf_mp4ves_video_object_layer_shape;
static int hf_mp4ves_user_data;
static int hf_mp4ves_data;

/* Initialize the subtree pointers */
static int ett_mp4ves;
static int ett_mp4ves_config;

static expert_field ei_mp4ves_config_too_short;
static expert_field ei_mp4ves_not_dissected_bits;

static dissector_handle_t mp4ves_name_handle;

static dissector_handle_t mp4ves_handle;

/*
14496-2, Annex G, Table G-1.
Table G-1 FLC table for profile_and_level_indication Profile/Level Code
*/
const value_string mp4ves_level_indication_vals[] =
{
	{ 0,    "Reserved" },
	{ 1,    "Simple Profile/Level 1" },
	{ 2,    "Simple Profile/Level 2" },
	{ 3,    "Reserved" },
	{ 4,    "Reserved" },
	{ 5,    "Reserved" },
	{ 6,    "Reserved" },
	{ 7,    "Reserved" },
	{ 8,    "Simple Profile/Level 0" },
	{ 9,    "Simple Profile/Level 0b" },
	/* Reserved 00001001 - 00010000 */
	{ 0x11, "Simple Scalable Profile/Level 1" },
	{ 0x12, "Simple Scalable Profile/Level 2" },
	/* Reserved 00010011 - 00100000 */
	{ 0x21, "Core Profile/Level 1" },
	{ 0x22, "Core Profile/Level 2" },
	/* Reserved 00100011 - 00110001 */
	{ 0x32, "Main Profile/Level 2" },
	{ 0x33, "Main Profile/Level 3" },
	{ 0x34, "Main Profile/Level 4" },
	/* Reserved 00110101 - 01000001  */
	{ 0x42, "N-bit Profile/Level 2" },
	/* Reserved 01000011 - 01010000  */
	{ 0x51, "Scalable Texture Profile/Level 1" },
	/* Reserved 01010010 - 01100000 */
	{ 0x61, "Simple Face Animation Profile/Level 1" },
	{ 0x62, "Simple Face Animation Profile/Level 2" },
	{ 0x63, "Simple FBA Profile/Level 1" },
	{ 0x64, "Simple FBA Profile/Level 2" },
	/* Reserved 01100101 - 01110000 */
	{ 0x71, "Basic Animated Texture Profile/Level 1" },
	{ 0x72, "Basic Animated Texture Profile/Level 2" },
	/* Reserved 01110011 - 10000000 */
	{ 0x81, "Hybrid Profile/Level 1" },
	{ 0x82, "Hybrid Profile/Level 2" },
	/* Reserved 10000011 - 10010000 */
	{ 0x91, "Advanced Real Time Simple Profile/Level 1" },
	{ 0x92, "Advanced Real Time Simple Profile/Level 2" },
	{ 0x93, "Advanced Real Time Simple Profile/Level 3" },
	{ 0x94, "Advanced Real Time Simple Profile/Level 4" },
	/* Reserved 10010101 - 10100000 */
	{ 0xa1, "Core Scalable Profile/Level 1" },
	{ 0xa2, "Core Scalable Profile/Level 2" },
	{ 0xa3, "Core Scalable Profile/Level 3" },
	/* Reserved 10100100 - 10110000  */
	{ 0xb1, "Advanced Coding Efficiency Profile/Level 1" },
	{ 0xb2, "Advanced Coding Efficiency Profile/Level 2" },
	{ 0xb3, "Advanced Coding Efficiency Profile/Level 3" },
	{ 0xb4, "Advanced Coding Efficiency Profile/Level 4" },
	/* Reserved 10110101 - 11000000 */
	{ 0xc1, "Advanced Core Profile/Level 1" },
	{ 0xc2, "Advanced Core Profile/Level 2" },
	/* Reserved 11000011 - 11010000 */
	{ 0xd1, "Advanced Scalable Texture/Level 1" },
	{ 0xd2, "Advanced Scalable Texture/Level 2" },
	{ 0xd3, "Advanced Scalable Texture/Level 3" },
	/* Reserved 11010100 - 11100000 */
	{ 0xe1, "Simple Studio Profile/Level 1" },
	{ 0xe2, "Simple Studio Profile/Level 2" },
	{ 0xe3, "Simple Studio Profile/Level 3" },
	{ 0xe4, "Simple Studio Profile/Level 4" },
	{ 0xe5, "Core Studio Profile/Level 1" },
	{ 0xe6, "Core Studio Profile/Level 2" },
	{ 0xe7, "Core Studio Profile/Level 3" },
	{ 0xe8, "Core Studio Profile/Level 4" },
	/* Reserved 11101001 - 11101111 */
	{ 0xf0, "Advanced Simple Profile/Level 0" },
	{ 0xf1, "Advanced Simple Profile/Level 1" },
	{ 0xf2, "Advanced Simple Profile/Level 2" },
	{ 0xf3, "Advanced Simple Profile/Level 3" },
	{ 0xf4, "Advanced Simple Profile/Level 4" },
	{ 0xf5, "Advanced Simple Profile/Level 5" },
	/* Reserved 11110110 - 11110111 */
	{ 0xf8, "Fine Granularity Scalable Profile/Level 0" },
	{ 0xf9, "Fine Granularity Scalable Profile/Level 1" },
	{ 0xfa, "Fine Granularity Scalable Profile/Level 2" },
	{ 0xfb, "Fine Granularity Scalable Profile/Level 3" },
	{ 0xfc, "Fine Granularity Scalable Profile/Level 4" },
	{ 0xfd, "Fine Granularity Scalable Profile/Level 5" },
	{ 0xfe, "Reserved" },
	{ 0xff, "Reserved for Escape" },
	{ 0, NULL },
};
static const range_string mp4ves_startcode_vals[] = {
	{ 0x00,	0x1f, "video_object_start_code" },
	{ 0x20, 0x2f, "video_object_layer_start_code" },
	{ 0x30, 0xaf, "reserved" },
	{ 0xb0, 0xb0, "visual_object_sequence_start_code" },
	{ 0xb1, 0xb1, "visual_object_sequence_end_code" },
	{ 0xb2, 0xb2, "user_data_start_code" },
	{ 0xb3, 0xb3, "group_of_vop_start_code" },
	{ 0xb4, 0xb4, "video_session_error_code" },
	{ 0xb5, 0xb5, "visual_object_start_code" },
	{ 0xb6, 0xb6, "vop_start_code" },
	{ 0xb7, 0xb9, "reserved" },
	{ 0xba, 0xba, "fba_object_start_code" },
	{ 0xbb, 0xbb, "fba_object_plane_start_code" },
	{ 0xbc, 0xbc, "mesh_object_start_code" },
	{ 0xbd, 0xbd, "mesh_object_plane_start_code" },
	{ 0xbe, 0xbe, "still_texture_object_start_code" },
	{ 0xbf, 0xbf, "texture_spatial_layer_start_code" },
	{ 0xc0, 0xc0, "texture_snr_layer_start_code" },
	{ 0xc1, 0xc1, "texture_tile_start_code" },
	{ 0xc2, 0xc2, "texture_shape_layer_start_code" },
	{ 0xc3, 0xc3, "stuffing_start_code" },
	{ 0xc4, 0xc5, "reserved" },
	{ 0xc6, 0xcf, "System start codes" }, /* NOTE System start codes are defined in ISO/IEC 14496-1:1999 */
	{ 0,     0, NULL }
};

static const value_string mp4ves_vop_coding_type_vals[] = {
	{ 0,	"intra-coded (I)" },
	{ 1,	"predictive-coded (P)" },
	{ 2,	"bidirectionally-predictive-coded (B)" },
	{ 3,	"sprite (S)" },
	{ 0,	NULL }
};

/*
 * FLC table for video_object_type indication
 */
static const value_string mp4ves_video_object_type_vals[] = {
	{ 0x0,	"Reserved" },
	{ 0x1,	"Simple Object Type" },
	{ 0x2,	"Simple Scalable Object Type" },
	{ 0x3,	"Core Object Type" },
	{ 0x4,	"Main Object Type" },
	{ 0x5,	"N-bit Object Type" },
	{ 0x6,	"Basic Anim. 2D Texture" },
	{ 0x7,	"Anim. 2D Mesh" },
	{ 0x8,	"Simple Face" },
	{ 0x9,	"Still Scalable Texture" },
	{ 0xa,	"Advanced Real Time Simple" },
	{ 0xb,	"Core Scalable" },
	{ 0xc,	"Advanced Coding Efficiency" },
	{ 0xd,	"Advanced Scalable Texture" },
	{ 0xe,	"Simple FBA" },
	{ 0,	NULL }
};
/* Visual object type */
static const value_string mp4ves_visual_object_type_vals[] = {
	{ 0x0,	"reserved" },
	{ 0x1,	"video ID" },
	{ 0x2,	"still texture ID" },
	{ 0x3,	"mesh ID" },
	{ 0x4,	"FBA ID" },
	{ 0x5,	"3D mesh ID" },
	{ 0x6,	"reserved" },
	{ 0x7,	"reserved" },
	{ 0x8,	"reserved" },
	{ 0x9,	"reserved" },
	{ 0xa,	"reserved" },
	{ 0xb,	"reserved" },
	{ 0xc,	"reserved" },
	{ 0xd,	"reserved" },
	{ 0xe,	"reserved" },
	{ 0xf,	"reserved" },
	{ 0,	NULL }
};

static const value_string mp4ves_video_object_type_indication_vals[] = {
	{ 0x0,	"Reserved" },
	{ 0x1,	"Simple Object Type" },
	{ 0x2,	"Simple Scalable Object Type" },
	{ 0x3,	"Core Object Type" },
	{ 0x4,	"Main Object Type" },
	{ 0x5,	"N-bit Object Type" },
	{ 0x6,	"Basic Anim. 2D Texture" },
	{ 0x7,	"Anim. 2D Mesh" },
	{ 0x8,	"Simple Face" },
	{ 0x9,	"Still Scalable Texture" },
	{ 0xa,	"Advanced Real Time Simple" },
	{ 0xb,	"Core Scalable" },
	{ 0xc,	"Advanced Coding Efficiency" },
	{ 0xd,	"Advanced Scalable Texture" },
	{ 0xe,	"Simple FBA" },
	{ 0xf,	"Reserved" },
	/* Reserved 00001111 - 11111111 */
	{ 0,	NULL }
};
/* 6.2.2.1 User data */
static int
dissect_mp4ves_user_data(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, int bit_offset)
{
	int start_bit_offset;

	/* user_data_start_code */
	proto_tree_add_bits_item(tree, hf_mp4ves_start_code_prefix, tvb, bit_offset, 24, ENC_BIG_ENDIAN);
	bit_offset+=24;
	proto_tree_add_bits_item(tree, hf_mp4ves_start_code, tvb, bit_offset, 8, ENC_BIG_ENDIAN);
	bit_offset+=8;
	start_bit_offset = bit_offset;
	/* while( next_bits() != '000 0000 0000 0000 0000 0001') { */
	while ( tvb_get_bits32(tvb,bit_offset, 24, ENC_BIG_ENDIAN) != 1){
		bit_offset+=8;
		/* user_data 8 bits */
	}
	proto_tree_add_item(tree, hf_mp4ves_user_data, tvb, start_bit_offset>>3, (bit_offset - start_bit_offset)>>2, ENC_NA);

	return bit_offset;
}
/*
next_start_code() {
zero_bit
while (!bytealigned())
one_bit
}
*/
static int
dissect_mp4ves_next_start_code(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, int bit_offset)
{
	guint8 zero_bit;
	int start_bit_offset;

	start_bit_offset = bit_offset;

	zero_bit = tvb_get_bits8(tvb,bit_offset,1);
	if (zero_bit != 0){
		/* Error */
	}
	bit_offset++;

	/* zero stuffing bits */
	if(bit_offset %8 == 0)
		return bit_offset;

	while(bit_offset %8 != 0){
		bit_offset++;
	}

	proto_tree_add_bits_item(tree, hf_mp4ves_stuffing, tvb, start_bit_offset, bit_offset-start_bit_offset, ENC_BIG_ENDIAN);

	return bit_offset;
}

#if 0
video_signal_type() {
	video_signal_type
	if (video_signal_type) {
		video_format 3 uimsbf
		video_range 1 bslbf
		colour_description 1 bslbf
		if (colour_description) {
			colour_primaries 8 uimsbf
			transfer_characteristics 8 uimsbf
			matrix_coefficients 8 uimsbf
		}
	}
}
#endif

static int
dissect_mp4ves_visual_object_type(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, int bit_offset)
{
	guint8 video_signal_type, colour_description;

	video_signal_type = tvb_get_bits8(tvb,bit_offset,1);
	proto_tree_add_bits_item(tree, hf_mp4ves_video_signal_type, tvb, bit_offset, 1, ENC_BIG_ENDIAN);
	bit_offset++;
	if (video_signal_type) {
		/* video_format 3 bits */
		bit_offset+=3;
		/* video_range 1 bit */
		bit_offset++;
		/* colour_description 1 bit */
		colour_description = tvb_get_bits8(tvb,bit_offset,1);
		if (colour_description) {
			/* colour_primaries 8 bits */
			bit_offset+=8;
			/* transfer_characteristics 8 bits */
			bit_offset+=8;
			/* matrix_coefficients 8 bits*/
			bit_offset+=8;
		}
	}

	return bit_offset;
}
/*
 * 6.2.3 Video Object Layer
 */

/*
 * Table 6-12 -- Meaning of pixel aspect ratio
 */

static const value_string mp4ves_aspect_ratio_info_vals[] = {
	{ 0x0,	"Forbidden" },
	{ 0x1,	"1:1 (Square)" },
	{ 0x2,	"12:11 (625-type for 4:3 picture)" },
	{ 0x3,	"10:11 (525-type for 4:3 picture)" },
	{ 0x4,	"16:11 (625-type stretched for 16:9 picture)" },
	{ 0x5,	"40:33 (525-type stretched for 16:9 picture)" },
	{ 0x6,	"Reserved" },
	{ 0x7,	"Reserved" },
	{ 0x8,	"Reserved" },
	{ 0x9,	"Reserved" },
	{ 0xa,	"Reserved" },
	{ 0xb,	"Reserved" },
	{ 0xc,	"Reserved" },
	{ 0xd,	"Reserved" },
	{ 0xe,	"Reserved" },
	{ 0xf,	"Extended PAR" },
	{ 0,	NULL }
};

/* Table 6-14 Video Object Layer shape type */
static const value_string mp4ves_video_object_layer_shape_vals[] = {
	{ 0x0,	"rectangular" },
	{ 0x1,	"binary" },
	{ 0x2,	"binary only" },
	{ 0x3,	"grayscale" },
	{ 0,	NULL }
};

static int
dissect_mp4ves_VideoObjectLayer(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, int bit_offset)
{
	guint32 dword;
	int current_bit_offset;
	guint8 octet, is_object_layer_identifier, aspect_ratio_info, vol_control_parameters, vbv_parameters;
	guint8 video_object_layer_shape, video_object_layer_verid = 0;

	/* if(next_bits() == video_object_layer_start_code) { */
	dword = tvb_get_bits32(tvb,bit_offset, 24, ENC_BIG_ENDIAN);
	if (dword != 1){
		return bit_offset;
	}
	octet = tvb_get_bits8(tvb,bit_offset+24, 8);
	if((octet>=0x20)&&(octet<=0x2f)){
		/* Continue */
	}else{
		return bit_offset;
	}
	/* video_object_layer_start_code */
	proto_tree_add_bits_item(tree, hf_mp4ves_start_code_prefix, tvb, bit_offset, 24, ENC_BIG_ENDIAN);
	bit_offset+=24;
	proto_tree_add_bits_item(tree, hf_mp4ves_start_code, tvb, bit_offset, 8, ENC_BIG_ENDIAN);
	bit_offset+= 8;

	/* short_video_header = 0 */
	/* random_accessible_vol 1 */
	proto_tree_add_bits_item(tree, hf_mp4ves_random_accessible_vol, tvb, bit_offset, 1, ENC_BIG_ENDIAN);
	bit_offset++;
	/* video_object_type_indication 8 */
	proto_tree_add_bits_item(tree, hf_mp4ves_video_object_type_indication, tvb, bit_offset, 8, ENC_BIG_ENDIAN);
	bit_offset+= 8;
	/* is_object_layer_identifier 1 */
	is_object_layer_identifier = tvb_get_bits8(tvb,bit_offset, 1);
	proto_tree_add_bits_item(tree, hf_mp4ves_is_object_layer_identifier, tvb, bit_offset, 1, ENC_BIG_ENDIAN);
	bit_offset++;
	if(is_object_layer_identifier) {
		/* video_object_layer_verid 4 uimsbf */
		bit_offset+=4;
		/* video_object_layer_priority 3 uimsbf */
		bit_offset+=3;
	}
	/* aspect_ratio_info 4 uimsbf */
	aspect_ratio_info = tvb_get_bits8(tvb,bit_offset, 1);
	proto_tree_add_bits_item(tree, hf_mp4ves_aspect_ratio_info, tvb, bit_offset, 4, ENC_BIG_ENDIAN);
	if (aspect_ratio_info == 0xf /*"extended_PAR"*/ ) {
		/* par_width 8 uimsbf */
		bit_offset+=8;
		/* par_height 8 uimsbf */
		bit_offset+=8;
	}
	/* vol_control_parameters 1 bslbf */
	/* vol_control_parameters 1 bslbf */
	vol_control_parameters = tvb_get_bits8(tvb,bit_offset, 1);
	proto_tree_add_bits_item(tree, hf_mp4ves_vol_control_parameters, tvb, bit_offset, 1, ENC_BIG_ENDIAN);
	bit_offset++;
	current_bit_offset = bit_offset;
	if (vol_control_parameters) {
		/* chroma_format 2 uimsbf */
		bit_offset+=2;
		/* low_delay 1 uimsbf */
		bit_offset++;
		/* vbv_parameters 1 blsbf */
		vbv_parameters = tvb_get_bits8(tvb,bit_offset, 1);
		bit_offset++;
		if (vbv_parameters) {
			/* first_half_bit_rate 15 uimsbf */
			bit_offset+=15;
			/* marker_bit 1 bslbf */
			bit_offset++;
			/* latter_half_bit_rate 15 uimsbf */
			bit_offset+=15;
			/* marker_bit 1 bslbf */
			bit_offset++;
			/* first_half_vbv_buffer_size 15 uimsbf */
			bit_offset+=15;
			/* marker_bit 1 bslbf */
			bit_offset++;
			/* latter_half_vbv_buffer_size 3 uimsbf */
			bit_offset+=3;
			/* first_half_vbv_occupancy 11 uimsbf */
			bit_offset+=11;
			/* marker_bit 1 blsbf */
			bit_offset++;
			/* latter_half_vbv_occupancy 15 uimsbf */
			bit_offset+=15;
			/* marker_bit 1 blsbf */
			bit_offset++;
		}
	}
	if(bit_offset-current_bit_offset > 0)
		proto_tree_add_expert(tree, pinfo, &ei_mp4ves_not_dissected_bits, tvb, current_bit_offset>>3, (bit_offset+7)>>3);
	/* video_object_layer_shape 2 uimsbf */
	video_object_layer_shape = tvb_get_bits8(tvb,bit_offset, 2);
	proto_tree_add_bits_item(tree, hf_mp4ves_video_object_layer_shape, tvb, bit_offset, 2, ENC_BIG_ENDIAN);
	bit_offset+=2;
	if (video_object_layer_shape == 3/*"grayscale"*/&& video_object_layer_verid != 1){
		/* video_object_layer_shape_extension 4 uimsbf */
		bit_offset+=4;
	}
	/* marker_bit 1 bslbf */
	bit_offset++;
	/* vop_time_increment_resolution 16 uimsbf */
	bit_offset+=16;
	/* marker_bit 1 bslbf */
	bit_offset++;
	/* fixed_vop_rate 1 bslbf */
	bit_offset++;


	return bit_offset;
}
/* Visual object */
/*
VisualObject() {
	visual_object_start_code
	is_visual_object_identifier
	if (is_visual_object_identifier) {
		visual_object_verid
		visual_object_priority
	}
	visual_object_type
	if (visual_object_type == "Video ID" || visual_object_type == "still textureID") {
		video_signal_type()
	}
	next_start_code()
	while ( next_bits()== user_data_start_code){
		user_data()
	}
	if (visual_object_type == "Video ID") {
		video_object_start_code
		VideoObjectLayer()
	}
	else if (visual_object_type == "still texture ID") {
		StillTextureObject()
	}
	else if (visual_object_type == "mesh ID") {
		MeshObject()
	}
	else if (visual_object_type == "FBA ID") {
		FBAObject()
	}
	else if (visual_object_type == "3D mesh ID") {
		3D_Mesh_Object()
	}
	if (next_bits() != "0000 0000 0000 0000 0000 0001")
		next_start_code()
}
*/
static int
dissect_mp4ves_VisualObject(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int bit_offset)
{
	guint8 is_visual_object_identifier, visual_object_type;
	guint32 dword;
	guint8 octet;

	is_visual_object_identifier = tvb_get_bits8(tvb,bit_offset,1);
	proto_tree_add_bits_item(tree, hf_mp4ves_is_visual_object_identifier, tvb, bit_offset, 1, ENC_BIG_ENDIAN);
	bit_offset++;
	if(is_visual_object_identifier){
		/* visual_object_verid 4 bits*/
		bit_offset+=4;
		/* visual_object_priority 3 bits*/
		bit_offset+=3;
	}
	/* visual_object_type 4 bits*/
	visual_object_type = tvb_get_bits8(tvb,bit_offset,4);
	proto_tree_add_bits_item(tree, hf_mp4ves_visual_object_type, tvb, bit_offset, 4, ENC_BIG_ENDIAN);
	bit_offset+=4;
	if ((visual_object_type == 1/*"Video ID"*/) || (visual_object_type == 2/*"still textureID"*/)) {
		/* video_signal_type() */
		bit_offset = dissect_mp4ves_visual_object_type(tvb, pinfo, tree, bit_offset);
	}
	/* next_start_code() */
	bit_offset = dissect_mp4ves_next_start_code(tvb, pinfo, tree, bit_offset);
	dword = tvb_get_bits32(tvb,bit_offset, 32, ENC_BIG_ENDIAN);
/*
	while ( next_bits()== user_data_start_code){
		user_data()
	}
*/
	while(dword==0x1b2){
		bit_offset = dissect_mp4ves_user_data(tvb, pinfo, tree, bit_offset);
		dword = tvb_get_bits32(tvb,bit_offset, 32, ENC_BIG_ENDIAN);
	}
	if (visual_object_type == 1/*"Video ID"*/) {
		/*
		 * video_object_start_code
		 */
		dword = tvb_get_bits32(tvb,bit_offset, 24, ENC_BIG_ENDIAN);
		if (dword != 1){
			/* no start code */
			return -1;
		}
		octet = tvb_get_bits8(tvb,bit_offset+24, 8);
		if(octet>0x20){
			/* Error */
			return -1;
		}
		proto_tree_add_bits_item(tree, hf_mp4ves_start_code_prefix, tvb, bit_offset, 24, ENC_BIG_ENDIAN);
		bit_offset+=24;
		proto_tree_add_bits_item(tree, hf_mp4ves_start_code, tvb, bit_offset, 8, ENC_BIG_ENDIAN);
		bit_offset+= 8;
		if(tvb_reported_length_remaining(tvb,(bit_offset>>3))<=0){
			proto_tree_add_expert(tree, pinfo, &ei_mp4ves_config_too_short, tvb, 0, -1);
			return -1;
		}
		/*
		VideoObjectLayer()
		*/
		bit_offset = dissect_mp4ves_VideoObjectLayer(tvb, pinfo, tree, bit_offset);
	}

	return bit_offset;
}

static int
dissect_mp4ves_VisualObjectSequence(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int bit_offset)
{
	guint32 dword;

	/*VisualObjectSequence() {
	do {
		visual_object_sequence_start_code
	*/

	/* Get start code prefix */
	dword = tvb_get_bits32(tvb,bit_offset, 32, ENC_BIG_ENDIAN);
	if ((dword & 0x00000100) != 0x00000100){
		/* No start code prefix */
		return -1;
	}
	proto_tree_add_bits_item(tree, hf_mp4ves_start_code_prefix, tvb, bit_offset, 24, ENC_BIG_ENDIAN);
	bit_offset+= 24;

	proto_tree_add_bits_item(tree, hf_mp4ves_start_code, tvb, bit_offset, 8, ENC_BIG_ENDIAN);
	bit_offset+= 8;

	/* Expect visual_object_sequence_start_code */
	if(dword != 0x1b0)
		return -1;
	/* 	profile_and_level_indication */
	proto_tree_add_bits_item(tree, hf_mp4ves_profile_and_level_indication, tvb, bit_offset, 8, ENC_BIG_ENDIAN);
	bit_offset+= 8;

	/* 	while ( next_bits()== user_data_start_code){
		user_data()
	}
	*/
	dword = tvb_get_bits32(tvb,bit_offset, 32, ENC_BIG_ENDIAN);
	bit_offset+= 32;
	if ((dword & 0x00000100) != 0x00000100){
		/* No start code prefix */
		return -1;
	}
	if(dword==0x1b2){
		/*
		 * user_data_start_code
		 * XXX call user data dissection here
		 */
		return -1;
	}
	if(dword==0x1b5){
	/*
	 * VisualObject()
	 */
		bit_offset = dissect_mp4ves_VisualObject(tvb, pinfo, tree, bit_offset);
	}
		/*
	} while ( next_bits() != visual_object_sequence_end_code)
	visual_object_sequence_end_code
	*/
	return bit_offset;
}

static int
dissect_mp4ves_config(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
	proto_item *item;
	proto_tree *mp4ves_tree;

	item = proto_tree_add_item(tree, hf_mp4ves_config, tvb, 0, -1, ENC_NA);
	mp4ves_tree = proto_item_add_subtree(item, ett_mp4ves_config);

	dissect_mp4ves_VisualObjectSequence(tvb, pinfo, mp4ves_tree, 0);
	return tvb_captured_length(tvb);
}

static int
dissect_mp4ves(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
	int bit_offset = 0;
	proto_item *item;
	proto_tree *mp4ves_tree;
	guint32 dword;

	/* Make entries in Protocol column and Info column on summary display */
	col_set_str(pinfo->cinfo, COL_PROTOCOL, "MP4V-ES");
	if (tree) {
		item = proto_tree_add_item(tree, proto_mp4ves, tvb, 0, -1, ENC_NA);
		mp4ves_tree = proto_item_add_subtree(item, ett_mp4ves);
	/*
	    +------+------+------+------+
	(a) | RTP  |  VS  |  VO  | VOL  |
	    |header|header|header|header|
	    +------+------+------+------+

	    +------+------+------+------+------------+
	(b) | RTP  |  VS  |  VO  | VOL  |Video Packet|
	    |header|header|header|header|            |
	    +------+------+------+------+------------+

	    +------+-----+------------------+
	(c) | RTP  | GOV |Video Object Plane|
	    |header|     |                  |
	    +------+-----+------------------+

	    +------+------+------------+  +------+------+------------+
	(d) | RTP  | VOP  |Video Packet|  | RTP  |  VP  |Video Packet|
	    |header|header|    (1)     |  |header|header|    (2)     |
	    +------+------+------------+  +------+------+------------+

	    +------+------+------------+------+------------+------+------------+
	(e) | RTP  |  VP  |Video Packet|  VP  |Video Packet|  VP  |Video Packet|
	    |header|header|     (1)    |header|    (2)     |header|    (3)     |
	    +------+------+------------+------+------------+------+------------+

	   +------+------+------------+  +------+------------+
	(f) | RTP  | VOP  |VOP fragment|  | RTP  |VOP fragment|
	    |header|header|    (1)     |  |header|    (2)     | ___
	    +------+------+------------+  +------+------------+

	     Figure 2 - Examples of RTP packetized MPEG-4 Visual bitstream

	So a valid packet should start with
	VS	- Visual Object Sequence Header
	GOV	- Group_of_VideoObjectPlane
	VOP	- Video Object Plane
	VP	- Video Plane
	Otherwise it's a VOP fragment.

	visual_object_sequence_start_code: The visual_object_sequence_start_code is
	the bit string '000001B0' in hexadecimal. It initiates a visual session.

	group_of_vop_start_code: The group_of_vop_start_code is the bit string '000001B3' in hexadecimal. It identifies
	the beginning of a GOV header.

	vop_start_code: This is the bit string '000001B6' in hexadecimal.


	*/
		if (tvb_reported_length(tvb)< 4){
			/* To short to be a start code */
			proto_tree_add_item(mp4ves_tree, hf_mp4ves_data, tvb, bit_offset>>3, -1, ENC_NA);
			return tvb_captured_length(tvb);
		}
		dword = tvb_get_bits32(tvb,bit_offset, 24, ENC_BIG_ENDIAN);
		if (dword != 1){
			/* if it's not 23 zeros followed by 1 it isn't a start code */
			proto_tree_add_item(mp4ves_tree, hf_mp4ves_data, tvb, bit_offset>>3, -1, ENC_NA);
			return tvb_captured_length(tvb);
		}
		dword = tvb_get_bits8(tvb,24, 8);
		bit_offset = bit_offset+8;
		switch(dword){
		/* vop_start_code */
		case 0xb6:
			proto_tree_add_bits_item(mp4ves_tree, hf_mp4ves_start_code_prefix, tvb, bit_offset, 24, ENC_BIG_ENDIAN);
			bit_offset = bit_offset+24;
			/* vop_coding_type 2 bits */
			proto_tree_add_bits_item(mp4ves_tree, hf_mp4ves_vop_coding_type, tvb, bit_offset, 2, ENC_BIG_ENDIAN);
			break;
		case 0xb0:
			/* VS start code */
			/*bit_offset = */dissect_mp4ves_VisualObjectSequence(tvb, pinfo, mp4ves_tree, 0);
			break;
		default:
			proto_tree_add_bits_item(mp4ves_tree, hf_mp4ves_start_code_prefix, tvb, bit_offset, 24, ENC_BIG_ENDIAN);
			/*bit_offset = bit_offset+24;*/
			break;
		}
	}

	return tvb_captured_length(tvb);
}
/*
 * Parameter name profileAndLevel
 * Parameter description This is a nonCollapsing GenericParameter
 * Parameter identifier value 0
 * Parameter status Mandatory
 * Parameter type unsignedMax. Shall be in the range 0..255.
 * H245:
 * unsignedMax       INTEGER(0..65535), -- Look for max
 */
static int
dissect_mp4ves_par_profile(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree _U_, void *data)
{
	int offset = 0;
	guint16 lvl;
	const gchar *p = NULL;
	asn1_ctx_t *actx;

	/* Reject the packet if data is NULL */
	if (data == NULL)
		return 0;
	actx = get_asn1_ctx(data);
	DISSECTOR_ASSERT(actx);

	lvl = tvb_get_ntohs(tvb, offset);
	p = try_val_to_str(lvl, VALS(mp4ves_level_indication_vals));
	if (p) {
		proto_item_append_text(actx->created_item, " - profileAndLevel %s", p);
	}
	offset += 2;
	return offset;
}
static int
dissect_mp4ves_par_video_object_type(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree _U_, void *data)
{
	int offset = 0;
	guint16 lvl;
	const gchar *p = NULL;
	asn1_ctx_t *actx;

	/* Reject the packet if data is NULL */
	if (data == NULL)
		return 0;
	actx = get_asn1_ctx(data);
	DISSECTOR_ASSERT(actx);

	lvl = tvb_get_ntohs(tvb, offset);
	p = try_val_to_str(lvl, VALS(mp4ves_video_object_type_vals));
	if (p) {
		proto_item_append_text(actx->created_item, " - video_object_type %s", p);
	}
	offset += 2;
	return offset;
}

static int
dissect_mp4ves_par_decoderConfigurationInformation(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
	asn1_ctx_t *actx;

	/* Reject the packet if data is NULL */
	if (data == NULL)
		return 0;
	actx = get_asn1_ctx(data);
	DISSECTOR_ASSERT(actx);

	dissect_mp4ves_config(tvb, pinfo, tree, data);

	return tvb_reported_length(tvb);
}

typedef struct _mp4ves_capability_t {
	const gchar *id;
	const gchar *name;
	dissector_t content_pdu;
} mp4ves_capability_t;

static mp4ves_capability_t mp4ves_capability_tab[] = {
	/* ITU-T H.245  capabilities ISO/IEC 14496-2(m*/
	{ "GenericCapability/0.0.8.245.1.0.0/nonCollapsing/0", "profileAndLevel", dissect_mp4ves_par_profile },
	{ "GenericCapability/0.0.8.245.1.0.0/nonCollapsing/1", "object", dissect_mp4ves_par_video_object_type },
	{ "GenericCapability/0.0.8.245.1.0.0/nonCollapsing/2", "decoderConfigurationInformation", dissect_mp4ves_par_decoderConfigurationInformation },
	{ "GenericCapability/0.0.8.245.1.0.0/nonCollapsing/3", "drawingOrder", NULL },
	{ "GenericCapability/0.0.8.245.1.0.0/collapsing/4", "visualBackChannelHandle", NULL },
	{ NULL, NULL, NULL },
};

static mp4ves_capability_t *find_cap(const gchar *id) {
	mp4ves_capability_t *ftr = NULL;
	mp4ves_capability_t *f;

	for (f=mp4ves_capability_tab; f->id; f++) {
		if (!strcmp(id, f->id)) { ftr = f; break; }
	}
	return ftr;
}

static int
dissect_mp4ves_name(tvbuff_t *tvb _U_, packet_info *pinfo, proto_tree *tree, void* data)
{
	asn1_ctx_t *actx;
	mp4ves_capability_t *ftr;

	/* Reject the packet if data is NULL */
	if (data == NULL)
		return 0;
	actx = get_asn1_ctx(data);
	DISSECTOR_ASSERT(actx);

	if (tree) {
		ftr = find_cap(pinfo->match_string);
		if (ftr) {
			proto_item_append_text(actx->created_item, " - %s", ftr->name);
			proto_item_append_text(proto_item_get_parent(proto_tree_get_parent(tree)), ": %s", ftr->name);
		} else {
			proto_item_append_text(actx->created_item, " - unknown(%s)", pinfo->match_string);
		}
	}

	return tvb_reported_length(tvb);
}

void
proto_register_mp4ves(void)
{


/* Setup list of header fields  See Section 1.6.1 for details*/
	static hf_register_info hf[] = {
		{ &hf_mp4ves_config,
		  { "Configuration",        "mp4ves.configuration",
		    FT_BYTES, BASE_NONE, NULL, 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_start_code_prefix,
		  { "start code prefix",		"mp4ves.start_code_prefix",
		    FT_UINT32, BASE_HEX, NULL, 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_start_code,
		  { "Start code",		"mp4ves.start_code",
		    FT_UINT8, BASE_RANGE_STRING|BASE_HEX, RVALS(mp4ves_startcode_vals), 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_vop_coding_type,
		  { "vop_coding_type",		"mp4ves.vop_coding_type",
		    FT_UINT8, BASE_DEC, VALS(mp4ves_vop_coding_type_vals), 0x0,
		    "Start code", HFILL }
		},
		{&hf_mp4ves_profile_and_level_indication,
		 { "profile_and_level_indication",		"mp4ves.profile_and_level_indication",
		   FT_UINT8, BASE_DEC,VALS(mp4ves_level_indication_vals), 0x0,
		   NULL, HFILL }
		},
		{ &hf_mp4ves_is_visual_object_identifier,
		  { "visual_object_identifier",		"mp4ves.visual_object_identifier",
		    FT_UINT8, BASE_DEC, NULL, 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_visual_object_type,
		  { "visual_object_type",		"mp4ves.visual_object_type",
		    FT_UINT32, BASE_DEC, VALS(mp4ves_visual_object_type_vals), 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_video_signal_type,
		  { "video_signal_type",		"mp4ves.video_signal_type",
		    FT_UINT8, BASE_DEC, NULL, 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_stuffing,
		  { "Stuffing",		"mp4ves.stuffing",
		    FT_UINT8, BASE_DEC, NULL, 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_video_object_type_indication,
		  { "video_object_type_indication",		"mp4ves.video_object_type_indication",
		    FT_UINT8, BASE_DEC, VALS(mp4ves_video_object_type_indication_vals), 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_random_accessible_vol,
		  { "random_accessible_vol",		"mp4ves.random_accessible_vol",
		    FT_UINT8, BASE_DEC, NULL, 0x0,
		    "video_object_type_indication", HFILL }
		},
		{ &hf_mp4ves_is_object_layer_identifier,
		  { "is_object_layer_identifier",		"mp4ves.is_object_layer_identifier",
		    FT_UINT8, BASE_DEC, NULL, 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_aspect_ratio_info,
		  { "aspect_ratio_info",		"mp4ves.aspect_ratio_info",
		    FT_UINT8, BASE_DEC, VALS(mp4ves_aspect_ratio_info_vals), 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_vol_control_parameters,
		  { "vol_control_parameters",		"mp4ves.vol_control_parameters",
		    FT_UINT8, BASE_DEC, NULL, 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_video_object_layer_shape,
		  { "video_object_layer_shape",		"mp4ves.video_object_layer_shape",
		    FT_UINT8, BASE_DEC, VALS(mp4ves_video_object_layer_shape_vals), 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_user_data,
		  { "User data",        "mp4ves.user_data",
		    FT_BYTES, BASE_NONE, NULL, 0x0,
		    NULL, HFILL }
		},
		{ &hf_mp4ves_data,
		  { "Data",        "mp4ves.data",
		    FT_BYTES, BASE_NONE, NULL, 0x0,
		    NULL, HFILL }
		},
	};

/* Setup protocol subtree array */
	static gint *ett[] = {
		&ett_mp4ves,
		&ett_mp4ves_config,
	};

	static ei_register_info ei[] = {
		{ &ei_mp4ves_config_too_short, { "mp4ves.config_too_short", PI_MALFORMED, PI_ERROR, "Config string too short", EXPFILL }},
		{ &ei_mp4ves_not_dissected_bits, { "mp4ves.not_dissected_bits", PI_UNDECODED, PI_WARN, "Not dissected bits", EXPFILL }},
	};

	module_t *mp4ves_module;
	expert_module_t* expert_mp4ves;

/* Register the protocol name and description */
	proto_mp4ves = proto_register_protocol("MP4V-ES","MP4V-ES", "mp4v-es");

/* Required function calls to register the header fields and subtrees used */
	proto_register_field_array(proto_mp4ves, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));
	expert_mp4ves = expert_register_protocol(proto_mp4ves);
	expert_register_field_array(expert_mp4ves, ei, array_length(ei));
	/* Register a configuration option for port */

	mp4ves_handle = register_dissector("mp4ves", dissect_mp4ves, proto_mp4ves);
	register_dissector("mp4ves_config", dissect_mp4ves_config, proto_mp4ves);

	/* Register a configuration option for port */
	mp4ves_module = prefs_register_protocol(proto_mp4ves, NULL);

        prefs_register_obsolete_preference(mp4ves_module, "dynamic.payload.type");

}

void
proto_reg_handoff_mp4ves(void)
{
	mp4ves_capability_t *ftr;

	dissector_add_string("rtp_dyn_payload_type","MP4V-ES", mp4ves_handle);

	mp4ves_name_handle = create_dissector_handle(dissect_mp4ves_name, proto_mp4ves);
	for (ftr=mp4ves_capability_tab; ftr->id; ftr++) {
	    if (ftr->name)
			dissector_add_string("h245.gef.name", ftr->id, mp4ves_name_handle);
		if (ftr->content_pdu)
			dissector_add_string("h245.gef.content", ftr->id, create_dissector_handle(ftr->content_pdu, proto_mp4ves));
	}

	dissector_add_uint_range_with_preference("rtp.pt", "", mp4ves_handle);
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 8
 * tab-width: 8
 * indent-tabs-mode: t
 * End:
 *
 * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 * :indentSize=8:tabSize=8:noTabs=false:
 */