Serializers

Serializers (historically called “send tables” in Source 1) define the field schema for each entity class. They describe what fields an entity has, their types, and how they are encoded in the bit stream.

Source Data

Serializer definitions arrive in the DEM_SendTables command, which contains a CsvcMsgFlattenedSerializer protobuf message. This message has three main parts:

1. Symbols — a string table of all type names, field names, and encoder names

2. Fields — a flat list of field definitions, each referencing symbols by index

3. Serializers — a list of serializer definitions, each referencing a subset of fields by index

Serializer Structure

A serializer is a named collection of fields:

Serializer "CCitadelPlayerController"
  fields:
    [0] m_iTeamNum:       U64
    [1] m_iszPlayerName:  String
    [2] m_steamID:        U64
    [3] m_PlayerDataGlobal: (nested serializer)
      [0] m_nHeroID:     U64
      [1] m_bAlive:      Bool
      [2] m_iPlayerKills: I64
      ...

Fields can be nested — a field may reference another serializer, creating a hierarchy. This is how dotted paths like m_PlayerDataGlobal.m_iPlayerKills work.

Field Properties

Each field carries:

Property	Description
var_type	Type string (e.g., "bool", "float32", "Vector", "CNetworkUtlVectorBase< int32 >")
var_name	Field name (e.g., "m_iHealth")
bit_count	Number of bits for quantized encoding
low_value / high_value	Range for quantized floats
encode_flags	Flags affecting encoding behavior
var_encoder	Special encoder name ("coord", "normal", "qangle_precise", etc.)
field_serializer	Nested serializer for compound types

Decoders

Each field is assigned a decoder based on its type, encoder, and bit count. The main decoder types are:

Decoder	Used For
Bool	Boolean fields
I64 / U64	Integer fields (varint encoded)
F32NoScale	Raw 32-bit IEEE floats
F32Quantized	Floats stored as N-bit values mapped to a [low, high] range
F32Coord	Source coordinate encoding (14-bit integer + 5-bit fraction)
F32SimulationTime	Tick count converted to seconds via tick * tick_interval
String	Variable-length byte strings
Vector2/3/4	Component-wise float vectors
QAngle*	Euler angles with various precision encodings

Special Field Types

• Fixed arrays: Type[N] — decoded as N sequential values

• Dynamic arrays: CNetworkUtlVectorBase<T> — prefixed with a varint length, then that many elements

• Pointers: Type* — a single boolean (present/absent)

Field Resolution

Serializers support resolving dotted field paths to packed 64-bit keys:

# Internally, this walks the serializer hierarchy:
key = serializer.resolve_field_key("m_PlayerDataGlobal.m_iPlayerKills")
# key is a packed u64 encoding the path [3, 2] (field indices at each level)

The packed key is what gets stored in the entity’s field map and used for O(1) lookup.