RTMP.AMF0 (rtmp v0.1.0)

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AMF0 encoding and decoding.

RTMP command messages (connect, publish, ...) and data messages (onMetaData) are sequences of AMF0 values.

Value mapping

AMF0 typeElixir (decoded)Encoded from
Numberfloat, or :nan / :infinity / :neg_infinityinteger, float, those atoms
Booleantrue / falsetrue / false
Stringbinarybinary shorter than 64 KiB
Long Stringbinarybinary of 64 KiB or more
Objectmap with binary keysmap (atom or binary keys)
ECMA Arraymap with binary keys{:ecma_array, map}
Strict Arraylistlist
Nullnilnil
Undefined:undefined:undefined
DateDateTime (millisecond precision, UTC)DateTime
Typed Object{:typed_object, class, map}same
XML Document{:xml, binary}same
Reference{:reference, index}same
Unsupported:unsupported:unsupported

Objects and ECMA arrays both decode to plain maps, so the distinction is lost on a round trip; encode a map as {:ecma_array, map} when the receiver needs an ECMA array (FLV onMetaData, for example).

NaN and the infinities can't be represented as BEAM floats, so they decode to atoms instead of failing — some encoders really do send them in metadata.

Robustness

Decoding never raises on malformed input; it returns {:error, reason}. Nesting deeper than 64 levels is rejected, so hostile input can't drive unbounded recursion. AMF3 values (the AVM+ switch marker) are not supported and decode to an error.

Summary

Types

value()

Functions

decode(binary)

Decodes one AMF0 value from the front of binary.

decode_all(binary)

Decodes every AMF0 value in binary, which must contain nothing else.

encode(value)

Encodes one value. Raises ArgumentError for terms with no AMF0 mapping — encoding is only ever done on your own data, never on network input.

encode_all(values)

Encodes a list of values back to back, the way command messages are laid out.

max_depth()

Maximum nesting depth accepted when decoding.

Types

value()

@type value() ::
  float()
  | :nan
  | :infinity
  | :neg_infinity
  | boolean()
  | binary()
  | map()
  | list()
  | nil
  | :undefined
  | :unsupported
  | DateTime.t()
  | {:ecma_array, map()}
  | {:typed_object, binary(), map()}
  | {:xml, binary()}
  | {:reference, non_neg_integer()}

Functions

decode(binary)

@spec decode(binary()) :: {:ok, value(), binary()} | {:error, term()}

Decodes one AMF0 value from the front of binary.

Returns {:ok, value, rest} or {:error, reason}.

decode_all(binary)

@spec decode_all(binary()) :: {:ok, [value()]} | {:error, term()}

Decodes every AMF0 value in binary, which must contain nothing else.

encode(value)

@spec encode(value()) :: binary()

Encodes one value. Raises ArgumentError for terms with no AMF0 mapping — encoding is only ever done on your own data, never on network input.

encode_all(values)

@spec encode_all([value()]) :: binary()

Encodes a list of values back to back, the way command messages are laid out.

max_depth()

@spec max_depth() :: pos_integer()

Maximum nesting depth accepted when decoding.