defmodule ExSDP.Attribute.FMTP do
@moduledoc """
This module represents fmtp (RFC 5576).
Parameters for:
* H264 (not all, RFC 6184),
* VP8, VP9, OPUS (RFC 7587)
* RTX (RFC 4588)
* FLEXFEC (RFC 8627)
* Telephone Events (RFC 4733)
* RED (RFC 2198)
are currently supported.
"""
alias ExSDP.Attribute.RTPMapping
alias ExSDP.Utils
@enforce_keys [:pt]
defstruct @enforce_keys ++
[
# H264
:profile_level_id,
:level_asymmetry_allowed,
:packetization_mode,
:max_mbps,
:max_smbps,
:max_fs,
:max_dpb,
:max_br,
# OPUS
:maxaveragebitrate,
:maxplaybackrate,
:sprop_maxcapturerate,
:maxptime,
:ptime,
:minptime,
:stereo,
:cbr,
:useinbandfec,
:usedtx,
# VP8/9
:profile_id,
:max_fr,
# RTX
:apt,
:rtx_time,
# FLEXFEC
:repair_window,
# Telephone Events
:dtmf_tones,
# RED
:redundant_payloads,
unknown: []
]
@type t :: %__MODULE__{
profile_level_id: non_neg_integer() | nil,
max_mbps: non_neg_integer() | nil,
max_smbps: non_neg_integer() | nil,
max_fs: non_neg_integer() | nil,
max_dpb: non_neg_integer() | nil,
max_br: non_neg_integer() | nil,
level_asymmetry_allowed: boolean() | nil,
packetization_mode: non_neg_integer() | nil,
# OPUS
maxaveragebitrate: non_neg_integer() | nil,
maxplaybackrate: non_neg_integer() | nil,
sprop_maxcapturerate: non_neg_integer() | nil,
maxptime: non_neg_integer() | nil,
ptime: non_neg_integer() | nil,
minptime: non_neg_integer() | nil,
stereo: boolean() | nil,
cbr: boolean() | nil,
useinbandfec: boolean() | nil,
usedtx: boolean() | nil,
# VP8/9
profile_id: non_neg_integer() | nil,
max_fr: non_neg_integer() | nil,
# RTX
apt: RTPMapping.payload_type_t() | nil,
rtx_time: non_neg_integer() | nil,
# FLEXFEC
repair_window: non_neg_integer() | nil,
# Telephone Events
dtmf_tones: String.t() | nil,
# RED
redundant_payloads: [RTPMapping.payload_type_t()] | nil,
# params that are currently not supported
unknown: [String.t()]
}
@typedoc """
Key that can be used for searching this attribute using `ExSDP.Media.get_attribute/2`.
"""
@type attr_key :: :fmtp
@typedoc """
Reason of parsing failure.
"""
@type reason ::
:invalid_fmtp | :invalid_pt | :string_nan | :string_not_hex | :string_not_0_nor_1
@spec parse(binary()) :: {:ok, t()} | {:error, reason()}
def parse(fmtp) do
with [pt_string, rest] <- String.split(fmtp, " ", parts: 2),
{:ok, pt} <- Utils.parse_payload_type(pt_string) do
rest
|> String.split(";")
# remove leading whitespaces
|> Enum.map(&String.trim(&1))
|> do_parse(%__MODULE__{pt: pt})
else
{:error, _reason} = err -> err
_other -> :invalid_fmtp
end
end
defp do_parse([], fmtp), do: {:ok, fmtp}
defp do_parse(params, fmtp) do
case parse_param(params, fmtp) do
{rest, %__MODULE__{} = fmtp} -> do_parse(rest, fmtp)
{:error, _reason} = error -> error
end
end
defp parse_param(["profile-level-id=" <> profile_level_id | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_hex_string(profile_level_id),
do: {rest, %{fmtp | profile_level_id: value}}
end
defp parse_param(["level-asymmetry-allowed=" <> level_asymmetry_allowed | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_bool_string(level_asymmetry_allowed),
do: {rest, %{fmtp | level_asymmetry_allowed: value}}
end
defp parse_param(["packetization-mode=" <> packetization_mode | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(packetization_mode),
do: {rest, %{fmtp | packetization_mode: value}}
end
defp parse_param(["max-mbps=" <> max_mbps | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(max_mbps),
do: {rest, %{fmtp | max_mbps: value}}
end
defp parse_param(["max-smbps=" <> max_smbps | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(max_smbps),
do: {rest, %{fmtp | max_smbps: value}}
end
defp parse_param(["max-fs=" <> max_fs | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(max_fs), do: {rest, %{fmtp | max_fs: value}}
end
defp parse_param(["max-dpb=" <> max_dpb | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(max_dpb),
do: {rest, %{fmtp | max_dpb: value}}
end
defp parse_param(["max-br=" <> max_br | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(max_br), do: {rest, %{fmtp | max_br: value}}
end
defp parse_param(["maxaveragebitrate=" <> maxaveragebitrate | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(maxaveragebitrate),
do: {rest, %{fmtp | maxaveragebitrate: value}}
end
defp parse_param(["maxplaybackrate=" <> maxplaybackrate | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(maxplaybackrate),
do: {rest, %{fmtp | maxplaybackrate: value}}
end
defp parse_param(["sprop-maxcapturerate=" <> sprop_maxcapturerate | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(sprop_maxcapturerate),
do: {rest, %{fmtp | sprop_maxcapturerate: value}}
end
defp parse_param(["maxptime=" <> maxptime | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(maxptime),
do: {rest, %{fmtp | maxptime: value}}
end
defp parse_param(["ptime=" <> ptime | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(ptime),
do: {rest, %{fmtp | ptime: value}}
end
defp parse_param(["minptime=" <> minptime | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(minptime),
do: {rest, %{fmtp | minptime: value}}
end
defp parse_param(["stereo=" <> stereo | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_bool_string(stereo),
do: {rest, %{fmtp | stereo: value}}
end
defp parse_param(["cbr=" <> cbr | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_bool_string(cbr),
do: {rest, %{fmtp | cbr: value}}
end
defp parse_param(["useinbandfec=" <> useinbandfec | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_bool_string(useinbandfec),
do: {rest, %{fmtp | useinbandfec: value}}
end
defp parse_param(["usedtx=" <> usedtx | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_bool_string(usedtx),
do: {rest, %{fmtp | usedtx: value}}
end
defp parse_param(["max-fr=" <> max_fr | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(max_fr),
do: {rest, %{fmtp | max_fr: value}}
end
defp parse_param(["profile-id=" <> profile_id | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(profile_id),
do: {rest, %{fmtp | profile_id: value}}
end
defp parse_param(["apt=" <> value | rest], fmtp) do
with {:ok, value} <- Utils.parse_payload_type(value), do: {rest, %{fmtp | apt: value}}
end
defp parse_param(["rtx-time=" <> value | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(value), do: {rest, %{fmtp | rtx_time: value}}
end
defp parse_param(["repair-window=" <> value | rest], fmtp) do
with {:ok, value} <- Utils.parse_numeric_string(value),
do: {rest, %{fmtp | repair_window: value}}
end
defp parse_param([head | rest] = params, fmtp) do
# this is for non-key-value parameters as `key=value` format is not mandatory
cond do
String.contains?(head, "=") -> {rest, Map.update!(fmtp, :unknown, &(&1 ++ [head]))}
String.contains?(head, "/") -> parse_redundant_payloads_param(params, fmtp)
true -> parse_dtmf_tones_param(params, fmtp)
end
end
defp parse_dtmf_tones_param([head | rest], fmtp) do
with dtmf_tones <- String.split(head, ","),
true <- validate_dtmf_tones(dtmf_tones) do
{rest, Map.put(fmtp, :dtmf_tones, head)}
else
_error -> {:error, :invalid_dtmf_tones}
end
end
defp parse_redundant_payloads_param([head | rest], fmtp) do
with redundant_payloads <- String.split(head, "/"),
{:ok, redundant_payloads} <-
Bunch.Enum.try_map(redundant_payloads, &Utils.parse_payload_type/1) do
# We need uniq because Chrome sends 111/111 most likely to avoid confusion with dtmf_tones_param
{rest, Map.put(fmtp, :redundant_payloads, Enum.uniq(redundant_payloads))}
end
end
defp validate_dtmf_tones(dtmf_tones) do
Enum.all?(dtmf_tones, &validate_dtmf_tone(&1))
end
defp validate_dtmf_tone(dtmf_tone) do
case String.split(dtmf_tone, "-") do
[start_range, end_range] ->
with {:ok, start_range} <- Utils.parse_numeric_string(start_range),
{:ok, end_range} <- Utils.parse_numeric_string(end_range) do
start_range < end_range and 0 <= start_range and end_range <= 255
else
_error -> false
end
[single_tone] ->
case Utils.parse_numeric_string(single_tone) do
{:ok, single_tone} -> 0 <= single_tone and single_tone <= 255
_other -> false
end
_other ->
false
end
end
end
defimpl String.Chars, for: ExSDP.Attribute.FMTP do
@impl true
def to_string(fmtp) do
alias ExSDP.Serializer
params =
[
# H264
Serializer.maybe_serialize_hex("profile-level-id", fmtp.profile_level_id),
Serializer.maybe_serialize("max-mbps", fmtp.max_mbps),
Serializer.maybe_serialize("max-smbps", fmtp.max_smbps),
Serializer.maybe_serialize("max-fs", fmtp.max_fs),
Serializer.maybe_serialize("max-dpb", fmtp.max_dpb),
Serializer.maybe_serialize("max-br", fmtp.max_br),
Serializer.maybe_serialize("level-asymmetry-allowed", fmtp.level_asymmetry_allowed),
Serializer.maybe_serialize("packetization-mode", fmtp.packetization_mode),
# OPUS
Serializer.maybe_serialize("maxaveragebitrate", fmtp.maxaveragebitrate),
Serializer.maybe_serialize("maxplaybackrate", fmtp.maxplaybackrate),
Serializer.maybe_serialize("sprop_maxcapturerate", fmtp.sprop_maxcapturerate),
Serializer.maybe_serialize("maxptime", fmtp.maxptime),
Serializer.maybe_serialize("ptime", fmtp.ptime),
Serializer.maybe_serialize("minptime", fmtp.minptime),
Serializer.maybe_serialize("stereo", fmtp.stereo),
Serializer.maybe_serialize("cbr", fmtp.cbr),
Serializer.maybe_serialize("useinbandfec", fmtp.useinbandfec),
Serializer.maybe_serialize("usedtx", fmtp.usedtx),
# VP8/9
Serializer.maybe_serialize("profile-id", fmtp.profile_id),
Serializer.maybe_serialize("max-fr", fmtp.max_fr),
# RTX
Serializer.maybe_serialize("apt", fmtp.apt),
Serializer.maybe_serialize("rtx-time", fmtp.rtx_time),
# FLEXFEC
Serializer.maybe_serialize("repair-window", fmtp.repair_window),
# Telephone Events
Serializer.maybe_serialize("dtmf-tones", fmtp.dtmf_tones),
# RED
Serializer.maybe_serialize_list(fmtp.redundant_payloads, "/")
]
|> Enum.filter(fn param -> param != "" end)
|> Enum.join(";")
"fmtp:#{fmtp.pt} #{params}"
end
end
