Encoder

• 1: Encoder Audio Routing
• 2: Encoder Status Screen Object
• 3: Encoder Configuration
• 4: Encoder Connections
• 5: Encoder Regionalization

1 - Encoder Audio Routing

Internally, the encoder provides a mixing engine that combines various audio sources. In this chapter, we give an overview about this mixing engine, and describe some common usage scenarios.

Inputs

Player Inputs

Player inputs provide a (virtual) playback devices in the Audio Routing configuration. When you assign the on air playback of a player to one of these devices, the audio is routed directly into the encoder module, not requiring any (physical or virtual) Windows soundcard. This will even work on datacenter servers with no physical audio hardware at all.

Each player input provides a separate DSP chain, accessible on the Soundprocessing tab on the Encoder configuration page.

The following player inputs are available:

• Player Input: This is the main player input for the encoder. It is simply labeled Encoder in the Audio Routing playback device list.
• Player Input 2/3/4: In addition to the main player input, the encoder offers three additional player inputs, labeled as Encoder - Player Input 2(/3/4) in the Audio Routing configuration. You can use these inputs when you need separate DSP processing for some players.
• High Priority Input: This is a special input which mutes the audio from all other inputs (primary player input, player input 2/3/4, live inputs) whenever audio is played into it. The other signals are briefly faded; the duration of this fade can be adjusted in the configuration. The High Priority Input is most frequently used for the Stream Monitor.

Live Inputs

The encoder provides three live inputs which can be used to pick up audio from a physical sound card:

• MIC: This input is meant to pick up a DJ microphone signal during live operation, in situations where no physical mixing console is used. It can be toggled via the MIC button in the Encoder Status screen object. According to the settings on the Encoder configuration page, optional ducking of the player inputs will take place when the MIC input is active.
• LINE: This input is most frequently used to pick up the master signal coming from your external mixing console. It is toggled via the LINE button in the Encoder Status screen object.
• AUX: This is an auxiliary input which can be used to pick up another line or microphone signal. There is no button in the screen object to toggle it. The only way to enable or disable it is through actions or scripts.

To assign a sound card to any of these inputs, go to the Audio Routing configuration page, Recording tab, and edit the assignment in the Encoder part of the device tree.

Just like the player inputs, each live input has a separate DSP chain accessible through the Encoder configuration page.

Outputs

Main Output

The encoder has one main output, which can be assigned to a physical output on the Audio Routing configuration page, Playback tab.

The signal of this main output will usually be the master bus of the encoder, but there are several options in the configuration to tweak the actual signal, e.g. make it pre-DSP or mute it while the MIC input is active.

Additional Outputs

In addition to the main output, you can add (virtual) connections of the type Additional local audio output in order to send the master signal to (additional) sound card outputs.

As with any connection, you can create region submixes, and there is also a separate DSP chain to add sound processing only for this particular output.

Best Practices

Audio can be routed freely to and from the encoder, but there are two common setups described here: Internal audio routing (no mixing console used) and external audio routing (recording master signal from external mixing console).

All audio settings described here refer to the Audio Routing page in the configuration app or mAirList Control Panel:

Internal Audio Routing

In this setup, the audio of all players is routed directly into the encoder, so it stays “inside” mAirList rather than being sent to a soundcard. Optionally, you can listen to the encoder master signal on any soundcard. You can also use the MIC button to toggle the microphone input when you want to make an announcement.

Internal audio routing can also be used on server hardware with no physical soundcard. All audio stays inside the application, no virtual soundcard etc. is required.

Steps to follow:

1. Set the Playback device for all players (“Playback -> Playlist 1 -> Player 1” etc.) and the cartwall to “Encoder”.
2. Optionally, as a precaution: Set the PFL device for all players and the cartwall to any other soundcard or “No audio output” so that it won’t be broadcasted on your stream.
3. Optionally: Set “Recording -> Encoder -> Mic input” to the soundcard input where your microphone is connected
4. Optionally: Set “Playback -> Encoder -> Playback device” to the soundcard on which you would like to listen to your broadcast
5. During your broadcast, use the MIC button to turn your microphone on and off. Note that, due to the nature of digital audio on computers, there will most likely be a delay between what you speak and what you hear on the playback soundcard. With high quality audio cards and ASIO or WASAPI, the delay can be minimized to a level that you don’t really notice. Alternatively, turn off Filter microphone signal from local playback in the encoder options so that you don’t hear yourself at all.

The LINE button is not used in this setup, you can disable it in the Encoder Status screen object settings in the configuration app.

External Audio Routing

This setup is for people who own a physical mixing console and use that console to mix the on air signal rather than using the encoder built-in mixer. In essence, you connect all audio sources (mAirList players and cartwall, microphones, CD players, etc.) to your mixing console, and then send the master signal back to your PC via Line In.

Steps to follow:

1. Set the Playback device for the players (“Playback -> Playlist 1 -> Player 1” etc.) and the cartwall to the soundcard output that is connected to the respective channels on your mixing console
2. Set “Recording -> Encoder -> Line Input” to the soundcard input where your the master signal from your console is connected
3. Important: Set “Playback -> Encoder -> Playback device” to “No audio output”. If you don’t, the encoder master signal is sent back to the soundcard, and there is a good chance that it will loop through your console, causing feedbacks and echoes.
4. Now when you start mAirList, click the LINE button in the encoder status window to enable recording from the Line input. (Note: To automate this step, go to Actions in the configuration app, select After startup in the list at the top, and add a new action of type “Encoder -> Toggle Input”.)

The MIC button is not used in this setup, you can disable it in the Encoder Status screen object settings in the configuration app.

2 - Encoder Status Screen Object

When setting up the streaming encoder, the first thing you should is to add up the Encoder Status screen object.

It provides the following controls:

• Buttons to toggle the MIC and LINE inputs.
• A Connect/Disconnect button to establish or terminate the actual server connections.
• A peakmeter showing the current output level of the (master) signal.
• A status label with information about the current connections and the number of listeners.

Configuration

To add the Encoder Status screen object, open the standalone configuration app, navigate to the Screen Objects page, click Add and select Streaming Encoder Status.

On the General tab, the following options are available:

• Show MIC button: Enable to display the MIC button that toggles the microphone input.
• Show LINE button: Enable to display the LINE button that toggles the line input.
• Show audio level when offline: By default, the peakmeter will be disabled when the encoder is in “Disconnected” master state. This is to provide visual feedback of the master state to the user. By checking this option, the peakmeter will always display the current audio level, regardless of the master state of the encoder.

The Advanced tab provides access to the common settings of all screen objects, in particular, the desired position in the GUI.

Usage

Once you have added the screen object to the configuration, restart the playout, and the object will appear in the GUI.

MIC and LINE Buttons

These buttons, when enabled in the config, can be used to toggle the respective live input of the encoder. When disabled (gray), the input will be muted.

If only the MIC or the LINE button is enabled in the config, that button will span the entire width of the screen object. If neither button is enabled, the height of the screen object will be reduced accordingly.

Connection Status

The label below the MIC and LINE buttons displays a brief summary of the current connections. The following texts may be displayed:

• Offline: The master switch is set to “Disconnected”. Click the Connect button to establish the server connections.
• No connections: The master switch is set to “Connected”, but no connections are configured or enabled.
• Online (x/x) - Listeners: (number): The master switch is set to “Connected”, all enabled connections are established successfully. The number of listeners displayed is the total of all listeners on all connections.
• Connecting (x/y) - Listeners: (number): The master switch is set to “Connected”, but some connections are not currently established. See the System Log for details on the failing connections.

When you hover the mouse cursor over the label, a hint will be displayed that gives you per-connection information on the current status.

Double-clicking the label will take you directly to the Encoder page in the Live Configuration (mAirList Control Panel).

Connect/Disconnect Button

The Connect/Disconnect button toggles the encoder connection master switch:

• In “Connected” state, all (enabled) server connections will be established; if a connection fails, or unexpectedly terminates, an automatic reconnection attempt will be made, according to the settings in the configuration.
• In “Disconnected” state, all server connections will be terminated.

Peakmeter

At the bottom of the screen object, there is a peakmeter that displays the current level of the audio sent to the encoder.

By default, the peakmeter will display the level of the stereo “Master” bus of the encoder, but there are several other signals to choose from, which you can access through the right-click menu.

If regionalization is enabled, the peakmeter will display a separate stereo pair for the common signal as well as for each region (1+n stereo pairs for n regions).

Depending on the Show audio level when offline option in the screen object settings, the peakmeter will be disabled when the encoder master switch is set to “Disconnected”.

3 - Encoder Configuration

Configuration of the encoder is done on the Encoder page in the configuration app, which can be accessed through the either the standalone configuration or the live configuration.

Connections

On the first tab, the server connections are managed. See the Connections section for the list of supported connection types and their configuration.

Options

The second tab contains general settings and options for the encoder.

The following settings can be made:

• Sample rate: This is the sample rate that the internal mixer of the encoder component runs at. All audio fed into the encoder module will be resampled to this rate. It will also be used as the default sample rate for all outgoing streams, unless a different sample rate is configured in the connection properties. Note that you must restart the playout when you make any changes here.
• Ducking level and speed: These options refer to the Duck player volume while microphone is active option below. Specify the attenuation of the ducking, and the duration of the fade.
• High priority fade length: When audio is played to the High Priority encoder input, all other inputs will be faded out and then muted, and later faded in again. Specify the duration of those fades here.
• Silence detection level: This is the level below which the signal is regarded as “silence”. It is only used for the GetSilenceDuration scripting method. For regular silence detection with configurable actions, use the Silence Detector DSP plugin.

Moreover, the following options are available:

• Connect/disconnect encoder when switching ON AIR mode: If enabled, the encoder master switch will be controlled by the system ON AIR status. When the instance is switched to ON AIR mode, the encoder will be set to “Connected”. When you switch back to OFF AIR, the encoder will be set to “Disconnected”. Note that this is only unidirectional; for controlling the ON AIR status from the encoder master switch, the option Switch ON AIR mode when connecting/disconnecting encoder must be enabled as well.
• Switch ON AIR mode when connecting/disconnecting encoder: This is the reverse of the Connect/disconnect encoder when switching ON AIR mode option above. When enabled, toggling the encoder master switch will also toggle the system ON AIR status.
• Duck player volume while microphone is active: If enabled, the volume of all player inputs will be ducked while the MIC input is enabled, according to the settings above.
• Line input is high priority: If enabled, the LINE input will work similar to the High Priority player input, i.e. it will mute all other inputs when it is active.
• Filter microphone signal from local playback: If enabled, the signal sent to the main encoder output (Encoder Playback Device in the Audio Routing) will not include the MIC signal, i.e. it will be a mix of the player and LINE/AUX inputs only. Note: This signal will always be Pre-DSP.
• Local playback is pre-DSP: If enabled, the signal sent to the main encoder output will be the master bus, but before any of the sound processing takes place. This option has no effect if Filter microphone signal from local playback is turned on as well.
• Mute local output during PFL: If enabled, the encoder main output will be muted while any PFL is active.

Sound Processing

The encoder provides several ways to add sound processing to the audio. See the Sound Processing chapter for a list of supported (built-in or external) DSP plugins and their configuration.

The following DSP chains are available:

• Master bus – this is the place where you usually add DSPs that should be applied to your outgoing on air signal.
• Player inputs
  • Player Input
  • Player Input 2
  • Player Input 3
  • Player Input 4
  • High Priority Input
• Live inputs
  • Mic Input
  • Line Input
  • Aux Input

Note that you can also add sound processing on connection level. This can be used as an alternative to the Master bus DSP chain, in situations where you only want to have DSP on some but not all connections.

4 - Encoder Connections

This section explains how to add and configure server connections for the built-in encoder.

Management of connections is done on the Connections tab of the Encoder configuration page in either the standalone configuration app or the live configuration.

In addition to regular connections to Shoutcast or Icecast servers, mAirList supports some additional (virtual) connection types, which are covered at the end of this section.

Shoutcast/Icecast

To add a new connection to a Shoutcast or Icecast server, click Add and select the appropriate type. The configuration dialog for the new connection will appear.

Server

On the first tab, we configure the server connection and stream format.

Connection Parameters

These are the general server connection parameters. You should have received this information from your streaming provider; or enter your own values in case of a self-hosted server.

• Host name or IP and Port: Enter the correct host name or IP address (not a URL!), and port number, for your server.
• User: Some servers require you to specify a user name. Most of the time this field can be left blank, in which case the default user source wil be used.
• Password: Enter the source password as configured in your server.
• Stream ID: (Shoutcast V2 only) When using a Shoutcast V2 server, enter the Stream ID, or leave this field blank to use the default Stream ID (1).
• Moint Point: (Icecast only) For Icecast servers, enter the mount point for your stream.

Stream Format

In the section section of the Server tab, the format, bitrate and stereo mode of your stream can be adjusted.

For Shoutcast servers, the only supported format is MP3.

For Icecast servers, the following formats are supported: MP3, Ogg Vorbis, Opus, FLAC.

The actual encoding is done with the help of a command line encoder. The appropriate encoders (lame.exe, oggenc.exe, opusenc.exe, flac.exe) are included in the distribution.

mAirList will call these encoders with the correct parameters to receive PCM data on STDIN, encode it according to the bitrate/mode settings, and send back encoded data on STDOUT.

For example, for MP3 (using lame.exe), 128kbit, joint stereo, and the encoder running at a samplerate of 48000, the command line will be:

lame.exe -r -s 48000 -b 128 -m j - -

If you want to tweak this command line with additional parameters, you can enter these into the Encoder options field. mAirList will insert the parameters just before the - - part of the command line.

For example, if you want to force LAME to create a high quality stream, enter -h into the Encoder options field, and the resulting command line will be:

lame.exe -r -s 48000 -b 128 -m j -h - -

The Encoder options field can also be used to use 3rd party command line encoders, even for stream formats not supported out of the box (e.g. AAC, using the 3rd party enc_aacplus.exe encoder).

To use a custom 3rd part command line encoder, proceed as follows:

• In the Audio Format dropdown, select “Custom” from the list.
• An empty text field will appear next to the dropdown. Enter the correct MIME type for your audio format, e.g. audio/aacp.
• In the Encoder options field, enter the full filename and parameters for your command line options; the parameters must be set up in a way so that raw PCM data (at 16bit, stereo, and the sample rate at which the encoder is running, see the Advanced tab below) is received via STDIN, and encoded data is returned via STDOUT.
• The Bit rate and Stereo mode fields will be ignored.

Settings

On the bottom of the Server page, the behavior of the server connection can be adjusted:

• Seconds between connect attempts and checks: As soon as the encoder master switch is set to “Connected”, a loop will be started that attempts to establish the server connection, retries if that fails (e.g. because the server is unreachable or the stream is busy), and then periodically check if the connection is still alive. The number entered here is the time between any of these checks/attempts. Note that, due to the nature of TCP, a failed connection may only be detected later than in the period specified here.
• Seconds before trying to re-establish a list connection: When the server connection is lost, mAirList will wait for the specified number of seconds before trying to reconnect. This setting can be tweaked to enlarge the time window before an (unattended) mAirList process tries to reconnect after purposely “kicking” it from the server.
• Retrieve listener count: If enabled, mAirList will periodically request the current number of listeners, and display it in the Encoder Status screen object. These requests use the regular XML APIs from Shoutcast/Icecast, so they will only work if the server supports them. This should be the case for the stock Shoutcast and Icecast servers; however some providers use their own implementation of the Shoutcast/Icecast protocols which may not support listener count retrieval.
• Do not stream, only count listeners: If you are using a network of relayed servers, and you want to include listeners numbers of the relay servers, you can add connections to these servers and check this box – mAirList will not actually send a stream to these servers then, but only use the XML API to retrieve the number of listeners.

Metadata

The settings on the second tab control the transmission of metadata to the streaming server.

Stream Metadata

Enter the stream title and optional other metadata (URL, description, etc.) that should be displayed to the user and in optional directories.

Title Update

Whenever an audio item is started in mAirList, the encoder can update the stream title with the artist, title etc. This is similar to to the Logging feature, but it is built into the encoder connection and does not require setup of a separate logging interface.

Shoutcast and Icecast only support a single text field for the current stream title, so you will want to merge the artist name and the song title into it. This is specified in the Log Format which defaults to %a - %b (“artist - title”). You can use any of the available logging variables.

If a Delay is set, mAirList will wait for the specified number of seconds before sending the new title to the server. This can be used to synchronize the title update with a possible delay due to buffering.

The Character Set will be determined automatically based on your connection type and matches the default configuration of the server types:

• Shoutcast V1: latin1
• Shoutcast V2: UTF-8
• Icecast: latin1 for MP3, UTF-8 for Ogg Vorbis, Opus and FLAC

If, for any reason, your server is configured to expect metadata in a different character set, you can set it manually in the dropdown.

The Item Type Filter determines which items, based on the type set in their properties, should be transmitted at all. For example, you can choose only to display “Music” items, but no jingles etc. Hint: Use the right-click menu to select all or no entries at once.

If the Forward song title updates of relayed streams option is checked, and you are playing a stream through a “Stream” playlist item, or the Stream Monitor, mAirList will transmit all incoming title updates “as is” to the connection.

Regions

If Regionalization is enabled for the encoder, this tab provides control over the downmix sent to this connection. See the Encoder Regionalization chapter for more information.

Sound Processing

In addition to the central sound processing of the encoder module, each encoder connection provides its own DSP chain that you can add DSP plugins to.

See the Sound Processing chapter for a list of supported (built-in or external) DSP plugins and their configuration.

The DSP plugins registered here will be applied after the central DSP plugins, and after region downmix. The signal will always be stereo.

Advanced

The last tab contains the following settings:

• Custom caption: Enter an optional caption under which this connection should appear in the configuration, System Log, etc.
• Sample rate: This setting provides optional sample rate conversion for this particular connection, in case it needs to run at a different sample rate than the one specified in the main encoder configuration. The sample rate will both be used for the raw PCM data fed into the command line encoder, as well as the DSP plugins. To disable sample rate conversion and use the default sample rate, leave this field empty.

Integrated Streaming Server

The Integrated Streaming Server provides a Shoutcast (V1) compatible streaming server.

To set up a new server, click Add and select Integrated Streaming Server.

In the connection properties, specify an optional local IP address (if you want have multiple network interfaces and only want the stream to be available on one of them), and the port number. Note that in the Shoutcast V1 protocol, there can only be one stream per port.

The Stream Format settings are similar to those of the regular Shoutcast/Icecast connections, see above.

If Retrieve listener count is checked, the number of listeners will be displayed in the Encoder Status screen object.

For the settings on the Regions, Sound Processing and Advanced tabs, see the Shoutcast/Icecast section above.

Record to File

Additional Local Audio Output

5 - Encoder Regionalization