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Audio Encoder Settings

The following table lists the Audio Encoder controls and settings:

Audio SettingDefaultDescription/Values
Codec MPEG-2 ADTS

The audio compression algorithm:

  • MPEG-2 ADTS - Encodes audio using the ISO/IEC 13818-7 MPEG-2 AAC-LC algorithm with an ADTS header. (Default)
  • MPEG-4 LOAS/LATM - Encodes audio using the ISO/IEC 14496-3 MPEG-4 AACLC algorithm with a LOAS/LATM header.

  • 16 bit Pass-Through -  Passes raw PCM (Pulse-Code Modulation) audio through the audio encoder for lossless audio transmission. In MPEG-2 TS streams, this audio codec uses the SMPTE 302M format, and currently supports the carriage of 16 bits of PCM data transported in 2, 4, 6, or 8 audio channels (i.e. 1 to 4 audio channel pairs). 

    Note

    In PCM Pass-Through audio:  

    • When the audio channel mode is set to mono, the audio content is duplicated in both channels of the single channel pair being sent.
    • When the audio channel mode is set to 3.0, 5.0, or 7.0, there is an extra audio channel carried in the 302M channel pair bundles. This extra channel will have zeroed (silent) content.
    • The encoder can detect and pass through Dolby AC3 and E-AC3 audio. 
Input InterfaceSDI-1

Select the Audio Input for the encoder.  

  • Analog
  • SDI-1 
Channel ModeStereo

General

The Channel Mode determines the audio channel layout (both the layout expected from the SDI input, and the layout expected upon output on the decoder end), and the number of audio channels required to process the audio input. 
Options are:

  • Stereo
  • Mono Left
  • Mono Right
  • 3.0 (3 ch)
  • 4.0 (4 ch)
  • 5.0 (5 ch)
  • 5.1 (6 ch)

  • 7.0 (7 ch) 

    Note

    Channel Mode 7.0 is only available when the Codec is set to 16 bit Pass-Through.

  • 7.1 (8ch)

Audio Channel Layouts

In order to ensure that your audio is processed properly, the audio channels in the upstream source should be configured as follows for each Channel Mode: 

Note

Generally, the encoder can process intelligible audio as long as each channel pair value is found in the channel mode, regardless of positioning.

The exception to this is LFE (Low-Frequency Effects, also known as the sub-woofer). The LFE must be the fourth channel in the input channel set, and the last audio object in the AAC elementary stream access unit when it is present (i.e. in modes 5.1 and 7.1) in order to produce intelligible audio. 

AC3 & E-AC3 Audio

When passing through encoded AC3 or E-AC3 audio, the Channel Mode will determine what audio data is passed through, which varies based on the SMPTE 337 encapsulation mode used in the upstream source. These encapsulation modes can hold PCM Audio, non-PCM audio, or a combination of both. To prioritize AC3/E-AC3 (i.e. non-PCM audio) select the appropriate channel mode according to the table below. 

Input Channelsn/aThe channels at which the audio input will start and end. The Input Channel ranges will change automatically depending on the required number of audio channels in the selected Channel Mode
Bitrate

128 kbps


The Audio Bitrate for the AAC encoder. Each Channel Mode supports a certain bitrate range. Users can select lower audio encoding bitrates for limited bandwidth streaming situations, or higher bitrates for higher quality audio encoding.

Note

The Makito X1 allows lower audio encoding bitrates (intended for very limited bandwidth streaming situations), as well as higher quality audio encoding at higher bitrates. 

The bitrate ranges for 16 kHz sample rate are different than the ranges for 48 kHz.

48 KHz sample rate: 

    • Mono: 12-288 kbps
    • Stereo: 14-576 kbps
    • 3.0: 16-864 kbps
    • 4.0: 18-1152 kbps
    • 5.0: 20-1440 kbps
    • 5.1: 21-1440 kbps
    • 7.1:  25-2016 kbps
16 KHz sample rate (analog only): 
  • Mono: 4 to 96 kbps
  • Stereo: 5 to 192 kbps
Sample Rate (kHz)48 kHz

The number of audio samples per second taken from the incoming signal.

  • 48 kHz

  • 16 kHz (Analog audio input only) 

0 dBFS Audio Level (dBu)0 dBu

(Analog Input only) Adjusts the maximum analog Audio Input signal level (0 dBFS) from -6dBu to 0 dBu. 

Note

This is useful in applications such as broadcast and streaming to allow higher audio headroom.

Languagen/aTo specify the language of the input, start typing letters and select the language from the list.

Statistics

n/a

Click the Statistics icon

to view statistics for the encoder. See Audio Encoder Statistics.

Mute

n/a

Click the Mute/Unmute icon

/
to encode silence instead of the selected audio input. For example, this may be used when you do not wish to encode the audio but the decoder being used does not support decoding of video only streams.

Stop

Start

n/a

Click the Stop icon

to stop an active encoder.

Click the Start icon

to start or restart a stopped encoder.

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