Limecraft Flow offers extensive support for multi-channel audio. This artikel explains how the different aspects of different audio layouts and audio channel layouts are displayed and can be used in Limecraft Flow.


What is Audio Layout or Audio Channel Layout?


The Audio Channel Layout, Audio Layout or Channel Mode of video or audio show the nature of sound reproduction. In case of video, it only refers to the way audio is played out. The two most common used Channel Layouts are mono and stereo, but also surround sound flavours and customised configurations are possible. Furthermore you can qualify the different audio channels according to the nature or the language of the audio, loudness, codec, etc.


Where can I find information about the Audio Channel Layout in Limecraft Flow?


With the audio layouts you can describe in detail how the audio of a media clip is structured. For clips containing audio layout information, the clip info sidebar will contain a section ‘Audio Layout’, describing how the audio in the original media of the clip is structured:


Audio Layouts are accessible in Limecraft Flow via the item detail

Each row of the audio layout represents a so-called “Channel layout”. A channel layout represents a collection of audio channels which are meant to be played out simultaneously in a particular way. The example in the screenshot is for a clip with 4 channel layouts:

  • The first channel layout is a 5.1 mix and is in French.

  • The second channel layout is a stereo mix and is in French.

  • The third channel layout contains a 5.1 mix in the original language. 

  • The last channel layout contains a stereo mix in the original language.


When hovering the mouse over a row, Flow will show in detail which audio channels constitute this channel layout:


Audio layout detail in Limecraft Flow


So we store explicitly which particular channel is the left channel of the 5.1 French channel layout, which is the center channel, etc.


In addition, a channel layout can contain descriptive metadata. The following fields can be set on a channel layout. This is a fixed list of fields and not configurable.


Field

Description

Example

Label

A descriptive label containing more information on the contents of the channel layout


Notes

Extra descriptive notes


Language

The language the spoken text in the audio is in. The value can be chosen from a list of languages.

Internally, this is stored as a language code (“fr”, “en”, …) but shown as the language label. Similar to how languages are treated in subtitle editor and transcriber.

We also added three “special” values to the list that do not represent a language directly but are often used to describe it:

  • International - Represents the international mix 

  • Original - Indicates this is the mix in the original language the media was in (no dubbing)

  • Unspecified - The language is not specified or not known (internally, “xx”)


French,
English

Nature

The nature of the channel layout contents. It can be chosen from a limited list of values:
(Mix, R12B Mix, DVD Mix, BR Mix, Cinema Mix, TV Mix, Ambiance, Dialog, Effects, Music, Music & Effects, Options, Audio Description, STEMS, Commentary, Voice Over, VOSC, Mute)


Loudness

The loudness, in units of Loudness Units (LU), of the audio mix. See also https://en.wikipedia.org/wiki/LKFS

6.7

Loudness Range (LRA)

The loudness range in units of Loudness Units Full Scale (LUFS)

-7.0

True Peak

The true peak audio level, in units of decibel True Peak (dBTP).

Represents the maximum value of the signal waveform in the continuous time domain. (can be higher than the max value in the sampled domain, hence the “true” in “true peak”).

-12.0

Codec

The audio codec used to encode the audio signal

Flow will fill this field in automatically, based on the media contents. It can be changed though.

pcm_s24le

Bit rate

The bit rate of the audio mix, in kilobits per second (kbps).

Initially, this will show the value calculated by Limecraft Flow based on the audio.

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