[Icecast-dev] Radio Loudness

[kiriki at streamguys.com]

I invite the list to also check out this work from AES regarding loudness standards in streaming media 
 
https://www.aes.org/technical/documentDownloads.cfm?docID=731
 
Jump to this section: Loudness and Dynamic Range Control Metadata
 
 
The relevancy in this thread is that there has been extensive discussion amongst AES leadership and members regarding the problem of loudness and dynamic range standards between content and chiefly, device manufacturers responsible for playback.
 
The consumers are suffering because there is not yet a standard for identifying the proper volume that content should be played back at. 

This is important because the proper dynamic range of the playback environment is dependent upon factors including if the users are wearing headphones, desktop speakers, prosumer speaker (home theater environment), Alexa’s and smart speakers etc… 

The usual has been to drive the audio up towards peak gain. A horrible technique as we all know. 

Those running DSP and conditioning could be presenting a nice stream. But there may be reasons to further adjust it. Especially if the station is being changed.
 
The committee is recommending standardizing on -24 lufs to provide adequate performance of the audio path, and a balance of headroom. But the important part you are inquiring about, is communicating the proper volume level to the end device, so it can be its own decisions about the final output gain. That is why there is a metadata layer to show the intended loudness. If the playback environment can match the actual speaker environments, we can both give the content at the best loudness and adjust it for proper playback.
 
At any rate, please take a look. I would be curious comments on if this approach could be implemented 
 
Cheers!
 
 
Excerpt of the public doc --- Examples of the Benefits of Loudness and DRC Metadata
 
• Loudness metadata is used by compliant players to normalize content loudness preceding the
user’s volume control. By allowing the playback device control of loudness normalization,
distributors can store and/or distribute content with its original loudness and dynamics. The
loudness metadata must be set properly for the distribution system being used so that the
recommended Distribution Loudness values (or relative values) in Table 1 are achieved in
playback. ANSI/CTA-2075 compliant players will apply peak limiting if needed to prevent their
output amplifiers from clipping.


• Dynamic Range Control metadata is included with the content at encoding without altering the
original audio. It allows a player to optionally reduce the dynamic range of the content it
receives, accommodating the capabilities of the playback device, noise environment and/or the
listener’s choice. Listeners in noisier conditions can set a limited dynamic range for improved
audibility, while listeners in quiet environments can choose to enjoy the content’s full dynamic
range.
 
 

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KIRIKI DELANY

President & Founder at StreamGuys

	


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From: Icecast-dev <icecast-dev-bounces at xiph.org> On Behalf Of Roman Gorshunov
Sent: Thursday, August 25, 2022 12:56 PM
To: Patrick.Schneider1 at swisscom.com
Cc: icecast-dev at xiph.org
Subject: Re: [Icecast-dev] Radio Loudness
 
You are welcome. I will be interested to hear how specifically you will make it work.
 
Regards,
Roman
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