Question 1

Which codec should I use?

Accepted Answer

LM1 can be used with any audio codec because it is an audio codec-independent metadata. For example, it can be used with MP3, AAC, FLAC, etc. that do not have separate loudness metadata.

Question 2

How is meta-data delivered?

Accepted Answer

The LM1 standard is designed to be an audio codec-agnostic form of extrinsic metadata that can be used in combination with a variety of audio codecs.
As such, it can be delivered in a number of ways, depending on the streaming service's approach.
It can be embedded in a container within the streaming content, or it can be passed as a base64 encoded string along with other metadata embedded in the content.

Question 3

Can I use LM1 on live streaming services?

Accepted Answer

It is challenging to extract metadata in real-time with the LM1 in live broadcasting scenarios.
In the LN SDK, there is a mode (LCO) that can handle loudness normalization without metadata, which is usually sufficient. However, there are some limitations in hitting the exact target loudness.

Question 4

Does LM1 require action in both server and client?

Accepted Answer

The server is only responsible for extracting and transmitting the LM1 metadata. Once the LM1 metadata is extracted for each sound source, no further processing for loudness leveling is required on the server.
When playing the sound source, the client receives the LM1 metadata and uses it to process the loudness level in real-time.

Question 5

Does LM1 solution include DRC?

Accepted Answer

The LM1 decoder includes a built-in DRC function, which enables comfortable loudness normalization with controlled dynamic range regardless of the listening environment, whether it's a noisy environment like a bus or subway, or when you need to listen quietly like in a quiet room.

Question 6

What is ANSI/CTA-2075 standard?

Accepted Answer

This standard, established by the American National Standards Institute (ANSI) and the Consumer Technology Association (CTA), defines the loudness normalization method required when playing streaming media such as OTT and OVD so that it can be played at a normalized loudness across various devices and playback environments, enabling users to consume content without inconvenience.
It emphasizes the use of metadata for loudness normalization, and Gaudio Lab's LM1 metadata standard is also reflected in ANSI/CTA-2075.1, an extended standard of ANSI/CTA-2075.

Question 7

What is the LM1 standard?

Accepted Answer

LM1 is a standard that specifies how the information required for the loudness normalization should be made into metadata and defined as a bitstream.
It was first established in 2020 as a standard specification of the Korea Telecommunications Technology Association (TTA) (TTAK.KO-07.0146) and was reflected in ANSI/CTA-2075.1 in 2022.
It is designed to solve the loudness problem of streaming media such as OTT, music, and podcasts, and the LM1 metadata specification enables easy loudness management on playback devices.

Loudness Normalization, LM1

A complete loudness solution for OTT and music streaming — fully compliant with SB 576. Eliminate loudness variance between sources with an internationally standardized and award-winning technology.

Key Features

SB 576-compliant loudness control, even in dynamic ad-insertion (SSAI/DAI) environments.

LM1, the only internationally standardized side-chain metadata technology for loudness management

Our product lineup is designed to meet diverse needs and deployment environments.

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California Just Got Quieter — And That’s a Good Thing (Complies with SB576)

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