Proposal to revoke the mandatory TV sound standard | ACMA

Proposal to revoke the mandatory TV sound standard

Issue for comment 24/2015—29 October 2015


The ACMA has considered submissions to the proposal to revoke the Broadcasting Services (Digital Television Format—Audio Component—Transmissions in SDTV Digital Mode) Technical Standard 2007 (the mandatory TV sound standard). In response, the ACMA will allow the current mandatory TV sound standard to sunset on 1 October 2017, in accordance with Part 4 of Chapter 3 of the Legislation Act 2003, without remaking the instrument.

Submissions received

Submissions closed COB, Friday 27 November 2015. The ACMA received 2 submissions. The submissions were received from: 

The submissions were generally supportive of the proposal to revoke the Mandatory TV Sound Standard. Foxtel requested that the ACMA defer the date of effect of the Revocation. Foxtel contended it needed time to deal with the issue of subscribers with ‘legacy’ set top boxes which are only capable of receiving MPEG-1 Layer 11 sound.


The ACMA is seeking comment on its proposal to revoke the Broadcasting Services (Digital Television Format – Audio Component – Transmissions in SDTV Digital Mode) Technical Standard 2007 (the mandatory TV sound standard).

A copy of the mandatory TV sound standard can be found at:

The mandatory TV sound standard requires that, when a television program is transmitted by a commercial television broadcasting licensee or a national broadcaster in standard definition television (SDTV) digital-mode, the audio component must be capable of being decoded by a television receiver that only has MPEG-1 Layer II audio decoding capability. The mandatory TV sound standard was made to ensure that SDTV broadcast transmissions would be compatible with cheaper digital receivers, which at the commencement of digital television Australia in 2001, could only decode a MPEG-1 Layer II audio stream.

The mandatory TV sound standard does not prevent broadcasters from transmitting other audio components, such as AC-3 (Dolby Digital), in addition to the requirement to transmit an audio component capable of being decoded by set receivers that only have MPEG-1 Layer II capability (as set out in paragraph 5(3)(a) of the mandatory TV sound standard). The mandatory TV sound standard does not apply to high definition (HDTV) services.


The ACMA is proposing to revoke the mandatory TV sound standard. The mandatory TV sound standard has achieved its underlying policy objective of ensuring that during the transition to digital television cheaper receivers, capable of decoding only MPEG-1 Layer II audio, were supported.

Broadcasting technology has continued to evolve since the mandatory TV sound standard was made. Since 2001, the cost of digital television receivers has fallen considerably. Digital television set top boxes that support more advanced sound encoding and decoding technologies are now available for less than $50. The ACMA anticipates that digital television broadcasting services will migrate to more efficient video compression standards such as MPEG-4  and High Efficiency Video Coding (HEVC) in the foreseeable future. Receivers that are capable of receiving these new video compression formats will be capable of decoding the associated advanced audio components. As a result, the MPEG-1 Layer II audio component will be rendered obsolete for owners of receivers capable of decoding advanced digital audio streams.

If the mandatory TV sound standard is not repealed, broadcasters will still be required to accompany MPEG-4 or HEVC video streams in SDTV with two audio streams, one using the newer suite of advanced audio coding standards as well as a second mandatory MPEG-1 Layer II audio stream.

On 30 June 2015, Standards Australia, the nation's peak non-government standards organisation, published the following standard: Digital television – Terrestrial Broadcasting Part 1: Characteristics of digital terrestrial television transmissions AS 4599.1-2015 (the voluntary transmission standard), which covers various aspects of digital television transmissions including audio transmissions. The voluntary transmission standard provides that television services transmitted in MPEG-2 SDTV will include, at a minimum, a MPEG-1 Layer II audio stream. The requirements of the voluntary transmission standard maintain the status quo for the legacy MPEG 2 SDTV services while at the same time allowing services provided in MPEG 4 video and HEVC to use more advanced sound formats, without the cost and loss of capacity associated with providing an additional legacy audio stream.

As a general rule, it has been the ACMA’s preference for the market to resolve the issue of technical standards for TV receivers and to only intervene in cases of market failure or where there is a clear public benefit in doing so.


The mandatory TV sound standard was made by the ACMA in April 2007 under section 130A of the Broadcasting Services Act 1992.

MPEG-1 Layer II is a digital audio compression standard that involves the coding of audio data (associated with moving pictures) that is compatible for use with MPEG-2 video compression. As MPEG-1 Layer II was the default audio format for affordable consumer grade receivers in 2000, it was adopted as the common audio standard for the introduction of digital TV in Australia. The introduction of the mandatory TV sound standard maximised digital receiver take up by ensuring that cheaper (MPEG-1 Layer II only) digital receivers would work in Australia. The standard did not prevent broadcasters from also carrying newer audio streams such as AC-3 (Dolby Digital) in addition to an audio stream compatible with MPEG-1 Layer II.

Until recently, MPEG 2 was the only video compression standard used on Australian free-to-air television.

The voluntary transmission standard

The voluntary transmission standard was prepared by the Australian members of the Joint Standards Australia New Zealand Committee CT-002 Broadcasting and Related Services (of which the ACMA is a member) to ensure consistency of implementation of terrestrial broadcasting transmissions and to enable the design of digital transmission equipment and television receivers. The voluntary transmission standard provides that television services transmitted in MPEG-2 SDTV will include, at a minimum, a MPEG-1 Layer II audio stream.

Testing of and migration to new broadcasting technologies

In 2014, the then Minister for Communications announced measures to assist commercial and national television broadcasters to test and migrate to new and more efficient broadcasting technologies, such as the MPEG-4 video compression format. MPEG-4 is a type of video compression standard used to deliver quality video content within television signal streams.  MPEG-4 allows greater compression of the information, enabling content to be delivered using approximately half the data rate of an equivalent MPEG-2 service. This surplus capacity can be used to either improve video quality or provide more content streams in the same amount of radiofrequency spectrum.

The MPEG-4 video compression format coexists with a suite of more advanced audio compression formats. The relatively newer MPEG-4 capable receivers are also capable of receiving these more formats. The relatively newer MPEG-4 capable receivers are also capable of receiving these more advanced sound compression formats. Therefore, for owners of MPEG-4 capable receivers, it is not necessary for broadcasters to provide sound in a format that is backwards compatible with the older MPEG-1 Layer II audio format. Older receivers that cannot decode more advanced sound compression formats are not capable of receiving broadcasts of MPEG-4 format.


Comments are invited from interested parties about the ACMA’s proposal to revoke the mandatory TV sound standard by COB Friday 27 November 2015.

Comments can be sent to or mailed to:

The Manager
Broadcasting Carriage Policy Section
Australian Communications and Media Authority
PO Box 78
Belconnen ACT 2616

Effective consultation
The ACMA is working to enhance the effectiveness of its stakeholder consultation processes, which are an important source of evidence for its regulatory development activities. To assist stakeholders in formulating submissions to its formal, written consultation processes, it has developed Effective consultation—a guide to making a submission. This guide provides information about the ACMA’s formal written public consultation processes and practical guidance on how to make a submission.

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The ACMA may only collect personal information if it is reasonably necessary for, or directly related to, one or more of its functions or activities.

The purposes for which personal information is being collected (such as the names and contact details of submitters) are to:

  • contribute to the transparency of the consultation process by clarifying, where appropriate, whose views are represented by a submission
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The ACMA will not use the personal information collected for any other purpose, unless the submitter has provided their consent or the ACMA is otherwise permitted to do so under the Privacy Act.

Submissions in response to this paper are voluntary. As mentioned above, the ACMA generally publishes all submissions it receives, including any personal information in the submissions. If a submitter has made a confidentiality claim over personal information which the ACMA has accepted, the submission will be published without that information. The ACMA will not release the personal information unless authorised or required by law to do so.

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Last updated: 20 April 2018