Public Broadcast Profile

Revision: v1.0

Revision Date: 2022-07-05

Prepared By: Audio, Telephony, and Automotive Working Group

Abstract:

The Public Broadcast Profile (PBP) defines how a Broadcast Source can use extended advertising data (AD) to signal that it is transmitting broadcast Audio Streams that can be discovered and rendered by Broadcast Sinks that support commonly used audio configurations.

Revision History

Acknowledgments

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1. Introduction

Many of the use cases for broadcast audio relate to public infrastructure and sound reinforcement applications, and use audio-frequency inductive loops, commonly known as telecoil or T-coil. These use cases include publicly accessible TVs (in bars, gyms, clinics, airports, and shops), as well as installations in conference centers, theatres, and mass transport vehicles. While telecoil functionality is limited to hearing aids, the higher audio quality and general accessibility of broadcast Audio Streams that use Bluetooth Low Energy (LE) Audio are expected to provide a new and enhanced user experience for everyone. The Basic Audio Profile (BAP) [3] and Common Audio Profile (CAP) [4] describe how a device can advertise and transmit broadcast Audio Streams. To support interoperability, certain broadcast Audio Stream configurations are defined as Mandatory for a Broadcast Sink in Table 6.4 in [3] . Other, higher-quality broadcast Audio Stream configurations are also defined in Table 6.4 in [3] , which are collectively defined as a group of High Quality Public Broadcast Audio configurations in this specification.

However, scanning devices cannot determine the broadcast Audio Stream configuration a Broadcast Source is transmitting from the presence of the Broadcast Audio Announcement Service UUID in an extended advertisement. To determine the codec configurations, the receiver must synchronize to the periodic advertisements to obtain the information from the Broadcast Audio Source Endpoint (BASE) data as defined in [3] .

Therefore, to enable a faster, more efficient discovery of Broadcast Sources that are transmitting audio with commonly used codec configurations, the Public Broadcast Profile (PBP) defines a Public Broadcast Announcement that a Broadcast Source can include in an extended advertisement to indicate that a Broadcast Source is transmitting at least one of the following:

• A broadcast Audio Stream with a configuration that every BAP Broadcast Sink can receive and decode (Standard Quality Public Broadcast Audio)

• A broadcast Audio Stream that uses a High Quality Public Broadcast Audio Stream configuration

The Public Broadcast Announcement also indicates whether the broadcast Audio Streams in the Broadcast Isochronous Group (BIG) are encrypted or not. If the Public Broadcast Announcement indicates that the broadcast Audio Streams are encrypted, a Broadcast Sink must use a Broadcast_Code to decrypt them.

This profile uses procedures defined in CAP [4] for broadcast Audio Streams. As shown in Figure 1.1, this profile extends only the Broadcast part of CAP.

Figure 1. Figure 1.1: Public Broadcast Profile hierarchy

1.1. Language

1.1.1. Language conventions

The Bluetooth SIG has established the following conventions for use of the words shall, must, will, should, may, can, and note in the development of specifications:

shall	is required to – used to define requirements.
	is used to express: a natural consequence of a previously stated mandatory requirement. OR an indisputable statement of fact (one that is always true regardless of the circumstances).
will	it is true that – only used in statements of fact.
should	is recommended that – used to indicate that among several possibilities one is recommended as particularly suitable, but not required.
may	is permitted to – used to allow options.
can	is able to – used to relate statements in a causal manner.
note	Text that calls attention to a particular point, requirement, or implication or reminds the reader of a previously mentioned point. It is useful for clarifying text to which the reader ought to pay special attention. It shall not include requirements. A note begins with “Note:” and is set off in a separate paragraph. When interpreting the text, the relevant requirement shall take precedence over the clarification.

If there is a discrepancy between the information in a figure and the information in other text of the specification, the text prevails. Figures are visual aids including diagrams, message sequence charts (MSCs), tables, examples, sample data, and images. When specification content shows one of many alternatives to satisfy specification requirements, the alternative shown is not intended to limit implementation options. Other acceptable alternatives to satisfy specification requirements may also be possible.

1.1.2. Reserved for Future Use

Where a field in a packet, Protocol Data Unit (PDU), or other data structure is described as "Reserved for Future Use" (irrespective of whether in uppercase or lowercase), the device creating the structure shall set its value to zero unless otherwise specified. Any device receiving or interpreting the structure shall ignore that field; in particular, it shall not reject the structure because of the value of the field.

Where a field, parameter, or other variable object can take a range of values, and some values are described as "Reserved for Future Use," a device sending the object shall not set the object to those values. A device receiving an object with such a value should reject it, and any data structure containing it, as being erroneous; however, this does not apply in a context where the object is described as being ignored or it is specified to ignore unrecognized values.

When a field value is a bit field, unassigned bits can be marked as Reserved for Future Use and shall be set to 0. Implementations that receive a message that contains a Reserved for Future Use bit that is set to 1 shall process the message as if that bit was set to 0, except where specified otherwise.

The acronym RFU is equivalent to Reserved for Future Use.

1.1.3. Prohibited

When a field value is an enumeration, unassigned values can be marked as “Prohibited.” These values shall never be used by an implementation, and any message received that includes a Prohibited value shall be ignored and shall not be processed and shall not be responded to.

Where a field, parameter, or other variable object can take a range of values, and some values are described as “Prohibited,” devices shall not set the object to any of those Prohibited values. A device receiving an object with such a value should reject it, and any data structure containing it, as being erroneous.

“Prohibited” is never abbreviated.

1.2. Table requirements

Requirements are defined as "Mandatory" (M), "Optional" (O), "Excluded" (X), “Not Applicable” (N/A), or "Conditional" (C.n). Conditional statements (C.n) are listed directly below the table in which they appear.

1.3. Conformance

If conformance to this specification is claimed, all capabilities indicated as mandatory for this specification shall be supported in the specified manner (process-mandatory). This also applies for all optional and conditional capabilities for which support is indicated.