This document details the technological requirements and protocols for implementing Bluetooth Low Energy (BLE) voice input functionality in Android-based TV remote controls.

Section 1: Introduction

Android-based TV systems utilize Bluetooth-compatible remote controls featuring directional navigation and voice input capabilities. Discussions in this document focus exclusively on those features and exclude elements such as broadcasting, pairing mechanisms, battery consideratiosn, d-pad operations, and LED functions.

Section 2: BLE for Remote Control Devices

Android TV systems act as BLE master devices, interacting with the remote control's slave-mode BLE operation.

ATV Voice Service

The ATV Voice Service is a primary BLE profile defined by a unique service UUID that accommodates the characteristics as follows:

UUIDs and Characteristics of the ATV Voice Service

| Feature | Short-form Identifier | UUID | Properties | |---------------------------|------------------------|----------------------------------------|------------| | ATV Voice Service | ATVV_SERVICE_UUID | AB5E0001-5A21-4F05-BC7D-AF01F617B664| | | Write Characteristic | ATVV_CHAR_TX | AB5E0002-5A21-4F05-BC7D-AF01F617B664| write | | Read Characteristic | ATVV_CHAR_RX | AB5E0003-5A21-4F05-BC7D-AF01F617B664| notify | | Control Characteristic | ATVV_CHAR_CTL | AB5E0004-5A21-4F05-BC7D-AF01F617B664| notify |

Characteristics Behavior

• ATVV_CHAR_RX: Designed for audio data transmission (20 bytes per packet), configured using Client Characteristic Configuration (CCC) descriptors.
• ATVV_CHAR_CTL: Used for command notifications, each packet conveying esssential control data.
• ATVV_CHAR_TX: Enables message-based communication between the Android TV and the remote control.

Secsion 3: Voice Input Recording and Operation

Recording Specifications

• The device must meet frequency response and amplitude standards, maintaining sound fidelity and minimum distortion.
• Audio data compression reduces Bluetooth transmission demand to less than 20% of available bandwidth.

Operation Protocols

Initialization Process

Upon pairing, the Android TV queries remote control capabilities through ATVV_CHAR_TX, and the remote returns its response via ATVV_CHAR_CTL notification.

Voice Search Implementation

Voice input begins with the user activating the microphone, initiating BLE interactions defined by specific commands and notifications.

D-pad Select Activation

Voice initialization via on-screen icon monitor involves command transmission through BLE notifications.

Section 4: Sequence Diagrams

Operations such as initialization, voice search, and timeout scenarios are depicted through diagrams, available within the extended specification documentation.

Section 5: Audio Stream Details

Compressed audio formats utilize specific codecs with a frame structure supporting 134-byte communication packets sent in chunks.