Android Automotive SIG Audio Hardware Abstraction Layer HAL

Android Automotive SIG - Audio Hardware Abstraction Layer (HAL) Android in a Car Audio System Suhasini Raghuram, Analog Devices ; Wassim Filali, BMW October 2020

Agenda • Assessment of the Proof of Concept • Role of Android in Car audio system • Use cases to be covered with Android • Audio transport in the car network • Virtualization & Containerization • Latency & performance • Using Linux components with Android • Bluetooth device control and support • Interaction of Android with external safety signals May 2020 |. Copyright © GENIVI Alliance 2020 2

Assessment of the Proof of Concept

Demo environment Linux VM Kitchen sink ALSA Audio. Flinger Audio HAL TCP listener audiorelay Android emulator TCP Windows HOST May 2020 |. Copyright © GENIVI Alliance 2020 TCP VMs router TCP Sound devices 4

Proof of Concept components • Genivi device configuration: configuration • custom audio hal: • audiorelay: May 2020 |. Copyright © GENIVI Alliance 2020 derived from Android emulator, altered to work with named sockets instead of tinyalsa reference component that receives audio data from HAL and exposes it to TCP ports 5

Zone configuration primary zone • bus 0_media_out • bus 1_navigation_out • bus 2_voice_command_out • bus 3_call_ring_out • bus 4_call_out • bus 5_alarm_out TCP ports • 5000 • 5004 • 5005 • 5001 • 5006 • bus 6_notification_out • 5007 • bus 7_system_sound_out • 5003 rear seat zone • bus 100_rear_seat May 2020 |. Copyright © GENIVI Alliance 2020 • 5008 6

Proof of Concept Details - why Data Flow Android Audio framework Audio HAL is forbidden to use network HIDL Audio HAL TCP is easy to access named socket TCP Audio. Relay May 2020 |. Copyright © GENIVI Alliance 2020 PCM Writer 7

System Design Discussions

Role of Android in a Car Audio system • Android as audio router - routing different streams? • Android as an audio control master - master controller that controls the overall audio system. • Android as a source only ? May 2020 |. Copyright © GENIVI Alliance 2020 9

Use cases to be covered with Android Applications – • Telephony • Voice assistance • Multichannel video streaming • Audio zones – ⁃ Play different audio at the same time on different speakers How does Android help / hinder these applications? • Sync between two operating systems – Head Unit and Rear Seat Entertainment unit? May 2020 |. Copyright © GENIVI Alliance 2020 10

Audio Transport in the car network Supporting and controlling external audio devices How android would handle this? May 2020 |. Copyright © GENIVI Alliance 2020 • Transporting protocols (AVB, A 2 B, MOST ) • Trunk amp / Rear seat entertainment units' control • Encryption - Decryption for content protected streams ( Netflix / Spotify streaming services) 11

Virtualization and Containerization Virtualization • Why do we really need to virtualize ? • Communication between host and guest ( hypervisor or container? ) • Performance vs practicality ? Shared memory ? TCPIP ? • Virt. IO? ( Android 11 is pointing to this) • Audio transport and communicating between containers / vms ? • Does a virtualized Ethernet support AVB ? May 2020 |. Copyright © GENIVI Alliance 2020 12

Virtualization and Containerization • Partitioning of Audio HAL and vendor development • Preference over virtualization • Transport mechanism • How to control effects? • Using different OS, one for infotainment and one for safety? May 2020 |. Copyright © GENIVI Alliance 2020 13

Latency and Performance • Latency ⁃ How is latency measured today (Testing ITU) ⁃ How can we support low latency applications with Android? (AAudio, . . . ) • CPU offloading • Low latency framework (Gaming, AAudio) ⁃ The framework is not directly one layer above HW. What do we do when there are many other layers above HW? (Gaming, AAudio) May 2020 |. Copyright © GENIVI Alliance 2020 14

Latency and Performance Game latency AAudio framework latency External mixer latency Car amplifier May

Linux components with Android Should we be looking at using some Linux components with Android? • Example : use Audio control from Android and audio routing transport libraries from AGL • Other examples exist such as the Genivi Linux Audio Manager • Counter example (bad example) : mixing two audio managements concepts in the same system, one in Android and one in Linux ⁃ integration complexities • Are there any features in Linux which is already adapted to automotive use cases that can be brought in directly into Android. • Is there scope for maybe making this more similar in design to AGL (for specific features) May 2020 |. Copyright © GENIVI Alliance 2020 17

Bluetooth support • Bluetooth device control and support ⁃ Any difficulties in accessing and

Safety and Android Audio? • Safety implementation in Audio? ⁃ Interaction of Android with external safety signals (or in general with external sources) ⁃ Assumptions : Android Audio subsystem is developed only for infotainment purposes. Safetyrelated features need to be implemented in another RTOS May 2020 |. Copyright © GENIVI Alliance 2020 19

Testing Lava Test Farm Status

Open Floor

Working with GENIVI Valuable Input but Few Resources ⁃ During GENIVI summits, different problem statements and suggestions are shared. The AUDIO_HAL resources however are limited. So problems statements and suggestions are prioritized by resource availability. ⁃ However some problems are being tackled alone in individual companies. Working with GENIVI ⁃ You don’t have to work alone. ⁃ Align your daily tasks to be part of the GENIVI tasks. ⁃ Attend the weekly status update. Your Advantages ⁃ Have your name and your employers name as part of the GENIVI Audio_HAL group. ⁃ Collaborate with different companies and learn other perspectives and experiences. ⁃ Be part of the team that delivers suggestions and AA change requests directly to Google. May 2020 |. Copyright © GENIVI Alliance 2020 22

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