Deliver Whole-Home Audio with Alexa Multi-Room Music and Device Targeting

David Frerichs Sep 20, 2018
Tips & Tools Multi-room Music SDK Alexa Voice Service

Customers love listening to music on devices through Alexa. In most cases, they’re asking Alexa to play music on the same device where they ask for it. In others, they want to play music in different locations at the same time, or on different devices in the same space. For example, when they say, “Alexa, play jazz in the Living Room,” they expect jazz music to start playing in the living room. “Living Room” could point to a single device or a group of devices. The Alexa Voice Service (AVS) has multiple technologies available to help device makers deliver this experience to customers: Named Device Targeting, Alexa Multi-Room Music (MRM), and proprietary cloud-controlled multi-room. The cloud-controlled solution, enabled by a Connected Speaker Skill, is for device makers that prefer to use their own proprietary multi-room synchronization protocol. Below is a simplified diagram showing how they fit together.

Alexa Blog

When the consumer says, “Alexa, play jazz in the Living Room,” the Named Device Targeting capability determines the meaning of “Living Room” and routes the play directive to a single device, cloud-controlled targets, or Alexa MRM targets as appropriate.

While there are exceptions, the technology is best summarized as follows:

  • For synchronized audio playback of Alexa music service provider (MSP) content between AVS devices and Amazon devices, add Alexa Multi-Room Music functionality to the AVS client.
  • For device makers with their own proprietary synchronization protocol to control devices without an AVS client, connect the device-maker cloud with the AVS cloud using Connected Speaker Skill.
  • For targeted playback on a single Alexa device, no action is needed. That functionality comes standard with Named Device Targeting.

Alexa Multi-Room Music

Alexa MRM enables synchronized music playback across multiple devices. In the case above, “Living Room” is the name of an Alexa MRM virtual device group. Those devices can be any mixture of Amazon Echo branded devices and other Alexa MRM-compatible devices. Alexa MRM uses a sender and receiver model to play content. One device in the group is selected as the sender, which connects to the MSP to retrieve the content. The others are assigned as receivers and are instructed to connect to the sender and play the content in sync with it. Alexa MRM is optimized to ensure reliable playback and maintain synchronized clocks between the devices over a standard home Wi-Fi network. The distinction of Alexa MRM device group members as either senders or receivers is invisible to the consumer.

Alexa MRM clients receive their directives from AVS. Since Alexa MRM group playback uses named targeting, that playback can be initiated from consumer input on one of the member devices in an Alexa MRM group or from a separate Alexa device. For example, in “Alexa, play jazz in the Living Room”, the named target is determined to be an Alexa MRM group and Alexa Named Device Targeting routes the request to be handled by Alexa MRM. The sender is instructed via the AVS downchannel to connect to the content source. Receivers are instructed via the AVS downchannel to connect to the sender to receive the content. All members in the group then play the content in sync.

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The diagram above shows Alexa MRM playback to a group of three AVS devices different from the AVS device receiving the voice command. The four devices may be include any Alexa MRM-compatible product (including Amazon Echo devices).

Getting Up and Running With Alexa MRM

For devices using the AVS Device SDK, getting up and running with Alexa MRM is straightforward. Some AVS development kits have Alexa MRM built-in, so you can just download and go.

Learn about the NXP i.MX 8M dev kit with Alexa MRM »

For other platforms, work with your Amazon business contact to get your platform evaluated for Alexa MRM compatibility. Once your platform is confirmed, Amazon will provide you with a pre-built Alexa MRM SDK binary, which you can integrate using the Alexa MRM patch for the AVS Device SDK. 

Music and Alexa go together naturally and Alexa MRM brings that experience to consumers across their entire home.