Many Hi-Fi network components and a range of multi-room devices typically feature support for Airplay2 or include a built-in Chromecast module, and frequently, they offer both options simultaneously. These technologies are user-friendly, facilitate the creation of multi-room systems, and, contrary to common assumptions, are cross-platform compatible. Most importantly, they utilize Wi-Fi or Ethernet for data transmission, ensuring superior sound quality. As a result, prospective users encounter a challenging decision regarding which communication protocol to choose.
The narratives surrounding Airplay, Google Cast, and other comparable technologies like Spotify Connect and DTS Play-Fi are closely tied to the development of two key industry standards: UPnP (Universal Plug and Play) and DLNA (Digital Living Network Alliance).
UPnP serves as a collection of protocols that enable communication among various network devices. This encompasses a wide range of devices, including computers, servers, network players, smart TVs, and wireless speakers. Essentially, UPnP acts as a universal language that facilitates interaction among these devices. Most contemporary multimedia protocols, such as Airplay and Google Cast, are built upon UPnP, indicating that they share the same technical framework and capabilities for delivering high-quality audio streams.
Most Hi-Fi network components, as well as various multi-room devices, can boast Airplay2 support or a built-in Chromecast module, and often both at once
The second standard, DLNA, was the first widely adopted protocol that integrated various devices into a cohesive network, enabling users to watch videos, listen to music, and perform a range of other functions. During the development of this standard, the specific roles that different network devices needed to fulfill were identified. The primary roles included a server for content storage, a player for file decoding, a media renderer for playback, and a controller for managing roles and processes.
In this context, the number of devices within the network and the functions they perform often do not align. For instance, when playing files from a home server using a smartphone, the smartphone serves as a media renderer, player, and remote control. However, when utilizing wireless speakers that support DLNA, the smartphone will function solely as a remote control, while the speaker takes on the role of the media renderer. The player function may either remain with the smartphone or transfer to the speaker, depending on its design.
A similar approach to role distribution is employed by the Airplay 2 and Google Cast protocols. The key distinction is that both are proprietary, and their developers are not forthcoming with detailed information. To better understand their functionality and determine the optimal choice for music listening, we will examine not only the official information provided by Google and Apple but also incorporate terminology from the DLNA protocol, which will aid in comprehending the architecture of Airplay 2 and Google Cast networks.
From both a functional and conceptual perspective, the Airplay and Google Cast protocols share numerous similarities. They are engineered to stream video and music over a network and are tailored for the general consumer, making them exceptionally user-friendly, particularly within their respective native ecosystems. The primary focus lies on ergonomics, facilitating a smooth transition from listening on a smartphone to utilizing speakers or a multi-room audio system. Additionally, operational stability is a key consideration. This emphasis is quite logical; while an audiophile might tolerate certain inconveniences for superior sound quality, this approach seems counterintuitive for users who have only recently transitioned from Bluetooth. Consequently, although Airplay and Google Cast possess the technological capability to transmit high-resolution audio, they were not specifically designed for music playback in the same way that platforms like Roon were.
Apple once formed a trend for closed ecosystems, and this was directly reflected in the Airplay 2 network architecture.
Apple has historically set a precedent for closed ecosystems, a characteristic that is evident in the architecture of Airplay 2. The mechanism for playing audio on compatible third-party devices is solely defined by developers as streaming from Apple devices. In this scenario, the Apple device serves as both the controller and the player, while the Airplay 2 component from a third-party brand functions merely as a media renderer, acting as a passive playback device that receives a pre-processed audio stream over the network. This methodology is fundamentally sound in terms of ensuring stability and user-friendliness. Most operations occur within the Apple ecosystem, allowing for complete oversight by the protocol’s creator. The Airplay 2-compatible component is tasked with a straightforward function and is not technically intricate.
What occurs with the audio? When streaming to an Airplay 2 device, the audio is transmitted using the ALAC codec in a 16-bit/44.1 kHz format. This choice is likely designed to mitigate potential issues related to the bandwidth of the Wi-Fi and Ethernet networks used for broadcasting, ensuring that even a less powerful router can manage the audio stream effectively. To maintain consistent performance, the playback device is equipped with a buffer that stores one minute of content, resulting in a slight delay when initiating music playback within the Airplay 2 network. This buffer also allows for seamless playback during brief disconnections of the iPhone from the network, even though the iPhone serves as the source of the digital stream at that time.
Interestingly, audio streaming between Apple devices follows the same principles. For instance, if one wishes to play a file stored on an iPhone through an Apple TV, the file is converted on the smartphone into an ALAC 16/44.1 stream and transmitted to the Apple TV, which functions as a passive media renderer.
What implications arise when playing Hi-Res music, which has been accessible on the Apple Music streaming service for some time and can also be stored on a user’s home server? The Apple TV hardware player supports a maximum output sampling rate of 24 bits/48 kHz, which qualifies as Hi-Res, albeit at the lower end of the spectrum. Additionally, within the Airplay 2 network, the Apple TV can operate not only as a media renderer but also as a player, directly receiving the audio stream from the server or streaming service, such as Apple Music. This capability enables the creation of an audio system that integrates a smartphone and a TV set-top box, allowing for music playback with sampling rates up to 24/48. Higher resolution audio can also be achieved within the Apple ecosystem by connecting an external DAC to an iPhone, iPad, MacBook, or iMac. In this scenario, Airplay 2 can also facilitate remote control of the device functioning as both a player and media renderer.
In terms of architecture, Google Cast has one important difference from Airplay 2
In the realm of architecture, Google Cast distinguishes itself from Airplay 2 through a significant feature. Devices within the Google ecosystem are equipped with a fully functional Chromecast player, as indicated by the corresponding logo. Originally, Chromecast serves as a hardware player, functioning similarly to Apple TV, and it is available for purchase as a standalone device. When you see the label “Chromecast built-in” on an amplifier, AV receiver, streamer, or wireless speaker, it signifies the presence of this hardware player, which includes an operating system, decoders, and integrated applications.
Consequently, devices with Chromecast functionality not only serve as media renderers but also as players that retrieve audio files from a server and decode them for playback, with the smartphone acting solely as a controller. The maximum audio file specifications supported by Chromecast over a network reach 24 bit/96 kHz. This means that if Hi-Res-quality music with a resolution of up to 24/96 is stored on a home server, a device with Chromecast built-in can play it without any loss in quality. Additionally, the Chromecast module is compatible with numerous online services that offer Hi-Fi-quality streaming, such as Deezer and Tidal, ensuring lossless playback of content from these platforms.
Another benefit of the Google Cast protocol is the ability to disconnect the smartphone from the network at any time or control playback from another device, while the previously selected playlist continues to play, thanks to the built-in Chromecast. In contrast, a similar scenario within the Airplay 2 network is only feasible when music is played through Apple TV, which, unlike Chromecast, is not integrated into third-party devices.
Google promises stable network operation, but does not specify the bit rate or sampling parameters of the audio stream transmitted by streaming from one device to another.
There may be instances when you need to play a file that is stored on your smartphone or to amplify the audio from a specific application. In such scenarios, the setup will mirror that of the Apple ecosystem: the smartphone will act as the media player, while Chromecast will function as a passive media renderer, receiving the pre-processed audio stream over the network. It’s important to note that sound quality might suffer, as the Wi-Fi network may struggle to handle the transmission of a 24/96 stream. This concern is somewhat supported by Google’s assurance of stable network performance, although they do not provide details regarding the bit rate or sampling specifications of the audio stream being transmitted between devices.
Conclusion
To summarize, both protocols offer adequate bandwidth for streaming CD-quality audio files, including via wireless connections. However, Airplay 2 features more intricate routing and relies on proprietary devices not only for decoding audio files but also for converting them to standardized sampling frequency and bit depth values, leading to additional digital stream conversions. In contrast, the Google Cast network integrates the Chromecast player directly into speakers or Hi-Fi components, allowing the device to run applications and stream files directly from the server without unnecessary conversions of bit depth and frequency. Essentially, devices with Chromecast built-in operate similarly to Hi-Fi network players equipped with their own operating systems.
Therefore, for users interested in establishing a convenient music listening network while also prioritizing superior sound quality, particularly for Hi-Res recordings, devices featuring a built-in Chromecast module are a more advantageous choice. Airplay 2 may be suitable for those who are content with CD-quality sound, such as users of Deezer Hi-Fi. It is important to note that both standards are continuously evolving, and future updates may bring changes, including through software upgrades.
