The analogy of a USB hub to describe the role of the television in audio transmission via HDMI ARC is misleading for several fundamental technical reasons. A USB hub is a passive device that allows multiple USB devices to connect to a single port on a computer, providing additional ports without modifying the data. As a simple relay of signals, it does not actively engage in processing or managing data. In contrast, a television connected via HDMI ARC functions as an active processor for audio and video signals, playing an essential role in managing and optimizing the entire audio chain.
In the context of audio transmission, the television establishes communication with the Blu-ray player using the HDMI protocol. This protocol allows the television to send and receive EDID (Extended Display Identification Data) information, which is essential for determining the audio and video capabilities of connected devices. This negotiation process is crucial, as it enables the television to check the supported audio formats, such as PCM, Dolby Digital, and other advanced formats like Dolby Atmos. The television then adjusts the transmission parameters accordingly, ensuring that the signal is correctly formatted before being sent to the soundbar.
The television also acts as an active intermediary between the Blu-ray player and the soundbar, as there is no direct communication between these two devices. The television negotiates separately with each of them, establishing compatible audio formats and capabilities. The HDMI ARC protocol requires bidirectional communication, where the television and the audio device exchange information about their respective capabilities. This dynamic dialogue allows for advanced features such as CEC (Consumer Electronics Control), which facilitates the control of volume and power for multiple devices using a single remote control.
The synchronization process, which ensures that all devices in the chain are properly aligned for optimal performance, is also distinctive in the context of television. Unlike a simple relay, the television actively manages this process, ensuring that each device operates harmoniously with the others. In terms of bandwidth, HDMI and ARC technologies must handle much higher data rates, which is particularly crucial for high-definition audio formats such as DTS-HD Master Audio or Dolby TrueHD. USB hubs, on the other hand, neither process nor modify the data they transmit; they simply relay signals without considering the specific requirements of connected devices.
Another major distinction lies in the ability of HDMI connections, particularly with ARC and eARC, to allow firmware updates via the cable. This ensures continued compatibility with new audio formats and features, a capability often absent from USB hubs, which typically do not support such updates, thereby limiting their adaptability to technological advancements.
In summary, the role of the television in an HDMI ARC configuration is not only dynamic and complex, but it is also fundamental to the effective and high-quality transmission of audio signals. In this configuration, two telecommunications channels can be distinguished: the first channel is dedicated to the simultaneous transmission of sound and image, allowing for the conveyance of the audio and video signals necessary for a multimedia experience. The second channel, on the other hand, is bidirectional and separate, integrating metadata to enable a complex communication protocol between all HDMI devices.
This two-channel architecture not only enhances transmission quality but also ensures smooth and efficient communication among different devices, which is essential for a high-quality audio-visual experience. Indeed, the television does not merely relay data; it processes, formats, and transmits these signals while facilitating protocol exchanges and bidirectional communications. This highlights the distinct capabilities of HDMI ARC technology compared to simple USB connections, emphasizing the importance of the television as a central player in the audio system.