When designing and building a home theater, I didn't expect to encounter so many device compatibility issues, such as HDMI incompatibility between projectors and sound systems.

The next problem I need to solve is how to properly wire the wireless audio system. Why does my wireless audio system need to be wired? In order to benefit both home theater users and device developers, I would like to share my experience here.

The optimal planning for home theater systems
I hope to make cinema equipment as cost-effective, simple, and wirelessly connected as possible while maintaining sound and video quality.

In order to reduce input and sound delay, I chose a game projector. For the audio system, I chose the Sonos Arc because when used with the Sonos subwoofer and two Sonos Era 300, the product can wirelessly simulate 7.1.4 surround sound through Dolby TrueHD and Dolby Atmos. To achieve this, traditional home theater systems can only physically connect 11 speakers and one subwoofer to the home theater receiver.

Dolby TrueHD provides the highest quality sound effects for home theater systems, while Dolby Atmos simulates the movement of sound sources around the audience on the screen. If a plane flies overhead, you will hear it starting from one side, slowly flying over you, and finally flying to the other side behind you - it's truly immersive.

The purpose of maintaining wireless connectivity is to increase immersion and convenience while reducing budget. But it has been proven that Sonos Arc can only connect wirelessly to a certain extent. This product can communicate wirelessly with other Sonos devices, but to connect the projector and audio/video (A/V) source, an HDMI eARC cable spanning the entire room is required.

How devices and communication protocols limit wireless design
After learning about the required physical connections, I have three options:

Find a long cable to connect Sonos Arc to the A/V source.
Replace that long cable with a wireless transmitter and receiver that can physically connect to HDMI eARC.
Abandoning the dream of wireless connectivity and choosing the classic home theater receiver setup is my wife's least favorite choice.
When researching solutions, I discovered some interesting things: many home audio devices have similar "wireless connection to a certain extent" settings, and using transmitters and receivers instead of HDMI cables can significantly reduce sound quality. Therefore, any home device compatible with home theaters needs to address the issue of wireless data transmission limitations.

To verify this, I calculated the following data:

According to the IEEE Standards Institute, the maximum Wi Fi bandwidth is:
Wi Fi 4 is 600 Mbps
Wi Fi 5 is 3500 Mbps (3.5 Gbps)
Wi Fi 6 is 9600 Mbps (9.6 Gbps)
According to the Bluetooth SIG, the current maximum bandwidth for Bluetooth technology is:
Low power Bluetooth is 2 Mbps
Classic Bluetooth is 3 Mbps
It is difficult to determine the bandwidth of Airplay. However, some Apple forums and enthusiasts have pointed out that:
Airplay 1 has a maximum bandwidth of 25 Mbps
Airplay 2 has a maximum bandwidth of 54 Mbps
The bit rate of Chromecast is also difficult to find. However, in its release note on July 18, 2022, Google stated that its Nearby Connections SDK (a peer-to-peer networking API that allows applications to connect and exchange data with nearby devices) defines connection quality as:
Between 6 and 60 Mbps is considered 'good'
Between 200 and 60 Kbps is considered 'normal'
If it is less than or equal to 5 Kbps, it is considered 'poor'
So, how do these data transmission limitations compare to the bit rates of audio and video signals?

According to the Dolby website, when data is stored on a local ultra high definition Blu ray disc, the transmission rate of Dolby TrueHD and Dolby Atmos audio signals can reach 18 Mbps. However, when streaming movies, audio signals are typically compressed into Dolby Digital Plus. When Dolby Atmos is added to the signal, its transmission rate can reach 1024 kbps.

Meanwhile, according to PCMag magazine, the video data transmission rate of ultra high definition Blu ray discs can reach 128 Mbps. Streaming media services, cable TV, and satellite TV also compress this data. For example, according to the Netflix technology blog, the maximum bit rate for this service is 16 Mbps. According to Google support personnel, YouTube offers 4K videos at up to 85 Mbps, far surpassing other competitors. For users who can handle 8K streaming, YouTube can even offer amazing 300 Mbps speeds. As for the bitrate of cable and satellite TV, it is expected to be between Netflix and YouTube's 4K products.

Therefore, in the worst-case scenario, for 4K cinema systems, the total bit rate for watching ultra high definition Blu ray movies is 146 Mbps, while for streaming playback it is approximately 86 Mbps. Except for Wi Fi, almost all other wireless communication protocols cannot keep up with the bitrate of streaming media. These protocols are also unable to handle A/V signals of ultra high definition Blu ray.

At this point, it is worth noting that Sonos ARC can connect to Wi Fi. However, it cannot connect to my projector or A/V source, which is likely a design choice made to prevent delays.

Can HDMI handle such a large amount of data transmission?

According to the HDMI licensing authority, it is possible. For example, specifically designed for 1080p and 4K@30Hz The designed high-speed HDMI cable can transmit data at a rate of 10.2 Gbps, which is 70 times the maximum ultra high definition Blu ray signal rate.