Setting up the digital output of SPDIF on Xiaomi TVs

Modern Xiaomi TVs, which run on Android TV or PatchWall global firmware, offer a wide range of multimedia capabilities. However, built-in acoustics are often not enough to create a full-fledged home theater, and users are eager to connect an external audio system. One of the most reliable and high-quality ways to transmit sound is using a digital optical interface known as SPDIF or Toslink.

Many owners of equipment face difficulties when trying to activate this output, as the audio settings in the menu can be hidden or have specific restrictions. In this article, we will discuss in detail how to properly configure the audio stream through the optical port, which formats to choose for maximum compatibility and what to do if the sound does not appear. Xiaomi Mi TV and Redmi TV have their own nuances in the organization of the menu, which must be considered.

Before you go to software settings, make sure your equipment is physically ready to go.You will need the TV itself with the Optical Out port, the appropriate optical cable, and a receiving device such as a sound bar (Soundbar) or AV-Getting the cable right is the first step to sound quality without interference or delay.

Physical connection and inspection of equipment

The first step in setting up should always be a smart connection of devices. The SPDIF interface transmits a digital signal in the form of light pulses, so it is immune to electromagnetic inputs, which ensures the purity of sound. However, the fiber inside the cable is fragile and it cannot be bend at sharp angles. Insert one end of the cable into the Optical Out port on the back or side of the Xiaomi TV before a characteristic click.

The second end of the cable connects to the Optical In input on your speaker system. After connecting the devices to the power grid, pay attention to the light indication. At the end of the optical cable inserted into the TV, a red glow often lights up, indicating that the signal is emitted. If there is no glow, this may indicate that the output is programmatically disabled or the cable itself is damaged.

• 🔌 Make sure that protective plastic plugs are removed from both ends of the optical cable before connecting.
• 💡 Check for red glow at the end of a cable connected to the TV as an indicator of activity.
• 🔊 Make sure that the external audio device has the correct source of the signal (Source: Optical/Toslink).

So volume control can be done either from the sound panel or, in some cases, through the TV remote, if HDMI CEC or IR port control is enabled.

Basic audio setting in the Android TV menu

After the physical connection, you need to activate the sound transmission through the software menu. On Xiaomi TVs with Android TV shell, the path to settings may vary slightly depending on the version of the operating system and the firmware region. You usually need to go to the main menu and select the Settings section, which is often indicated by the gear icon in the upper right corner of the screen.

In the menu that opens, look for Sound or Display & Sound. That's where all the audio output options are concentrated. You'll need to find the option for selecting the output device. By default, the TV can use TV Speakers, which blocks the signal from being transmitted to the external port. Switch this to Audio System, External Speakers or SPDIF.

⚠️ Warning: If the menu does not have an explicit external output switch, try changing the format of the digital audio, which sometimes automatically activates the port.

Next, you should pay attention to the digital format settings. The Digital format submenu or Digital Audio Format often offers a choice between PCM, Auto and Pass-through. Auto mode is the most versatile, since the TV itself determines the capabilities of the connected device. However, some older receivers may require manual installation of the format.

Some models, such as the Xiaomi Mi TV P1 or Mi TV 4A, may have a simplified menu where output choices are combined with equalizer settings. Carefully examine all tabs in the audio section. If you use IPTV apps or streaming services, the settings inside the apps themselves can also override system settings, requiring separate verification.

Configure in the PatchWall interface

Users of Xiaomi TVs that come with PatchWall may encounter a different layout of menu items.This shell greatly modifies the standard Android TV, making navigation more visual, but sometimes hiding technical settings deeper. To access the full settings menu, you often need to press the menu button on the remote or hold the settings button.

In PatchWall, go to Settings -> Sound. You may need to switch from TV Speaker to External Speakers. PatchWall is aggressively optimizing the sound for embedded speakers, so when you connect to an external system, it's important to turn off all audio enhancements like DTS Virtual:X or Dolby Audio if they cause conflicts.

If you can't activate the output using standard methods, you can try resetting the audio settings to factory settings, which will return all parameters to the original state, which often helps to eliminate software failures that block the optical output. After reset, re-select the external output device.

• 🛠️ To access hidden menus, try pressing the button combination on the remote if the standard path doesn’t work.
• 🔄 Resetting sound settings can eliminate conflicts of audio stream processing software modules.
• 📺 PatchWall update can change the location of menu items, watch for the relevance of the instructions.

It is worth noting that in some versions of PatchWall firmware, optical output may be software limited for certain applications, for example, an embedded player can transmit sound, but a third-party player cannot. In such cases, it helps to install universal players, such as VLC or MX Player, which have their own audio output settings.

Selecting audio stream formats: PCM, Dolby Digital and Passthrough

One of the critical things to do is to choose the right audio encoding format. Choosing the wrong format can lead to no sound or an unpleasant hiss. On the TV menu, you'll find several basic options: PCM, Dolby Digital, and Passthrough (or Auto).

The Pulse Code Modulation (PCM) format is uncompressed dual-channel sound. If you choose this mode, the TV will decode any multi-channel signal (like Dolby Digital 5.1) into stereo, which guarantees compatibility with any, even the oldest acoustics, but you lose surround sound. This mode is ideal if your sound system does not support multi-channel format decoding.

Passthrough (or Auto) is the preferred mode for modern systems, where the TV transmits the digital signal in its original form to an external device that decodes it itself, allowing you to enjoy full Dolby Digital 5.1 or DTS surround sound, if the content and hardware support it.

If you watch terrestrial TV or low-quality streaming video, the difference between formats may not be noticeable, but when watching Blu-ray discs or movies in high bitrate, the right Passthrough format becomes critical to getting the manufacturer's declared sound quality.

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If you’re missing the sound when choosing Dolby Digital, switch to PCM, which means your acoustics don’t support the codec or the cable has bandwidth limitations.

Solving problems with lack of sound

Even with the right setup, you can have situations where the audio doesn't go through the optical output. One of the common reasons is that you can desynchronize your devices. Try changing the switching sequence: turn on the TV first, wait for the system to boot, and then turn on the external acoustics, which will allow the signal source to correctly identify the connected device.

Another common problem is sampling frequency incompatibility. Some older receivers may not receive a signal above 48 kHz. In advanced audio settings (if available in your model), try to force the sampling frequency to 48 kHz or 44.1 kHz. It is also worth checking whether the TV Only function is activated, which can block external outputs.

⚠️ Note: When using cheap optical cables, the signal may disappear when switching sources. Replace the cable with a quality analog with gilded contacts if the problem recurs.

If the sound appears and disappears, check for firmware updates on the TV. Xiaomi engineers regularly release patches to fix peripheral errors. Go to Settings -> About -> Update and check the software's relevance.

• 🔇 Make sure that the TV does not have a headphone only mode or similar restriction.
• 🔌 Reconnect the optical cable, having previously pulled it from the socket on 5-10 seconds.
• 📀 Check the sound playback in different apps to rule out the problem of specific content.

In rare cases, the problem may be in the TV port itself. If you have the opportunity, check the optical output with another device. If the cable and acoustics work with another TV, and Xiaomi does not, there is likely a software error that requires resetting to factory settings.

Using HDMI ARC as an alternative to SPDIF

It’s worth mentioning that optical output has its limitations, in particular, it doesn’t support the latest audio formats like Dolby TrueHD or DTS-HD Master Audio due to limited bandwidth. If your TV and audio system support HDMI ARC (Audio Return Channel) or eARC technology, this will be a much more preferred connectivity option.

HDMI ARC It allows you to transmit audio over the same cable as the video, but in the opposite direction - from the TV to the receiver, which eliminates the need to use a separate optical cable and allows you to control the soundboroud directly from the TV remote without additional settings of the IR ports. Quality of sound transmission through HDMI considerably higher.

To activate HDMI ARC, you need to connect the HDMI cable to a port labeled as HDMI (ARC). Then, in the TV settings in the Sound section, select the HDMI ARC output instead of the optical one. It is also recommended to enable HDMI Control or CEC to synchronize device management.

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HDMI ARC provides better sound quality and more convenient control over optical output, as long as your technology supports this standard.

However, if your audio system was released a few years ago and does not have an HDMI input, the SPDIF optical output remains the only viable option for producing high-quality digital audio, in which case careful format tuning, as described above, becomes the key to great sound.