Audio Passthrough, Dolby Atmos and eARC Explained for Streaming Boxes

Audio passthrough means your streaming box sends the original surround-sound signal untouched to your TV, soundbar or AV receiver, which then decodes it. This guide explains passthrough versus decoding, the Dolby and DTS formats, ARC versus eARC, where to find the settings, and how to fix no sound and lip-sync problems.

Quick answer: If you have a soundbar or receiver, use passthrough for the formats it supports and let everything else fall back to stereo or 5.1. If you only use TV speakers, leave the box on automatic or PCM. For Dolby Atmos from a TV app over HDMI, you generally need eARC or a compatible ARC path.

Menu names differ between devices and versions, so use this as a map. For video-side settings, see HDR, Dolby Vision and frame rate.

What is the difference between passthrough and decoding?

Audio arrives as a compressed stream. Two things can happen:

• Decoding: the box unpacks the audio itself and sends plain PCM (uncompressed stereo or multichannel) over HDMI. Works with almost everything, but can limit surround formats and object audio.
• Passthrough (bitstream): the box sends the compressed stream unchanged, and your soundbar or receiver decodes it. This is how a receiver can show "Dolby Atmos" or "DTS:X" on its display.

Passthrough only helps if the receiving device supports the format. If it does not, you may get silence or noise.

What do Dolby Digital, DD+, TrueHD, Atmos, DTS and DTS:X mean?

UK broadcast TV is commonly stereo or 5.1 (Dolby Digital variants), so Atmos only matters for content that actually contains it.

What is the difference between ARC and eARC?

Both are features of one HDMI port on your TV, used to send audio from the TV to a soundbar or receiver.

• ARC (Audio Return Channel): limited bandwidth. It handles Dolby Digital and DTS, and Dolby Digital Plus carrying Atmos, but not lossless TrueHD or DTS-HD.
• eARC (enhanced ARC): much higher bandwidth, which supports lossless formats and the highest-quality object audio.

There is an important detail: if your streaming box plugs into the TV, the sound travels via ARC or eARC to the soundbar. If the box plugs directly into the receiver, the TV only receives the video and the ARC limits do not apply. Plug the HDMI cable into the port labelled ARC or eARC, and check that your TV's HDMI-CEC settings are on. Details differ by model.

Which passthrough settings should I use?

On a Fire TV or Google TV box

Look in the sound settings (for example Settings > Display & Sounds > Audio on Fire TV, or Settings > Display & Sound > Advanced sound settings on Google TV and Shield). Options usually include Auto, Surround sound off/PCM, and a manual choice of formats. Use Auto first. If you get no sound, switch to PCM or turn individual formats off.

On an Nvidia Shield

NVIDIA places format controls at Settings > Device Preferences > Display & Sound > Advanced sound settings > Available formats. NVIDIA's own guide shows choosing Manual and disabling Dolby formats other than AC3 for a soundbar that cannot handle newer ones.

In Kodi

Kodi has its own audio settings. Go to Settings > System > Audio (set Settings level to Advanced or Expert to see all options), choose your Audio output device, then set Number of channels and enable Allow passthrough. Individual options such as Dolby Digital, Dolby Digital Plus, TrueHD and DTS-HD capable receivers appear below. Which entries you see depends on the platform and Kodi version. See the Kodi beginner's guide.

In TiviMate and other players

Players may have an audio or decoder section that picks hardware or software decoding and, in some cases, passthrough. TiviMate's audio options vary by version, so check its settings (see the TiviMate setup guide). If a player has no passthrough setting, the device-level setting is what counts.

Why do I have no sound?

Work through these in order:

1. Check the TV and soundbar are on the right input and not muted.
2. Switch the box's audio output to PCM or stereo. If sound returns, the problem is a format your device cannot decode.
3. Turn off the individual formats your equipment does not support.
4. Try another HDMI port, a certified high-speed HDMI cable, or reboot everything in this order: soundbar, TV, box.
5. Check the specific channel. A stream may use an audio format your player cannot handle, and a different channel will tell you which.

Our buffering guide helps if the sound cuts out together with the picture.

How do I fix lip-sync problems?

1. Look for audio delay or lip-sync settings on the soundbar, receiver and TV. Adjust in small steps.
2. In Kodi, there is an audio offset in the playback controls.
3. Try turning off frame-rate matching in case it triggers a resync (see the HDR and frame rate guide).
4. If the problem is on one channel only, the source is out of sync and nothing on your side will fix it.
5. Disable processing modes on the TV (game or PC modes often reduce video delay).

Where can I ask for help?

Post your TV, soundbar, box and app in the Android TV boxes forum.

Should I use my TV, soundbar or a receiver for decoding?

It depends on what you own. If you only watch through the TV's speakers, the TV decodes whatever it supports and you have little to configure. If you have a soundbar connected through ARC or eARC, you can pass the audio onwards. An AV receiver gives the most flexibility, particularly with a box plugged straight into it. In every case, keep to the simple rule of enabling only the formats the final device can decode.

It is also worth knowing that many streaming sources only contain stereo or 5.1. A big Atmos setup will not add height channels that were never recorded, though some soundbars and receivers can upmix stereo to a wider sound field.

What cables and ports do I need?

Use certified high-speed HDMI cables and the correct port. On a TV, the HDMI port labelled ARC or eARC is the only one that sends audio back to a soundbar. A box connected directly to a receiver does not need ARC at all. If you have intermittent dropouts, a cable swap is cheap and quick to try before changing any setting. For a wider look at what else can affect your setup, see router settings for streaming.