Guides ·
Optical vs HDMI for soundbars
Most soundbars in the comparison table list Optical in their Available inputs, and most also list HDMI, HDMI Arc or HDMI eArc. Both connections can take the sound from the TV to the soundbar. They differ in which audio formats they carry, in how the TV remote controls the soundbar, and in what else the cable can do. This guide compares the two with manufacturer documentation, HDMI.org and Dolby as the sources.
What travels over an optical connection
An optical connection runs from the TV's optical output to the soundbar's optical input. Samsung documents what a TV sends over it: when the TV's optical output is set to "Simultaneous Optical Output", the audio is output in either PCM or Dolby Digital format.
Samsung describes those two formats on its soundbar audio formats page:
- PCM: a common method for converting analog signals into digital signals.
- Dolby Digital: a digital signal format from Dolby Laboratories that supports 5.1 channel audio.
Optical-only soundbars publish a similar list. Sonos lists the home theater audio formats of the Sonos Ray, which connects to the TV's optical port, as Stereo PCM, Dolby Digital and DTS Digital Surround. Sonos adds that the TV or PC must have an optical output.
See all soundbars with an optical input.
What travels over HDMI
HDMI can carry more formats. Samsung states it directly in its Dolby Atmos setup guide: on Samsung soundbars, Dolby Atmos is only supported in HDMI mode. The guide connects the soundbar's HDMI OUT (TV-ARC) port to the TV's HDMI IN (ARC) port.
With eARC, the newer version of the audio return channel, the list grows again. HDMI.org lists support for uncompressed 5.1 and 7.1, up to 32 channels of uncompressed audio, and formats such as Dolby TrueHD, DTS-HD Master Audio, DTS:X and Dolby Atmos.
Samsung describes two of the formats that optical does not carry:
- Dolby Digital Plus: an enhanced Dolby Digital format with up to 7.1 channels, backward compatible with Dolby Digital.
- Dolby TrueHD: lossless encoding that supports up to 8 channels at 96 kHz/24-bit, or up to 6 channels at 192 kHz/24-bit.
| Format | Optical output of a Samsung TV | HDMI eARC |
|---|---|---|
| PCM | Yes | Yes |
| Dolby Digital | Yes | Yes |
| Dolby TrueHD | No | Yes |
| Dolby Atmos | No | Yes |
For the difference between ARC and eARC, see HDMI ARC vs eARC: what passes through.
Remote control
With HDMI, the TV and the soundbar can talk to each other. Samsung's guide asks you to turn on Anynet+, Samsung's name for the HDMI-CEC protocol, in the TV settings, and notes that the connection may not work without it.
Optical soundbars use another route for control. Sonos says you can use your existing TV remote with the Sonos Ray, which is compatible with an infrared-enabled TV remote.
HDMI passthrough needs HDMI
Some soundbars have HDMI inputs and an HDMI output, so a streaming box or a console connects to the soundbar and the soundbar passes the picture on to the TV. Dolby describes this as HDMI passthrough: the soundbar needs at least one HDMI input and a dedicated HDMI output. An optical input cannot do this.
See all soundbars with HDMI passthrough, or filter for at least two HDMI inputs.
Soundbars with both
Many soundbars have both connections, so the choice depends on the ports of the TV. The Sonos Arc lists HDMI eArc and Optical in its inputs, and so does the Samsung Q990B. See all soundbars with both HDMI eARC and optical.
What comes in the box differs too. The table's What's in the box column shows an optical cable for the Sonos Ray and an HDMI cable for the Sonos Arc and the Samsung Q990B.
Which connection to use
Dolby recommends eARC whenever possible for a soundbar with Dolby Atmos. In short:
- Optical: PCM or Dolby Digital (5.1) from the TV. The TV needs an optical output.
- HDMI ARC or eARC: the formats optical carries, plus Dolby Atmos and, with eARC, Dolby TrueHD and uncompressed 5.1 and 7.1. HDMI-CEC lets the TV and the soundbar talk to each other.
- HDMI passthrough: only over HDMI, for sources that connect to the soundbar instead of the TV.
For the immersive formats themselves, see Dolby Atmos vs DTS:X on soundbars.
Sources
- https://www.samsung.com/my/support/tv-audio-video/understanding-the-audio-formats-displayed-on-your-samsung-soundbar/
- https://www.samsung.com/uk/support/tv-audio-video/how-to-use-dolby-atmos-with-your-samsung-soundbar/
- https://www.hdmi.org/spec21sub/enhancedaudioreturnchannel
- https://www.dolby.com/experience/home-entertainment/articles/connecting-your-dolby-atmos-enabled-soundbar-to-your-tv/
- https://www.sonos.com/en-us/shop/ray