Soundbar Audio Formats: PCM, Dolby Digital, DTS, and More

What are audio formats?

An audio format is a scheme for encoding digital sound. Soundbars receive these encoded streams from your TV, a streaming device, or a game console, and convert them into analog sound. Some formats are uncompressed, carrying raw audio data; others compress audio to save bandwidth. The format in use affects how many channels you can reproduce, how detailed the sound is, and whether effects like vertical height are possible.

Your TV's output settings and the physical connection between the TV and soundbar determine which formats can be delivered. For example, HDMI is designed to carry both audio and video signals, and newer versions offer increased bandwidth for high-quality audio. Bluetooth is another option, but its Classic radio is mainly used for wireless audio streaming, and it typically has lower bandwidth than HDMI, so it may not support the most demanding formats.

PCM: the uncompressed baseline

Pulse-Code Modulation (PCM) is the fundamental digital audio format. It represents sound as a series of amplitude samples. Most TVs, soundbars, and streaming sources support PCM. Because it is uncompressed, PCM preserves the original signal faithfully, but it requires a direct digital-to-analog conversion. When you connect a TV to a soundbar via HDMI and set the TV to 'PCM' output, the soundbar receives raw audio and handles amplification directly. PCM is the safest fallback when you are unsure about compatibility.

PCM can carry multiple channels (stereo or surround), but it does not include the metadata for height effects like Dolby Atmos. For most TV shows, music, and games, PCM delivers excellent clarity. If your soundbar lacks a built-in decoder for compressed formats, PCM is often the default output from your TV.

Dolby Digital and DTS: compressed surround

Dolby Digital and DTS are compressed audio formats that store surround sound information in a more efficient package. They reduce file size while retaining multichannel audio, typically supporting 5.1 or 7.1 configurations. These formats require a decoder either in your TV or in the soundbar. If your TV cannot pass through the raw bitstream over HDMI or optical, it may convert the audio to PCM instead, which means the soundbar receives an already-decoded signal. In that case, the TV must be capable of decoding Dolby Digital or DTS internally.

To get true surround from a Blu-ray or streaming service, your TV's audio output should be set to 'Bitstream' or 'Passthrough.' This sends the compressed format directly to the soundbar, which decodes it. If your TV only outputs PCM, you may still hear surrounding sound, but the soundbar might be limited to the number of channels the TV can decode. Check your TV's manual for its audio output options.

Dolby Atmos and DTS:X: object-based audio

Dolby Atmos and DTS:X are object-based formats that move beyond fixed channels. They treat sound as individual objects placed in a 3D space, so your soundbar can reproduce effects from above and around you if it has up-firing drivers or virtual processing. These formats require end-to-end support: the source, TV, and soundbar must all handle them. Typically, you need an HDMI eARC connection to carry the full-bandwidth object data, though some soundbars can accept Atmos over regular ARC with a compressed version.

For a true experience, your TV must support Atmos or DTS:X passthrough. Many streaming apps deliver Dolby Atmos, and some support DTS:X. If your TV lacks the required passthrough, the soundbar may not receive the object metadata, and you will only get the base surround track. Check whether your TV's HDMI ports support eARC or at least ARC with Audio Return Channel. Our guides on HDMI ARC vs eARC and DTS:X vs Dolby Atmos explain these differences in depth.

If you are shopping for a soundbar that handles these formats, look for models that explicitly list Dolby Atmos or DTS:X support. For more choices, see our best Dolby Atmos soundbars roundup.

Connection types and format support

The connection method between your TV and soundbar dictates which formats are available. HDMI (ARC or eARC) is the most flexible, carrying both audio and video and supporting the highest bandwidth. The HDMI specification continues to evolve; the latest version offers significantly higher bandwidth to handle premium audio and video. Optical connections can carry stereo PCM and compressed 5.1, but they lack the capacity for object-based formats. Bluetooth, while convenient, uses a lower-bandwidth wireless link that may compress audio further.

For best results, use HDMI eARC when your TV and soundbar both support it. This allows lossless formats like Dolby TrueHD or DTS-HD Master Audio, which are often found on Blu-ray discs. If you are using an optical cable, you are limited to compressed Dolby Digital or DTS. In many cases, the TV will automatically negotiate the best format based on the connection.

What your TV needs to support

Before you buy, check your TV's audio output settings. Look for options like 'PCM,' 'Bitstream,' or 'Dolby Digital.' If you want to pass through Dolby Atmos, ensure your TV has an eARC port. If your TV is older, it may only support ARC, which can still pass compressed Atmos but not full-lossless. For a complete guide to HDMI connections, see our HDMI connections guide.

You should also confirm that your soundbar's inputs match your TV's outputs. Most modern TVs offer at least one HDMI port with ARC, and many now include eARC. If your TV only has an optical output, you are limited to Dolby Digital and DTS formats. In that case, a soundbar with a good built-in decoder and virtual surround processing, like those in our best 5.1 soundbars list, might be sufficient.

Listen at a safe level

As you explore audio formats, remember that volume is a health consideration. The National Institute on Deafness and Other Communication Disorders notes that long or repeated exposure to sounds at or above 85 A-weighted decibels can cause hearing loss. Many streaming services and movies have dynamic range that can vary widely, so it is wise to start at a low volume and gradually increase only if needed. Your soundbar may have a night mode or volume leveler that helps maintain a consistent level.

You can also use the dialogue enhancement features to keep speech intelligible without turning up the whole mix. For more tips on dialogue clarity, see our article on center channel dialogue.

What to pick for your use

Questions

What is the difference between PCM and bitstream?

PCM is uncompressed digital audio. Bitstream is the raw compressed data (like Dolby Digital) sent to the soundbar for decoding. If your TV outputs PCM, it is decoding the audio itself; if it outputs bitstream, the soundbar does the decoding.

Can a soundbar play Dolby Atmos over an optical cable?

No. Optical cables do not have enough bandwidth to carry the full Dolby Atmos metadata. You need HDMI ARC or eARC for object-based audio. Some soundbars may accept a compressed Atmos signal over ARC, but the best experience requires eARC.

Does all content include a specific audio format?

Every TV show, movie, or game has an audio track encoded in a format. Streaming services usually offer a range, from Dolby Digital Plus to Dolby Atmos. Your TV decides which format it can pass through based on its capabilities and the connection.

Do I need a soundbar that supports DTS:X if I only watch streaming?

Not necessarily. Most streaming services use Dolby Audio formats, not DTS. DTS:X is more common on Ultra HD Blu-ray discs. If you don't watch physical discs, Dolby Atmos support is more important.

Why does my soundbar sometimes show 'PCM' even when I selected Dolby Digital on my TV?

This happens when your TV cannot pass through the bitstream. It decodes the audio internally and sends PCM to the soundbar, which then plays it. The soundbar cannot see the original format, but you still hear audio.