TV Audio Output: PCM vs Bitstream for Your Soundbar

PCM and bitstream: what they mean

Pulse code modulation (PCM) is a digital audio format that converts analog sound into uncompressed digital data. CDs and many streaming services deliver PCM. It is the simplest audio format, and every soundbar can accept PCM over optical or HDMI.

Bitstream (or audio pass-through) sends the original encoded audio stream, such as Dolby Digital or DTS, directly from the TV to the soundbar. The soundbar must have the matching decoder to convert that bitstream into sound. If it does not, you get silence.

How the TV output setting affects soundbar compatibility

When your TV is set to PCM, it decodes whatever audio it receives from an app or broadcast, then sends a PCM stream to the soundbar. Because PCM is uncompressed, it does not require any special decoder in the soundbar. This makes PCM the most universally compatible choice, especially with older soundbars or optical connections.

Bitstream, in contrast, requires the soundbar to decode the audio. If your soundbar supports the format (for example, Dolby Digital), you get the full multi-channel signal. If not, you get no audio or a loud error. This is why many TVs have an 'Auto' setting that chooses between PCM and bitstream based on the source and the soundbar's capabilities.

Before you change anything, check your soundbar's supported audio formats. Our TV compatibility guide explains how to match your TV and soundbar. For most setups, a HDMI ARC connection is the best way to carry either PCM or bitstream.

When to choose PCM for maximum compatibility

If your soundbar is a basic 2.0 or 2.1 model without built-in Dolby Digital or DTS decoding, choose PCM. The soundbar will accept the uncompressed signal and produce stereo sound. For dialog-heavy shows and music, PCM can sound excellent and avoids any decoding mismatches.

PCM also works over optical cables, which have lower bandwidth than HDMI. Optical cannot carry Dolby Atmos or other high-bitrate formats, so PCM is the safe way to get audio from an optical connection. See our optical vs HDMI comparison for more details.

If you are using a compact soundbar or a budget model, PCM ensures you never lose sound. Many 2.1 soundbars, like those in our best 2.1 soundbars guide, handle PCM without issues.

When to choose bitstream: Dolby Atmos and DTS:X

Object-based audio like Dolby Atmos and DTS:X requires bitstream delivery. These formats embed spatial audio metadata with the sound, and a soundbar with the correct decoder reconstructs the location of each object. If your TV is set to PCM, this metadata is discarded, and you lose the 3D effect.

To get Atmos, your soundbar must support Atmos and your TV must send the bitstream over HDMI. An HDMI eARC connection is recommended because it can carry the full lossless bitstream (Dolby TrueHD, DTS-HD MA) needed for the best quality. Our best Dolby Atmos soundbars guide lists models that handle this properly.

If you frequently watch movies with surround sound, bitstream lets your soundbar use its own decoders, which are often more capable than the TV's. Check our Dolby Digital vs PCM article for a deeper comparison.

The role of HDMI ARC and eARC

HDMI ARC (Audio Return Channel) sends audio from the TV back to a soundbar over an HDMI cable. Standard ARC can handle compressed formats like Dolby Digital, but it lacks bandwidth for uncompressed 5.1 or object-based audio. Enhanced ARC (eARC), introduced with HDMI 2.1, supports these high-bandwidth formats.

The HDMI 2.2 specification, announced by the HDMI Forum, further increases bandwidth to 96 Gbps, which can support even more advanced audio and video features (source: HDMI.org). For most users, eARC is enough to pass Dolby Atmos from streaming apps, while HDMI 2.2 is future-proof for next-gen systems.

If you have a soundbar with eARC, setting your TV to bitstream unlocks the full potential of lossless audio. If you are still using ARC, you may need to fall back to PCM for formats like Dolby Atmos that exceed the ARC bandwidth. Our ARC vs eARC guide covers the differences in detail.

How to change the audio output setting on your TV

Look for 'Audio Output', 'Sound Output', or 'Digital Audio Out' in your TV's settings menu. The exact label varies by manufacturer. You will usually see options like 'PCM', 'Bitstream', or 'Auto'.

Selecting 'Auto' lets the TV choose based on the content and the connected device. This is often the best choice because it sends bitstream when the soundbar supports it and falls back to PCM otherwise. If you experience issues, manually switch to PCM to test.

For a step-by-step walkthrough of connecting and configuring a soundbar, see our soundbar setup guide. Keep in mind that some TVs may have separate settings for optical and HDMI, so check both if you use multiple connections.

Troubleshooting common audio output issues

If you encounter sound issues, the first step is to switch the TV output to PCM. This resolves most compatibility problems. If the issue persists, verify the soundbar's supported formats and try a different cable.

• No sound at all: Change the TV output from Bitstream to PCM. The soundbar may not support the codec.
• Distorted audio or loud static: Switch to PCM to bypass decoding problems.
• Dolby Atmos icon missing on the soundbar: Ensure the TV output is set to Bitstream and the content is Atmos. Also check that your soundbar has Atmos and eARC.
• Low volume or missing dialogue: Try PCM. Some soundbars handle compressed bitstream poorly.

Extra tips for audio output

Always keep the volume at a comfortable level. Listening at high volume for long periods can cause noise-induced hearing loss, as explained by the NIDCD. If you often need to turn the volume up to understand dialogue, consider a soundbar with a dedicated center channel or dialogue enhancement.

For gaming, bitstream can reduce latency if your soundbar supports low-latency HDMI features. Read our PCM vs bitstream for gaming article to find the best setup for consoles.

What to set for your soundbar setup

Questions

Is PCM or bitstream better for soundbar quality?

Neither is inherently better. PCM is simpler and ensures compatibility but limits you to stereo (or sometimes 5.1). Bitstream lets your soundbar decode multi-channel and object-based formats like Dolby Atmos, giving more immersive audio, provided your soundbar supports those codecs.

Does bitstream cause a loss of quality?

No, bitstream passes the original encoded audio untouched. The soundbar decodes it and should output the same quality as the source. If your soundbar decodes formats well, bitstream is the higher-quality option for multi-channel content.

Will bitstream work with an optical cable?

Optical cables have a bandwidth limit and cannot carry uncompressed 5.1 or Dolby Atmos. Bitstream over optical only works with compressed formats like Dolby Digital and DTS, and many TVs limit this. For full support, use HDMI ARC or eARC.

Can I use PCM with Dolby Atmos?

No. Dolby Atmos requires the Atmos bitstream. PCM strips the spatial metadata, so you will only get stereo or regular surround, losing the height information. To get Atmos, your TV must send the bitstream and your soundbar must decode it.

What is the 'Auto' setting on my TV output?

Auto lets the TV read the soundbar's capabilities via HDMI and choose whether to send PCM or bitstream. It is the safest option because it switches based on the content and the connected device. If you experience issues, manually set a specific mode.