Dolby Digital vs PCM for Soundbars: Bitstream or Not?

What are bitstream and PCM?

Bitstream and PCM are two ways to send digital audio from a source to a soundbar. A bitstream is a compressed or object-based audio stream, such as Dolby Digital, DTS, or Dolby Atmos, that is sent as-is for the soundbar to decode. PCM, or pulse-code modulation, is uncompressed audio that has already been decoded by the sending device, like your TV.

When a TV outputs PCM, it has already turned the audio into linear samples, effectively stripping away any encoding metadata. That means the soundbar receives a straightforward digital signal with no further decoding required. The choice between these two affects how many channels survive the trip and how well the soundbar can process the audio.

In simple terms, bitstream passes the original audio package for the soundbar to unpack, while PCM repackages the audio into a simple format that any device can play. For multichannel content, the way the TV handles that repackaging can make a big difference.

• Bitstream: compressed or object-based audio that needs decoding by the soundbar.
• PCM: uncompressed audio, already decoded, sent as linear samples.

How your TV and soundbar handle audio

When you connect a soundbar to a TV, the TV becomes the hub for audio. It sends either a bitstream or PCM depending on your audio output settings. Many TVs will re-encode audio to a format they support, or they may force PCM for simplicity. The HDMI connection, governed by the HDMI specification from HDMI.org, is the most common way to carry these signals with high bandwidth. Other connections like optical or even wireless options such as Bluetooth have more limited bandwidth and often force stereo PCM.

For most soundbars, HDMI ARC or eARC is the preferred link because it can carry full bitstream formats without compression. If you are using an older optical cable, you might only get Dolby Digital at best, and PCM is often the safer bet. The key is to understand which connection your TV and soundbar share and what formats that connection allows. You can learn more about HDMI ARC versus eARC and soundbar HDMI connections to see how the interface affects audio quality.

Which gives better multichannel sound?

In general, bitstream gives better multichannel sound because the soundbar can decode the native format and use its own DSP. This is especially true for 5.1 and object-based formats like Dolby Atmos, which require the original stream for full spatial audio. When a TV sends PCM, it often strips the extra channels or downmixes to stereo unless the TV can decode and re-encode to multichannel PCM. For soundbars with many channels, bitstream is the preferred choice.

A soundbar with a dedicated subwoofer and rear speakers will benefit from a true 5.1 or 7.1 bitstream. The soundbar can then apply channel levels, timing, and room correction to match your space. PCM, on the other hand, may come as a stereo signal that the soundbar then simulates, losing the discrete placement of effects. If you want the best from your 5.1 soundbar or an Atmos-enabled model, set your source to output the original bitstream.

When to use PCM instead

PCM is a good fallback when your soundbar does not support the bitstream format your source is sending. Some TVs and soundbars have compatibility issues that cause audio dropouts or no sound at all. In that case, setting the TV to PCM ensures a stable, standard audio signal. PCM also works well for stereo sources because it avoids unnecessary processing. If you have a 2.0 or 2.1 soundbar, the difference is less noticeable.

For a simple stereo setup, like a 2.0 soundbar or a 2.1 model, PCM will often deliver exactly the same quality as bitstream because the content is already two channels. There is no benefit to decoding a 5.1 stream when your soundbar cannot reproduce the full five channels. In that scenario, PCM can reduce handshake issues and lip-sync problems. It is a reliable choice for older TVs or budget soundbars.

What about object-based audio formats?

Object-based formats like Dolby Atmos and DTS:X use metadata to place sounds anywhere in a three-dimensional space. That metadata is embedded in the bitstream, not in a PCM downmix. To experience the full effect, the soundbar must receive the original bitstream and decode it with its own Atmos or DTS:X processor. If the TV converts to PCM, it typically discards the object metadata, and you lose the height and placement cues.

So for anyone with an Atmos-enabled soundbar, bitstream is not just better, it is essential. Even if your TV can decode Atmos into PCM with multiple channels, the soundbar misses the spatial information. That is why the audio output setting on your TV should be set to pass through or bitstream whenever possible. You can compare more details in Dolby Digital vs Dolby Atmos and DTS:X vs Dolby Atmos if you are deciding between these formats.

How to choose the right setting

Check your soundbar's supported audio formats in its manual. If it supports Dolby Digital or DTS, choose bitstream. If you have an HDMI ARC or eARC connection, bitstream is usually automatic. For optical connections, bitstream may still work for Dolby Digital, but PCM is more reliable. Always prefer a connection that carries the highest bandwidth, which HDMI provides according to the HDMI specification.

In your TV's audio settings, look for options called "Bitstream", "Pass Through", "Auto", or "PCM". Select the one that matches your soundbar's capabilities. If you are unsure, start with bitstream and listen for issues. If you hear dropouts or the sound cuts out, switch to PCM. You can also consult our guides on soundbar audio formats and TV audio output formats for more detailed advice.

Practical tips

Here are a few simple rules to keep in mind when setting up your soundbar:

• Set your TV to pass through bitstream for movies and games if your soundbar supports the format.
• Switch to PCM if you experience audio sync issues, dropouts, or no sound at all.
• Use a high-quality HDMI cable that meets the required specification for your connection type.
• Remember that Bluetooth audio is typically limited to stereo, so use a wired connection for multichannel content.

What to pick for your use

Questions

Should I use bitstream or PCM for gaming?

For gaming, bitstream is generally better if your soundbar supports the format your console sends, such as Dolby Digital or Atmos. This preserves positional audio cues. If your setup causes audio lag, switching to PCM can reduce latency on some TVs.

Does PCM support 5.1 surround sound?

Yes, PCM can support multichannel audio, but only if the TV encodes it that way. Many TVs only output stereo PCM, so the soundbar may not receive a full 5.1 signal. Bitstream preserves the compressed 5.1 stream for the soundbar to decode.

Is bitstream always better for dialogue clarity?

Not necessarily. Dialogue clarity depends more on the soundbar's center channel and processing. Bitstream can deliver a dedicated center channel, which helps. But a good PCM stereo downmix can also keep dialogue clear on 2.0 soundbars.

Why does my TV force PCM when using optical?

Optical connections have limited bandwidth and may not support advanced codecs like Dolby TrueHD or DTS-HD. TVs often fall back to PCM to ensure compatibility. For full bitstream support, use HDMI ARC or eARC.