PCM vs DTS: Which Audio Output Should You Choose?

Many TVs, media players, game consoles and computers offer an audio output setting labelled PCM, with an alternative such as Bitstream, Auto or a DTS option. This guide explains what changes when you switch between them, so you can pick the setting that matches your output device and connection.

Define the alternatives

PCM (pulse-code modulation) is uncompressed digital audio. When a source device outputs PCM, it has already decoded the soundtrack itself and sends plain audio samples, described by channel count, sample rate and bit depth, to the TV, soundbar or receiver.

DTS is a family of audio codecs used on discs, some streaming and download content, and some games. Core DTS is a compressed lossy format. Extensions such as DTS-HD Master Audio add a lossless layer, and DTS:X adds object-based audio. When a source sends DTS as a bitstream, it passes the encoded data unchanged and the receiving device does the decoding.

So the real choice is not between two sound qualities in the abstract. It is a choice of where decoding happens: in the source (PCM output) or in the downstream device (DTS bitstream). This article covers that playback setting only; it does not apply to recording formats for microphones or cameras.

Compare meaningful differences

Connection limits

The cable often decides for you. HDMI can carry multichannel PCM as well as DTS bitstreams, including lossless DTS-HD Master Audio, when both ends support them. HDMI ARC has narrower limits than eARC; eARC is designed to carry multichannel PCM and lossless formats, while ARC is generally limited to stereo PCM or compressed surround formats. Optical (TOSLINK) and coaxial S/PDIF connections carry only two-channel PCM, so surround sound over these cables requires a compressed bitstream such as DTS or Dolby Digital.

Device support

DTS output only works if every device in the chain can handle it. Some TVs do not decode DTS or do not pass it through to a soundbar, and some soundbars support only certain DTS variants. If a device in the path cannot handle DTS, you may get silence, a stereo downmix or a fallback format. Check the published audio specifications of the TV, soundbar or receiver and the firmware version, because support can change with updates.

What the decoder does

Decoding DTS to PCM in the source does not by itself reduce quality: the decoded audio is what the codec contains. The practical differences are about decoder capability. Some sources decode only the DTS core and ignore lossless or DTS:X extensions, and object-based DTS:X information is generally rendered only when a DTS:X-capable receiver gets the bitstream. When a source decodes to PCM, you get channel-based audio instead.

Controls and mixing

With PCM output, the source can mix in other sounds such as menu effects, system notifications or secondary commentary tracks, and it can apply its own volume or audio adjustments. With bitstream output, some players disable that mixing because they cannot add sounds to an encoded stream. Bitstream also lets the receiver display the incoming format, which is useful for confirming what you are actually playing.

Computers and live audio

On a computer, the operating system normally mixes all apps into PCM for the selected output device. Sending DTS untouched usually requires a player app that supports passthrough and a compatible output device. Video calls, microphones and other live audio are produced as PCM, so a DTS setting does not apply to them; leaving the output on PCM keeps system sounds and call audio working normally.

Practical trade-offs

Published specifications tell you what a device should accept. How it actually behaves, including whether audio stays in sync with video, whether there are dropouts when switching formats and whether a downmix sounds acceptable, depends on the specific devices and firmware and needs a test in your own setup.

• TV speakers or headphones only: PCM is the straightforward choice, since the TV or source decodes everything it supports.
• Soundbar on optical: stereo content works fine as PCM, but surround from DTS content needs bitstream, provided the soundbar decodes DTS.
• AV receiver on HDMI or eARC: both settings can deliver multichannel sound; bitstream preserves DTS:X objects and lets the receiver show the format, while PCM lets the source mix menu and system sounds.
• Computer used for calls and media: PCM avoids problems with notifications and call audio; use passthrough only in a player app when you specifically want the receiver to decode DTS.
• Game console: games usually output audio that the console mixes in real time, so PCM is often the native path; check the console documentation for which bitstream formats it supports.

To check what is happening, play a title with a known DTS track and look at the receiver or soundbar display or its info menu. If it reports PCM, the source is decoding; if it reports a DTS format, bitstream is reaching it. If you hear nothing on one setting, switch back and confirm that each device supports the format.

Choose for the use case

• Choose PCM if your audio system cannot decode DTS, if you use the same output for calls and system sounds, or if you want the source to mix menu audio and secondary tracks.
• Choose DTS bitstream if you have a receiver or soundbar that decodes the DTS formats in your content, especially DTS:X, and you want it to handle decoding and show the incoming format.
• Choose bitstream over optical or coaxial when you need surround sound from DTS content, because those connections cannot carry multichannel PCM.
• Use an Auto setting, where available, if you want the source to negotiate with the connected device, then verify the result on the receiver display.

Neither option is better in every setup. Start from your connection type and the published DTS support of each device, then confirm the result with a short playback test.