PCM vs Dolby Digital Plus: Which Output Should You Choose?

Many TVs, streaming boxes, game consoles and computers offer an audio output setting with choices such as PCM, Dolby Digital Plus, Bitstream or Auto. The choice decides which device decodes the sound and what format travels over the cable to your soundbar, receiver or speakers. This guide explains what each option does and how to pick one for your setup.

Define the alternatives

PCM (pulse-code modulation, often labelled LPCM) is uncompressed digital audio. When you select PCM, the source device decodes whatever it is playing, whether a streaming soundtrack, a game or a video call, and sends plain audio samples to the output device.

Dolby Digital Plus (also called E-AC-3 or DD+) is a lossy, compressed surround format widely used by streaming services. Selecting it, or a bitstream or passthrough option, sends the encoded stream unchanged so that the soundbar or receiver decodes it. In many streaming catalogues, Dolby Digital Plus is also the carrier for Dolby Atmos content.

The real comparison is therefore not which format sounds better in the abstract, but where decoding happens: in the source device with PCM, or in the connected audio device with Dolby Digital Plus. The setting affects playback only; it does not change your microphone, input device or input level.

Compare meaningful differences

Connection compatibility

The cable and port often decide for you. Optical (S/PDIF) carries two-channel PCM and older compressed formats such as Dolby Digital, but not multichannel PCM, and it generally does not carry Dolby Digital Plus. Standard HDMI ARC usually carries stereo PCM plus compressed surround formats including Dolby Digital Plus, while eARC and a direct HDMI connection to a receiver can carry multichannel PCM. Support varies by model and firmware, so confirm the formats listed in the specifications of both your TV or player and your audio device.

Surround and Atmos

With PCM, the number of channels you receive depends on what the source decodes and what the link supports; on a stereo-only link, a surround soundtrack is downmixed to two channels. With Dolby Digital Plus passthrough, the receiving device gets the original surround mix and, where present, the Atmos information. On many devices, decoding Atmos content to PCM means the height information is not passed along, but some players handle this differently, so check your device documentation.

Controls and processing

When the source outputs PCM, it can mix system sounds, notifications and game audio with the main soundtrack, and its own volume, equalizer or spatial audio settings usually apply. With passthrough, the decoder in the soundbar or receiver applies its own features, such as dialogue enhancement or night mode, and some sources mute interface sounds or switch formats between apps. Which controls remain available depends on both devices.

Sample rate and audio quality

PCM is uncompressed, so nothing further is lost on the link after decoding, and on a computer the output device's sample rate and bit depth setting applies to it. Dolby Digital Plus is lossy: the audio was compressed when the content was prepared, and passing it through does not restore anything. Selecting PCM for a Dolby Digital Plus source does not make it lossless either; it only moves the decoding step. Any audible difference between the two paths depends on your equipment and needs a listening test rather than a spec sheet.

Privacy and file handling

Neither output format changes what an app records, uploads or stores. The setting governs how audio travels between devices, not how call or recording data is handled, so review each app's own privacy and storage settings separately.

Practical trade-offs

These common situations show how the choice plays out:

• Streaming films to a soundbar over ARC: Dolby Digital Plus or Auto usually keeps surround and Atmos that PCM over the same link could reduce to stereo.
• Video calls on a TV, computer or streaming box: call audio is usually mono or stereo, so PCM is a simple choice and lets the device mix notification sounds; try the other setting if voices drop out or sound delayed.
• Game console to a receiver over HDMI: many consoles produce game audio as PCM, so multichannel PCM avoids an extra encoding step where the link supports it.
• Recording or editing audio and video: keep working files in PCM formats such as WAV; Dolby Digital Plus is a delivery format, not an editing format.
• Older receiver or optical-only connection: PCM gives stereo; for surround, a plain Dolby Digital option may be needed if the source offers it.

Published specifications tell you which formats a port and device accept. They do not tell you about audio delay, lip-sync drift, dropouts when formats switch or audible quality, because those depend on the specific combination of devices and firmware. Test with your own content: play a clip with clear speech, confirm that the soundbar or receiver shows the format you expect, and adjust the lip-sync or audio delay setting if needed.

Choose for the use case

• Choose Dolby Digital Plus, bitstream or passthrough if your soundbar or receiver decodes it, you watch streaming content with surround or Atmos, and the connection is HDMI ARC or eARC.
• Choose PCM if your audio device cannot decode Dolby Digital Plus, you use a stereo output device such as headphones or desktop speakers, you want the source to mix system and call sounds, or you have eARC or a direct HDMI link and prefer the source to decode.
• Choose Auto if the device offers it and both devices report their capabilities correctly; the source then selects a format the output device accepts.
• If you hear silence, crackling or missing channels after changing the setting, switch back and recheck the format support of each device and the cable path.

There is no universal winner. Start from what your output device can decode and what the connection carries, then pick the option that preserves the channels you need while keeping the controls you rely on.