PCM Audio on Chromecast: Output and Compatibility

Does Chromecast output PCM audio?

Yes. HDMI Chromecast models can send decoded audio to the TV, soundbar or AV receiver as PCM. If a cast app delivers audio in a codec the Chromecast decodes itself, such as AAC, MP3, Opus, Vorbis or FLAC, the device decodes it and outputs PCM over HDMI. Dolby formats work differently. Models that support passthrough can send the compressed bitstream unchanged, and the connected output device decodes it. Which path is used depends on the Chromecast model, what the TV or receiver reports it can accept, and the audio settings on both ends. Chromecast can also play PCM sources in the form of WAV files, as long as the app you cast from supports them.

How PCM fits into casting

PCM (pulse-code modulation) is uncompressed digital audio. It is a series of samples described by a sample rate, a bit depth and a channel count. Every compressed format ends up as PCM once it is decoded, and PCM is what a digital-to-analog converter turns into sound. That is why PCM is the baseline audio format any HDMI audio device has to accept.

When you cast, your phone or computer does not stream the audio itself. It tells the Chromecast what to play, and the Chromecast fetches the stream from the network. The Chromecast then either decodes the audio and sends PCM, or passes a compressed surround bitstream through. Over HDMI, the TV or receiver reports which audio formats it accepts, and the Chromecast uses that report together with its own settings to choose.

Supported codecs, sample rates, channel counts and passthrough formats differ between Chromecast generations and can change with firmware updates. For your device, check Google's official supported media list for Cast and the specifications for your model. Don't rely on a general rule.

Chromecast Audio

The discontinued Chromecast Audio had no HDMI port. It connected to speakers or an amplifier through a combined analog and optical jack. On the optical connection it sent digital audio to the external device, so the DAC in your amplifier or receiver did the conversion. On the analog connection, the dongle did the conversion itself.

Applying this to common setups

The receiver or soundbar display is the quickest diagnostic. If it shows PCM, the Chromecast or the TV has already decoded the audio. If it shows a Dolby format, the bitstream is being passed through for the receiver to decode.

• No sound, or sound only in some apps, through a soundbar or receiver: on models with surround sound settings, choose the stereo or PCM-only option so the Chromecast always sends decoded audio.
• You want the receiver to decode surround: allow passthrough in the Chromecast audio settings, and make sure the receiver supports the format the app is sending.
• Audio goes Chromecast to TV to soundbar: the TV's digital audio output setting (often labelled PCM, Auto, Bitstream or Passthrough) decides what the soundbar receives, regardless of what the Chromecast sends.
• Playing WAV files: cast from an app that supports local or network file playback. Check that the file's sample rate and bit depth fall within the formats your model supports.

If only one app misbehaves, play something from a different app to compare. Some apps request specific audio formats, so a fault limited to one app usually points to that app, not to your HDMI chain.

Limits and related questions

Multichannel PCM depends on the connection after the Chromecast. Standard HDMI ARC and optical (S/PDIF) can carry two-channel PCM or compressed surround formats, but not multichannel PCM. eARC can carry multichannel PCM. If your soundbar sits behind the TV on ARC or optical, decoded surround from the Chromecast may arrive as stereo.

Don't assume bit-perfect output. The Chromecast, the TV or the receiver may resample audio to a different sample rate or apply processing. Audiophile claims about a particular model should be checked against its specifications, not inferred from the fact that it outputs PCM.

Mirroring a browser tab or a screen is different from casting from an app. The sender encodes the audio for streaming, so quality depends on that step, not on the original file. In a video call shown on a TV, casting only changes where you hear the call. The input device, its input level and any background noise it picks up are still controlled on the phone, laptop or webcam you are calling from.