How to have audio passthrough in MPV?

[magnilens]

Now that I have a soundbar that uses a HDMI connection and has Dolby and DTS support, I am interested in a media player that passthrough high quality audio formats to the bar. Like VLC can but VLC has a problem with displaying styled subs on HDR video. I would prefer if I could keep using MPV.

I searched discussions here but the most I could find was someone talking about a passthrough profile which I'm not sure how specific that was to their setup. I would like to know about options, profiles, scripts or anything that can make MPV automatically passthrough any Dolby or DTS audio its playing.

[pratikrath126]

To enable audio passthrough for Dolby and DTS formats in MPV, use the --audio-spdif option followed by the desired formats. For example:\n\nmpv --audio-spdif=ac3,dts file.mkv\n\nThis will pass through AC3 and DTS audio without decoding them. Ensure your audio output device (e.g., HDMI to your soundbar) supports these formats. For more details, refer to the MPV manual on audio passthrough options.

[magnilens]

Thanks for the heads up. I found the entry for the audio-spdif option in the manual. Can you help me with understanding this Warning on the entry?

There is not much reason to use this. HDMI supports uncompressed multichannel PCM, and mpv
supports lossless DTS-HD decoding via FFmpeg's new DCA decoder (based on libdcadec).

Do I understand this correctly, high-definition Dolby and DTS formats are decoded into multichannel PCM for playback whether it's by software (in MPV) or hardware (in the soundbar) and both should sound the same on the same soundbar?

[pratikrath126]

Yes, your understanding is essentially correct. For lossless formats like DTS-HD MA and TrueHD, software decoding (MPV via FFmpeg) produces a mathematically identical PCM output to what the soundbar would produce decoding the bitstream itself in hardware. So the end result going to your speakers should be audibly the same either way.

That's exactly why the warning exists — since MPV can already decode these losslessly to multichannel PCM and send it over HDMI, passthrough offers no quality advantage and just adds complexity.

The main scenarios where passthrough could still make sense:

• Your soundbar supports a format MPV/FFmpeg can't decode
• You specifically want the soundbar's onboard DSP or room correction to process the raw bitstream before decoding
• You want your receiver/soundbar's display to show "DTS-HD" or "Dolby Atmos" instead of "PCM"

But for pure audio quality on a standard Dolby/DTS setup, letting MPV decode it to PCM is perfectly fine and the warning is essentially telling you not to overthink it.

[magnilens]

Your soundbar supports a format MPV/FFmpeg can't decode

Can I even specify an unknown format on that option, how?

You want your receiver/soundbar's display to show "DTS-HD" or "Dolby Atmos" instead of "PCM"

I take it that means FFmpeg can decode Atmos to MC-PCM?