Surround and lossless audio on a PC

A film can carry a full multi-channel mix, and it is often quietly folded down to stereo before you hear any of it.

What gets thrown away

Downmixing collapses several channels into two. It is necessary for laptop speakers, but done badly it buries dialogue and loses the placement that made the mix worth having.

Keeping the mix intact

AIX Player decodes multi-channel soundtracks and keeps them intact rather than flattening them by default, so a disc rip sounds the way it was mixed when you have the speakers to hear it. Every soundtrack format it decodes is listed on the sound page.

Choosing how it routes

The audio channel setting decides how the mix reaches your speakers — full multi-channel where the hardware supports it, or a controlled downmix that keeps dialogue clear where it does not. Settings → Audio → Audio channel / downmix offers Default (System), Stereo, Reverse Stereo, Left, Right and Surround (matrix).

Why a bad downmix buries dialogue

In a surround mix, most speech sits in the centre channel with music and effects around it. Collapsing that to two speakers means the centre has to be folded into both, and if it is folded in too quietly the dialogue disappears under everything else. Downmixing is one factor to check when dialogue is difficult to hear.

What to choose for your setup

On a laptop or a pair of desk speakers, a well-judged downmix beats raw multi-channel every time, because the channels you have no speakers for have to go somewhere. On headphones, the same is true but a lighter touch sounds more natural. With an actual surround setup or a soundbar, keep the file’s own channel layout and let every speaker carry its part. AIX Player always decodes the soundtrack itself; it does not pass the encoded stream through to an AV receiver.

Surround and casting

Many televisions cannot decode a cinema surround mix themselves, which is why casting a disc rip so often arrives with picture and no sound. A file the TV plays directly retains its audio; a converted stream uses AAC. Where available, try another audio track.

Worth knowing