Why Do 2.1-Channel Soundbars Decode Surround Sound?

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Q I am planning to buy a 2.1-channel soundbar and have noticed many are only capable of decoding standard Dolby Digital soundtracks. However, one 2.1-channel model I looked at, Sony's HT-NT5, supports Dolby Digital, Dolby Digital Plus, Dolby TrueHD, DTS, DTS-HD Master Audio, DTS-HD High Resolution, DTS ES, and DTS 96/24. What is the advantage of a 2.1 channel soundbar being able to decode multiple multichannel audio formats? —Joe Pop

A The main advantage is that the soundbar should be able to handle almost any digital audio bitstream that you feed it. That said, keep in mind that while some 2.1-channel soundbars can decode advanced multichannel audio formats, it doesn’t mean you’ll get any of the immersive benefits that those formats offer. The soundbar’s built-in decoder simply reformats the multichannel information in the soundtrack for two-channel playback. The center and left/right surround channel information is still utilized, but gets “downmixed” into the main left and right channels reproduced by the soundbar.

Another advantage is that Dolby True HD and DTS-HD Master Audio are uncompressed high-resolution audio formats, so even though you’re hearing a stereo downmix of a multichannel soundtrack, it’s still presented with higher quality than standard Dolby Digital. The same thing goes for Dolby Digital Plus, a format developed as a successor to Dolby Digital that provides higher bitrates plus support for channel counts greater than 5.1.

Finally, some 2.1-channel soundbars — the Sony HT-NT5 you mention, for example — can be paired with optional wireless surround speakers. So, if you do decide to upgrade, the 2.1 soundbar’s ability to decode multichannel sound formats means that rear-channel information can be passed on to the wireless satellites so you can hear movie soundtracks with real, as opposed to virtual, surround.

WildGuy's picture

Dolby TrueHD and DTS-HDMA are actually lossless compression codecs which have the exact 100% quality as uncompressed but save space by losslessly compressed the data a little bit.

So lossless compression codec is better than uncompressed because it save a bit more data space than uncompressed but has the same quality as uncompressed.