Blu-ray discs offer you a choice of the default to PCM/Dolby Digital Plus which adds a second additional rear center speaker for up to 7.1 channels, but the bit rate is still low compared to either Dolby TrueHD at 18.64 Mbps, DTS-HD Master Audio at 24.5 Mbps, or LPCM at 27.64 Mbps, the best of the uncompressed, lossless audio content on a Blu-ray disc. For an extra fee you can buy High Definition broadcasts via HD cable, fiber, or satellite which improve the performance up to Dolby Digital EX, adding a single rear center speaker for up to 6.1 channel performance with less compression, up to DVD-A quality. Standard definition broadcasts over cable, satellite, or the internet are limited to first generation Dolby Digital with the lowest bit rate and highest compression, know in the trade as “lossy”. For comparison’s sake, lets look at regular TV first. If you play a Blu-ray disc without first setting the audio output of the player up for Bitstream output via HDMI and choose one of the lossless versions of the soundtrack from the disc’s audio set-up menu, you will not be hearing the highest resolution content. Notably it’s important to understand that PCM is the default standard for Blu-ray audio but it does not have the highest bitrate, it’s the equivalent of Dolby Digital Plus, several orders of magnitude below whats considered Hi Res Audio today, but still as good as CD. Specification of Blu-ray Primary Audio Streams: Everything lower is known as “lossy”, meaning the dynamic range is compressed dramatically. Hi Res Audio is defined as 24 bit at either 96K or 192K sample rate, nothing lower. One way to learn what all the specs mean is to look at the chart below of specifications for the Primary Audio Streams on a Blu-ray disc. That is simply impossible and this post will help explain why. I’ve written today’s post to help everybody learn how this works because many recent audiophiles think they can use their notebook computers to store and watch Blu-ray Hi Res Audio and Hi Def video with no less performance than on an actual Blu-ray player. Unlike the FTC rating for power amps, there is no regulation or regulator on the beat to call them out, it’s up to us as consumers to figure it out on our own. I know those are strong words to use but there is often no truth to the specs you read and the claims they make, it’s merely specsmanship to make a sale. Believe it or not, the audio specs of the various content platforms such as Roku, Chromecast, Fire, Apple TV, Amazon Prime, and Netflix are in many cases confusing, misleading, or simply untrue.
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