7/15/08

Blu-ray and Hi-def Audio



Yeah, yeah, yeah… So, by now we know that Blu-ray won the Hi-definition format wars. Hi-definition is an obvious and welcome improvement to what we see, but what about the sounds we hear?

What about our ears? What do they get out of this deal..?

Well, there is good news..! Your ears will be happy, and I’m not talking diamond earrings!

Here is a quick primer – a few notes to help clear a little fog. I will get into more detail in future discussions…

Good: Dolby Digital and DTS – these are the two audio formats that you are familiar with from current DVDs – the standard definition type. They are referred to as lossy formats, meaning that they are compressed and have bits missing from the original studio recording.

Note: This compression and removal of bits was done so that the audio would fit on the DVD discs along with the video. Blu-ray discs, compared to DVD, have a significantly greater storage capacity; this enables the studios to include the Hi-definition video files as well as the new audio files.

Better: Dolby Digital Plus and DTS-HD High Resolution – Here you have what are essentially improved versions of the above mentioned formats. They have higher bit rates and more efficient compression for better detail, but they still are not equivalent to the original studio recording.

Best: Dolby TrueHD and DTS-HD Master Audio – Both of these formats are considered lossless, meaning that all the bits from the original studio recording are present. There is a type of compression going on, but when your home theater gear plays it back, it uncompresses and all the original sound bits are accounted for. Just as hi-definition video looks substantially better than standard definition, there is a marked improvement in audio quality here.

As for that original soundtrack recording, it is what is referred to as the PCM track (pulse-code modulation). This is an exact mirror-image duplication of what the studio engineer produced – no compression or removal of sound bits is involved. You could almost think of PCM as the “best of the best”.

There you have it folks, a quick guide to soundtrack audio on Blu-ray discs. More details will follow, but for now, happy listening and let those ears enjoy…

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