It has changed a lot! I started covering the home-theater industry as a journalist 20 years ago, when Dolby Digitalthen more commonly known as AC-3, the name of its underlying lossy-compression algorithmwas just being introduced. Up to then, movies used Dolby Pro Logic, which matrix-encoded the center channel and one surround channel in the front left and right channels. (This reminds me of quadraphonic from the 1970s, which I remember as a student, except that instead of four speakers in the corners of the room, Dolby Pro Logic was intended for three front speakers and two speakers playing the same surround signal on the sides or in the back of the room.)
Since then, we've seen movie soundtracks evolve from four matrixed channels to 5.1 and now 7.1 discrete channels. And this number could grow even more with the rise of 9.1 AVRs and 11.1 formats such as Audyssey DSX and DTS Neo:X.
Twenty years ago, CDs provided the bestheck, the onlydigital audio widely available to consumers; MP3 was just being finalized. There was no online audio streaming or downloading and no iPods back thenin fact, cassettes were still the dominant form of portable audio. Remember the original Walkman? I do.
I also remember well the format war between SACD and DVD-Audioin retrospect, a pointless battle with no winner as consumers chose the convenience and portability of MP3 over the quality of either disc format. Fortunately, quality has returned, at least in movie soundtracks, with the Dolby TrueHD and DTS-HD Master Audio lossless formats.
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