The long evolution of storage media began in 1876 with Edison’s wax cylinder, then came shellac 78 rpm discs, but did not stop with vinyl albums, CD, SACD, or DVD. We have been squeezing more and more bandwidth and dynamic range into a series of storage formats all these years since. Online downloading of music at lower resolution became an option and now for those with audiophile sensibilities its possible to download content that exceeds the CD but not the SACD or DVD-A version. 96/24 files are still compressed 2 to 1.
From the 78 rpm mono shellac records in the 30’s and 40’s, to magnetic open reel tape, to the 45’s of the 50’s and 33.3’s stereophonic vinyl records and cassette tapes of the 60’s and 70’s, each could only hold a limited amount of play time and content. Bass and treble came via the RIAA equalization curve injected by the phono section, dynamic range increased to 60 dB and the hifi industry as we know it today was born, along with a group of dedicated listeners called audiophiles.
I was a pioneer of that era, I know the historical context into which all of today’s products fit. As the software got better, speakers and amps got bigger and better. The movie theaters were the test beds for increased performance, Hollywood studios competed with one another for the best sound. The Academy of Motion Picture Arts and Sciences along with the Audio Engineering Society set standards of performance that drove technology forward, trickling down to consumers along the way.
The hardware makers did their part, Arnie Nudell founded Infinity Systems and really launched the high-end speaker business as we know it today. Morris Kessler’s SAE began building the first high powered amps and we overcame compression with power, up to the point where we ran out of headroom because the peaks were compressed to make 12 songs fit on two sides within 45 minutes. DBX made dynamic range expanders but they had there own issues. The Sheffield records showed us there was more dynamic range to be had on vinyl but the studios could not mass produce them.
When the CD came out in 1980, it achieved full bandwidth without equalization and 90 dB dynamic range, a 30 dB increase from the vinyl record. The holy grail was close but still compressed 4 to 1. CD’s could only hold 700 MB of data so the dynamic peaks were left out in order to fit 12 songs on a single sided disc.
No amount of up- sampling or re-clocking can squeeze more dynamic range out of a CD if it’s not there to begin with. In the late 90’s and early 00’s, DVD-A came out on a disc that could hold a 2 hour movie and a less compressed soundtrack, thanks to Bob Stewart, the founder of Meridian. He presented a paper to the AES revealing an algorithm that reduced compression down to 2 to 1, adding another 10 dB of dynamic range. Sony and JVC in Japan created a competitor called SACD using DSD, potentially even better than DVD-A. The studios didn’t find a groundswell of demand for either and they’ve lingered to this day. A few years ago, the record labels began allowing their PCM encoded recordings with MLP to be sold as downloads at 96/24, a big improvement over CD but still compressed 2 to 1. These downloads are really very good and for content released only as a CD a far better option for music lovers. Lets agree though, these are not the equal of the actual studio masters in digital form, but closer than anything else so far.
The Studios realized that soon they would need a disc that could not only store a 2 hour movie in un-compressed 1080p HD but also the un-compressed soundtrack, bit for bit identical to the studio master recording. The increased power of microprocessors led Dolby and DTS to create encode/decode codecs that could play back the full dynamic range of the original master recording but only under the toughest of security protocols. If HDMI with HDCP is the connection, its possible to see and hear the best content in history now on Blu-ray.
“From a purely technical standpoint, the audio resolution of a DVD-Audio disc can be substantially higher than standard red book CD audio. DVD-Audio supports bit depths up to 24-bit and sample rates up to 192 kHz, while CD audio is 16-bit, 44.1 kHz. In both cases, the source recording may have been made at a much higher bit and sample rate, and down-converted for commercial release.
Many DVD-Audio releases are older, standard-definition audio recordings that have been remixed in 5.1 and up-sampled to DVD-Audio’s higher resolution. However, the fidelity of the up-sampled audio will be limited by the source material quality when the master recording is in digital format and may not exceed the quality of existing CD releases of the same albums. Recordings that are made using high-resolution PCM encoding can be released with a resolution that is higher than standard CD”.