Lossless audio boosts Blu-ray

By DON LINDICH, Special to the Star Tribune

Last update: September 25, 2009 - 4:32 PM

Q You've explained the benefits of Dolby TrueHD and DTS-HD Master Audio on Blu-ray soundtracks. Do Dolby TrueHD and DTS-HD Master Audio improve the sound of standard music CDs? Since there seems to be big improvement in sound using Dolby TrueHD and DTS-HD Master Audio, I would hope to see concert videos become available in Blu-ray format.

STEVE PITZL, Shoreview

A Dolby TrueHD and DTS-HD Master Audio are "lossless" compression schemes. That means the digital information is compressed to save space but the sound quality of the original studio master tape is completely retained. "Uncompressed PCM" is another version of lossless sound, but it does not use compression so it takes up much more space on the disc. Content producers have largely moved to Dolby TrueHD and DTS-MA so they can use the saved space on better video quality or more special features.

There are no Dolby TrueHD or DTS-MA tracks found on CD discs so CD playback will not benefit from having the feature on your electronics. A Blu-ray audio-only format is under development, and there are indeed many concerts available on Blu-ray.

One of my favorites is "The Pyongyang Concert," featuring the January 2008 performance of the New York Philharmonic in Pyongyang, North Korea. It contains the full concert with lossless PCM soundtracks in stereo and 5.1 surround, as well as an excellent documentary recounting the visit. Video and sound quality are top-notch and the second encore, the Korean folk song "Arirang," is beautiful and haunting. Be sure to check it out.

When Blu-ray was launched, usage of the two formats was split about evenly between the studios, but DTS-MA has taken a commanding lead. Readers tout the sonic superiority of DTS-MA over Dolby TrueHD, or uncompressed PCM over either, but they are all sonically identical when recorded the same way from the same master tape. Any differences are due to the master tape used or tweaking done by the technicians. As long as you have one of the lossless formats and the equipment to decode it, you are assured of the finest possible sound quality.

Lenses in their prime

Q What is meant by a "prime" lens? I have been reading about digital SLR cameras on message boards and frequently see this term.

K. MARTINOVIC, GRAND FORKS, N.D.

A A prime lens is a lens that does not vary its focal length, such as a 50-millimeter or 100mm. Zoom lenses are lenses that vary their focal length, such as 14-42mm or 50-200mm. If you divide the larger number by the smaller number, you get the zoom range. A 14-42mm is a 3x zoom; a 50-200mm is a 4x zoom.

Many photographers prefer prime lenses because they tend to be sharper than zooms, and they work better in low light. If you have a Canon digital SLR, you really should have its excellent 50mm 1.8 lens in your bag. It is only $100, and the difference in sharpness compared with the kit zoom will shock you. Pentax has excellent prime lenses (the pancake series) as well.

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