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Blu-ray Sound in the Eye of the Beholder

30 Nov, 2009 By: Chris Tribbey

Everyone knows what the yardstick is for measuring video quality on Blu-ray Disc: 1080p.

Where disagreement still exists for the high-def format is on audio standards, specifically how the studios should treat the original mono tracks from older films. Leave things be? Upgrade with all the audio codecs and speakers Blu-ray supports? Do both?

“The purists would consider it blasphemy, of course,” John Polito, engineer with Burbank, Calif.-based audio remastering studio Audio Mechanics, said about upgrading older audio tracks for Blu-ray. “Those shows were meant to be mono, they’d say.”

Independent Blu-ray producer Van Ling compares upgrading older audio tracks to the debate over colorizing black-and-white films or remaking films that are considered classics. It’s an issue “fraught with impassioned views on both sides,” Ling said.

“Some believe it is a matter of bringing new relevance to an older title that deserves to have newer generations see it, by making what they consider cosmetic alterations that will bring the audio mix up to current standards,” Ling said. “Others see this as pure anathema to the art itself, and that what makes a piece of artwork a classic is ironically that it is a product of its moment in time.”

Bill Hunt, editor of TheDigitalBits.com, pointed to director Martin Scorsese’s keynote at the recent Blu-Con 2.0 conference as a guide for the studios and Blu-ray audio.

“When it’s possible to upgrade the audio from mono to stereo or even surround, to help new audiences become more engrossed in an older film, it’s worth trying,” he said. “The key thing is, with DVD, and especially Blu-ray, you have room to also include the original mono audio as it was seen in theaters.”

Most agree if a studio is going to upgrade audio for the Blu-ray release of an older film, it had better include the original audio as well.

“We feel we must also provide the original theatrical mono mix as a choice for purists,” said George Feltenstein, SVP of theatrical catalog marketing at Warner Home Video.

That is made easier by Blu-ray’s greater capacity. The process for restoring audio for DVD and Blu-ray isn’t all that different. What the two formats can handle in your living room is.

“The difference is that standard-definition DVD had lossy, compressed audio, and now Blu-ray has full frequency, which takes better advantage of work we have done in the past,” Feltenstein said.

He, however, stands with the purists on audio for older films when original elements aren’t available.

“If the film was mono, it should stay mono, unless you have, as we sometimes do, multiple channel source production elements that can allow for a genuine stereo track to be created from these sources,” Feltenstein said. Multiple channel sources were available and used, for instance, for the Blu-ray releases of The Wizard of Oz, Gone With the Wind and North by Northwest, Warner classics that were all originally presented in mono.

“What we won’t do is create a ‘fake stereo’ or ‘fake 5.1’ derived from a single mono track,” he added. “There’s no point to it. Consumers can synthesize that kind of manipulation on the audio receivers. For us, unless it comes from genuine elements, we keep mono mono.”

Hunt pointed to what the studio did with the audio for its recent Oz Blu-ray release.

“The audio is available in DTS-HD 5.1 lossless, but it still retains the character of the original presentation,” he said. “It’s just a little more … ‘involving’ is the word I’d use. But the original mono is also included, so you have the choice.”

Still, some — such as Arnaud Dudemaine, VP of sales and business development for Audionamix, a Paris-based tech company that specializes in audio signal processing and audio treatment for high-def — see an advantage in reverse-engineering a mono track, even without the original elements. Audionamix technicians reverse-engineer mono and stereo recordings into multitrack components, isolating voices, music and sound effects from each other.

When it comes to upgrading the audio of older films for Blu-ray, it’s all about “cheats and tweets and jiggles,” Dudemaine said.

“Today’s recordings are mixed according to the director’s wishes, but the films of the past don’t have that,” he said. “Now we have the technology to isolate individual sounds and enhance [audio tracks] for Blu-ray.”

Polito said the technology for upgrading original mono tracks to 5.1 and 7.1 options “is still difficult and time consuming” and “a work in progress.” And the costs can be high. With studios so focused on what people see — that 1080p picture their HDTVs and Blu-rays advertise — worrying about the audio tracks can become secondary in both the priorities and the budget.

“It’s limited to higher potential releases,” Dudemaine said. “Audio comes after video. Both the home theater manufacturers and the studios put picture quality first.”

Dudemaine pointed to the Blu-ray release of Casablanca from Warner as an example of a film for which his company could have upgraded the audio. The release saw an elaborate upgrade for the black-and-white picture, but there was no 5.1 remaster of the audio, with the studio sticking to the mono track.

“For a Blu-ray, I found that surprising,” Dudemaine said. “They spent a lot to upgrade the picture but did nothing with the audio.”

Warner’s Feltenstein said there’s a reason for that.

“We don’t pursue anything that would be ‘synthesized,’” he said. “Unless we have discrete production elements that can help us build a multichannel soundtrack without creating something inauthentic, we stay within the pure-mono realm.

“That’s why Casablanca will always be in its original mono as far as we’re concerned.”

The question of whether to upgrade the audio is often answered by the materials the studios can get their hands on. Are the original elements even available? Has the master deteriorated?

“Keep in mind that until the late  ’40s to early ’50s, all audio was optical, or even earlier, disc,” said film preservationist and restorer Robert Harris. “MGM, via Roger Mayer, did major preservation on their product. Warner Bros., ditto. Universal also. It’s been a huge uphill battle for all, but much original audio has been preserved. Occasionally one finds gems such as the stereo tracks for some of the MGM [films].”

“They were never meant to be heard … with precise digital clarity,” Harris said. He pointed to the 70mm film version of Vertigo, which had prints produced with both a DTS track and a single magnetic audio track.

“Reproducing the quality of those original tracks, which were not up to modern standards, the magnetic sounded much smoother and generally more forgiving,” he said.

Polito pointed to problems with the original materials for Alien, which is getting a Blu-ray upgrade.

“It was mixed in London and stored in airtight tin cans,” he said. “That’s really bad for the acetate [film]. It develops ‘vinegar syndrome,’ and ages 20 more years than it should have.”

Ling added it’s not just about finding the right, original audio elements. It’s also about finding the right people — with the right ears — to supervise the upgrades.

“We need to resist just taking a final mixed track and using automated digital channel splitters, and we need to pay attention to what the original intent was with the audio,” he said. “This means committing to a lot of real, painstaking work and diligent attention.”

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