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The audience is listening
Mar. 8th, 2007 03:51 amObsession du jour: DTS sound.
I've been reading up on DTS vs Dolby, and it's interesting what I find. Theatrically, they're very different systems; Dolby encodes its audio on the film print, whereas DTS uses separate CDs (a sort of digital descendent of early talkies that used a separate phonograph, as seen in Singin' in the Rain). But on DVD, they're rather similar. And not content to stop with just 5.1 channels, some of them offer 6.1 or even 7.1.
I'm a bit ambivalent about the 6.1 channel DTS-ES system, as is used in the Lord of the Rings box sets. According to what I read, for backward compatibility to 5.1 systems, it drops the 6th channel altogether, rather than matrixing it into the other two speakers. This means that if I watch it in DTS, I could potentially be missing sounds, if there are any sounds that show up only in the rear center channel but not either of the rear surrounds. (Although I wonder how likely it is that there are such sounds; you would think that they would know not everyone would have a rear speaker and use it just to augment what's in the surrounds. But I don't know for sure that's what they did.) But if I watch the Dolby 5.1, I know I'm hearing everything, because there isn't a rear center channel into which to extend the mix.
And of course on DVD the difference between DTS and Dolby (otherwise known as AC-3) is not as wide as most people think. There seems to be a perception that DTS is much higher quality, and to an extent this is true—theoretically. From Wikipedia:
But—almost nobody actually uses DTS at its maximum bitrate. Looking at this list of DTS encodings with their bitrates, it is evident that the vast majority of DVDs chop their DTS to 754 or 768. The Lord of the Rings discs are encoded at 754 (not really a surprise as many audio tracks as they have to cram in there). Even the much-vaunted mastered-without-extras-for-superior-video-and-sound-quality Superbit discs are encoded at 754. You generally only see musical titles like The Eagles: Hell Freezes Over and the video portion of DVD-Audio discs encoded at the maximum rate.
And, of course, on my fairly cheap Logitech 5.1 speaker set, any difference in sound quality is probably academic anyway.
But I noticed an interesting thing. I was looking at some Hong Kong import DVDs that have DTS tracks on them—the Hong Kong releases of the Jackie Chan film The Accidental Spy and the Jet Li movie Fearless—and I found that both of them feature 1536 kilobit per second DTS encodings. The Fearless one even claims to be DTS-ES, though I saw no evidence of that in the disc itself. Furthermore, even on the DVDs that don't feature DTS, a lot more of them than you would expect at least feature a Dolby 5.1 surround mix. Even fairly old kung-fu flicks like Wheels on Meals or Dragons Forever have it, as does John Woo's actioner Once a Thief. You pretty much have to go all the way back to the '70s to find Hong Kong films that don't. And these aren't exactly all that effect-heavy films, either—though I have to admit the 5.1 does add considerable solidity to the "whack!" sounds of kung-fu blows landing.
And that's my obsession for the day. Hope you enjoyed it.
I've been reading up on DTS vs Dolby, and it's interesting what I find. Theatrically, they're very different systems; Dolby encodes its audio on the film print, whereas DTS uses separate CDs (a sort of digital descendent of early talkies that used a separate phonograph, as seen in Singin' in the Rain). But on DVD, they're rather similar. And not content to stop with just 5.1 channels, some of them offer 6.1 or even 7.1.
I'm a bit ambivalent about the 6.1 channel DTS-ES system, as is used in the Lord of the Rings box sets. According to what I read, for backward compatibility to 5.1 systems, it drops the 6th channel altogether, rather than matrixing it into the other two speakers. This means that if I watch it in DTS, I could potentially be missing sounds, if there are any sounds that show up only in the rear center channel but not either of the rear surrounds. (Although I wonder how likely it is that there are such sounds; you would think that they would know not everyone would have a rear speaker and use it just to augment what's in the surrounds. But I don't know for sure that's what they did.) But if I watch the Dolby 5.1, I know I'm hearing everything, because there isn't a rear center channel into which to extend the mix.
And of course on DVD the difference between DTS and Dolby (otherwise known as AC-3) is not as wide as most people think. There seems to be a perception that DTS is much higher quality, and to an extent this is true—theoretically. From Wikipedia:
In the consumer (home-theater) market, AC-3 and DTS are closer in terms of audio performance. When the DTS audio track is encoded at its highest legal bitrate (1.5 MBps), most technical experts regard DTS as achieving perceptual transparency (i.e. indistinguishable to the uncoded-source in a double-blind test.) At AC-3's maximum bitrate of 640 Kbps, Dolby claims similar transparency. However, the DVD format limits AC-3 audio tracks to 448 Kbps, and some publishers limit the AC-3 bitrate further (to 384 Kbps.) Even at 448 Kbps, (DVD) AC-3 operates at a higher bitrate than theatrical (35 mm movie) AC-3, therefore a properly-equipped home-theater already achieves surround sound superior to a cinema AC-3 installation. Likewise, DTS-audio on movie DVDs is commonly encoded at a reduced bitrate, allowing a single title to fit multiple 5.1 soundtracks (AC-3 + DTS.) At this reduced rate (768 Kbps), DTS no longer retains audio-transparency.So the best bitrate that Dolby 5.1 can have on the disc is not capable of audio-transparency—but the best bitrate that DTS 5.1 can have is.
But—almost nobody actually uses DTS at its maximum bitrate. Looking at this list of DTS encodings with their bitrates, it is evident that the vast majority of DVDs chop their DTS to 754 or 768. The Lord of the Rings discs are encoded at 754 (not really a surprise as many audio tracks as they have to cram in there). Even the much-vaunted mastered-without-extras-for-superior-video-and-sound-quality Superbit discs are encoded at 754. You generally only see musical titles like The Eagles: Hell Freezes Over and the video portion of DVD-Audio discs encoded at the maximum rate.
And, of course, on my fairly cheap Logitech 5.1 speaker set, any difference in sound quality is probably academic anyway.
But I noticed an interesting thing. I was looking at some Hong Kong import DVDs that have DTS tracks on them—the Hong Kong releases of the Jackie Chan film The Accidental Spy and the Jet Li movie Fearless—and I found that both of them feature 1536 kilobit per second DTS encodings. The Fearless one even claims to be DTS-ES, though I saw no evidence of that in the disc itself. Furthermore, even on the DVDs that don't feature DTS, a lot more of them than you would expect at least feature a Dolby 5.1 surround mix. Even fairly old kung-fu flicks like Wheels on Meals or Dragons Forever have it, as does John Woo's actioner Once a Thief. You pretty much have to go all the way back to the '70s to find Hong Kong films that don't. And these aren't exactly all that effect-heavy films, either—though I have to admit the 5.1 does add considerable solidity to the "whack!" sounds of kung-fu blows landing.
And that's my obsession for the day. Hope you enjoyed it.
