Has anyone already compared an LD AC3 or LD DTS soundtrack with a Blu-Ray DTS HD Master Audio or Dolby Digital TrueHD audio track ?
What do you think, can LD still outrun those 100% "lossless" studio master tracks that are available right now ?

Perhaps these titles are a nice reference to compare:

True Lies
Blade
Apollo 13
Phantom Menace
Jurassic Park
....

I was curious. I do have the setup to do these tests also, but one missing link (projector) still needs to be added to make it complete so ill have to wait a bit.

Blade and True Lies are not currently available on blu ray, at least in the US don't know about other regions

Blade is available in Canada on Blu-ray, in english, which is basically not very far for any U.S. collector thats interested.
Axel Music and probably other companies ship worldwide.

DTS tracks might have a fighting chance, but AC3 (aka Dolby Digital) audio was limited to only 384kbps on LD. While it's not much less than the DVD-standard 448kbps, even the embedded legacy DD signal in lossless Dolby TrueHD tracks is at 640kbps.

Well, that kind of depends as far as Dolby Digital goes. Were the Dolby Digital tracks on blu-rays mixed properly? Or were they mixed to be heavy on the front channels so that they would downmix to a 2-channel setup better like a lot of DVDs?

Doubtful. This time around they're really trying to push at least the home theater in a box setups on all consumers. The speakers they put in TVs these days are much more awful than the ones they put in CRTs. My parents were never interested in a sound system until they bought their plasma TV, then after hearing how god awful the TV speakers were they opted for a home theater system. If this is the way the industry is going, it would only make sense that BDs would be mixed to take full advantage of 5.1 setups. Plus BD has an ever growing number of 7.1 soundtracks. These I can tell you sound awesome. You have seen Nightmare on Elm Street, until you've seen it on BD with a 7.1 system.

i guess its a regional issue indeed, because blade is available here, in a very good quality.

as true lies goes, the best presentation is (or was) available on D-theater with a great DTS full bitrate track, indeed no blu-ray yet.
i got a little carried away because i see it regulary on d-vhs in 1080i...

Has anybody ever heard the 6.1 DTS ES soundtrack on the japanese True Lies DVD? I always wanted to compare it to the dts ld. Hopefully they bring out a 7.1 dts ma True Lies soon

Is that so? I've always thought that Ac3 on LD could have a bitrate up to 640 kbps...

if i'm not mistaking the limitation of dolby digital (ac3) that can be outputted trough a digital cable is 640 kbps max, but laserdisc always used the 384 standard.
D-VHS d-theater tapes used 640 kbps if i am correct.

The encoding of AC-3 in QPSK digital form on the erstwhile channel 2/R analog FM audio carrier is limited to 384 kbps by issues having to do with the sidebands of the digital modulation, the allowed bandwidth & dynamic range of the audio carrier, & interference with other signals (notably one of the beat products of the chroma subcarrier with the video carrier). If I recall, theatrical AC-3 (printed between the sprocket holes of the film) is limited to 320 kbps by other technical considerations.

If I'm to believe the various articles I've read, you can throw as high a bit rate as you want at any soundtrack, but ultimately it is the mix that truly defines the aural experience. I guess it is really a case by case thing.

Honestly from my understanding of compression technologies what you get with higher bit rates is a broader scope for the range of frequencies available. In most humans you get to a point where you really can't notice any significant difference. This happens especially with old age as you slowly lose your ability to hear higher frequencies.

In conventional digital audio, higher bitrate buys you either higher sampling rate (wider frequency range) or greater bit depth (more dynamic range & signal-to-noise ratio). With compressed digital audio, things are not so simple. A sub-band coder like Dolby AC-3 either throws away or coarsely quantizes frequencies which are present at a low or constant level, while allocating more bits to the frequencies where most of the amplitude or dynamic range are. Cutting down the bitrate, therefore, generates bizarre sorts of anharmonic distortions, while adding bitrate brings you an ever-closer recreation of the original audio, at whatever sampling rate & bit depth it was originated. There's a psychoacoustic model (of the human auditory system) involved which tries to keep the damage done by throwing away components to a minimum in terms of what can actually be heard.

So it generates a kind of digital generation loss?

That exactly what they mean by a lossy compression technique. However, the Blu Ray audio compression is mostly lossless TrueHD, DTS MA, or in some cases the uncompressed LPCM 5.1 or 7.1 tracks.

Due to the fact that my wife has no interest in LaserDiscs or my taste in films, I really only listen to the uncompressed digital audio stereo tracks through headphones late at night. The quality then is quite comparable to BD in that respect.

One thing I'm actually confused about with BD audio tracks is that if the DTS an Dolby tracks are 'lossless' then why aren't they just PCM tracks?

Dolby Digital Plus, formerly known as Meridian Lossless Packing (MLP, used on the DVD-Audio format), & DTS HD-MA are "lossless" formats. This means that, when you decode them, what you get out is bit-for-bit identical to the PCM audio which was input. They simply require less storage space. In the computer environment, it's the difference between a .wav & a .flac file. Both contain the exact same audio data, but one stores it more efficiently. In non-audio terms, compare a .bmp image to a .png image. Again, lossless compression gives a smaller file size.

That is really cool. Thank you for enlightening me. There are some amazing people out there, I don't know if I'd ever be able to get my head around the complexity of the algorithms they must use to achieve that.

Here's another question. Would a soundtrack sound the same as Dolby true HD or DTS Master? Are there inherent strengths and weaknesses between the formats or is it really just down to file size?

Apologies if I've taken this thread way off topic.

There are significant differences in the way the encoding is done, but the output is bit-for-bit identical, & thus there can be no difference in the sound.

At least, that's the principle, which assumes that there aren't, say, automatically applied settings in the encoder which mess with the mix levels, or something like that. There are long-standing controversies about, eg, DTS soundtracks with levels set differently (by a significant margin) from their Dolby counterparts, or a Dolby setting known as dialnorm which shifts the level of the center channel. These, however, apply to the lossy compression systems. If we're lucky (hah!), the people in charge of lossless compression will simply take the digital master tape they're given & pack the audio without alteration.

Thats the theory. Lossless audio should be the same as the master. I have also read one reason to use lossless compressing instead of uncompressed PCM tracks is because they can achieve a higher bit rate with a Dolby TrueHD or DTS MA than with an LPCM track. This again is because of the space constraints.