Why laserdisc soundtracks are better...

...than most of the DVD - and few BD, as I read also in these forum. I don't want to talk about MUSE laserdisc audio now, because I'm not expert in that branch, but whoever wants to talk about it, is welcome!

OK, let's start!

NTSC laserdiscs could contain a different combination of soundtracks:

• two mono analog
• one stereo analog
• two mono analog + two mono PCM
• two mono analog + one stereo PCM
• one stereo analog + two mono PCM
• one stereo analog + one stereo PCM
• AC3 + one mono analog + one stereo PCM
• DTS + one stereo analog

I'm pretty sure there is no AC3 laserdisc with two mono digital soundtracks, as PCM is used for stereo (surround) soundtrack, and almost sure there is no DTS laserdisc with two mono analog soundtracks, as analog is used for stereo (surround) soundtrack, but I'm sure there is NO laserdisc that contain both DTS and AC3 soundtracks!

Things are easier for PAL laserdiscs:

• two mono analog (on laservision)
• one stereo analog (on laservision)
• two mono digital
• one stereo digital
• DTS (well, only one titles ever released!)

The PAL laservision is practically another standard, as PAL laserdisc video could be watched on old laservision player, but digital soundtracks could not be heard! The contrary is usually not true, as the most part of the PAL laserdisc players could also play analog soundtracks. There is NO AC3 PAL laserdisc!

Now, let's take a closer look at the different soundtrack types.

ANALOG

Albeit analog soundtrack on laserdisc is the worst of the possible ones that could be found on it, the quality is pretty good - here you are some numbers:

• Frequency response: 20-20000hz (±3dB)
• Signal-to-noise ratio (CX off): >50dB (up to 58dB)
• Signal-to-noise ratio (CX on): >62dB (up to 74dB)
• Channel separation: >50dB

Not that bad, uh? Better than vynil, audio cassette, second only to VHS HiFi Stereo. It could contain also surround sound; some concerts could be found only on analog laserdiscs, as they are never released with digital audio; the most part of japanese bilingual laserdiscs have the japanese language recorded onto the analog soundtrack... why? Maybe because it sounds better? The answer is yours...

PCM (Pulse Code Modulation)

The first (and most used) digital soundtrack that appeared on the laserdisc format was PCM, stereo or dual mono, 16bit 44.1KHz 1441kbps - it has the same technical specifications and quality of the CD-audio, but it was available years before it!

• Frequency response: 4-20000hz (±0.1dB)
• Signal-to-noise ratio: 96dB - up to 117db (EIAJ)
• Dynamic range: 96dB - up to 99dB (EIAJ)
• Channel separation: 80dB - up to 90dB (EIAJ)
• Wow & Flutter: <0.001% (EIAJ)

All the PAL laserdiscs after the end of 1980's have digital audio; NTSC continued to have both analog and digital soundtrack, as the standard allowed it; several surround types could be found on laserdisc, not only the famous Dolby Surround, but also DTS Surround and CHACE surround.

AC3 (Dolby Digital)

The first AC3 laserdisc was "Clear and Present Danger" and was released in 1995; the AC3 soundtrack is stored in the right analog channel, and is RF modulated; to be decoded, a laserdisc player with the AC3 RF output is needed, and must be connected to an RF demodulator and a Dolby Digital decoder, or to an amplifier with built-in RF demodulator and DD decoder.

The AC3 soundtrack has always the 384kbps bitrate at 48KHz, almost always 20bit 5.1 channels, but in some (rare) cases the number of channels could vary - usually during extra material like making of, documentary etc.

I found no proof (until now), but there are evidences that the theatrical mixes are used for AC3 laserdisc soundtracks "as is"; infact, many argue that laserdisc Dolby Digital sounds better than the DVD counterpart, also if the latter has an higher bitrate; infact, most DVD DD soundtracks are mixed taking in account home users, and they should sound good with any kind of audio configuration, and hence it's a sort of compromise, while the laserdisc has that "in your face" sound typical of theaters.

Someone could think that is not possible, as the theatrical AC3 soundtrack is 320kbps, while laserdisc has 384kbps... think that the LD AC3 is stored on analog form, and surely the signal contains some sort of stronger error correction, due to the fact that analog reading is not perfect; also, it is possible that the signal is simply padded from 320kbps to 384kbps, as it was more economic to take the theatrical mix and copy to laserdisc than remake a home version...

DTS (Digital Theater System)

The first DTS laserdisc was "Jurassic Park" and was released in 1997; DTS soundtrack takes the place of the PCM soundtrack, leaving free two analog tracks, (almost) always used for the movie soundtrack, allowing the owner of an old analog-only player, or who has not a DTS decoder, to listen to it. To be decoded, a laserdisc player with digital output is needed, and a DTS decoder, or an amplifier with built-in DTS decoder.

As the DTS soundtrack are in place of the PCM one, it has the same technical data, 16bit 44.1KHz 1441kbps but, at the contrary of the PCM two channels, it has 5.1 discrete channels.

The laserdisc DTS soundtrack IS NOT the same of the theatrical one: infact, in theaters, DTS uses a different codec, APT-X, encoded as ADPCM at 882kbps and recorded on CD-ROMs, with a compression of 4:1, while DTS on laserdisc uses Coherent Acoustics perceptual coding compression scheme, encoded at 20bit 44.1KHz with a bitrate of 1235kbps (padded to 1441kbps to be the same of PCM soundtracks) and a compression of 3:1. Hence, the DTS laserdiscs should be better than the theatrical DTS, as the home codec is newer and better, and bitrate higher with less compression.

As almost all DTS DVD have the so-called "half bitrate" soundtracks (754kbps padded to 768kbps) instead of full bitrate (1509kbps padded to 1536kbps), the laserdisc DTS soundtracks is always better than "half bitrate" DTS DVD; in some cases, could be preferable to full-bitrate DTS DVD due to different mixes used.

CONCLUSIONS

Using a laserdisc soundtrack for preservation purposes is often a good choice; when the DVD or BD soundtracks are of low quality, or technically inferior, or "improved";  when the DVD or BD soundtracks have different formats; when the DVD or BD have no soundtrack in a certain language; or, simply, when there are no DVD or BD of a certain title or version at all!

There is only a price to pay: capturing and converting laserdisc soundtracks is an HARD task... but really rewarding! - just finished JP2 AC3 and DTS, I know what I'm talking about... (^^,)

The main reason some LDs sound better is that the surround mix was done purely to be a surround mix.

When DVD came along one of the priorities was that if the doofus that bought the DVD only had TV speakers or a mono or stereo setup and chose the surround track to listen to, that the dialogue would still be intelligible and the sound would still be okay. This led to many DVD soundtracks having severely compromised 5.1 mixes compared to the LD mix which was only ever designed to sound great in 5.1

Heat was one of the titles that really suffered in DVD vs LD.

Now BD sound quality craps all over laserdisc from a technical standpoint, but LD can sometimes have a better mix, especially on films that came out before they started doing 7.1 etc.

Just how good can a VHS audio track be? I'm considering looking at VHS audio for a project where the only other source is heavily compressed DVD audio (96 kbp/s mono and time compressed on top of that). Can hi-fi audio stand up to a lossless transfer, and if necessary can non-hifi VHS audio work?

VHS Hi-Fi is stereo, 20-20.000Zz, 70dB S/N; it's as good as analog tracks on laserdisc, and it will be better than a heavy compressed AC3 soundtrack IMHO; at the contrary, VHS not Hi-Fi has a mono track, 100-10.000Hz, 42dB S/N, so it should be used only as the last resource...

Actually, I used VHS Hi-Fi stereo tracks for two projects, and the sound is very good indeed - not good as PCM CD/laserdisc soundtrack, but at least the original source is not compressed; the only problems are due to cracks and pops that could happen caused by the tape wear; if the VHS tape is unopened, not too old, and stored correctely it *could* happen that the audio is perfect, but it's not guaranteed... mine were bought brand new in 1995, played three or four times, then stored properly, but occasional crackle were unavoidable...

...where laserdisc tracks will not wear, and - when not affected by laser rot - will play as well after 30 years as when brand new!

The non-HiFi linear tracks on VHS tapes were in stereo as well, but very few HiFi machines played or recorded the linear tracks in stereo, instead using the lower quality linear track as a mono backup alternative.

I know now that most VHS commercial releases had Hi-Fi and linear tracks both in stereo... but, when I listen to Hi-Fi stereo tracks, the left and right tracks on the V-meters clearly shows different levels, while when I switch to linear tracks, the V-meters levels are always the same for both channels... and I have two S-VHS recorders!

I must admit I have very few VHS cassette left, and maybe the ones I have, have not stereo linear tracks, but I'm pretty sure, back in the days, that all the commercial VHS tapes I watched (both bought and rented) on the same recorders, have only mono linear tracks, and I watched A LOT...

I remember the Hi-Fi tracks from old VHS tapes like Braveheart, Outbreak, and even the GOUT sounding pretty awesome for what they were, so long as the tape is in good shape.

The idea of having AC3/DTS/PCM LaserDiscs tracks to sync to Blu-ray makes me happy.  

But let's be careful to still evaluate and not assume just because it's LaserDisc that it is better.  GoldenEye's AC3 LaserDisc track has bloated LFE, which was fixed on the DTS LD.  I always felt the PCM track for the Lion King was better than its AC3 track.  Forrest Gump's AC3 track always confused me: the surrounds don't seem to be active at all (unless that is by design).  Early DTS titles, including both JP and Apollo 13 had levels set incorrectly for the LFE and Surrounds.

That being said...I'll still take a LD track of a catalog title over most Blu-rays and almost any DVD out there. 

That too can depend on the film.  Take Batman Forever.  The PCM mix is great, but lacks the spatial characteristics of the AC3 mix.  Both great, but the AC3 is truer to the intent of the film.

The Lion King?  Yeah, PCM hands down.  

A lot of folks also prefer the PCM track of Top Gun to the AC3 version.  I surely don't.  I think the AC3 one rocks big time.  There's a preservation that is worthy!

I remember the first time I heard a DTS soundtrack... it was "Independence Day" on laserdisc... I was blown away!

Another thing I remember, when I started to buy DVD (i was "forced" to do it, just because we had only 300 PAL italian titles to choose from) was the fact that AC3 5.1 soundtracks on DVDs, that all magazines of the time called "the definitive home theater experience", were infact weaker (a lot weaker) than the simples PCM italian soundtrack...

Obviously, there is NO definitive better soundtrack... it depends from mix type, mix quality, type of movie... when we watch a classic 1940's movie, we aspect a mono sountrack, while a modern 1990's action movie should "pump up the volume", possibly with a 5.1 soundtrack...

borisanddoris said:

GoldenEye's AC3 LaserDisc track has bloated LFE, which was fixed on the DTS LD. 

Is this on the LD as was reputed to be on the SE DVD? It would make sense as the LFE is very bloated.

borisanddoris said:

That too can depend on the film.  Take Batman Forever.  The PCM mix is great, but lacks the spatial characteristics of the AC3 mix.  Both great, but the AC3 is truer to the intent of the film.

The Lion King?  Yeah, PCM hands down.  

A lot of folks also prefer the PCM track of Top Gun to the AC3 version.  I surely don't.  I think the AC3 one rocks big time.  There's a preservation that is worthy!

On Forever it's neck and neck. The PCM has a more natural soundstage and bass, but the ac3 has intensive clarity and defined discrete channels.

Apocalypse Now is best on the 1991 release in PCM. The later 5.1 LD and DVD/BDs aren't the same.

Hunt For Red October, Die Hard and Batman all sound better on LD PCM than the remixes, even the LD ones! Especially Batman. One of the best Dolby Stereo mixes ever done IMO.

Yes, but in standard Dolby format. Only October had split surrounds, the prior two were LCR + mono surround enhanced by two baby booms with spectral recording noise reduction. To my ears, Batman on LD has a certain clarity unheard on any of the later video 5.1 remixes.

I resume this old thread because I've discovered this webpage, and I found very interesting this paragraph in particular:

This paper presented listeners with a choice between high-rate DVD-A/SACD content, chosen by high-definition audio advocates to show off high-def's superiority, and that same content resampled on the spot down to 16-bit / 44.1kHz Compact Disc rate. The listeners were challenged to identify any difference whatsoever between the two using an ABX methodology. BAS conducted the test using high-end professional equipment in noise-isolated studio listening environments with both amateur and trained professional listeners.

In 554 trials, listeners chose correctly 49.8% of the time. In other words, they were guessing. Not one listener throughout the entire test was able to identify which was 16/44.1 and which was high rate [15], and the 16-bit signal wasn't even dithered!

That's why we all love so much laserdisc PCM soundtracks...