Question on 48KHz/24-16 bit

Camper · 07-01-2008, 04:49 PM

I see reviews of various discs and they say

48KHZ/24 bit soundtrack or 48KHz/16 bit.

What does this mean? Are there other KHz number values besides 48 or bit numbers other than 24 or 16 bit.

i assume 24 bit is better than 16 bit. Bigger is better right?

Is there anyone who could explain to a layman what these numbers mean?

I see some players are 'limited to 48KHz/24 bit playback' what does that mean? That they won't play 16 bit or that there are other larger bitrates they won't play?

Thanks a lot for any info.

Camper · 07-03-2008, 02:07 PM

I know somebody here knows this probably lots o folks!!

Please help out a newbie blu-ray person.

Thanks.

Stephen_J_H · 07-07-2008, 08:52 PM

It's all about "word length" and sample rate. In this case 48kHz is the sample rate and the digital bitstream is broken up into either 16 bit or 24 bit words. Both of these are higher than the CD audio standard, which is 44.1kHz/16 bit. the general rule is that the higher the sample rate and longer the word length, the more transparent the audio signal. Sample rates come in multiple "flavours"; as an example, dts has mastered several titles in 96/24, or 96 kHz/24 bit, and Sony's DSD (used on SACD) is a lossless compression system that uses variable word length, as is Meridian Lossless Packing, which is the lossless compression system that forms the basis of Dolby TrueHD. Toshiba marketed DVD players with 192kHz/24 bit processing, but that was a case of oversampling for error correction (something that many CD players boasted of in the late 80s/early 90s).

As far as quality goes, it's a straight GIGO situation: the sound is only going to be as good as the original source. Let your ears be the judge.

Camper · 07-08-2008, 11:38 AM

Thank you for that !!!
I think I get it now, sample rate & 'word length' higher should be better if I can hear it.

Now I only need to understand what it means when they say that a player if 'limited to 48khz/24 bit playback'.

Does that mean it WON'T PLAY a (example) 96khz encoded soundtrack OR
that it would simply 'down-rez' ??? the soundtrack to 48 khz ??

Thanks again folks.

Jari K · 07-08-2008, 05:29 PM

I guess with PCM 5.1 audio..

*24bit = 6.9 Mbps
*16 bit = 4.6 Mbps

Right?

I noticed, that e.g. "3:10 to Yuma (2007)" PCM 7.1 was 6.1 Mbps, though..

**HTF Ads**

Stephen_J_H · 07-08-2008, 06:59 PM

Are you reading this in the player's literature or on the discs?

Camper · 07-09-2008, 11:30 AM

The origin of my question is that
I remember reading that a particular Blu-ray player was
'limited to 48khz/24 bit' in the TrueHD soundtracks.

I haven't yet rented or bought a disc that was higher than 48khz/24 in TrueHD.
But that above phrase made me wonder what would be the result of trying to play a disc encoded with a higher sample or bit rate.
Would it not play or would it simply 'downscale' the soundtrack to something it could play?

Mabe it's moot. Maybe there aren't any TrueHD soundtracks above 48/24 available.

Stephen_J_H · 07-10-2008, 04:44 PM

Now that you mention that it's in reference to TrueHD, I believe you are correct that there are no TrueHD soundtracks above 48/24. In fact, if I recall correctly, when Sony made the announcement that they were going to start encoding their BDs in TrueHD, they stated that they would be encoding in 48/16, which led to some hullaballoo over why they didn't opt for the longer word length. Anyone who recalls the thread better can feel free to chime in on this.

Joe Wong · 07-12-2008, 02:38 PM

Quote:

Originally Posted by Camper

Mabe it's moot. Maybe there aren't any TrueHD soundtracks above 48/24 available.

Some concert Blu-rays have a 96kHz/24bit soundtrack. For example, Dave Matthews:

DVD Empire - Item - Dave Matthews & Tim Reynolds: Live At Radio City / Blu-ray

Blu-ray Review: Dave Matthews and Tim Reynolds: Live at Radio City | High-Def Digest

Cheers,

Joe