It is currently 25 Nov 2017, 08:54




 Page 1 of 1 [ 16 posts ] 
Author Message
 Post subject: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 18 Nov 2015, 11:35 
True fan
True fan
User avatar

Joined: 11 May 2009, 11:12
Posts: 268
Location: Norway
Has thanked: 0 time
Been thanked: 0 time
Hi!

I've always used a stereo amp for my laserdiscs and are considering getting equipment for AC3, but the selling point is how much better the audio is on the ac3 soundtrack. PCM soundtracks are crystal clear on my amp and the bass isn't anywhere near what a blu-ray gives me (know its hard to compare bd to ld, but still). Is ac3 just good for its 5.1, or is ac3 better for bass etc?

- pix
_________________
Pioneer KURO KRP-500M, Crystalio 2 VPS3300, HLD-X9
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 18 Nov 2015, 14:04 
True fan
True fan
User avatar

Joined: 16 Jun 2015, 15:40
Posts: 416
Location: Australia
Has thanked: 8 times
Been thanked: 3 times
LD was my introduction to DD and DTS (and home theatre) back in the day, so maybe I'm a little biased but for movies, especially 'effects' bass I think that .1 channel can make all the difference.

Of course you really need a dedicated sub-woofer to fully realise its potential.
_________________
HLD-X9/HM-D101/TU-MDC100, Lumagen 2144, Epson EH-TW5500. For PAL CLD-925.
Online
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 18 Nov 2015, 18:55 
Jedi Candidate
Jedi Candidate
User avatar

Joined: 14 Jan 2010, 09:44
Posts: 2269
Location: United States
Has thanked: 2 times
Been thanked: 13 times
The difference is pretty huge. I only have small 6 speaker Bose satellite system, not even one with discrete bass (the .1), instead using a conventional crossover. Even with this setup the move to DD was really massive!

My only advice is that you look at the list of DD LDs and make sure there is something to watch. It's a much much bigger selection than DTS, but it's still only a few years worth of movies before LD just died out completely.
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 18 Nov 2015, 20:22 
Jedi Initiate
Jedi Initiate
User avatar

Joined: 16 May 2009, 18:05
Posts: 2751
Location: MA USA
Has thanked: 1 time
Been thanked: 14 times
AC-3 in LD is 384kbps combined for all 6 channels. If you divide that by 3, its 128kbps per every 2ch. Listen to a 128kbps mp3 or aac file, the fidelity of AC-3 is exactly that much if not less. If you are one of those who says they can't hear a difference between mp3 and CD, then AC-3 will sound just as good as PCM. Some AC-3 soundtracks are mastered in a way to hide flaws of this lossy codec, those are not too bad.

As for the lfe, this was added to compensate the lack of dynamic range in the lossy AC-3 codec. Lfe is recorded at 10db higher. With the lfe track, AC-3 can mimic the dynamic range of 20bit PCM. Also keep in mind, in the early days of AC-3 and DTS, most mixes were very enthusiastic. To show off the discrete nature and dedicated bass speaker, most mixes had cooked up surround effects and heavy bass.

As signo mentioned, check out the list, there is about 600-700 titles with AC-3, about a 100 of them are very good mixes.
_________________
Wanted
HD-VMD Discs
Hi-Vision/Muse Discs Only complete/mint!
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 20 Nov 2015, 03:58 
Advanced fan
Advanced fan
User avatar

Joined: 18 Mar 2011, 22:12
Posts: 903
Location: Windsor, Ontario, Canada
Has thanked: 0 time
Been thanked: 0 time
substance wrote:
AC-3 in LD is 384kbps combined for all 6 channels. If you divide that by 3, its 128kbps per every 2ch. Listen to a 128kbps mp3 or aac file, the fidelity of AC-3 is exactly that much if not less. If you are one of those who says they can't hear a difference between mp3 and CD, then AC-3 will sound just as good as PCM. Some AC-3 soundtracks are mastered in a way to hide flaws of this lossy codec, those are not too bad.

As for the lfe, this was added to compensate the lack of dynamic range in the lossy AC-3 codec. Lfe is recorded at 10db higher. With the lfe track, AC-3 can mimic the dynamic range of 20bit PCM. Also keep in mind, in the early days of AC-3 and DTS, most mixes were very enthusiastic. To show off the discrete nature and dedicated bass speaker, most mixes had cooked up surround effects and heavy bass.


i didn't know that
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 20 Nov 2015, 04:30 
Jedi Initiate
Jedi Initiate
User avatar

Joined: 16 May 2009, 18:05
Posts: 2751
Location: MA USA
Has thanked: 1 time
Been thanked: 14 times
elieb wrote:
substance wrote:
AC-3 in LD is 384kbps combined for all 6 channels. If you divide that by 3, its 128kbps per every 2ch. Listen to a 128kbps mp3 or aac file, the fidelity of AC-3 is exactly that much if not less. If you are one of those who says they can't hear a difference between mp3 and CD, then AC-3 will sound just as good as PCM. Some AC-3 soundtracks are mastered in a way to hide flaws of this lossy codec, those are not too bad.

As for the lfe, this was added to compensate the lack of dynamic range in the lossy AC-3 codec. Lfe is recorded at 10db higher. With the lfe track, AC-3 can mimic the dynamic range of 20bit PCM. Also keep in mind, in the early days of AC-3 and DTS, most mixes were very enthusiastic. To show off the discrete nature and dedicated bass speaker, most mixes had cooked up surround effects and heavy bass.


i didn't know that


If you don't know, now you know...
_________________
Wanted
HD-VMD Discs
Hi-Vision/Muse Discs Only complete/mint!
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 20 Nov 2015, 18:13 
Advanced fan
Advanced fan
User avatar

Joined: 02 Oct 2008, 04:35
Posts: 585
Location: Minnesota, United States
Has thanked: 0 time
Been thanked: 0 time
substance wrote:
Also keep in mind, in the early days of AC-3 and DTS, most mixes were very enthusiastic.

This is probably the main reason people prefer AC-3 tracks to the PCM. The sound mix is going to make all the difference. If the PCM was mixed with small TV speakers in mind and the AC-3 was intended to be played back on a full dynamic range discrete system, the AC-3 will probably win out. Personally, I have a "2.1" setup so AC-3 vs PCM makes little difference to me unless the mixing is substantially different. If you intend to keep a stereo system, you're really not missing out.
_________________
Laserdisc Players
CLD-3080 w/ AC-3 : LX-1000 : CLD-1010
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 20 Nov 2015, 18:39 
Jedi Initiate
Jedi Initiate
User avatar

Joined: 16 May 2009, 18:05
Posts: 2751
Location: MA USA
Has thanked: 1 time
Been thanked: 14 times
That is very true for DVD but I don't think they ever anticipated that LD owners will watch their films on a pair TV speakers. PCM tracks on LD is very aggressive. I think the analog tracks were meant for TV speakers, even those sound very good comparing to 2ch DVD tracks which are generally 192kbps Dolby Digital 2.0 encoded.

16bit audio(PCM on LD and CD) has a theoretical dynamic range of 96db and 20bit audio is 120db. With AC-3, due to the added LFE, you can get 110+db peaks. This is of course one parameter. The sampling is very low. This argument is very similar to whether you would prefer a very high bitrate 480i DVD or a very low bitrate 1080p stream from Netflix?
_________________
Wanted
HD-VMD Discs
Hi-Vision/Muse Discs Only complete/mint!
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 20 Nov 2015, 18:45 
True fan
True fan
User avatar

Joined: 16 Jun 2015, 15:40
Posts: 416
Location: Australia
Has thanked: 8 times
Been thanked: 3 times
gumbyandpals wrote:
Personally, I have a "2.1" setup so AC-3 vs PCM makes little difference to me unless the mixing is substantially different. If you intend to keep a stereo system, you're really not missing out.


This may be true if you are maintaining a '2.0' or perhaps '2.1' system in terms of speaker set-up, but if you intend using a 5.1 speaker set-up for playback of 5.1 audio tracks, then all other things being equal I think you'll definitely get a better result that way.

Music LD's without multi-channel encoding (PCM) still sound better played back on my system (6.1 speaker set-up) as '2.1' rather than turning on pro-logic, neo etc but if the disc has a 5.1 track then there's no doubt it sounds better that way rather than hearing it as '2.1'.

Being able to properly decode that discrete .1 channel does make a difference as opposed to just deriving it.

Going back to your original question there is a fair bit of material on-line to suggest you'll get an equally good result compared to BD if not better (LD tends to use original theatre sound mixes rather than 'optimised' for home), and as substance points out in the early days perhaps 5.1 tracks were a bit overblown to emphasise the benefits. I don't think I have anything by way of stuff on BD and also on LD with either DD or DTS to compare in this way.
_________________
HLD-X9/HM-D101/TU-MDC100, Lumagen 2144, Epson EH-TW5500. For PAL CLD-925.
Online
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 22 Nov 2015, 18:52 
True fan
True fan
User avatar

Joined: 21 Jun 2010, 20:03
Posts: 426
Location: TN, United States
Has thanked: 0 time
Been thanked: 1 time
If you're going to watch a lot of multichannel movies, practically anything post 1992-1994, then a full surround system is a must at least to overcome dynamic range compression.
With ac3 vs PCM the key difference is both the mix and the original audio format. LD presents everything warts and all unlike DVD and BD which can quite frequently re-compress and remix channels for nearfield home listening and the like. On LD typically the PCM and ac3 mixes are identical in their source, and it is only the presentation that is different. The ac3 is discrete in all channels so there is no sound leakage between them as in PCM matrix ProLogic. The matrixed mono surround is far more limited but if the film was originally mixed in that, a 5.1 remix really doesn't do very much unless it came from a different source such as a 70mm 6track mix.
It's really a matter of preference. From my experience ac3 tracks are a bit louder and more forceful than their PCM counterparts, but it goes on a film by film basis over which is preferred. It's only by doing back and forth comparisons that you can see the difference.
In other words, only worry about LD ac3 if you can find a cheap rf-demodulator. ;)

But some films really lose a touch of impact without the consistent low sub rumble in the 2.0 matrixing. In ROTJ, every single Jabba line has a slight edge of thunder, gone in the SE 5.1 ac3 track. Batman Forever is arguably better in 2.0, Goldeneye sounds near identical save for the mono surround vs. stereo surround, and Temple of Doom in 2.0 matrixed is so incredible you'd swear it was 5.1 half the time.
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 22 Nov 2015, 22:46 
Jedi Initiate
Jedi Initiate
User avatar

Joined: 16 May 2009, 18:05
Posts: 2751
Location: MA USA
Has thanked: 1 time
Been thanked: 14 times
The cinema AC-3 is actually even less bitrate at 320kbps than the laserdisc bitrate of 384kbps. AC-3 on DVD has 488kbps but it is remixed in a way that all 6ch can be folded down to 2ch. For this common tones on the mains and surrounds are out of phase so when fold down instead of doubling,they cancel out. They use multiple techniques like this so a successful fold down from 6ch to 2ch can occur. Obviously this compromises the 6ch mix. Some of the good DVD releases include a separate 5.1 mix and a 2.0 mix but mors often is a single 5.1 soundtrack with fold downable mix. LD obviously never had this issue as the AC-3 and 2.0 mix were always separate.
_________________
Wanted
HD-VMD Discs
Hi-Vision/Muse Discs Only complete/mint!
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 14 Jan 2016, 17:03 
Shows curiousity
Shows curiousity
User avatar

Joined: 25 Jun 2015, 01:53
Posts: 26
Has thanked: 1 time
Been thanked: 0 time
substance wrote:
AC-3 in LD is 384kbps combined for all 6 channels. If you divide that by 3, its 128kbps per every 2ch. Listen to a 128kbps mp3 or aac file, the fidelity of AC-3 is exactly that much if not less. If you are one of those who says they can't hear a difference between mp3 and CD, then AC-3 will sound just as good as PCM. Some AC-3 soundtracks are mastered in a way to hide flaws of this lossy codec, those are not too bad.
While it's true that the total bitrate is 384 kbps on LaserDisc AC3, one can't just use the rule of three to conclude that 2 channels would get 128 kbps since this is dynamically allocated by the encoder.

Furthermore, the statement regarding the difference "MP3 and CD" is too general and thus invalid. Since the MP3 standard only specifies the decoder, different encoders achieve different results depending on their psycho-acoustic model. Depending on the bitrate, MP3 may well exceed the level of transparency so in blind studies, virtually no one hears any difference anymore. I would never claim that their might not be individuals with amazing hearing capabilities who are still able to spot LAME MP3s for instance at 192 kbps and more, but to claim that MP3 is a bad thing by definition or flawed, is a bold overstatement. The problem often enough begins with the source.

This says the one who often keeps the FLAC data out of TrueHD and DTS-HD MA out of pure psychological reasons. ;) However, interestingly, some are even smaller than their lossy counterpart and with nowadays HDD capacity, one can save the headache worrying about lossy vs. lossless.

substance wrote:
AC-3 on DVD has 488kbps but it is remixed in a way that all 6ch can be folded down to 2ch. For this common tones on the mains and surrounds are out of phase so when fold down instead of doubling,they cancel out.
Do you know what the situation is for Blu-ray releases here? I mean despite all the (technically meaningless) "HD-Audio" fuss they make about it, the playback situation is still the same: most people use a downmix and not to rarely even crappy equipment.
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 14 Jan 2016, 20:00 
Jedi Initiate
Jedi Initiate
User avatar

Joined: 16 May 2009, 18:05
Posts: 2751
Location: MA USA
Has thanked: 1 time
Been thanked: 14 times
little-endian wrote:
substance wrote:
AC-3 in LD is 384kbps combined for all 6 channels. If you divide that by 3, its 128kbps per every 2ch. Listen to a 128kbps mp3 or aac file, the fidelity of AC-3 is exactly that much if not less. If you are one of those who says they can't hear a difference between mp3 and CD, then AC-3 will sound just as good as PCM. Some AC-3 soundtracks are mastered in a way to hide flaws of this lossy codec, those are not too bad.
While it's true that the total bitrate is 384 kbps on LaserDisc AC3, one can't just use the rule of three to conclude that 2 channels would get 128 kbps since this is dynamically allocated by the encoder.

Furthermore, the statement regarding the difference "MP3 and CD" is too general and thus invalid. Since the MP3 standard only specifies the decoder, different encoders achieve different results depending on their psycho-acoustic model. Depending on the bitrate, MP3 may well exceed the level of transparency so in blind studies, virtually no one hears any difference anymore. I would never claim that their might not be individuals with amazing hearing capabilities who are still able to spot LAME MP3s for instance at 192 kbps and more, but to claim that MP3 is a bad thing by definition or flawed, is a bold overstatement. The problem often enough begins with the source.

This says the one who often keeps the FLAC data out of TrueHD and DTS-HD MA out of pure psychological reasons. ;) However, interestingly, some are even smaller than their lossy counterpart and with nowadays HDD capacity, one can save the headache worrying about lossy vs. lossless.

substance wrote:
AC-3 on DVD has 488kbps but it is remixed in a way that all 6ch can be folded down to 2ch. For this common tones on the mains and surrounds are out of phase so when fold down instead of doubling,they cancel out.
Do you know what the situation is for Blu-ray releases here? I mean despite all the (technically meaningless) "HD-Audio" fuss they make about it, the playback situation is still the same: most people use a downmix and not to rarely even crappy equipment.


You go from 1.2mbps to 128kbps, it doesn't matter from what directions you look at it, you are losing %90 of the info. At much higher bitrates, lossy audio can be transparent enough. I don't know the very specifics of lossy codecs, I never cared to study them because I don't have any lossy music in my collection. I find used CDs for much cheaper and many other reasons. From the few occasions my wife and I listened to a few tracks on lossy codecs, both of us were able to tell right away, and she didn't know what source it was. Granted, I have a very revealing setup, on a more mainstream gear, the situation would be different.

When we come to AC-3 vs DTS. They both studied each others encoding scheme and hardware and they both released statements publicly pointing out each others flaws. Some of it was obviously pure bashing but some claims were on scientific basis with proofs. From what I can remember without going to those files again,

DTS at 1.5mbps has a response of 19KHz, and at a 768KHz(mostly found on DVDs) it is 17Khz. These are -3db points, so DTS encoding rolls off high frequencies to get rid of excessive space.
Dolby Digital even at its lowest bitrate 320Kbps, has a response of 20Khz but any info above above 14KHz is on a single stream and distributed to all channels equally at the decoder. Therefore high frequencies are not discrete on the AC-3. Here I am sure AC-3 decoder uses vector steering (such as in Pro Logic) and mutes the less dominant channels for high frequency distribution.
Now there were differences how bass was handled between DTS and AC-3. They both bashed each other on this. From what we know, DTS had 5.0 originally, and I believe the theatrical releases are 1.2mbps 5.0ch. DTS soundtrack isn't on the film but on a CD. I do own the DTS encoder (CAE-4) which was used to encode vast majority of the theatrical CDs and DVD up until early 2000s.

I have already explained how backwards compability work on my previous posts. I won't go into that again. On Blu-ray discs, Dolby TrueHD doesn't have backwards compability. Because of this, every disc which comes with a TrueHD track is provided with a Dolby Digital track. Some Discs, include a DD 5.1 and a separate DD 2.0 track but most are a single DD5.1. Due to this, TrueHD doesn't suffer from backwards compatible mixing. It is recorded with a lower dial norm to increase the dynamic range. This makes it quieter overall on a standard system. Most people wrongfully think its inferior( DTS HD) due to this.

DTS-HD MA is fully backwards compatible. It has a core DTS track at 1.5mbps which is derived from the DTS-HD MA track. This results compromises when you first look at it.
_________________
Wanted
HD-VMD Discs
Hi-Vision/Muse Discs Only complete/mint!
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 14 Jan 2016, 20:07 
Jedi Initiate
Jedi Initiate
User avatar

Joined: 16 May 2009, 18:05
Posts: 2751
Location: MA USA
Has thanked: 1 time
Been thanked: 14 times
I mean seriously, they announced Dolby Atmos capable soundbars recently. Yes, there is science and progress but then there is the laws of physics. How the heck do you expect to get 64ch(yes, sixty four) Dolby Atmos mix from a two feet wide single speaker? I doubt you can even get a decent stereo separation.
_________________
Wanted
HD-VMD Discs
Hi-Vision/Muse Discs Only complete/mint!
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 14 Jan 2016, 20:30 
Advanced fan
Advanced fan
User avatar

Joined: 02 Oct 2008, 04:35
Posts: 585
Location: Minnesota, United States
Has thanked: 0 time
Been thanked: 0 time
Image
Drivers on drivers on drivers?
_________________
Laserdisc Players
CLD-3080 w/ AC-3 : LX-1000 : CLD-1010
Offline
 Profile  
 
 Post subject: Re: Bass in AC3 soundtracks VS PCM digital audio.
PostPosted: 16 Jan 2016, 03:07 
Shows curiousity
Shows curiousity
User avatar

Joined: 25 Jun 2015, 01:53
Posts: 26
Has thanked: 1 time
Been thanked: 0 time
substance wrote:
You go from 1.2mbps to 128kbps, it doesn't matter from what directions you look at it, you are losing %90 of the info.
Technically true but the crucial question is: how much of the actual information contained in those 1.2mbps will ever reach your consciousness once it passed all the steps required to be processed? It's a fact that most of the information can be indeed discarded without the loss being perceivable. In essence, most you lose you wouldn't ever have noticed anyway. Philosophically: can something considered to be lost if lost in the first place?

Maybe it's a psychological thing - people are not even as half as keen on having lossless video as they wanna have lossless audio although it's comparable.

substance wrote:
At much higher bitrates, lossy audio can be transparent enough.
What is considered to be much higher? Higher than AC3@384 kbps? Maybe. Higher that DTS@1536 kbps? Most certainly not. Some guys at a German forum took the task to compare the lossless result of a DTS-HD MA track with its core. Even when subtracted from each other, virtually nothing is left. The difference even when only the distortion which is introduced by the lossy reduction is left, is so minor that is well masked by any musical content.

But this discussion is endless and leading nowhere. By definition, lossy sources are worse than lossless ones, especially when one wants to reencode to another lossy format. Whether or not it's good enough, everyone has to decide on his own.

substance wrote:
Now there were differences how bass was handled between DTS and AC-3.
The only difference I'm aware here is the DTS music vs. DTS movie thing where movies require a 10 dB gain of the LFE channel whereas music content doesn't due to the different mastering. Some AVRs allow this adjustment, some do it in a fixed way, some will do it wrong for either DTS music or movie content.

Technically, a dedicated LFE channel is obsolete, too. In theory, ~ 44 kHz / 16 Bit, properly dithered, will be good enough to cover everything what humans will ever be able to perceive until they get better ears.

Note that the dB values you gave roughly actually refer to the SNR; the dynamic range may be higher thanks to dither (on the cost of a few dB of lost SNR).

substance wrote:
I believe the theatrical releases are 1.2mbps 5.0ch.
I don't recall the exact bitrate now, but you're right about the 5 channels for cinema DTS which uses APT-X1000. No dedicated LFE channel there, but big bangs are contained in the surround channels. A few guys at originaltrilogy.com preserved some cinema DTS tracks and converted it to conventional DTS with a LFE retrieved by low pass filtering the source according to some white papers.

substance wrote:
It is recorded with a lower dial norm to increase the dynamic range.
Since the dialnorm parameter chances the whole audio level of the program, the dynamic range isn't changed this way by definition. Nonetheless, dialog normalisation can be annoying when reencoding which is why each to tries to get rid of it by patching the source.

substance wrote:
Most people wrongfully think its inferior( DTS HD) due to this.


The usual problem of louder appearing to be better at first. My personal opinion: AC3 at 448 kbps or 640 kbps and DTS at 1536 kbps will be good enough for 5.1 forever (until new ears grow). Against better knowledge and archival purposes, I often keep the DTS-HD MA and True HD as FLAC to comfort myself, haha.

substance wrote:
DTS-HD MA is fully backwards compatible. It has a core DTS track at 1.5mbps which is derived from the DTS-HD MA track. This results compromises when you first look at it.


I don't understand this conclusion. Besides the HD MA track or core, both carry the 5.1 content so the problem of down mixing for 2 channel systems is just the same.

I can easily understand why 5.1 mix might have been released in an uncompromised way thanks to a 2.0 mix always provided in addition, but I don't see the difference of a DVD with 5.1 only or BD with 5.1 only due to the lack of a dedicated 2.0 mix.
Offline
 Profile  
 
Display posts from previous:  Sort by  
 Page 1 of 1 [ 16 posts ] 


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to: