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Why SACDs?
Ron Jones
post Sep 14 2007, 21:05
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QUOTE (Borbus @ Sep 13 2007, 11:13) *
It has a silly, low and fixed sample rate (44.1kHz).

44.1 kHz is low? The way I see it, 44.1 kHz is a totally acceptable sampling rate for reproduction purposes. For manipulatory purposes, I have no reservations about working with 88.2 kHz, 96 kHz, 176.4 kHz or 192 kHz (particularly helpful when leveraging too much TC/TE, as I tend to do too frequently), but the audible differences between a 44.1 kHz master and a 192 kHz master will be slight to essentially nonexistent on most playback systems. I think even 40 kHz would have been easily acceptable for a consumer-grade format considering the qualities of Nyquist filters.

As for the original question: why SACDs? My answer to that would be: why not?
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Mercurio
post Sep 14 2007, 21:38
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QUOTE (Ron Jones @ Sep 14 2007, 12:05) *
As for the original question: why SACDs? My answer to that would be: why not?


They and the equipment you need are more expensive, even to produce, and they are harder to rip than CD, with all their DRM.

apart from DRM, they could substitute CD in the future, why not?... but in the near future we will not need to care about physical media anymore.

I still buy CD, but only to rip them.
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saratoga
post Sep 14 2007, 22:09
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QUOTE (krabapple @ Sep 13 2007, 08:27) *
QUOTE (sammydee @ Sep 13 2007, 10:35) *

Hi guys

Something that's been bothering me for a while... Please somebody correct me immediately if I am wrong on this but I'm pretty sure the general consensus on this board is that nobody (or very close to nobody) can tell the difference between a properly encoded 320kbps mp3 and the original cd, right?

So the difference between a normal cd and a "high quality" SACD is likely to be even more difficult to distinguish, likely going completely beyond any human's ability to tell the difference.

So what the hell is the point of SACDs!?

Please somebody explain this to me.

Sam



DSD was originally envisioned and developed as a high-quality archiving format for record companies, one that could be easily converted to consumer format -- e.g. Redbook PCM.


From what I've seen, it was originally proposed as a lower cost alternative to PCM. Once it didn't work out for that, then it was suggested as a higher quality option.

Now I think its mostly an excuse to slip more DRM into the market.
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krabapple
post Sep 14 2007, 23:12
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QUOTE (Light-Fire @ Sep 14 2007, 00:19) *
QUOTE (Borbus @ Sep 13 2007, 10:38) *

CD Audio is a poor format anyway, but most people probably won't realise this...


How can they realise this??!!

QUOTE (Borbus @ Sep 13 2007, 10:38) *
...For me, the main attraction of SACD and DVD-A is multichannel audio. Also DVD-A uses a proper file system and error correction so it's much easier to rip DVD-As. SACDs are proprietary so they don't interest me one bit.


Have you ripped DVD-A?!
Perhaps you ripped the DVD-V audio also present in the DVD-A disc instead.



IME, you can rip some (not all) commercial DVD-A, but 'easy' isn't the word I'd use to describe the process.

Apparently Borbus thinks that back in the late 70's, CD developers should have anticipated 1) the desire for
bit-perfect copying (and facilitated it), 2) reconstruction filtering issues near 20 kHz (I presume that's his objection to that baseband limit, and not some idea that we actually hear much of anything beyond that)
and 3) the exploitation of the format to *reduce* dynamic range, even though at the time one of the prime advertised reasons for buying CD was to finally be able to reproduce the actual dynamic range of recordings, at playback.

This post has been edited by krabapple: Sep 14 2007, 23:12
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Borbus
post Sep 15 2007, 12:44
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Hold on... Since when do we care when technology was invented? Back in the early 90s MP3 was absolutely amazing... is it still? No.

When the mobile telephone was introduced, did people shake their head and say "no.. back when Bell invented the phone we wouldn't have needed mobile phones so we don't now". Of course not.

The original question was "Why SACDs?" and I interpreted that to be "Why drop an older technology for a newer technology?" My answer is simple, in THIS day and age, CD Audio just doesn't cut it. I don't care how perfect it was back in the 70s.
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KikeG
post Sep 15 2007, 18:27
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SACD is a great way to waste bits and make a sub-par audio format, compared with conventional PCM. Ok, it can sound as good as hi-res PCM, but it's still a stupid way of storing digital audio because it mostly carries high frequency noise that has to be removed in order for the format to be usable. It's a marketing-driven format which has little sense from a technological point of way.

Hi-res PCM (DVD-A) is much more efficient and better from an objective quality point of view.

As to CD not being good enough the only drawback it has is not being multi-channel. It can be easily ripped (try to rip any SACD or DVD-A disk you can find), and quality is good enough. We can't perceive all the extended bandwidth and dynamic range that hi-res formats provide. They are just selling numbers.

This post has been edited by KikeG: Sep 15 2007, 18:29
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greynol
post Sep 15 2007, 19:05
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QUOTE (KikeG @ Sep 15 2007, 10:27) *
SACD is a great way to waste bits and make a sub-par audio format, compared with conventional PCM. Ok, it can sound as good as hi-res PCM, but it's still a stupid way of storing digital audio because it mostly carries high frequency noise that has to be removed in order for the format to be usable.
Reconstruction of DSD really isn't all that difficult. Where did you come up with this nonsense?

QUOTE (KikeG @ Sep 15 2007, 10:27) *
Hi-res PCM (DVD-A) is much more efficient and better from an objective quality point of view.

From the document that krabapple referenced:
QUOTE
Practice so far shows that DSD is at least as sonically transparent as 192kHz/24 bit and better than 96kHz/24bit. However, one channel of DSD takes up only 2.8Mbit/s, whereas one channel of 192kHz/24bit takes up 4.6Mbit/s.

So, how exactly is DVD-A more efficient or better from an "objective quality" point of view than SACD?

huh.gif

This post has been edited by greynol: Sep 15 2007, 19:20


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Mercurio
post Sep 15 2007, 19:18
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Well, we are going DVD-A vs SACD here, after we have understood that both them are useless.

Great laugh.gif

Only I would really like to understand what "is at least as sonically transparent" means. blink.gif
even a PCM 44Khz/16bit is "at least as sonically transparent as" 192kHz/24 bit and it need much less space.
Isn't it?
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greynol
post Sep 15 2007, 19:22
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Point taken.

BTW, I'm not a believer of high resolution formats when it comes to reproducing 2-channel audio.


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saratoga
post Sep 15 2007, 19:34
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QUOTE (greynol @ Sep 15 2007, 11:05) *
QUOTE (KikeG @ Sep 15 2007, 10:27) *
Hi-res PCM (DVD-A) is much more efficient and better from an objective quality point of view.

From the document that krabapple referenced:
QUOTE
Practice so far shows that DSD is at least as sonically transparent as 192kHz/24 bit and better than 96kHz/24bit. However, one channel of DSD takes up only 2.8Mbit/s, whereas one channel of 192kHz/24bit takes up 4.6Mbit/s.

So, how exactly is DVD-A more efficient or better from an "objective quality" point of view than SACD?

huh.gif


Your example is pretty far off. 24 bit PCM has a flat SNR all the way from DC out to 96khz. SACD has no where near that. Instead the SNR starts out comparable to 24 bit PCM and then drops off rapidly as frequency increases, somewhat similar to vinyl. The bitrate of the SACD is 1/2 as much, but its only storing a tiny fraction as much information.

If your metric is bandwidth*SNR/bitrate, then PCM is a indeed a much more efficient encoding. Every time you add a bit to your word length, you half your error energy. For 1 bit DSD, to half your error energy, you need a 4 fold increase in sample rate, which means you need exponentially more data to give a linear increase in SNR, compared to PCM where you need linearly more data for exponential increases in SNR.

Edit: At least thats my understanding.

This post has been edited by Mike Giacomelli: Sep 15 2007, 19:35
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greynol
post Sep 15 2007, 19:41
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Ok, so at what point does DVD-A overtake SACD assuming you can incrementally adjust the number of bits and sample rate in DVD-A and assuming a middle-of-the-road SACD player in terms of signal reconstruction?

Do we have any objective studies that indicate that DVD-A is audibly superior to SACD when it comes to multichannel applications?

This post has been edited by greynol: Sep 15 2007, 19:45


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saratoga
post Sep 15 2007, 19:47
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QUOTE (greynol @ Sep 15 2007, 11:41) *
Ok, so at what point does DVD-A overtake SACD assuming you can incrementally adjust the number of bits and sample rate in DVD-A and assuming a middle-of-the-road SACD player in terms of signal reconstruction?

Do we have any objective studies that indicate that DVD-A is audibly superior to SACD when it comes to multichannel applications?



According to this paper:

http://sjeng.org/ftp/SACD.pdf

QUOTE
Finally, consider 8-bit, four-times-oversampled PCM with
noise shaping. This is also a data rate one-half that of DSD and
double that of CD, with a sampling rate of 4 × 44,100 =
176,400 Hz. It can achieve a noise floor 120 dB below full
scale up to 20 kHz, using 96 dB of noise shaping, and a total
noise power of –19 dBFS. Its frequency response would be
flat to 80 kHz. This example is perhaps the most instructive of
the lot. For a data rate one-half that of DSD, it achieves a
comparable signal bandwidth, with a similar noise power
density up to 20 kHz, but much lower power above this
frequency, and 28 dB lower total noise power. It is fully
TPDF-dithered, and so is completely artefact free. At one-half
the data rate it outperforms DSD on every count! DSD is a
profligate wastrel of capacity.


It would seem that somewhere between CD bitrate, and twice CD bitrate DSD is overtaken by PCM. Though I cannot comment on the analysis done to conclude that.
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greynol
post Sep 15 2007, 19:58
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Thanks.

Considering that SACD has only twice the bitrate as CDDA, we're actually in the ballpark.

...and my second (meat and potatoes) question?

This post has been edited by greynol: Sep 15 2007, 20:01


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saratoga
post Sep 15 2007, 20:18
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QUOTE (greynol @ Sep 15 2007, 11:58) *
Thanks.

Considering that SACD has only twice the bitrate as CDDA, we're actually in the ballpark.


Well, 4x the bitrate of CD anyway (705kbps vs 2.8Mbps).


QUOTE (greynol @ Sep 15 2007, 11:58) *
...and my second (meat and potatoes) question?


Since its still up for debate if either is even better then CD on a per channel basis, I don't think theres likely to be much difference between the two. Efficiency is nice to have, but if you put the bitrate high enough, almost anything can be made to sound transparent.
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greynol
post Sep 15 2007, 20:24
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QUOTE (Mike Giacomelli @ Sep 15 2007, 12:18) *
Well, 4x the bitrate of CD anyway (705kbps vs 2.8Mbps).
So 2-channel SACD has a bitrate of 5.6Mbps?

QUOTE (Mike Giacomelli @ Sep 15 2007, 12:18) *
QUOTE (greynol @ Sep 15 2007, 11:58) *
...and my second (meat and potatoes) question?

Since its still up for debate if either is even better then CD on a per channel basis, I don't think theres likely to be much difference between the two. Efficiency is nice to have, but if you put the bitrate high enough, almost anything can be made to sound transparent.
I'm not sure I follow you. Do we have any objective studies that indicate that DVD-A is audibly superior to SACD when it comes to applications with more than two channels?

This post has been edited by greynol: Sep 15 2007, 20:30


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saratoga
post Sep 15 2007, 21:41
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QUOTE (greynol @ Sep 15 2007, 12:24) *
So 2-channel SACD has a bitrate of 5.6Mbps?


Yes.

QUOTE (greynol) *
Do we have any objective studies that indicate that DVD-A is audibly superior to SACD when it comes to applications with more than two channels?


Since I doubt such a difference exists, I cannot provide you with evidence that such a difference exists. Otherwise I would not be in doubt.
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greynol
post Sep 15 2007, 21:49
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QUOTE (Mike Giacomelli @ Sep 15 2007, 13:41) *
QUOTE (greynol @ Sep 15 2007, 12:24) *
So 2-channel SACD has a bitrate of 5.6Mbps?
Yes.
Are you absolutely sure? I'm having a hard time verifying this. A follow-up question would be, how is the information for each channel split? Everything I'm reading is extremely vague.

So if you doubt that there's no audible difference in applications of more than 2 channels and you also believe SACD is an inefficient format in terms of bw and snr, where's the trade-off? Is SACD not capable of storing as much audio (number of channels * duration of each channel) as DVD-A?

This post has been edited by greynol: Sep 15 2007, 22:34


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eevan
post Sep 16 2007, 03:25
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SACD is also divided in 1/75 second frames of interleaved channels. So at 64×fs a frame covers 37632 DSD samples per channel with total bitrate of 5,6Mbps (when DST is not used—it is optional for 2-channel-only disks).

This post has been edited by eevan: Sep 16 2007, 03:26


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Light-Fire
post Sep 16 2007, 05:06
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QUOTE (Borbus @ Sep 15 2007, 06:44) *
Hold on... Since when do we care when technology was invented? Back in the early 90s MP3 was absolutely amazing... is it still? No.

Late 90's, not early. And yes. it still.

QUOTE (Borbus @ Sep 15 2007, 06:44) *
The original question was "Why SACDs?" and I interpreted that to be "Why drop an older technology for a newer technology?" My answer is simple, in THIS day and age, CD Audio just doesn't cut it. I don't care how perfect it was back in the 70s.


It is as perfect today as it was in the 80's (not 70's.)
You don't even know why it doesn't cut it and yet you say it!!!
And yes. It does cut it.

The only reason for SACD existence is multichannel capabilities.

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DigitalMan
post Sep 16 2007, 05:33
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What problem does SACD solve for the vast majority of listeners?

Sound quality? Not likely on almost all consumer listening gear for almost all listeners (especially with loudness war, current pop mastering techniques, etc.)
Cost? Nope, more expensive.
Convenience? No - less content; less hardware selection and more copy restrictions. A lot less convenient vs. MP3, AAC, etc.
Size? No - same 12cm disc.
Availability? No - more limited distribution.
Features - some - stores images, text, multichannel, video(?), but CD can store text and the rest don't seem worth switching a format for.

I'm not convinced there is a compelling case for mass market SACD. DVD-Audio isn't really much different. Guess thats why I've never bought either one.


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dmckean
post Sep 16 2007, 06:22
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QUOTE (DigitalMan @ Sep 15 2007, 21:33) *
Cost? Nope, more expensive.
Convenience? No - less content; less hardware selection and more copy restrictions. A lot less convenient vs. MP3, AAC, etc.
Size? No - same 12cm disc.
Availability? No - more limited distribution.


These are key. If the studios released everything on microSD cards with a normal file system where everything was simply MLP compressed PCM files or something similar consumers would be all over it. Either that or go the cost route and release audio only non-DRM blu-ray titles where one disc can have the entire works of an artist for $30. Consumers would be all over that too!
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greynol
post Sep 16 2007, 06:42
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QUOTE (dmckean @ Sep 15 2007, 22:22) *
have the entire works of an artist for $30

Keep DREAMING!


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dmckean
post Sep 16 2007, 08:37
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QUOTE (greynol @ Sep 15 2007, 22:42) *
QUOTE (dmckean @ Sep 15 2007, 22:22) *
have the entire works of an artist for $30

Keep DREAMING!


If you look at the cost of used CDs on amazon for any band that has come out since 1989 you can already do that now. And you can do the same thing on Vinyl for any artist older than that. The music industry needs to come to terms with the true value of their music catalog. The only albums that cost more are the ones that were never popular in the first place.
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Axon
post Sep 16 2007, 08:49
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Of course! Because the Beatles never really were all that popular.
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euphonic
post Sep 16 2007, 09:04
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QUOTE (Axon @ Sep 16 2007, 00:49) *
Of course! Because the Beatles never really were all that popular.


You beat me to it! Another not-obscure group still at full-price, and with a large catalogue of LP-length discs, is the Rolling Stones. I remember spending a nice amt of my army-draftee pay years ago on their stuff from 1964-73.
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