PCM vs DSD

[emm7th]

Back to basics... which is better DSD or PCM? Considering the fact that Philips and Sony were the main backers of Blu-ray and SACD, why is there no DSD audio codec (similar to SACD) in Blu-ray? What is the equivalence of DSD to PCM (sample rate and bits)?

Can someone explain these things in-depth? Thanks...

[Mr. Hanky]

Though the respective "coding" schemes are radically different, the concept of dsd is essentially like a "variable" pcm. With pcm, you have a single sampling rate, which determines the bandwidth. Over that bandwidth, you have a single bit-depth that applies to any signal that exists within that bandwidth.

The equivalent pcm to dsd, attempts to address a larger bandwidth while redistributing the effective bit depth across that bandwidth in a more "economical" way. Essentially, it puts greater bit depth in the range that is most relevant to human ears, while exploring the ultrasonic treble range at decreasing bit depths (the higher you go). The idea is that if human auditory range is highly compromised in that upper range, dsd can then tolerate reduced dynamic range and increased noise (via noise shaping scheme) in that upper range while still technically encompassing an "extended range".

Classic pcm could cover the same range, but with only a static bit depth that applies across the entire range. This would work fine (in fact, technically superior to dsd), but is extremely wasteful of data bandwidth (since you cannot scale down bit depth at ultrasonic frequencies).

[JadedRaverLA]

Mr. Hanky gave an excellent explanation above...

But I'll just say that since movies are almost always mastered in 24/48 PCM, converting that to DSD would be completely pointless.

I do wish they would have tried to make it a part of the spec for music titles, but... oh, well.

[dobyblue]

Originally Posted by JadedRaverLA

But I'll just say that since movies are almost always mastered in 24/48 PCM, converting that to DSD would be completely pointless.

100% agreed. I prefer DSD for music, but the film industry isn't about to start archiving everything in said format.

[Ascended_Saiyan]

Originally Posted by JadedRaverLA

I do wish they would have tried to make it a part of the spec for music titles, but... oh, well.

I thought there was a profile 3.0 for music. I could have sworn I heard that from paidgeek. I could be wrong.

[Clark Kent]

On music playback I believe fully native DSD playback is superior to PCM. The following player can play SACD via native DSD or with DSD converted to PCM playback.

http://www.teac.com/esoteric/X-01D2.html

In my experience well mastered DSD will sound better than the equivalent PCM. It's very close though and most mastering engineers are more familiar with PCM manipulation and more tools exist to handle PCM. It's a shame that consumers never really accepted SACD as a medium.

[Gremal]

DSD is considered a single-wordlength (one bit), 2.4 MHz technology. While it may seem pointless to simply remaster 24-bit 48 kHz content in DSD, my ears have repeatedly told me otherwise. For example, on the early digital recording of Dimeola, McLaughlan and de Lucia--Passion, Grace and Fire (an excellent album by the way), the SACD version sounds markedly better than the CD, even though the original recording was early digital. If you go back and listen to SACDs made from PCM, they often have a more realistic or euphonic feel to them.

So, yeah, I would love it if Sony pushed for DSD on the audio tracks of Blu-rays, but I don't see it happening. That ship has sailed.

[oscar_in_fw]

There's been some technical mumbo-jumbo that 2.88MhZ DSD generates a lot of HF noise which needs to be filtered out resulting in lost content at the higher frequencies. In the midrange though, DSD is pretty awesome; maybe even better than 24 bit/192 Mhz PCM which the Blu-ray standard already supports.

I believe the (alleged?) noise issue would go away if they doubled the DSD sampling rate (5.6 Mhz) though I doubt we'd see this added to Profile 3. Heck, I have serious doubts we'll ever see a Profile 3 player.

[TauRus]

If Blu-ray was strictly a Sony format, then I am sure they would have included DSD among supported formats. However, Panasonic, the major backer of DVD-Audio, an arch-nemesis of SACD, probably objected to including SACD.
I agree that re-converting movies into DSD would not be economical or meaningful, however, having some music Blu-SACDs would be certainly great - great audio presentation along with some hi-def video material.

[Gremal]

Originally Posted by oscar_in_fw

There's been some technical mumbo-jumbo that 2.88MhZ DSD generates a lot of HF noise which needs to be filtered out resulting in lost content at the higher frequencies. In the midrange though, DSD is pretty awesome; maybe even better than 24 bit/192 Mhz PCM which the Blu-ray standard already supports.

Yeah, all SACD players use noise shaping to push the noise well above 20 kHz...so unless you're a dog with very good hearing, or some other animal, don't worry about it.

[HDJK]

Originally Posted by Gremal

DSD is considered a single-wordlength (one bit), 2.4 MHz technology. While it may seem pointless to simply remaster 24-bit 48 kHz content in DSD, my ears have repeatedly told me otherwise. For example, on the early digital recording of Dimeola, McLaughlan and de Lucia--Passion, Grace and Fire (an excellent album by the way), the SACD version sounds markedly better than the CD, even though the original recording was early digital. If you go back and listen to SACDs made from PCM, they often have a more realistic or euphonic feel to them.

So, yeah, I would love it if Sony pushed for DSD on the audio tracks of Blu-rays, but I don't see it happening. That ship has sailed.

But I'm sure they didn't just re-encode the disc. There must have been some remastering before they released it as an SACD. So this is not a true PCM - DSD comparison. Agree?

Originally Posted by oscar_in_fw

...

I believe the (alleged?) noise issue would go away if they doubled the DSD sampling rate (5.6 Mhz) though I doubt we'd see this added to Profile 3. Heck, I have serious doubts we'll ever see a Profile 3 player.

And there is another problem with DSD: it's a closed box and cannot be expanded (for 5.6 Mhz or anything else). It is what it is now (if you don't believe me read the book 'Digital Audio explained' by Nica Aldrich or look him up on the internet; he hangs out on a couple of forums).

[emm7th]

The PCM is quite straight forward (you've got the sample rate on X-axis and the bit depth on Y-axis)... How do you interpret the sigma-delta principle of DSD?