Sorry, yes, I was referring to post-processing such as the remodulation of DSD256 to DSD512. Obviously a recording captured natively at DSD256 contains more information than one captured natively at DSD128. But how much of that is musical (i.e. actually audible) information? I don’t know.
In PCM the difference between the actual information captured at 96kS/s vs 192kS/s is completely inaudible (audio frequencies of 48kHz and up, totally ultrasonic), it is the difference in the filter that can be used and the audible side effects thereof that causes the perceived difference in sound quality.
I strongly suspect that similarly, most (all?) of the increased payload in increasing bitrates of DSD is ultrasonic and inaudible. But that is just my guess, as I said my understanding of DSD is pretty rudimentary. I will discuss with James next time I am in the office and see if I can get a better understanding.
In the meantime this article by the ever-dependable Archimago provides some insights:
I think the general term you’re looking for is “interpolated” sample-points.
Whether for PCM or DSD, and whether offline (eg. Merging Pyramix DAW) or done in real-time (eg. Vivaldi Upsampler, HQPlayer etc.), interpolation is responsible for converting from a lower bit-rate to a higher one with new music data sample-points interpolated from existing samples. The new additional sample-points, though not from actual capture, naturally increases the file size (or bit-rate for real-time upsampling).
In the case of DSD-to-DSD upsampling like for DSD256-to-DSD512, the interpolation is I believe a 2-stage process; decimation of the lower rate DSD, and then re-modulation of that to the higher rate DSD.
I actually wasn’t trying to venture down the rabbit hole on post-recording DSP with either format, but was reacting to–apparently my misunderstanding of-- the statement that the higher sample rate files do not contain more information. If they are originally recorded at the higher sample rate, I.e., PCM 192 v 44.1, or DSD256 v DSD64, they clearly do.
Re: choice of PCM or DSD, in both cases, if one is increasing the sample rate of an audible signal, the amount of audible information captured must also increase.
I’m afraid I’ve taken us off topic from @Lee’s thoughtful review (apologies!), but am happy to continue under one of the DSD threads.
Not necessarily. In PCM increasing the sample rate enables you to capture higher frequency sounds. But if they are ultrasonic they are inaudible (although your amp doesn’t know that so it waste a lot of energy amplifying them if they aren’t filtered out). So increasing the sampling rate of an audible signal does not necessarily increase the amount of audible information captured (unless it is below 44.1 kis/s to start with). I am as interested as you are to understand how this plays out in DSD.
Just pointing out that the difference in file size is not trivial.
A DSD256 file is 300% larger than a DSD64 file. In the example I shared, it’s more than 180MB larger, for just one song.
If only a small fraction of that storage is audible, I would be very, very surprised. Furthermore, it would shed a very negative light on Sony’s engineers, which, IMHO, would be even more surprising
Great explanation by Anup and excellent comment by Richard.
I always questioned the concept, which the download services tried to sell (wink, wink), to get people to pay more to purchase higher bit rate files. The “implication” was there was more resolution and detail to be heard. How could they take something recorded, for example, in the 50’s, and then miraculously add additional recording information and give it the famous “hi resolution” tag - implying increased resolution and detail.
Hi Res was not even invented yet - so how did some of Louie Armstrongs early ecordings suddenly become “hi res”?
What they are doing for these older recordings is going back to the original analog tape from the 50s, and then playing and resampling it at an higher, HD rate, e.g., 192kHz.
So, they are not capturing more information than what was originally on the tape, but they are capturing a lot more information than what was lost by previously sampling the tape to the redbook CD format of 44.1 kHz.
As an alternative, one could, as @Dunc on this forum has done, buy the old tapes and an old tape player, and just play the analog tape this way. In this manner, one remains entirely in the analog domain. The digital domain, for many, is simply more convenient.
On good sites like HD Tape Transfers and NativeDSD they are usually very specific about provenance, and you can read more about this in the notes. As a general “rule of thumb” you will find original HD recordings in 192kHz, occasionally DXD (384kHz) and DSD64 - DSD256. You will virtually never find an original recording at DSD512, and all of those files are upsampled post production (I personally avoid them).
On your system, for example, you should be able to notice a meaningful difference between the original “Kind of Blue” redbook CD, for example, and a resampled HD version from the original tape/record press.
Extremely helpful explanation Richard - thank you.
Taking it even further (with reference to the quoted passage), one could say playing the original vinyl record yields more information than many differing resolution digital files.
Both tape recorders (electrical signal + magnetizable material onto tape) and vinyl records (vibrations + stylus into etched lacquer master) remain in the analog domain and therefore have no A2D losses (though they could have source-to-recording, i.e., A2A losses).
Not sure I follow. Why would it be Sony Engineer’s fault? (That DSD isn’t an efficient lossless compressed format?)
I believe as was mentioned previously (and may have been discussed in the extensively debated DSD256 support topic ), the primary value of high-rate DSD is to push noise-shaped quantization noise even higher into the ultrasonic range, not necessarily higher resolution.
Ostensibly, DSD128 already pushes it well beyond where it could impact the audio band from DSD64’s 20kHz to above 40kHz. DSD256 I believe doubles that to move quantization noise above 80kHz. Is that really necessary, and maybe more importantly, is there any real-world improved audibility? I don’t think there’s any objective data one way or another
), the primary value of high-rate DSD is to push noise-shaped quantization noise even higher into the ultrasonic range, not necessarily higher resolution.