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In Reply to: RE: Digital Resolution -- An Analysis posted by AbeCollins on September 05, 2020 at 11:23:00
Okay! Here's the bit-speed for the various formats. However, this doesn't include the reduction from FLAC compression.
Edits: 09/05/20Follow Ups:
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Gsquared
Without understanding the information value conveyed per bit, "Bit density" is a meaningless metric to use in comparing PCM to PDM ("DSD").
What matters is the level of information that is conveyed per unit time. "Resolution" relates the accuracy of the decoded information per unit to represent the original signal. Since a 1 bit converter only has two states compared to a given N-level multi-bit converter, the DSD format needs far more symbols to be transmitted per unit time to convey the same information as a multi-bit converter. DSD is therefore the least efficient way to convey information and why coding in DSD results in larger file sizes. The problem to solve is to recover the encoded signal with the least error.
Back in the 80s and 90s due to the manufacturing challenges in achieving perfect trimming of the resistors down to the LSB, multi-bit converters suffered from poor linearity which is where the shift to PDM gave a theoretical advantage. However, the code/decode accuracy is highly dependent on the level of jitter on the reference clock signals. Additionally, coding a signal with a 1 bit converter results in residual quantisation noise due to the fundamental inability to adequately dither the signal compared to a multi-bit converter - 3 to 4 bits is required for perfect dither.
Therefore any claim of the superiority of DSD to PCM is pointless - the question should be which method gives the smallest error signal between the recovered signal and the original signal. Unfortunately that comes down to the equipment used.
Regards Anthony
"Beauty is Truth, Truth Beauty.." Keats
...should be on the same page
Regards Anthony
"Beauty is Truth, Truth Beauty.." Keats
brought this link over from Classical & thought it might be pertinent as the same subject is being chewed on:
best regards,
I find John Ellison's analysis of digital resolution relevant and useful.
The bit length x sampling frequency, which he listed for various formats in comparison to Redbook CD format, expresses the potential resolution of those formats, eg. the obtainable throughput (or bandwidth in its digital sense) of digital information (one can use either bits or bytes).
Insofar as digital audio entails conversion of analog signals to digital signals and then back to analog signals, and neither signal can be more than an approximation of the other, higher potential resolution allows closer approximation of the signals.
Of course what one hears is what matters. The ear has differential perception of frequencies much as the eye has for instance increased perception of tonal difference in shadowy verses brightly illuminated scenes.
To my elderly ears, higher resolution digital music offers audible improvement over lower resolution digital music at least up to, as John Ellison listed, 13.06 times CD resolution, ie that of so-called DXD. For me the audible difference inaudio format, DSD versus PCM, diminishes with increasing resolution such that at DXD or DSD256 the difference is scarcely if at all perceivable.
Let me conclude by citing Rushton Paul's newly released article in 'Positive Feedback' where he notes that several studios now record in DXD or DSD128. Having purchased a few albums in DXD format, and aware that recording technology continues to improve in respects other than digitization, I consider that money well spent.
Seventies
I'm not sure I understand it completely, but I'll study it some more.
Thanks again!
John Elison
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