Saturday, 13 January 2018

DEMO: Dunkirk - Resolution difference between 1080P Blu-Ray and 4K/2160P UHD Blu-Ray (It's CES 2018 also!)



A friend who works in the world of video production saw my post a few weeks back about "4K, Dunkirk and 70mm IMAX" sent me some segments of Dunkirk from the recently released UHD Blu-Ray set so I could have a look at the differences between 4K compared to standard 1080P Blu-Ray. Remember as discussed a few weeks back, this movie was filmed to a large extent with 70mm IMAX (65mm/15perf) gear, we know the VFX rendering was done using >4K with a true 4K digital intermediate. It represents the "pinnacle" of analogue film technology mixed with the best of today's digital effects and processing. I highly doubt we'll see much more of this level of literal "film-making" over the years. As such it's a nice "benchmark" for comparisons.

Saturday, 6 January 2018

Audiophile Myth #260: The Detestable Digital Filter Ringing and Real Music...

For the 2016 edition, go here.
In the audiophile world, there are many targets of angst and anxiety that "practitioners" of this hobby are well aware of.

For years we've been worried about the "dreaded jitter". However, we know that these days, with asynchronous interfaces like USB and ethernet, there's nothing to be concerned of. Sure, we can see jitter anomalies with old S/PDIF, but I doubt anyone should purposely not use the interface for fear of audible issues assuming otherwise decent gear. For years and still to this day, various "practitioners" of audiophilia hang on to beliefs around cables of all sorts; assuming normal hook-ups with decent quality cabling (and even with poor quality cables), we are typically hard pressed to find evidence of audible differences.

Then we have beliefs that bit-perfect streamers sound different, really? We also hear of esoterica like folks who think lossless file formats sound different, seriously? How about the folks who think that computer OS's make a difference, or software players sound markedly different (assuming it's all bitperfect of course and sent to the same DAC)...

Feel free to browse this blog for discussions and thoughts around countless other audiophile items of faith. Today, let's address the audiophile "myth" that has gained prominence among those trying to sell things and those that advertise said "things" over the last few years.

As per the title, today, let's explore this "myth" of the detested ringing with digital filtering and audio playback since I've been posting a bit of a series on this topic over the last little while.

Monday, 1 January 2018

MUSINGS: More fun with digital filters! Archimago's "Goldilocks" Intermediate Phase suggestion...


Today's post is a bit of a continuation from last time's look at the different types of upsampling antialiasing playback filters using my Raspberry Pi 3 "Touch"piCorePlayer and SoX. As you can see from that discussion, across the audiophile equipment spectrum, manufacturers utilize all kinds of digital filter settings in their gear. Each company ends up choosing compromises between how much frequency roll-off, how much aliasing, how much temporal/phasic anomaly each would accept. And of course no matter what a company chooses, there are ways of advertising the decision as "good"; whether it be on the basis of frequency spectral accuracy, temporal accuracy, or just claims from pure subjectivity - "it just sounds better"!

The end goal of audiophilia is a bit like the modern interpretation of Goldilocks (and the Three Bears)... We're all trying to figure out for ourselves what is "just right" as we wade through the commercial and mainstream audiophile literature, unofficial blogs and forums, mix-and-match speakers with amplifiers, try out different accessories perhaps, and the like. So too it seems with digital filters and all the variants attached to the DACs we buy.

Remember that the only reason we're even talking about this is because of that 44.1kHz (and to a lesser degree 48kHz) samplerate such that the Nyquist frequency is at 22.05kHz; relatively close to the usual 20kHz upper limit of hearing acuity that the younger ones among us might be able to perceive. This is literally the only reason for all the hand wringing and millions of spilt keystrokes over the years around filtering by audiophiles (the few who still obsess over this...)

These days, we essentially have 2 major options for filter "types" among the DACs out there... Linear phase (the default for most mainstream DACs, Chord) or Minimum phase (Apple, MQA, Pono) - pick your "poison" :-). Of course within each phasic variety we have different levels of steepness and allowance for aliasing. We intuitively know that due to the biological phenomenon of auditory masking, maximum phase (where the group delay is pushed forward so "pre-ringing" is accentuated) is not desirable. But is there another choice?

Yes, there is of course... We can try to figure out a "just right" state with intermediate phase settings. Accepting that maybe there's some value to ensuring that pre-ringing isn't an issue even with some of the worst audio recordings out there, while maintaining awesome frequency and temporal accuracy - let me show you my choice for the filter that I listen to daily with the Pi 3 streamer...