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In Reply to: RE: Agree with this sentiment posted by knewton on February 15, 2017 at 12:55:49
24/96 FLAC streams at around 2-2.5 Mb/s, which is comparable to high quality 1080p video. Given the millions and millions of people who stream HD video every day, high res streaming via FLAC cannot possibly be an undue burden on the internet. That is why it is a solution in search of a problem.
Thank you, Dave - interesting to know these numbers, and this is a useful reference. While, by and large, bandwidth keeps increasing (and costing less, just like disc space), I do feel like bandwidth may be groaning ...
AT&T wants my mobile plan, by default, to begin using their "streamsaver" feature - which dumbs down hi-res video to a lesser resolution. (Yes, you can shut this feature off.) Additionally, a number of my friends who stream hi-res video *do* complain of frequent drop-outs & freezes, etc. Ok, yeah, perhaps you gotta just pay for more bandwidth, but at least one of these people already has a monster bandwidth plan.
To me "video-hiccups" are annoying but dealable as long as they are not too bad. But in the audio realm ... personally, I can't stand "audio-hiccups," it just destroys the listening pleasure for me. So, I want *flawless* (or pretty darn close) audio streaming. Enabling hi-res with less bandwidth can certainly help with this.
MQA also promises "temporal de-blurring." I haven't heard it. But I have read many of the technical papers. I can believe this is a real feature. Though, yes, the proof must be in the pudding. We'll see.
In any event, I'm very happy to see hi-res music streaming. I confess I love Tidal; and Tidal Masters (as much as I've listened) sounds outstanding to me. Up to this point in my listening-life, I've wanted to own everything I like - whether LP, CD, SACD, or hi-res digital file -- and sometimes multiple copies in different formats (I'm not alone, here, you know who you are ;-) But I just *can't* keep it up! I'm out of space - and out of time - and out of the energy to corral it all together. And my music "likes" keep expanding ... ! It gets to the point where, if the quality is good enough (and for me, Tidal Masters seems pretty much there), I'm willing to "rent" my content. Of course, I still have a lot of homework to encode, for convenience, the physical media that I already have. And, I still buy some things that I *really* love - the need to *possess* is a strong obsession!
AT&T wants my mobile plan, by default, to begin using their "streamsaver" feature - which dumbs down hi-res video to a lesser resolution.
I'm also an AT&T mobile customer, but choose to watch hi-res video on either a 65" or 42" monitor at home with broadband access where such considerations are rendered moot since I get a terabyte of bandwidth per month. Do you watch video on your phone?
Of course, I still have a lot of homework to encode, for convenience, the physical media that I already have.
For those of us who have already ripped our entire audio and video collections, I find that to be the best answer! I can stream all the content that interests me across multiple audio and video systems.
I suspect that a key technical objective of MQA is being overlooked by some. From what I've gleaned, MQA sets a requirement and specification for a transient optimized chain - recording through playback. Such a requirement could absolutely be delivered via other high sample rate formats, however, there is no standard requirement. Transient optimization (minimizing transient blurring) is the primary performance objective of MQA.
MQA is currently being used as a compressed audio format to stream Warner titles that were previously mastered for a hi-res PCM release e.g. DVD-A or download. Universal is said to follow.
For existing recordings, MQA have claimed that if the ADC is known, its identity or characteristics can be encoded, and then the decoder can utilize that information to select a reconstruction filter. I guess you would have to assume the same ADC is used for all the tracks of a multi-track recording. But I haven't seen them discuss the details of this process publicly or give examples, so I don't know what to think about its potential benefits, if any. Also, given how quickly Warner encoded their catalog, I think there is a very high probability that the encoding was generic.
Those are just practical issues though. My real complaint about MQA is theoretical. In their AES paper, Stuart and Craven proposed a Gaussian as an ideal system impulse response. In image processing, a Gaussian filter is also known as a blur filter or unsharpen filter. It is used to reduce sharpness or to artistically blur images. It will have the same result on a music waveform, smoothing over transients and blunting attack. How is that transient optimized? In the paper, Stuart & Craven note their ideal is equivalent to "only" 30m of air. Why is 30 meters ideal and not zero meters? From an engineer's POV, their idea just seems dumb.
Gaussian filters provides smooth rather than abrupt transitions, both in the frequency and the time domains. It provides a ripple free frequency response, while simultaneously exhibiting an aperiodic (non-ringing) impulse response. It's the aperiodic impulse response that MQA apparently values.
I'm not as familiar with image processing applications, and unsure this is directly comparable to pixel smoothing within an image. Possibly, image processing utilizes Gaussian filters for their natural Guassian shaped frequency domain properties, while MQA utilizes them for their natural Gaussian shaped time domain properties mentioned above.
The narrow channel bandwidth relative to the information bandwidth of CD necessitates the well known SINC function brickwall bandlimiting anti-alias and anti-image filters associated with it. It seems to me that MQA uses a much wider channel bandwidth, not for any musically significant ultrasonic content, but to enable utilization of relatively slow sloped aperiodic filters, such as the Gaussian, without incurring aliasing.
As for the audibility of MQA's time domain optimization, that's the key question for we audiophiles. MQA's strategy seems to be to offer performance benefits to music consumers so that they pull the format, while offering distribution management and cost savings to the music industry so that they push the format. If MQA delivers the promise of a compellingly better sounding digital listening experience combined with lower vendor cost, it has a chance of success. The key words are: compellingly better. Of course, fear of a new format, some of it rational, some of it irrational, is also playing it's usual and expected role.
Have you heard MQA? Just asking
So far, I have listened to a handful of Warner's MQA releases on Tidal using the Tidal app's software decoding. I picked ones that I already had on CD and DVD-A or high res download, and where I felt there was a pretty big difference between the CD and DVD-A. Selections were from:
Buena Vista Social Club
Fleetwood Mac Rumours
Yes Close to the Edge
Grateful Dead American Beauty
Phil Collins Face Value
Chris Thile Bach Sonatas
The MQA files sounded a lot like the DVD-A rips/hi-res downloads. I'm pretty sure they were made from the same master files as the DVD-A or download, and not the CD master. I would have to do more careful listening to say whether the MQA files are as good as the DVD-A rips, but they are at least close.
As a compression algorithm, I think MQA is pretty novel, but I don't think it is necessary given the near-ubiquity of high bandwidth broadband connections. Thanks to the demand for streaming HD video, we have the bandwidth we need to stream hi-res audio using a lossless, open standard like FLAC.
As a technology that aims to control the whole end-to-end chain from recording to playback, I think MQA is bad. Digital audio and computer-based audio are thriving because of open standards. MQA is a power grab that would change the landscape into something much more label friendly and not consumer friendly. And on top of that, their choice of system impulse response is just wrong.
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