Phantom and Tidal MQA Hi-Res

[mixart]

So Tidal will come with hi-res MQA streaming in 2016. Is that something Dialog can support with a software upgrade or do the Phantom need a new Dac?

[iliapas]

MQA decoding is done in software, so Phantom should be able to support it with a firmware upgrade.
Then again, MQA is kind of pointless if you are able to select the streaming format: one of the primary features of MQA is that non-MQA equipment will be able to play it back almost losslessly (f.e. 12-15bit dynamic range instead of 16bit for 44/16 stream). Another feature is being able to receive only the lossy parts without the "touch-up" signal part, and getting a lossy version of full-range signal (96/24 f.e.) using lower bandwidth.
If you don't need this backwards compatibility feature, have enough bandwidth not to care about whether to add the "touch-up" stream or not, and same music source is available in FLAC/ALAC, there is really no point in using MQA. Simply stated: MQA is not "better" than standard lossless formats, unless your equipment cannot decode modern lossless formats, or you are interested in saving bandwidth and getting lossy quality, albeit from high-quality 96/24 source material.

[sleach]

I gather the appeal of MQA is that hi-res quality, that is up to 24/192, can be provided in a file the same size as 16/44. So you will now be able to stream a track and hear it at 24/192 quality where previously 16/44 was the best possible streaming.

Personally, I can hear the difference, especially between 16bit and 24bit tracks on the phantom. If I can stream higher quality, I will be very happy.

I hope very much that devialet can find a way to support MQA on phantoms.


Sent from my iPhone using Tapatalk

[iliapas]

MQA is _NOT_ better at compressing losslessly any audio than FLAC/ALAC and other competing formats.
The only advantages of MQA is
1) ability to play it on devices that do NOT understand FLAC/ALAC and only understand plain PCM, and
2) ability to transparently choose to play a LOSSY stream, which may compress to a smaller size and need less bandwidth than LOSSLESS FLAC/ALAC.

If you want _lossless_ 24bit/192KHz on Phantom (the maximum of it's DAC) in smallest size - choose FLAC/ALAC/etc.
Do not believe the marketing-style reviews. Most reviewers don't take time to try to undertand the technology and write up some wishful thinking without even checking.

Unless you want LOSSY compression or your equipment cannot play FLAC/ALAC, MQA is not better for you in any way.

[sleach]

MQA is _NOT_ better at compressing losslessly any audio than FLAC/ALAC and other competing formats.
The only advantages of MQA is
1) ability to play it on devices that do NOT understand FLAC/ALAC and only understand plain PCM, and
2) ability to transparently choose to play a LOSSY stream, which may compress to a smaller size and need less bandwidth than LOSSLESS FLAC/ALAC.

If you want _lossless_ 24bit/192KHz on Phantom (the maximum of it's DAC) in smallest size - choose FLAC/ALAC/etc.
Do not believe the marketing-style reviews. Most reviewers don't take time to try to undertand the technology and write up some wishful thinking without even checking.

Unless you want LOSSY compression or your equipment cannot play FLAC/ALAC, MQA is not better for you in any way.

Hm, I don't think that's right. FLAC/ALAC is PCM. DSD is the one that most DACs still can't handle. And they are telling us that MQA is as good as lossless at 16/44 even if you don't have an MQA decoder and as good as high res music up to 24/192 if you do. And the file size will only be as big as 16/44. It's a better way of packing the info into the file, which is why it is so appealing for streaming applcations. Yes of course there's marketing hype, like saying you'll hear exactly what the Mastering Engineer heard and sure some of that is hyperbole, but underneath that there is some meaningful information. Now whether the MQA will REALLY be as good as 24/192 is another story and will assuredly be debated by enthusiastic audiophiles for the next few years once the technology is released in the field.


Sent from my iPhone using Tapatalk

[iliapas]

Hi, sleach. The phrase "They are telling us" is exactly the part that is the marketing. Can't blame you for falling for it, as these "claims" are repeated on almost every review site. Notice, however, that these things are said only by the reviewers, and not claimed by Meridian at all. In fact, the patents for the technology are completely open. The one you might want to read is WO2013061062 and WO2013186561. The latter explains the main idea of MQA, but the former is important to understand one of the ways how it's done. There is nothing lossless about making the stream playable on legacy PCM players, and nothing lossless about adding watermarks to the stream either.

So what happens to your audio stream is this: take any input stream with quality higher than 44/16, for this example, using a 192/24 stream (you'll see that tech is same for any input stream).
Now let's get the 3 features: playback on legacy devices + watermarking(+DRM) + lossy fallback, step by step:

To get the lossy "regular PCM" playback on legacy 44/16 devices, you need to supply a 44/16 PCM stream.
To do that you will need to resample your original stream into 44/16, while applying some sort of a dither. Read details of this and other tricks in the first patent, but basically you dither the least-important 3 bits of the 16bit 44/16 stream, using a data stream as dither. In this data stream you insert the watermark as well as a compressed (lossy) difference between the original 192/24 signal and the 44/16 signal that "legacy PCM equipment" would play. So you get a 44/16 stream which includes a data stream of less than 16KByte/sec (3bit*44khz=132kbit/sec) to decode lossily the original 192/24 signal. Now difference between original 192/24 stream and this high-quality lossy stream is again compressed into a separate data stream, hopefully fitting into 8bits added to 44/16 stream, so extra 44KByte/sec data bandwidth. (8bits*44Khz=352Kbit/sec=44KByte/sec)

Results:

Using the 44/16 stream on a legacy 44/16 device, you get playback _almost_ like the original signal resampled to 44/16. (almost because it's dithered with some data stream and not a standard dither, but if the data stream is compressed enough, it should be almost indistinguishable).

Using the 44/16 stream on an MQA-understanding device, you get a lossy version of your original signal. So you get 192/24 if you had 192/24 before, but compressed and decompressed lossily. It's lossy because it tries to compress difference between the original 192/24 stream and the 44/16 stream inside just <16KByte/sec data stream(3bits*44khz=132Kbit/sec). On lots of content with little data in higher frequencies it will be enough, but please not that it's still lossy compression.

Using a bigger 44/24 (or higher) MQA stream, you losslessly get your original 192/24 stream, by first playing the 44/16, then applying the lossy 16KByte/sec data stream correction to get it to a lossy 192/24, and then applying the 44KByte/sec data stream correction to fix the errors left and get to lossless quality.

In the end, you compress the 192/24 stream into, say, 44/24, getting legacy-playable 44/16 along the way. But because you need to keep the 44/16 stream legacy-playable, you lose a lot of bandwidth that could be compressed.

This is why at least in theory, FLAC/ALAC (which can compress everything) can get much better lossless compression.
The examples given by MQA were that for 48/24 stream, it compresses into 44/16's 1.4Mbit stream. Well, FLAC can fit 96/32 input into a ~3Mbit stream today, so there's nothing magical in that.
What MQA also provides, and which may be more important and a reason NOT to support it by public, is DRM. As both correction ("touchup") streams are just data streams, they can easily be encoded by some secret key, (akin to current HDCP signals over HDMI) which will make it impossible to make open-source/homebrew hardware or software to decode licensed MQA files, at least until the secret key is extracted from one of the licensed players. Or maybe the DRM scheme is even more involved, in which case, even more reason to forget about MQA.

TLRD: MQA gives differently-dithered but legacy-playable 44/16 PCM stream with embedded ~10KByte/sec data stream for DRM/watermark and lossy full-signal playback, and extra ~40KByte/sec or bigger data stream to fix lossy full-signal to lossless quality. Because of this approach it cannot compete on lossless compression with standard formats which do not need to keep uncompressed PCM streams or embed watermark/DRM data.

[iliapas]

Just checked some 192/32 flacs: average bitrate used is 2.3Mbit/sec, which is roughly the bitrate of 48/24 (16 bit PCM + 8 bit data) which is what MQA is using as it's distribution format. No magic. And FLAC doesn't have to use the whole 2.3Mbit, is much easier to decode and open-source.

[sleach]

Huh, I guess I did fall for it!


Sent from my iPhone using Tapatalk

[iliapas]

Hi again, Sleach.
It seems MQA is not _just_ what was written above.
In addition to the above tricks, it actually does employ a novel technology: it resamples the data (or samples it anew if used during recording) focusing on timing of the samples, somewhat reminding of DSD. What happens is that it claims to retain more of the timing information, by convolving the signal first with a triangle function during sampling, and then interpolating during decoding part. As this adds some new noise, they claim that resulting data fits into a 900kbit/sec 96/24 stream. Some of the ideas were previously used in various papers on non-sinc kernels.

The claim to "lossless" reproduction is thus murky - it changes the signal irreversibly, but the "losses" are hard to quantify.
DSD signal even at standard sampling rate retains much better timing information, and thus MQA cannot compete with DSD128 and higher.
Moreover, DSD has a _very similar_ approach/tradeoff between sampling frequency and bit-depth to MQA.

[Hifi_swlon]

There are two very active topics on MQA over at the Roon forums (I'm not really sure why there specifically), and they've generated a lot of heated debate.

As far as my layman brain understands it, the main alleged benefit of MQA, on top of lower streaming bitrate and file size (versus 'normal' high-res files), is that the timing info of the original recording is delivered to/from your DAC exactly as intended in the recording/mastering studio, and that in demo's people have been 'blown away' by what this brings to music. It seems hotly debated, not least since only a handful of people have actually heard it so far, and many of them with a vested interest. That said, some without a vested interest also seem to be saying it was the best sound they'd ever heard.

Time will tell I guess - revolutionary new technology for our benefit, or another new way to re-market/re-sell music people already own. Or somewhere in between.

It appears the DACs have to be MQA 'certified' which will require firmware updates if that's possible, or a new MQA ready DAC - to get the full benefits above. Otherwise the files can still be played 'normally'. Or it can be done in software, it all seems very confused at the moment.

Seems like its really early to say one way or the other - assuming it even takes off. One things for sure, once its actually out there in force, some people will decide with their ears, others with maths and measurements, and we'll probably have an excellent new topic for people to endlessly debate/argue about for 2016 and beyond

Couple of Roon forum links:

https://community.roonlabs.com/t/tidal-t...-2016/5408

https://community.roonlabs.com/t/mqa-support-by-roon/88