The MQA Hooh-hah

Written by Published | Rapallo AV Team

The annual Munich High End show has kicked off. We can very much envision what it will be like; we were there last year and we have to say it is an extremely well organised and pleasant audio-event. Unfortunately, it’s not for us this time around. Airplane tickets to the other side of the world tend to be a deciding factor. But it doesn’t stop us from watching the whole event with eagle-eyes. 

Just this morning, a Munich High End article announcing new MQA hardware and software partners as well as the use of the format for CDs tumbled into our mailbox. Coincidence has it that we had a conversation with one of our Rapallo customers on the very same topic just yesterday. We took it as a clear sign it’s time to write a blog on the topic and explain what the big hooh-hah is about. 

But before we get started, we want to be clear of the fact that the whole MQA topic is rather controversial. As it stands, we at Rapallo haven’t made up our minds on the matter and will just basically aim at giving you an overview of the whole MQA landscape, gore and all, but without any intention of starting violent arguments. No murders, right!?

 

So what is this whole MQA business? 

MQA stands for Master Quality Authenticated – it’s an audio technology developed by Bob Stuart, co-founder of Meridian Audio. And it’s the technology making hi-res audio streaming a reality.

With music streaming services like Spotify and Apple Music becoming the main medium to listen to music, a lot of talk (read ‘criticism’)  has been going on about the lossy, compressed music files.

Not Tidal though. Since it released its Tidal Masters Service in 2017, it offers Hi-res audio and it uses MQA to make that happen. So, MQA basically is a method of digitally storing recorded music as a file that’s small and convenient enough to download, or even stream, without the sonic sacrifices traditionally associated with compressed files. At least , that is the version of the MQA marketing machine.

The reason why AVS forum was writing the article from the Munich High-end show, was because the increasing MQA integration in a wide variety of products and services including Roon Labs, Dragonfly, Bluesound, Pioneer, Onkyo, NAD etc. So saying that MQA is attracting a fair amount of attention, is definitely not an understatement.

 

How does it work? 

Obviously that is a question that doesn’t have an easy answer. What you have to take from it is this:

It’s different than all the other lossy techniques of reducing file size, but still relies on PCM coding, which is the standard form for digital audio. What makes MQA interesting is that it isn’t really a direct rival to something like the FLAC codec, because MQA streams can actually be delivered within the FLAC container. Or ALAC, the Apple lossless format, or WAV. It doesn’t require a whole new order of audio hardware and that makes MQA potentially pretty important.

So without getting too technical, how does it work?

To put it simply, the difference between a ‘normal’ hi-res file and an MQA file is in the priority that is given to certain music data.Most of the file above a certain frequency is considered ‘noise’. Normal linear PCM coding treats all information in the file as equal, this makes high sample rate files hugely inefficient, especially for streaming. But not MQA; it folds big files into smaller more manageable sizes, but retains all the “good parts” when unfolded at the end.  This is dubbed ‘audio origami’

How does it do that? Basically, when you convert analogue sound to a digital format, you reduce sound to a number of snapshots per second, a bit like the frames that make up a film. One of the core ideas behind MQA is that more than one snapshots’ worth of data can be crammed into each snapshot, because of how little of the thing is actually used up by data. Call it high-density data cramming.

As a final step to the MQA encoding, a reversible lossless digital watermark is embedded. This includes instructions on how to ‘unfold’ and play the file back into the higher sample rate when decoded with the appropriate (read ‘MQA certified’) gear and software. If no MQA decoder is found, it simply plays back at CD resolution meaning an MQA file is still considered ‘good stuff’ despite the lack of a decoder.

At present there are two quality rates of MQA talked about, a ‘download’ quality that uses about 3Mbps for a stereo feed and a ‘stream’ quality that requires uses 2Mbps, each representing a different sampling rate. ‘True’ high-res uncompressed 24-bit, 192KHz audio uses up just over 9Mbps.

This all sound pretty high-tech, but it surely it’s something to be very, very excited about, right?

 

So what’s all the criticism about? 

For starters, MQA has portrayed itself as a ‘desirable format’. But in in demonstrating how amazing MQA is, it compared its audio streams to 128kbps MP3s, which no-one in their right mind has been listening to since the turn of the millennium. Trusted Review argues that the ear will have a hard time telling the difference between a Spotify Premium file and an MQA quality file. Don’t get caught into audio OCD over bit depths and sample rates, they say.

This argument takes more flight when you look at the other reason for a lot of the criticism, which targets the MQA licensing requirements. Hifi brand Linn-and with them many others- claims the whole MQA-thing is bad for music because they ‘attempt to control and extract from every part of the supply chain’. They argue that it’s the consumer who in the end will be presented the higher price for music, but also for Hifi-gear.

And then there is also critique on the whole MQA encoding process itself. Some critics say that playback demonstrated gross distortion and reconstruction failure. Technically apt people claim that the MQA’s sales pitch about the whole origami and reconstruction story while still maintaining studio sounds is kind of hard to believe. According to a good amount of experts, the math simply doesn’t add up.

 

So what do we make of all this? Depending on the source you listen to, it’s either THE technology to make hi-res audio streaming a reality, or it’s a cynical, calculated “land grab” by MQA and big music labels to establish themselves as toll collecting gatekeepers for high quality audio. The most annoying thing is that at this stage, it is unclear because the heavyweights of the industry can’t seem to agree between themselves. So, when us humble folk at Rapallo get asked what we think, we say… we don’t know. At this stage, we’re watching the whole argument unfold together with the rest of the audiophile world. 

 

Sources: AVsforums, What Hifi, Trusted Reviews, Arstechnica, Askaudio. Photo credit to AudioQuest.