MQA is Vaporware

[Dr Tone]

I just found the following snippet in the Stereophile review of the Aurender A10.

 

We discovered that prior to applying the MQA firmware update earlier this year, MQA had recommended that we adopt using MQA up-sampling for all content in order to eliminate possible issues with click or pop noises when switching between non-MQA and MQA content. After some discussion with Alan at MQA about this, he had the following comment: 'The MQA decoder provides an optional up-sampler for PCM to simplify implementation and to enable a smooth, clean, click-free user experience. The reason this is offered is that the implementer may not know if the incoming stream is MQA and so the decoder is used to detect MQA and to provide a seamless switch to the usually higher output rate. By using Upsample Always, the user-experience is guaranteed to be accurate from the first sample of an MQA song and also to be free of clicks and pops if the user skips within a song or if there are cross-fades between songs.

Read more at https://www.stereophile.com/content/aurender-a10-network-music-playerserver-measurements#hQJtAPr6yk2L6e6T.99

 

Might be better to stay away from any DAC that does MQA period.

[mansr]

Mytek DACs suffer from the same infestation.

[rickca]

6 minutes ago, Dr Tone said:

The MQA decoder provides an optional up-sampler for PCM to simplify implementation and to enable a smooth, clean, click-free user experience. The reason this is offered is that the implementer may not know if the incoming stream is MQA and so the decoder is used to detect MQA and to provide a seamless switch to the usually higher output rate. By using Upsample Always, the user-experience is guaranteed to be accurate from the first sample of an MQA song and also to be free of clicks and pops if the user skips within a song or if there are cross-fades between songs.

So @vortecjr is this why the ultraRendu upsamples non--MQA files when MQA unfolding is enabled?  When I asked previously why you do this, you simply said 'it works better that way'.

[botrytis]

Upsampling DOES NOT make the file high res. I mean I can do that with my TEAC UD-501, with CD quality FLAC's or CD's. That does not make them high res.

 

 

[tmtomh]

Wow, this is dreadful - it means the end of bit-perfect output. And if the MQA upsampler upsamples everything to the same resolution (in other words upsampling 44.1 and 48 both to 96 rather than 88.2 and 96, respectively), then it's also effectively the end of on-the-fly resolution-switching, which is kind of the most core aspect of high-res computer/streaming audio.

 

In fact, the entire 3rd-party music player market, at least for the Mac, is based on the macOS's built-in limitation in this regard: Every app's core claim to better sound quality lies in the fact that it can bypass the AudioMIDI/core audio single-resolution output setting.

[mansr]

4 minutes ago, tmtomh said:

And if the MQA upsampler upsamples everything to the same resolution (in other words upsampling 44.1 and 48 both to 96 rather than 88.2 and 96, respectively)

The MQA resampler is able to do this, but from what I've seen, it isn't normally used that way.

[Fair Hedon]

1 hour ago, rickca said:

So @vortecjr is this why the ultraRendu upsamples non--MQA files when MQA unfolding is enabled?  When I asked previously why you do this, you simply said 'it works better that way'.

Easy solution..make sure MQA unfolding is not engaged. It never will be on my unit if I decide to upgrade the firmware.

 

 

[rickca]

42 minutes ago, Fair Hedon said:

Easy solution..make sure MQA unfolding is not engaged. It never will be on my unit if I decide to upgrade the firmware.

Yes, I've already said that I would do that.  I don't want my non-MQA files upsampled with an unknown filter.  

[Fair Hedon]

1 hour ago, rickca said:

Yes, I've already said that I would do that.  I don't want my non-MQA files upsampled with an unknown filter.  

Agreed, Nobody should ever want that..I don't MQA within 10,000 Kilometers of my audio files.

 

The sooner it fades into oblivion we can get ready for the next fraud to be perpetrated by an audio charlatan.

[Miska]

Just couple of notes as long as I have these again on top of my mind...

 

In addition, lot of MQA-equipped hardware has strange bugs or otherwise annoying features that make it really hard to properly compare MQA vs non-MQA and easily mislead the listener by screwing up normal PCM playack.

 

For example:

1) MQA-rendering sticks-on. If you initially play normal PCM, things are normal. Then you play first MQA track and the decoder and rendering kicks in. You switch back to normal PCM; MQA decoder goes out, but the rendering and awkward noise-shaping is left enabled screwing up normal PCM. One example of such device is Meridian Explorer2, but there seem to be others too.

2) Everything goes to MQA upsampling filters. If MQA is enabled, also normal PCM goes through MQA upsampling filters, screwing up normal PCM. Examples of such seem to be Mytek Brooklyn (/ Manhattan II) and Aurender A10.

 

These make proper listening comparisons harder and easily misleading.

 

[FredericV]

5 hours ago, mansr said:

Mytek DACs suffer from the same infestation.

I played with the mk1 and mk2 versions of the Manhattan. I can confirm.
 

1 hour ago, Miska said:

These make proper listening comparisons harder and easily misleading.

I believe this is per design, to cripple redbook more.

[FredericV]

6 hours ago, Dr Tone said:

By using Upsample Always, the user-experience is guaranteed to be accurate from the first sample of an MQA song and also to be free of clicks and pops if the user skips within a song or if there are cross-fades between songs.

 

Read more at https://www.stereophile.com/content/aurender-a10-network-music-playerserver-measurements#hQJtAPr6yk2L6e6T.99

 

Might be better to stay away from any DAC that does MQA period.

How can this be from the first sample? MQA decoder needs some data from the bitstream in the 16th bit (the control stream) before the PCM is recognised as MQA.

Unless MQA has a delay.

16th bit is confirmed by uncle Bob:


 

[Miska]

2 minutes ago, FredericV said:

How can this be from the first sample? MQA decoder needs some data from the bitstream in the 16th bit (the control stream) before the PCM is recognised as MQA.

Unless MQA has a delay.

 

I think it has delay (look-ahead buffer), but this is reason why many manufacturers opt to keeping MQA decoder with it's upsampling in chain all the time. Because otherwise they'd need to switch the DAC chip and it's programmed filters (ESS) between two sample rates (44.1/88.2 or 48/96) when the music is already playing. This can be tricky... The Pro-Ject DAC is doing that, but then people tend to complain somewhat that there's annoying lag before MQA kicks in and some samples are lost from the beginning. No problem with normal PCM playback though, so it is not crippling normal use cases.

 

[oneway23]

Does anyone happen to know if the Bluesound Vault 2 is using the MQA filter on PCM files as well?

[FredericV]

3 minutes ago, Miska said:

No problem with normal PCM playback though, so it is not crippling normal use cases.

 

There is no win-win:

1. MQA decoder active with always upsample (like Mytek): redbook also goes through those leaky filters with aliasing
2. MQA decoder active with switching sample rates when enough MQA data has been found to start decoding: gaps/delays/clicks/lost parts

So the customer always loses, unless he turns off MQA decoding.

[Confused]

Reading all this I keep remembering that word.....

 

Elegant.

[knickerhawk]

27 minutes ago, Miska said:

 

IThe Pro-Ject DAC is doing that, but then people tend to complain somewhat that there's annoying lag before MQA kicks in and some samples are lost from the beginning. No problem with normal PCM playback though, so it is not crippling normal use cases.

 

I've noticed on my BlueSound Node streaming Tidal content that when the track first starts playing there's a little "HR" icon (instead of the normal "CD" for Redbook tracks). After a couple of seconds the HR icon switches to the MQA icon. I'm wondering if that delay is the same thing that's going on with the Pro-Ject DAC? Something weird happened this past weekend. For about an hour or so, every MQA track I played never switched from the HR icon to the MQA icon. However, if I paused the play the MQA icon appeared soon after unpausing. I haven't noticed that problem since.

[Miska]

20 minutes ago, FredericV said:

1. MQA decoder active with always upsample (like Mytek): redbook also goes through those leaky filters with aliasing
2. MQA decoder active with switching sample rates when enough MQA data has been found to start decoding: gaps/delays/clicks/lost parts

So the customer always loses, unless he turns off MQA decoding.

 

Yeah, as long as you can disable/bypass that MQA stuff and stick to play normal PCM/DSD content, things work better. Aurender doesn't have option to turn off the MQA?

 

[rickca]

14 minutes ago, Confused said:

Reading all this I keep remembering that word.....

 

Elegant.

LOL.  I guess that's why @Lee Scoggins said he finds the business model elegant.  He doesn't want to talk about how MQA actually works, because he's still researching that.

[rickca]

24 minutes ago, FredericV said:

 

There is no win-win:

1. MQA decoder active with always upsample (like Mytek): redbook also goes through those leaky filters with aliasing
2. MQA decoder active with switching sample rates when enough MQA data has been found to start decoding: gaps/delays/clicks/lost parts

So the customer always loses, unless he turns off MQA decoding.

So some vendors just do a quick and dirty implementation and upsample non-MQA files when MQA decoding is enabled.  Then they tell you 'it works better that way'.

[Dr Tone]

23 minutes ago, Confused said:

Reading all this I keep remembering that word.....

 

Elegant.

 

Does it make you all warm and fuzzy inside thinking about how Devialet will implement it, if they do? 

[FredericV]

22 minutes ago, rickca said:

So some vendors just do a quick and dirty implementation and upsample non-MQA files when MQA decoding is enabled.  Then they tell you 'it works better that way'.

Some also manage to combine opensource players with a proprietary MQA alsa plugin. Usually the open source player renders to a pipe instead of the soundcard (e.g. attached USB dac), and some other closed source process at the other end of the pipe is opening the proprietary MQA alsa plugin, which then opens the soundcard.

Blusound uses a process named dspout, which receives the data from the standard decoders as available in most linux distro's, like madplay for mp3. This article is no longer availble and only in google cache, so screenshot:



They do the same for flac. At the other end a proprietary program can exist which links to the proprietary upsampler, and not violate the GPL. This way, no open source program is linking directly to the MQA decoder.
 

This is a well known way to circumvent the GPL.

[Confused]

21 minutes ago, Dr Tone said:

 

Does it make you all warm and fuzzy inside thinking about how Devialet will implement it, if they do? 

Oh yes!  So fuzzy that I’d need a thorough deblurring to recover.....

[mansr]

1 hour ago, Miska said:

I think it has delay (look-ahead buffer)

It does. In fact, the data stream is bounced around between so many buffers that I lost track of them. It's horrible code.

[ARQuint]

9 hours ago, Dr Tone said:

I just found the following snippet in the Stereophile review of the Aurender A10.

 

We discovered that prior to applying the MQA firmware update earlier this year, MQA had recommended that we adopt using MQA up-sampling for all content in order to eliminate possible issues with click or pop noises when switching between non-MQA and MQA content. After some discussion with Alan at MQA about this, he had the following comment: 'The MQA decoder provides an optional up-sampler for PCM to simplify implementation and to enable a smooth, clean, click-free user experience. The reason this is offered is that the implementer may not know if the incoming stream is MQA and so the decoder is used to detect MQA and to provide a seamless switch to the usually higher output rate. By using Upsample Always, the user-experience is guaranteed to be accurate from the first sample of an MQA song and also to be free of clicks and pops if the user skips within a song or if there are cross-fades between songs.

Read more at https://www.stereophile.com/content/aurender-a10-network-music-playerserver-measurements#hQJtAPr6yk2L6e6T.99

 

Might be better to stay away from any DAC that does MQA period.

Dr. Tone

The issue with the A10 filter upsampling all content (MQA and otherwise) is old news. John A reported his findings in October of last year but since then, with the Aurender software update in mid-December, users can easily defeat that filter. It was Aurender's feeling that the filter improved the SQ of all formats but (appropriately, I think) they decided to give people the choice of whether to use it or not—in part, I'm sure, because of all the objections that were raised in places like CA.