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RE: 2L MQA Files

Hi,

I think to make any call we would need:

1) Original 384k/24(32) bit Master

2) 48k/24Bit MQA file encoded from and then decoded back to 384/24(32); as the way I read it, it is being claimed full MQA decoding can restore the original 384/24 file lossless, if this is incorrect I will happily be corrected and apologise in advance for my misreading.

The intermediate 48/24 MQA file is a bit pointless without decoding, unless it is claimed that the 48k MQA file deliver 384/24 performance directly (which is not my reading of the promotional material).

More crucially, I'd like to see how MQA does with 0dBFS peak noise-loading over a bandwidth of 50kHz.

For anyone who does not know noise-loading, it uses uncorrelated white noise with peaks at 0dB(FS) comb filtered (visually speaking notches cut into the otherwise flat FFT spectrum) to the nominal noisefloor of the format. This can only really be digitally generated if we want that).

If we look at the analogue spectrum after D-A conversion how much the "notches" filled in tells us about noisefloor and noisefloor modulation. Of course the same applies to D-D conversion (interesting to see what "170dB dynamic range" ASRC's do in this) except the job is way easier that way, no DA/AD.

If we take FLAC, we know (well, I know having done so) it can pass the above tests with no alteration to the source file (presuming the sample rate is high enough, read after decoding we have precisely what went into the encoder. Actually it also passes a binary compare meaning the data is bit for bit identical.

Only lossless codecs have so far been able to do that, MP3 even at 320k leaves a gross observable difference (a null test leaves around -66dB residue for MP3 320k and -52dB for MP3 @ 192k VBR).

The price paid for using lossless codec's is that compression rate is not great, a sample 384k/24 FLAC from 2L shows around 2.75 compression factor.

Now if Meridian have achieved the same feat (namely lossless compression of a 384k/24 file so it can be completely restored) while getting a compression ratio of 16.7 once FLAC encoded, this is a huge achievement.

I mean we are talking a reduction from 51MB/min to 11MB/min, that is packing 384k/24 into a data-stream that is about twice the classic CD standard 44.1k/16 uncompressed and two thirds the file size for 96k/24 uncompressed.

So I am looking forward to the public release of the encoder/decoder (even as cripple-ware with silences inserted every other minutes or such) in order to verify this extraordinary feat.

Indeed, if Meridian really want to show off what their system can do and achieve the widest possible adoption, releasing such trial-ware encoder/decoder would likely do much to convince both those indifferent and the sceptics.

Ever which way, good on Meridian for pulling it off.

Of course, this says jack about the commercial side.

For now MP3 (Spotify and most other streaming services) and AAC (Apple iTunes/Music) rule streaming delivery and they seem adequate for > 90% of the people who listen on Dr Dre Beats or Apple Earpods via their phones or Laptops.

And even if the rest of the people were to pay triple for getting MQA (which they are unlikely to do) it does not equal anywhere near the revenue generated from the "90%".

And going from 320k MP3 / 256k AAC to MQA will mean a huge infra-structure investment and increase in bandwidth used (around 4 - 5 times the disk-space/cpu-load/bandwidth per MQA track over MP3/AAC) for streaming services. And all of these (disk-space/cpu-load/bandwidth) equal cold hard cash expended.

Without necessarily equal (or greater) increases in revenue potential than what is spend, I doubt services will clamour for MQA, so I think we have to watch this space.

Now as for the "improved filter response" or whatever is being applied in the re-mastering I see no direct requirement to have this tied into the MQA codec. Moreover it seems a pretty simple re-filtering using something related to apodising filter Meridian have been championing, based on my reading. And this is available with a wide range of hardware (both Meridian and not) anyway.

But again, there is way too little information to be conclusive in any way.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?


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