Meridian MQA

At CES earlier this year, Meridian announced their new MQA audio format. Supposedly the problem they’re trying to solve is that of packing high-quality audio into low(er)-bandwidth audio streams. I’ve been hearing grumblings that they may have made some fairly questionable decisions regarding data prioritization1, so I was searching for any technical data they may have released.

This post isn’t actually about the technical implementation of MQA, though. It’s about the absurdity of their marketing materials for MQA. In particular, this graph set me off:

Quality and convenience trade-off graph

There are so many things wrong here. In what world do DVD-A, SACD or even just regular old CDs have lower quality than LPs? Let’s just look at frequency response and dynamic range. LPs generally only contain frequency information up to 20KHz2. All three digital storage forms exceed that, with DVD-A and SACD blowing it out of the water. LPs typically have a dynamic range of only 60-70dB3, while CDs can store 96dB, and a DVD-A disc with 24-bit audio stores 144dB (wider than the range from the threshold of pain to the threshold of hearing!).

I also take issue with the convenience plot. I can’t accept that DVD-A and SACD were less convenient than LPs. You may not have had portable music players that could handle either format, but you were a lot more likely to be able to listen to DVD-A/SACD in your car than LPs. And downloads have been far more convenient than CDs from the introduction of the first iPod, which could hold the equivalent of ~7 CDs (when ripped at CD quality) in physical volume of just one.

At the end of the day, this marketing is just playing up to tropes in the audiophile world. I know that. I shouldn’t let it get to me like this. But I also can’t accept an audio format that’s predicated on misinformation as opposed to a strong technical foundation.

  1. This thread discusses some of the patents they’ve filed for, and it looks like they’re trading off bit depth to maintain frequency information above 20KHz. Thumbs down. ↩

  2. From Wikipedia:

    An essential feature of all cutting lathes—including the Neumann cutting lathes—is a forcibly imposed high frequency roll-off above the audio band (>20 kHz).

    ↩

  3. Again, from Wikipedia:

    The dynamic range of a direct-cut vinyl record may surpass 70 dB.

    ↩

Spinning Off a Git Repo

I’ve been hacking away at this one project for the last three-plus years. It started out with a limited scope, and it made sense to keep it buried in an existing git repo - it was closely related to the rest of the code base. Quickly the scope grew, and for the last two years I’ve known I should pull it out into its own repo. That’s a daunting project, so I kept putting it off.

Until today. This codebase is going to get some wider circulation, so it was finally time to take the plunge. Greg Bayer put together a fantastic guide for how to get this done: Moving Files from one Git Repository to Another, Preserving History. I’m capturing the commands here, just in case I ever need to do this again.

First, make a local clone of the starting repository, and filter out everything except the subdirectory of interest:

git clone <git repository A url>
cd <git repository A directory>
git remote rm origin
git filter-branch --subdirectory-filter <directory 1> -- --all

Then, clone the destination repository, and pull in the master branch of your stripped local clone of the starting repository:

git clone <git repository B url>
cd <git repository B directory>
git remote add repo-A-branch <git repository A directory>
git pull repo-A-branch master
git remote rm repo-A-branch

I probably would have tried to pull this off in my working copies of the two repositories, so Greg’s comments to start with new clones and then disconnect them from the remote were solid.