Dr. AIX

Mark Waldrep, aka Dr. AIX, has been producing and engineering music for over 40 years. He learned electronics as a teenager from his HAM radio father while learning to play the guitar. Mark received the first doctorate in music composition from UCLA in 1986 for a "binaural" electronic music composition. Other advanced degrees include an MS in computer science, an MFA/MA in music, BM in music and a BA in art. As an engineer and producer, Mark has worked on projects for the Rolling Stones, 311, Tool, KISS, Blink 182, Blues Traveler, Britney Spears, the San Francisco Symphony, The Dover Quartet, Willie Nelson, Paul Williams, The Allman Brothers, Bad Company and many more. Dr. Waldrep has been an innovator when it comes to multimedia and music. He created the first enhanced CDs in the 90s, the first DVD-Videos released in the U.S., the first web-connected DVD, the first DVD-Audio title, the first music Blu-ray disc and the first 3D Music Album. Additionally, he launched the first High Definition Music Download site in 2007 called iTrax.com. A frequency speaker at audio events, author of numerous articles, Dr. Waldrep is currently writing a book on the production and reproduction of high-end music called, "High-End Audio: A Practical Guide to Production and Playback". The book should be completed in the fall of 2013.

8 thoughts on “Downmixing 5.1 to Stereo

  • Kit Kimes

    That is an awful lot of work, but I’m glad you take the time and effort. I’m sure it will be appreciated by all that hear it.

    Reply
  • A related issue is “how good are conversions?” If the original had been mastered at 88.2, I would naturally prefer it over it being converted to 96/24. This is a reason why I prefer 88.2 being the cutoff for HD-Audio; but I’m a follower of JAS now.

    This does matter consider Transparent’s release of Haydn: http://transparentrecordings.downloadsnow.net/haydn-in-america Does there comment make sense:

    “Provenance: Haydn in America was originally recorded to 8824 PCM (8824 is our short hand for 88.2kHz and 24-bit sampling). The 8824 WAV files are the original digital file generation sent to us. The DSF and FLAC files are considered second generation and made from conversions using our Blue Coast conversion methods. DSF and FLAC will offer the convenience of metadata that the WAV files will not.

    “After several blindfold tests, it is our opinion that the 8824 wav files sound the best, followed by DSF and after that the FLAC 8824. The difference is minimal. We suggest you purchase files for your best performing home DAC. The DAC will make more difference than the file type.”

    I purchase FLAC 8824, then converted them to AIFF.

    Reply
    • Admin

      I have no problem with 88.2 kHz/24-bit PCM as a capture and release format. The only reason to choose these specs is because the project is headed for a CD release….which is not important to me. I would prefer to capture at 96 kHz/24-bits and then release FLAC files with the metadata. This algorithm is lossless and is not a “second generation” copy. It is a losslessly encoded metatdata rich encode. You can always decode it back to AIF or WAV if you prefer.

      Downconverting to DSD in a DSF file format is a bad idea. You’d be throwing away information as compared to the PCM version…but there’s a sound to DSD that some people like. I concur with the statement that the DAC is more important than the format…as long as you stay with PCM.

      Reply
  • Bill Brandenstein

    Mark, as always your engineering makes absolute complete sense. And Shawn Murphy is one of my favorite engineers, so this is a project I’ll be watching for.

    I’m glad you mentioned that in the downmixing process there’s some latitude for taste and interaction with each individual mix. However, I can’t imagine a time when downmixing the rear channels at -10dB would even be conceivable without substantially altering the effect of the total mix. Maybe that’s desirable from time to time, but not with anything I can think of! Several years ago I mixed a 5.1 master of classical music for video, and the mastering engineer applied the coefficients for me (thank you very much), reducing the rear channels by merely 3dB. The end result was a regrettably dry mix because ambiance and reverb were no longer in the “sweet spot” of balance. (Maybe I should’ve had them louder in the surround mix.) If 3dB could do that, I can only imagine that 10 would be akin to dumping them altogether! So I’m curious: where have you encountered rear channels mixed so aggressively to justify so much reduction?

    Reply
    • Admin

      In my experience, it depends on the individual tracks and the amount of musical material in the rear speakers. I’ve set up coefficients for downmixes of the Allman Brothers, Bad Company, and others (live concert DVDs) and the -10 dB works. It means that the audience cheering and applause doesn’t drown out the music.

      In the case of a studio recording like the Christmas project, Shawn prepared a “surround light” style 5.1 mix. The only thing in the read channels is room ambiance…no tubas. If I had moved those two channels into the front speakers the level of reverberation would be much too high. This was all digital reverb…not the actual sound of the room. I tried to match the sound of the stereo recording but using real 96 kHz/24-bits.

      Reply
      • Bill Brandenstein

        Thanks, Mark, that makes sense and is good to know!

        Reply
  • Dave

    The process on how the music was recorded and mastered in the first place is what is confusing to me.
    Why is everything downgraded BEFORE the mastering and mixing is done?
    Why not just master and mix everything at the highest quality possible,
    then after that it can me downconverted to match the needs of CD and streaming codecs?
    I really don’t know much about these things, but I do try to follow what is happeningin the HRA industry.
    It just baffles me why so many people couldn’t care less about the fidelity and quality of their own music,
    as well as the studios and producers responsible for the process that makes the product from beginning to end.

    Reply
    • Admin

      I asked the very same question. Why did they capture all of the sessions at 96/24, mix and master the 5.1 version at 96/24 but follow a completely different signal path for the stereo CD. I can only imagine that the mastering engineer had a preferred piece of equipment or capability that wouldn’t work at full 96 kHz/24-bits or 88.2. Their procedures were surprising.

      Reply

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