Standardization of audio magnitude

Discussion in 'General Electronics Chat' started by SPQR, Jan 21, 2013.

  1. SPQR

    Thread Starter Member

    Nov 4, 2011
    379
    48
    Howdy,

    General question about audio data.

    I have many many CDs and DVDs, and the vast majority of the sound fine when you play them through the audio/video system.

    A few of them are problematic in that their "volume" or "magnitude of the audio" is so low that I have to crank up the volume significantly to hear them at the usual level for my ears.

    My question is if there is a "standard" way of recording data on a CD/DVD such that the "average" magnitude of all the audio is similar for all audio data?

    Another way of asking - Is there an audio standard which says something like "before recording an audio track on a DVD or CD, you must adjust the mean volume/magnitude will be X."

    I thank you in advance
     
  2. Veracohr

    Well-Known Member

    Jan 3, 2011
    552
    76
    No, there's no standard. In general for professionally-produced popular music, these days the average level is much higher than in the past. They call it "the loudness wars", and it's generally regarded as a bad thing, because it got out of hand and sucked the interesting dynamics out of music.

    I'd say the problem is not necessarily your 'quite' CD's, but the loud ones.

    By the way, this is all done in the mixing and mastering, before the data actually gets written to the CD. It's done with dynamic range processors like compressors and limiters.
     
  3. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    One option is to make a media center.

    Essentially, rip all of your CDs to high bitrate/high resolution MP3s, with "Volume Normalization" enabled.

    You could then play the MP3s through a PC interface.

    Another, messy option would be to rip all of the CDs to .wav format (no quality loss as you get with lower sampled .mp3), with Volume Normalization enabled, then write the songs back to a CD-R to play in your home system.

    Volume Normalization is but one of hundreds of options that can be applied when ripping/encoding CDs, equalization, dynamic range expansion/compression, hiss suppression (for old (80's era) AAD CDs), and more.

    Many producers will emphasize or de-emphasize bass based on the flavor of music, record at a lower average level for wide dynamic range for classical, etc. These enhancements can be undone very well with modern DSP on fast systems.
     
  4. SPQR

    Thread Starter Member

    Nov 4, 2011
    379
    48
    Ok, very interesting.
    The one thing in electronics that isn't standardized!!!!:)

    I was just thinking about it while driving in my car at lunch.
    I have 30-40 CDs uploaded to my car DVD player, and all of them sound "pretty close" except for one CD (Muti's "I Pini di Roma") where I have to really crank up the volume.

    Then I switch back to Led Zeppelin - and my eardrums are toast!:D

    Thanks again!
     
  5. Veracohr

    Well-Known Member

    Jan 3, 2011
    552
    76
    It's not an electronics thing, it's an artistically-based production thing.
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,447
    3,363
    My copy of Audio Cyclopedia, section 10.8, page 447, says 1 mW into 600Ω which works out to 0.773 volts.
    This corresponds to the 0dBm level on a VU meter.

    (Tremaine, Howard M. (1973). Audio Cyclopedia. Howard W. Sams & Co..)

    Also see

    http://en.wikipedia.org/wiki/DBm
     
  7. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    That is the science specification for recommended standard.

    "Artists" think science is icky, you can get two CDs of an orchestra playing the same sheet music, from different producers, and they usually sound vastly different.
     
  8. MrChips

    Moderator

    Oct 2, 2009
    12,447
    3,363
    That's why artsies should learn some science.
     
  9. SPQR

    Thread Starter Member

    Nov 4, 2011
    379
    48
    Aha! That's the type of "rule" I was looking for!!
    But as stated in Ghostbusters..."it's more of a guideline than a rule":D
     
  10. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    It wasn't Ghostbusters -- it was the pirate sidekicks with the goofy eyeballs in "Pirates of the Caribbean" -- Eh poppet!
     
Loading...