David Esp Video Technical Blog

I audio-recorded some lectures by using the Voice Memo app in-built on my iPhone 4.  How does one get such recordings out of the phone and into an audio editing (or indeed audio/video editing) app on Mac or PC?  Here’s what I found, mainly by experiment:

• For a Mac:
  • The iTunes app allows you to transfer/sync an iPhone’s Voice Memo audio recordings onto the computer.  In iTunes, under the device representing the phone, there is a Voice Memos folder. Inside this there is a list of recordings (objects) e.g. as follows:
    • 1  ✓ 21/09/2011 09:33
    • 2  ✓ 21/09/2011 10:43
    • 3  ✓ 21/09/2011 11:01
  • These entries correspond to M4A (FourCC=”MP4A”) files.
    • These files can be transferred (moved/copied) as follows:
      • Copy a file by dragging it out of Voice Memos folder in iTunes’ interface.
      • Move a file by dragging it out of iTunes’ user-specific Voice Memos folder in file system.  That folder is described below.
    • Additionally iTunes can export MP3 equivalent copies of the files:
      • iTunes (Voice Memos): Recording >RtClk> Create MP3 Version
  • The files are stored at (in my case) at:
    • /Users/davidesp/Music/iTunes/iTunes Media/Voice Memos
      • 21_09_2011 09_33.m4a
      • 21_09_2011 10_43.m4a
      • 21_09_2011 11_01.m4a
  • The nature of the files:
    • These files are stated by Mac’s Finder to be of type “MPEG-4 audio”, and are about 30 MB per hour.
    • VideoSpec is able to analyse them, it reports:
      • Container: M4A – QuickTime
      • Encoding: MP4A (FourCC), constant bitrate of 64 kbps, 16 bits, 44.1 kHz, stereo
        • However it makes no sense to encode stereo from a one-microphone device and indeed when imported to an audio editor (Audacity 1.3.13 beta) it only produces a single mono track.
  • Audio Editing/Processing (cuts/envelopes/effects e.g. dynamic range compression) was subsequently achievable by any of these:
    • Audacity (1.3.13 beta) can import the M4A file.  My (multi-platform) old-familiar.
    • Garage Band (e.g. as explained at http://macmost.com/editing-audio-files-in-garageband.html).
    • SoundTrack Pro (but can’t simply drag the file in – instead have to use File>Open).  OK but a little clunky (in my “newbie-to-this-app” opinion)

This entry was posted on Monday, September 26th, 2011 at 20:16 and is filed under audio, Encoding, file mgt, iPhone, Mac. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.